What is a ventilated roof? Roof ventilation: recommendations for calculation and design. Video: installing a ridge aerator

It’s not even worth talking about the need for roof ventilation. Everyone knows this. But this article will discuss how to make it effective, durable, and also install it yourself, using advanced engineering practices.

Why do you need roof ventilation?

The importance of the roof is difficult to overestimate. Therefore, when erecting a building, experienced builders arrange the roof with special care, providing it with reliable insulation, insulation and a ventilation system.

During the operation of the house, steam is generated indoors, which, according to the laws of physics, rises into the under-roof space. And if there is no properly adjusted roof ventilation, then steam settles on the roof structures, rendering them unusable and destroying the load-bearing elements of the building.

A roof without ventilation is dangerous. Increased humidity will lead to the formation of mold and mildew on the walls, wetting of the insulation, and therefore deterioration of thermal conductivity and freezing of the house. A well-established roof ventilation system will help to avoid this, which will remove condensation outside and prevent it from ruining the entire structure.

In order to extend the life of the roof, it is equipped with a high-quality ventilation system

Home ventilation can be spot or continuous, natural or forced. The most common sources of air circulation include:

• dormer windows;
• ridges of pitched roofs;
• gaps provided in the roofing pie and eaves strips;
• exhaust fans on roofs and other piece elements of the ventilation system with holes.

For small or medium-sized roofs, natural ventilation is sufficient. Forced ventilation elements are installed on large roofs, where natural air exchange of the under-roof space is insufficient.

Elements of roof ventilation system

The assembly of ventilation components (including labor) is no more than 2–5% of the cost of the roof itself, which is much less than what will be required to repair the roof, individual sections of the house, or even the entire building as a whole, if the ventilation system is not installed or installed on “maybe, I suppose, somehow.”

The main tasks assigned to the elements of the ventilation system:

• removal of steam entering the under-roof space from the interior of the house;
• decline heat flow penetrating under the roof due to its heating in the sun;
• equalizing the temperature of the roof to prevent the formation of icicles on the edges of the eaves and ice on the roof surface.

The ventilation system of a building consists of various elements that perform one common task: to ensure normal temperature regime roof and under-roof space

Ventilation roofing tape

The ventilation tape covers all the cracks in the roof, while ensuring sufficient air exchange and protecting the under-roof space from debris, invasion of birds and other small animals.

Ventilation tape TOP ROLL S 240 mm ensures good air circulation and protection of the under-roof space

Depending on the purpose there are:

• ridge ventilation tape;
• perforated cornice tape (overhang aerial element).

Advantages of using roofing tape:

• creates good breathability;
• emphasizes decorative finishing roofs;
• Provides protection from moisture, debris and insects.

Ridge roofing tape protects the roof ridge from precipitation and snow getting under the roof. Along with this, it removes steam from roofing pie, preventing wetting and rotting of the rafter system and covering material.

Good ventilation tape famous manufacturers, as a rule, is treated with special compounds against UV radiation, which provides additional protection of roof joints from destructive solar radiation.

The ridge strip is laid along the edge of the roof, and the ridge is mounted on top of it. Work is carried out at air temperatures from +5 °C.

The ridge ventilation tape is placed under the metal plate of the ridge

Eaves perforated tape is used to cover eaves overhangs. It not only protects the under-roof space from rodents, birds, insects, dirt and creates free air exchange, but also increases the strength of some roofing components.

PVC ventilation strip reinforces the eaves structure

For pitched roofs, in addition to proper air exchange, protection from insects is also an important task. Hornets, wasps and small birds populate the under-roof space, build nests, thereby not only creating a noise effect and unsanitary conditions, but also interfering with the natural ventilation of the roof. To combat such a scourge, a ventilation mosquito net with cells measuring 2–3 mm is designed.

Stainless steel mesh is considered the best, as it is the most durable and strong. It is resistant to corrosion, does not spoil the exterior of the house, and has a much longer service life than analogues. The only downside is the high price compared to other types of mesh.

Stainless steel ventilation mesh for roof ventilation is considered the most durable and strong

It is undesirable to use steel mesh, as they corrode due to condensation leaks, rot and rust. In order to save money, it is better to use a painting mesh with small cells as a budget option. Its advantage is its low cost and ease of installation - the mesh is laid overlapping and fastened with a stapler to the wooden parts of the roof. However, the painting mesh is not very strong and therefore short-lived.

Fiberglass paint mesh does not have sufficient strength and is easily torn and pecked by birds, so it is best used as a temporary option.

Roof ventilation passage elements

Passing elements (penetrations) - component ventilation pipes. They are designed to seal roof openings. As a rule, they are not included in the delivery package, but are selected separately for each type of roof.

Penetrations are varied in shape, size, color, which is determined primarily by the manufacturer, and secondly by the roofing covering (soft roofing, corrugated sheeting, metal tiles). But they are all easy to install. They are installed both at the construction stages and on a finished roof.

Penetrations are used to seal the joints between ventilation pipes and roofing.

Only with precisely selected passage parts corresponding to the covering material can we talk about the durability of the ventilation system, the absence of leaks in the tie-in areas and the ability of the roofing components to withstand all climatic loads.

Aerator for roof ventilation

Roofing accessories such as aerators are designed for more effective ventilation of soft roofs. These are elements of forced ventilation that reduce pressure under the roof and increase draft, which ensures the necessary air flow.

An aerator for ventilating a roof made of soft tiles reduces the pressure in the under-roof space, which ensures good ventilation attic spaces

Aerators are selected depending on the roof area, observing the following rules:

• aerators are installed in the highest places of the slopes along the entire length of the roof for uniform ventilation of the entire under-roof space;
• the distance between adjacent devices is maintained at least 12 m;
• aerators are mounted on dowels or anchor bolts and equipped with filters that prevent the ingress of dirt, moisture and insects;
• to set up the system during roof construction, select areas at the joints of the seal;
• To prevent leaks, use sealant or special tape.

Ventilation accessories also include an overhang ridge, which has a frequent row of teeth that protect the eaves gap and the adjacent under-roof space, as well as roof fans. They are indispensable on flat roofs with insufficient natural convection and on pitched roofs when it is not possible to equip natural ventilation.

The overhang ridge is mounted directly under the final row of groove tiles using self-tapping screws

Video: installation of the Systemair DVS roof fan

Ventilation passage through the roof

Any ventilation duct is led to the roof of the house and forms a so-called passage unit (PU) at the exit points in the form of a pipe inserted either into the roof itself through the outlet or into reinforced concrete glasses.

Each element of the ventilation system requires a sealed unit to pass through the roof

Industrial ventilation passage units are manufactured in accordance with GOST 15150 and are:

Depending on the type of roofing and design features roofs and air vents, they differ in shape:

Along with typical elements, non-standard units are often manufactured, designed for ventilation systems that are original in structure and assembly. However, all of them must meet the requirements defined by GOST:

• metal thickness for manufacturing is at least 11.9 mm;
• the size of the support ring is 30–40 cm larger than the diameter of the pipe;
• mandatory treatment with anti-corrosion compounds;
• the length of the unit design without valve is no more than 1 m.

The passage units for chimney ducts are arranged in strict compliance with fire safety regulations.

Ventilation gap on the roof

Many people wonder whether a ventilation gap is needed and, if so, why. Is it possible not to do it, since there is already a gap between the covering and the sheathing.

But is it really necessary to have a ventilation gap on the roof? Let's try to figure it out. Ventilation of the under-roof room consists of three gaps: the eaves, through which air flows, the gap between the roof and the insulation (the membrane does not count) and the gap at the highest point of the roof (ridge or abutment).

Their goal is to ensure good air circulation under the roof and prevent the insulation from getting wet. And if you neglect the gap on the roof, the consequences will be very disastrous - you will have to dismantle the roofing pie and change the insulation. And this is the least of all troubles.

To keep the house warm in winter and cool in summer, ventilation on the roof must be arranged according to all the rules.

Additionally, hard surfaces typically require repainting every 10 to 20 years. But if there is no gap, the resulting condensation will spoil the flooring sheets from the inside. And while painting them on top is quite simple, it is impossible to do this from the inside without dismantling the entire roofing pie and replacing the sheets completely.

So the answer to all questions is obvious - make gaps. Allow your roof to breathe to avoid problems that are initially unnoticeable but snowball. In addition, the gap on the roof must be sufficient to ensure the operation of the entire chain.

If you block the roof ridge, that is, do not create a gap, there will be no benefit from the gap between the insulation and the roof, as well as the eaves clearance.

Metal roof ventilation

A metal roof is beautiful, modern, durable and reliable, but it has one big drawback - limited air exchange, i.e. it does not allow air to pass through well. To ensure normal circulation, ventilation is installed according to the following algorithm:

Video: ventilation of the under-roof space in metal roofs

Ventilation of soft tile roofs

Ventilation of a soft roof faces the following tasks:

• removal of condensate;
• preventing overheating of the lower layers of the roofing;
• ensuring temperature balance on the roof surface.

With properly organized ventilation, cold air flows enter the under-roof space at the overhangs and exit through the ridge or aerators.

The arrows indicate the direction of air flow in the under-roof space when correct device ventilation

Ventilation of soft roofs can be single- or double-circuit. But for it to be sufficient, a number of conditions must be met:

• the thickness of the air gap between the sheathing and the insulation is calculated in advance based on the angle of inclination and the length of the slopes (but less than 4 cm);
• make additional holes along the bottom of the slope, tightening them with perforated tape, mesh, comb, lining the roof overhangs with breathable soffits;
• arrange gaps on the roof in the form of ventilated ridges or aerators for forced ventilation.

If the roof is not new, and the soft roof is being repaired, then look for places with the greatest swelling, and install aerators there.

Video: ventilation of the under-roof space in roofs made of flexible bitumen tiles

Hip roof ventilation

Ventilation hip roofs can be roughly divided into two groups - ventilation of a cold attic and an insulated attic.

Arranging ventilation for a cold attic space will not present any difficulties. Due to the large volume of the attic, there are practically no barriers to normal air circulation. Air exchange occurs through the eaves overhang, ridge and ridge. Dormer windows covered with bars and located on opposite sides of the roof provide a draft.

Natural air circulation occurs through the ventilation gap in the roof and dormer windows

When it is necessary to increase ventilation, aerators are installed along the passage of the valleys. But they make sense if the slope angle is more than 45°. Otherwise, in difficult areas in winter time Due to the accumulation of snow, the operation of aerators will be ineffective.

For small slopes, it is better to do forced ventilation using roof fans, inertial turbines or nozzles of sufficient height so that they are not covered with snow.

Video: how to eliminate condensation in the attic

Ventilation of insulated under-roof space (attic)

It is advisable to plan the ventilation of the attic during construction, since its arrangement is more labor-intensive than the ventilation equipment for a cold attic space. There is no free air circulation here, which is why the space for air exchange is created by the sheathing installed between the insulation and the flooring.

Air circulation in the insulated room occurs due to the ventilation gap in the roofing pie

In addition, a gap of at least 2–3 cm between the hydro- and thermal insulation is required. If the depth of the rafters does not allow for the required gap, then they are built up using boards.

But this method of air exchange is quite difficult to implement on roofs of complex shapes with many kinks and junctions. Therefore, roofers advise installing diffusion membranes (vapor-permeable) directly on the insulation, which allow moisture to pass through only in one direction.

Video: ventilated ridge on an attic roof

Seam roof ventilation

A seam roof, like all other types of roofs, requires normal air circulation in the under-roof space. And this is ensured by a gap between the coating and the heat-insulating layer of at least 50 mm, for which a sheathing of 50x40 or 50x50 mm timber is assembled. In addition, for greater reliability, the insulation is protected with a vapor barrier film.

To remove moisture from the ventilation gap on the roof, install a ventilation outlet for a seam roof at a distance from the ridge of no more than 0.6 m.

The ventilation outlet for seam and soft roofs is used to remove moisture from the ventilation gap

A seam roof laid in accordance with all the rules and well ventilated will last about 25 years without major repairs.

Pitched roof ventilation

To equip the ventilation of pitched roofs you need:

• supply gaps in the lower roof area;
• channels for air circulation above the insulation (due to the sheathing);
• hoods at the top of the roof have an area of ​​15% larger than the area of ​​the supply openings, since good ventilation requires reduced pressure in the attic.

It is not difficult to arrange ventilation with your own hands. General scheme one is to provide gaps under the eaves overhangs, protect them with tape or mesh, and make a gap between the sheathing and the insulation.

Further work depends on the roof slope. When the slopes have a slope of 10–45°, the exhaust gap is located in the ridge and is covered with a ridge aerator with a protective filter made of polyurethane foam. One such aerator, about 60 cm long, ventilates 25 m² of attic space.

Video: installing a ridge aerator

If the structure of the roof does not provide for a ridge or the slope of the slopes is from 5 to 12°, then it is necessary to increase the number of supply holes at the bottom of the roof, and install aerators in the upper zone at a distance of 0.5–0.8 m from the highest point of the roof.

With this arrangement, the aerator ventilates 5 m² of the attic space, but if the building is located in a well-ventilated area, then it throughput increases to 25 m².

Video: installation of a point aerator

Ridge vent size

The size of the ventilated gap depends on the slope of the slopes - the lower the roof slope, the greater the height of the gap. The type of thermal insulation material does not affect the size of the gap, but the type of roofing is very important. Under a hard covering (metal tiles, corrugated sheeting), you can use a counter-batten for lathing a small section of 25x50 mm, since this is not a continuous covering, but has its own gaps and joints, through which air also circulates. Although experts do not advise experimenting and, for greater reliability and durability, they recommend using 50x50 mm bars for all coatings, i.e., making the optimal gap height 50 mm.

How to remove a pipe through a roof made of corrugated sheets

Any home heating system, with the exception of electric, requires access to the roof. chimneys for the release of combustion products into the atmosphere. Let's look at how to remove a chimney through corrugated sheeting.

1. First you need to make sure correct location chimney pipe - the exit point should be in the darkened northern side, where little sun reaches.
2. The shape of the pipe and the size of its cross-section are selected, taking into account the climatic conditions of the area, the topography and the temperature of the outlet gases.
3. Then they are determined with the height of the pipe according to SNiP.
4. They make the pipe themselves, or buy a ready-made one and install it.

Video: pipe passage through a corrugated roof

Height of ventilation shafts according to SNiP

When calculating the height of ventilation shafts, take into account:

• the elevation of the pipe relative to the highest point of the roof and adjacent buildings;
• total length of the smoke channel;
• head size;
• design height.

Requirements and standards according to SNiP:

If there are outlets of other ventilation ducts nearby, the height should exceed the others by 20 cm.

Video: how to calculate the height of the chimney

Ventilation aerators are special devices for ventilating the under-roof space and removing moisture and water vapor to the outside. Used on flat roofs, preventing swelling of the covering roll material due to temperature changes, and on pitched roofs For effective ventilation and removal of condensate.

Vanes (aerators) are produced in different sizes and designs. They are considered the most effective elements of ventilation systems. On a flat roof, they are installed evenly over the entire surface at the joints of the slabs. On pitched structures placed closer to the ridge (0.6 m from it) or in places where valleys pass (on complex roofs).

On pitched roofs, aerators are installed closer to the ridge or in places where the roof breaks.

The manufacturing material is AISI 316 stainless steel or durable polypropylene, thanks to which they can withstand a wide temperature range from -40 to + 90 °C.

Installation of aerators on a flat roof

When covering with two layers of rolled materials, aerators are installed in the bottom layer:

1. A hole along the diameter of the aerator tube is cut through the screed and layers of insulation.
2. Cover with gravel and attach the aerator to hot mastic.
3. After cooling, fix with self-tapping screws.
4. The top layer of the roofing decking is fused so that the aerator is at the point of overlap (15 cm) of the sheets, and the junction points are sealed.

Video: DIY aerator installation on a two-layer soft roof, part 1

In single-layer flooring, aerators are installed on the screed, making a hole up to the vapor barrier. The coating is laid on the skirt of the aerator, hot mastic and a patch are applied on top, covering the skirt and extending about 15 cm onto the coating. The aerator is then secured with self-tapping screws, and the joint is treated with sealant.

Video: installation of an aerator on a two-layer soft roof, part 2

Installation of aerators on metal tiles and corrugated sheets

Installation ventilation outlets on roofs made of metal tiles and corrugated sheets is the same and is associated with damage to the roofing covering, so it must be carried out especially carefully so that you do not have to change damaged sheets of covering material.

1. Apply the template (included in the kit) to the installation site, outline and carefully cut a hole along the intended line.
2. The seal is secured with screws and sealant is applied.
3. Install the aerator, secure it with hinges and additional screws.
4. From inside the attic, the passages of ventilation pipes are puttied with sealant.

When installing ventilation elements, you must use proprietary fasteners, which are included in the kit.

Video: installation of ventilation on metal tiles

Main mistakes in installing a ventilation system: how to avoid them

Considering that today many people install the roof of their home on their own, let’s look at the most common mistakes when installing ventilation systems.

1. SNiP standards are not taken into account.
2. Unsuitable ventilation elements selected.
3. The ventilation ducts are not located symmetrically.
4. The system throughput was incorrectly calculated and the heat balance was not taken into account.
5. Installation work was carried out incorrectly.

The basic rule when designing ventilation systems is that the more proportional and shorter the ventilation is, the more efficiently and with less noise it will work.

Overview of ventilation systems

When setting up ventilation, sometimes it becomes difficult to select components. Let's look at the most popular manufacturers whose products deserve attention.

Roof ventilation "Virplast"

WirPlast equipment is used for various purposes - installation of ventilation of rooms or fan exits ( sewer system), as a kitchen hood, for installing antennas or constituent elements solar panels.

Advantages:

• easy installation due to the built-in spirit level, which eliminates any errors;
• complete tightness on the roof;
• stylish design;
• a variety of models for all types of coverage;
• 10 year warranty.

WirPlast ventilation equipment is of high quality, which is confirmed by a ten-year guarantee for all products

Roof ventilation "TechnoNIKOL"

TechnoNIKOL ventilation systems are available in two variations:

• for ventilation of the under-roof space;
• for forced air circulation in attics and attics.

Advantages:

• aesthetic design and affordable price;
• increased reliability and impact resistance of all elements. Achieved thanks to additives introduced into the composition of the base material HDPE;
• easy installation with detailed instructions.

Roof ventilation Vilpe

Vilpe products are developed by the Finnish company SK Tuote Oy. Excellent as forced ventilation systems installed both during the construction stages and during renovation.

Advantages:

• made of impact-resistant polypropylene and therefore not subject to corrosion;
• resistant to ultraviolet radiation and climatic changes;
• environmentally friendly material, withstands constant temperature changes from -40 to + 80 °C and occasional surges from -55 to +120 °C;
• Wide variety of colors and modern design.

Vilpe roof ventilation is made from impact-resistant polypropylene and can withstand large temperature changes

Roof ventilation Kronoplast

The success and demand for Kronoplast products is due to the fact that the company produces almost all parts for the ventilation of a private home - under-roof ventilation, kitchen outlets, vacuum cleaner outlets, sewer risers, etc.

The main feature of this product is 100% impermeability of all exits on the roof, without which full ventilation is impossible. Roofing elements Available for any coating in six basic colors.

Video: installation of ventilation on an ondulin roof

Installation of roof ventilation is an important and necessary process that requires attention and responsibility. It is not difficult to do it yourself, observing the mandatory rules and regulations. Only in this case the roof of the house will never “cry”. Good luck to you.

Despite the hype around some roofing materials, the comfort and warmth in the house is influenced not so much by them as by competent installation of the roof. If the construction was carried out professionally, observing existing standards, then any covering will be a reliable barrier to nature’s surprises, be it cheap slate or expensive metal tiles, and the entire roofing structure will save heat in the house and eliminate excess moisture. But the presence of condensation and high humidity “hints” that not everything is going smoothly with your roof. Well, to be more specific: during installation, the roof ventilation was created incorrectly (if it was created at all!).

And there are several reasons: either the roof was laid by non-professionals, or vapor barrier or waterproofing films were applied incorrectly, or the ventilation system was created without taking into account the type of roofing. There is only one result: you will have to disassemble the roofing pie and reinstall it.

What layers should a roof ventilation system be made of?

Roof ventilation consists of three components, each with its own function:

1. Ventilation between the roofing and the waterproofing layer. Its task is to remove condensation from the roof that forms on the back side of the covering.
2. Ventilation between waterproofing and insulation. It is needed so that moisture that has entered the insulation from the air has the opportunity to leave the roof. If this layer is not created, the insulation may absorb water as a result of roof leaks or during the rainy season and cease to function as a heat insulator.
3. Ventilation of the internal under-roof space. This layer is responsible for removing vapors from the premises and preventing them from settling as condensation on the inside of the roof.

In this roof, the ventilation of the under-roof space is not thought out, so there is a lot of condensation on the roof

What laws of physics should be taken into account when installing ventilation?

Steam and water will seep into the roofing pie from both sides. The ventilation system should either prevent this from happening, or, if it gets in, allow the moisture to evaporate. It should be remembered: the steam does not flow perpendicularly upward, but slightly deviating to the side. The water does not flow perpendicularly downwards, but also deviates slightly.

This deviation is not always taken into account when forming a roofing pie, and the following installation errors are made:

Ventilation of the under-roof space. Errors in ventilation installation will lead to destruction of the roof structure

Mistakes in using vapor barrier and waterproofing films

Even if all the necessary air gaps are created in the roofing pie, ventilation will not be able to ventilate all the moisture if the waterproofing or vapor barrier films were installed incorrectly. They are often confused due to their external similarity. But these films have different tasks, and, accordingly, a completely different structure.

Let's consider what problems will fall on the head of the owner who has mixed up the purpose insulating materials:

1. If you laid a vapor barrier film instead of a waterproofing film. The vapor barrier film completely eliminates the ingress of moisture from both sides. If you lay it on top of the insulation, then the moisture that gets from the air into the heat-insulating material (and it will definitely get in, especially during seasons of high humidity!) will remain there because it will not find a way out. As a result, every year the insulation will become more and more moistened until it finally loses its properties completely, and the owners will be faced with high heat losses.
2. If you laid a waterproofing film instead of a vapor barrier. Waterproofing films (also called diffusion membranes) have special properties: one side “breathes”, and the other is waterproof. They are laid under the roofing, turning the breathable side towards the heat-insulating layer. In this case, there should be a ventilation vent between the layers. Then the moisture from the insulation will partially escape through the air gap, and the rest will seep through the funnel-shaped holes of the film under the roof and evaporate. If after roofing If water accidentally gets in (as a result of leaks, through cracks, etc.), it will settle on the film and will not be able to penetrate deeper. And in the same way as moisture from the insulation, it will go home.

If secured correctly waterproofing material on a skate, then the steam will not find a way out

When installing a waterproofing film, it is the other way around, i.e. on the “breathing side” of the insulation, water and moisture entering from the outside will easily enter the insulation through the funnels, and will no longer be able to get out. As a result, the entire design of the roofing pie loses its meaning.

Another option is to lay a waterproofing film instead of a vapor barrier film. If you place it with funnels inside the house, then all the steam will instantly seep into the insulation, if on the contrary, then the moisture from the insulation will return back into the under-roof space, although not much.

Errors in a ventilation system created without taking into account roofing material

Some owners, out of ignorance, create not as many ventilation layers in the pie as a certain roofing requires. For example, metal tiles and euro slate are afraid of condensation on the back side, so a ventilation gap must be provided between them and the waterproofing layer. Those. They fill not a solid sheathing, but a timber one, leaving gaps for air to circulate. If water gets under the roof from the outside, then with the help of this layer of ventilation it will be able to evaporate through the ridge.

The grille paired with the counter-lattice will create an air gap sufficient for condensation to find its way out

At the same time, anti-condensation films are used as waterproofing, which do not release vapors from the insulation under the roof, thereby relieving the roofing of additional condensation. But here is the second point: where will the moisture go from the thermal insulation material if it is not released under the roof? To do this, create a second layer of ventilation, leaving an air “cushion” between the insulation and the anti-condensation film.

You cannot lay diffusion and superdiffusion membranes as waterproofing, because they are designed to allow steam to pass under the roof, and in such roofs this can lead to corrosion of the metal tiles.

Only a properly created ventilated roof will retain heat and remove excess moisture from the house.

In the roof pie, the waterproofing material is surrounded by a double ventilation gap

Soft tile roofs

And these roofs are not afraid of condensation, so they do not require a serious air gap between the coating and the waterproofing. A continuous sheathing of plywood, boards, etc. is installed under them. Wooden materials themselves allow air to pass through well, so natural ventilation will work in any case.

Creating an air gap between the waterproofing and insulation will depend on what film you choose:

• IN soft roofs Anti-condensation films are not installed. Diffusion membranes are used here. But to prevent the funnels from becoming clogged with insulation particles, an air gap must be left.
• If you plan to lay a superdiffusion membrane, then it does not need an air gap. The level of moisture passage is high and allows you to do without a ventilation layer. Such a membrane is laid directly on the heat-insulating material.

In this cake, the waterproofing layer is created using a superdiffusion membrane. It does not require a ventilation gap, but lies directly on the insulation

Having created all the necessary ventilation gaps, it should be remembered that steam will tend upward and water downward only when there is air movement. Don’t forget to make a ventilated underlayment and install aerators on the upper edge of the roof or on the ridge. Otherwise, the roof will not be properly ventilated.

A large country means large volumes of housing construction. Not only multi-storey, but also private. And every developer needs and needs knowledge on general construction issues, norms and rules, including roofing processes.

Competently executed roofing structures- this is not only a guarantee warm home and a comfortable atmosphere, but also the durability of other elements of the structure.

Roofing is an important stage in the construction of buildings.

Physical heat transfer processes

In a heated house, temperature changes and the presence of moisture in the air in the form of steam and condensation are inevitable. Steam is produced by human or animal activity and penetrates into building construction, cools and moisturizes them. The vast majority of building materials are permeable to some degree. Therefore, any residential building, individual or multi-apartment, is an air volume in which warm air rises upward through all structures.

In the high multi-storey buildings a traction effect appears. Warm air rises to the upper floors, this is especially noticeable in the entrances, and penetrates outside through windows and attics. On the lower floors, on the contrary, there is an influx of outside cold air. This process also occurs in a one-story heated house, only with less dynamics.

On the other hand, warm air vapor condenses in structures into water, which not only moistens them, but also has the ability to flow down, filling cavities in the structures. The main function of condensing water vapor is assumed by the top part buildings - roof. In winter, this process occurs intensively and constantly, and in summer, mainly during the cool night time.

The most modern and effective method prevent or significantly reduce moisture condensation in the roof - make it ventilated naturally or forcefully.

Natural cold ventilation does not require energy costs, so its design is preferable. However, there are roofs of complex architecture that lack the strength of natural ventilation, then forced ventilation comes to the rescue.

Ventilation removes warm, moist air into the surrounding space, thereby leaving supporting structures and insulation dry, extending service life and providing thermal insulation. We need to manage this process, which is done using the so-called roofing pie. The concept appeared relatively recently and denotes a multi-layer roof structure, in which the leading place is given to the creation of ventilation ducts. There are two types of roofing pie: for heated and insulated rooms and for cold roof

. Each layer is functionally interconnected with other layers, and the absence of any reduces the protective properties of the entire cake.

• If the attic is a cold, uninsulated part of the building, it is done in several successive layers. The following tools will be required for the work.
• hammer;
• drill with drills 4-12 mm;
• wood hacksaw;
• stapler (stapler) electric or mechanical with staples 14x8 mm;
• level, meter ruler, square;
• scissors;
• screwdrivers of different sizes;
• brush-fleet for antiseptic cutting of wooden parts;

construction sealant.

A waterproofing film (not to be confused with a vapor barrier) is laid on the upper side of the rafters. The film sag should be 20-40 mm to drain condensate. It is secured along the rafters with a counter-lattice 30-50 mm thick and a width equal to the thickness of the rafters themselves. It is better to glue the film at the attachment point with double-sided tape.

To reduce waste, the film can be laid in horizontal rows from bottom to top and with an overlap of 100-150 mm. The junctions of the strips are glued, creating a continuous web. The water generated from condensation will flow down the film to the roof eaves.

1. After installing the waterproofing layer, the roofing lathing is sewn across the rafters onto the counter-lattice. The width of the boards and the gap between them are selected depending on the roofing material. For ceramic and soft tiles, use an inch board 100 mm wide for the sheathing. It is laid with a gap of 50-100 mm, after which the top is completely covered with building board or waterproof plywood with a thickness of at least 9 mm. Under The underlying layer is still being laid.
2. Lathing made of boards 30x100 and in increments of 300-400 mm is made under metal tiles or corrugated sheets;
3. For a metal seam roof, use a lathing made of an inch board 150-250 mm wide, sewn onto a counter-lattice with a minimum gap of 20-50 mm.

Finally, the roofing material is laid directly on the sheathing or building slab. It is attached with special nails, screws or clamps to the sheathing. The roof fastening points are protected with sealants, and the sheathing is pre-treated with an antiseptic. Additionally, you can perform rough filing along the rafters from the attic side.

Between the roof there was a ventilation gap equal to the total thickness of the sheathing and counter-lattice. This is 55-80 mm of the height of the under-roof space along the slope of the rafters. In winter, warmer attic air, partially penetrating through the waterproofing, will rise to the roof ridge and be released into the atmosphere without having time to condense moisture. And in summer, the air heated by the roof is also removed from under the roof.

Attic ventilation is important for the under-roof space. It is carried out through dormer windows located on the gables from different sides. Ventilation of the living space, attic and under-roof space are interconnected, and one of their goals is to reduce steam and condensation in the roofing pie.

Ventilated insulated roof design

Often the attic space is used as an attic and is insulated from the roof side. In this case, several more layers are added to the roofing pie. Now there is no attic air gap between the living space and the roof. Warm and humid attic air immediately penetrates into the under-roof space. And if you don't accept additional measures Once it is removed, there will be much more condensate and the structures will begin to get wet. Thermal insulation materials will cease to perform their functions and the air in the room will be cold. We'll have to turn up the heating.

In addition to those layers that are already made in cold roof, add a thick layer of insulation, laid between the rafters on the inside. If ordinary rafters are 150 mm wide, then the thickness of the insulation between the rafters can be no more than 100 mm. The reason is the need to leave a minimum gap (do not touch) until the waterproofing sag, which reaches 40 mm. If there is a touch, water flowing down the insulation will get into the insulation. To increase the thickness of the layer, timber of the required thickness is sewn onto the rafters and insulation is added.

Then it is closed vapor barrier film. The goal is to minimize the penetration of steam from the room into the insulation so that it does not get wet. Wet insulation is no good, it does not retain heat and, in addition, moisturizes the surrounding structures. First, a rough lining is sewn onto the vapor barrier, and then a finishing lining.

Now the path of wet steam to the roof is blocked, and although a small part of it still penetrates, it is carried out into the atmosphere by the under-roof ventilation air flow, without causing harm to the roof structures. And if the warm room itself is not ventilated, where will the steam go? Through all sorts of microscopic pores and cracks it will still go up to the roof. This will also be facilitated by the excess pressure generated in the warm attic room.

Ventilation of the room itself will help relieve excess pressure, reduce the moisture content in the living room and thereby help under-roof ventilation remove moist air into the atmosphere.

Ventilated cornice device

Longitudinal ventilation ducts roofing pie will not work effectively if, on the one hand, in the lower part, at the very eaves, there is no influx of atmospheric air. On the other hand, it is necessary to allow the humidified air to escape from the very top part of the roof - from the ridge.

Waterproofing film is the strongest of all types of films used in home construction, so it does not allow water or moisture to pass through, even under high pressure.

The waterproofing film is removed and glued with sealant to the metal cornice strip installed in the plane of the sheathing. The roof is fixed on top. Air flow is carried out in 3 ways. Firstly, through the gaps of the profile of the roofing material, secondly, through the gable overhangs and, thirdly, through the micropores of the waterproofing film, drawing vapor from the insulation.

When covering the cornice, ventilation holes or gaps are provided in its lower part, depending on the many options for the design of the cornice. One of the modern methods is continuous filing of the cornice plastic panels with perforations for roof ventilation.

Creating a ridge hood

Depending on the design of the roof covering, the air flow from under the roof is collected in the ridge and discharged into the atmosphere either through structural gaps along the length of the ridge, or through gable openings. For example, complete with ceramic and metal tiles There are special ridge elements with ventilation gaps. Additionally, there are additional elements for a non-standard ridge shape.

This is the outer part of the roof. The internal structure is performed in a certain sequence.

• the counter-lattice along the rafters is not brought to the geometric height at the same distance of 20-40 mm. The bars of the oncoming slopes do not join;
• sheathing in 2 solid boards from both slopes on the ridge is also performed with a longitudinal gap of 40-80 mm;
• the waterproofing film along the ridge is cut with a hem margin of 200 mm on both slopes;
• between the ends of the counter-lattice and the sheathing along the ridge, a ridge beam of 40x100 mm is installed vertically;
• a waterproofing sheet is attached to it and sealed with sealant;
• From above this structure is covered with a ridge according to the instructions and technology;
• Install ridge end elements on the gable side, in which ventilation holes or gaps are provided.

Some features of a ventilated roof

Roof ventilation is not an independent process. On the contrary, ventilation or its absence in the premises directly affects the air exchange in the roof. To effectively remove damaging moisture from residential premises through the roof, it is necessary to consider the ventilation of all elements of the building as a single process.

If the shape of the roof is complex, has many transitions, valleys, ventilation processes must be divided into sections and air flows in the roof must be formed separately. As a result of effective ventilation, the air in the under-roof space should be replaced approximately 2 times within an hour.

The effectiveness of a ventilated roof depends on the slope of the slopes. The steeper they are, the stronger the ventilation process occurs. And, conversely, in roofs with a slope of less than 20%, under-roof ventilation is unstable and effective only under wind pressure.

It is always useful to install additional exhaust elements (aerators) on the roof to help enhance the natural ventilation of the roof. They should be placed on roofs of complex shapes, when conventional means are no longer sufficient. Aerators are installed near the ridge.

The thermal insulation properties of insulation and the durability of roof structures directly depend on the presence of moisture in them. Therefore, a ventilated roof and the design of room ventilation are economically beneficial even when it is necessary to install forced air exchange.

Everyone who is somehow involved in construction should at least vaguely know the structure of a ventilated roof.

Let us remind you that there are 3 main ventilation circuits:

There should be a ventilated space with some room for fresh air to flow. It is they who will take the resulting moisture in the summer and remove it outside. In order for such a ventilated roof design to work efficiently and without interruptions, it is very important to competently approach the issue of laying the roof on the sheathing.

If rafter system already installed, take care roofing material. It must match the type of room. For example, if an unheated room is planned, then its service life will be limited only by the shelf life of the selected materials, and ventilation will be natural.

But to make the building last even longer, use forced ventilation, where the ventilation outlet to the roof, or more precisely, the outlet space, will be occupied by a weather vane.

Let's remember what elements an uninsulated roof consists of:

• Rafters;
• Lathing;
• Roofing material;
• Waterproofing films.

The waterproofing film plays an important role, because, attached to the rafters with the help of slats, even after the roof has worn out, it will provide some protection from moisture from the outside. Also, waterproofing has a long service life, so it can reliably protect the passage of ventilation through the roof.

Especially similar material suitable for summer cottages. A film covered with slate under favorable conditions can withstand up to 50 years of constant use! But do not forget about the special structure of the “roofing pie” for all private houses.

In addition to insulation for ventilation, a diffusion waterproofing film is usually applied. Thanks to it, the under-roof structures will remain dry, and steam will be able to pass through the smallest pores of the material. Another advantage is also reliable protection from the wind while using this film.

But the use of diffusion film is justified only during the installation of certain gaps. The film can best show itself by filling the gaps between the thermal insulation structure, the roof and the film. In almost all other cases, this film will not allow water vapor to pass through, causing the roof ventilation outlets to stop working properly. Instead, it would be better to use anti-condensation film.

weather vane for the roof, which organizes forced ventilation. It is worth noting that it is possible to make.

Let us remember that a ventilated roof consists of finishing materials and insulation. Water vapor usually reaches the last layer and stops in this layer, due to which the insulation quickly loses its original properties. In the future, excess moisture will appear on the walls and ceiling, and this can have serious consequences.

To avoid bad consequences, ventilation is installed. But we must not forget about roofing materials, because they also play an important role in insulating a home. By showing balance, you will definitely be able to achieve the desired result in construction!

With constant fluctuations in daily temperature, condensation forms on some parts of the roofing. This happens especially often in the winter, when the interior warms up and the difference between the temperatures inside and outside the building turns out to be large.

The insulation undergoes the greatest load. Its lower and upper edges experience temperatures differing by tens of degrees. In addition, the lower the degrees outside, the greater the pressure of water vapor rising from the room upwards appears in the under-roof space. And the cold air does not allow the steam to move further.

As a result, the insulation absorbs a lot of moisture and stops “working” for its intended purpose.

It will help you cope with such phenomenaventilated roof. In winter, it will help reduce the costs of heating the building and optimize heat loss. In the summer, such a design will perfectly withstand the heat, since the warm air entering the roof tends to rise upward and take with it the heat that it received from the roofing coverings and the evaporating moisture that appears in the insulation.

Ventilated roof installation

Before starting work on installing such a roof, you should find out what materials will be used. This will be the determining moment for the choice of other roofing building materials.

For example, what kind of waterproofing film is suitable for pitched roof, and how, in this case, the counter battens will be located, how many ventilated gaps will be required, and what pitch of the sheathing will be optimal. The height of the ventilated space also directly depends on the selected roofing material.

For example, if you intend to use bitumen shingles, then the ventilated channel can be made smaller than when using tiles made from natural materials.

And for metal tiles, an average size is designed between the previous two. The size of the canal varies between 5 - 10 centimeters. What is a ventilated roof? It consists of three necessary circuits:

• ventilation of the space between the waterproofing and roofing. With any complex roof structure, it must include all surfaces without exception in this process.
• areas located under the roof itself. This is one of the important components of the ventilation system of the entire structure.
• the gap between the waterproofing layer and the insulation. The presence of stagnant zones should be completely excluded here.

Ventilation design

Imperfect technologies of many decades in the past and flawed Construction Materials those years, led to the fact that the constructed buildings breathed due to brickwork, wooden window frames.

Thanks to this “breathing”, the heat loss of the house was significant. Breaks roll materials on the roof and all of the above factors contributed to the formation of a triple ventilation circuit.

As a result of all this, there was a draft in the rooms, dampness often appeared, and as a result, it was necessary to fight the fungus. The costs of heating buildings also increased, and finishing work inside houses could not always be done efficiently. In older houses, ventilation ducts were designed only in bathrooms, toilets and kitchens.

IN modern construction There are new roofing technologies and new materials for its insulation and waterproofing. Even at the design stage, it is necessary to pay the necessary attention to systems.

When installing a ventilated roof, you must remember the rules of the roofer: steam invariably rises upward, and water can only flow downwards.

It is necessary to pay attention to the following points that must be taken into account during design and operation.

Experts advise paying close attention to the ventilation of small rooms, making vapor barriers closer to interior spaces Houses. If the waterproofing is done incorrectly and moisture penetrates inside, the situation can only be changed by dismantling the roofing and correcting the mistakes.

Pitched roofs

When installing a ventilated roof, it must be taken into account that air flows must enter through the lower overhang of the roof and exit through the top, where the ridge is installed. This will remove excess moisture. To prevent birds from flying into the roof and leaves from getting in, eaves ridges with ventilation grilles are used.

Additional forced ventilation can be done using. This will be relevant if the roof structure is complex, where it is quite difficult to ensure free passage of air.

If the roof is covered wavy slate, then it is very simple to organize an air gap; during installation, it is formed between the ridge and the roofing sheet, due to its configuration. It is only necessary to provide lower gaps for air entry. So, an uninsulated roof consists of:

• rafter design;
• lathing, depending on the roofing material;
• waterproofing film;
• roofing material.

A waterproofing film is attached to the rafters using counter-lattice slats. She must long years protect the roof of the building from unnecessary moisture. With proper use, the film will last for many years. All this is suitable for the construction of a country house.

In a household where people live even in winter, it is necessary to lay a diffuse waterproofing film, which is mounted on top of the attic floor insulation. Such a film will allow steam to escape from the room, but water will not get inside through it. It is also possible to use anti-condensation film. It can be used with any roofing material. It will protect against moisture, soot and dust.

This material includes:

• propylene fabric, which is resistant to UV rays;
• non-woven moisture-absorbing material;
• 2 layers of laminated film

Flat roofs

Ventilated flat roofs began to be used in the 80s of the twentieth century. Then insulation with built-in ventilation ducts appeared, which help quickly remove excess moisture.

Ventilation here occurs thanks to the holes located along the edges of the roof. They must be covered with nets so that insects cannot get inside. If the structure uses wooden parts, then a vapor barrier should be laid under the thermal insulation layer.