Roof ventilation provides long-term operation of the roof and improves the microclimate in the house. The fact that the roof was erected incorrectly, owners often find out late, noticing smudges on the ceiling or drops of water in the attic. These are the first signs of a poorly ventilated roof and they are not the worst.
Roof ventilation required
Often, the owners order expensive building materials, but try to save on ventilation of the roof space. People who are far from construction do not understand: why and what needs to be ventilated there?
In villages, hundreds of houses without any complex and expensive roof ventilation systems have been serving their masters for centuries. In fact, these houses are well ventilated. Through the dormer windows in the attic, the gaps between the wooden boards of the pediments and the logs. Modern houses are being built almost airtight. And this is the main reason why the building needs ventilation.
Let us now consider what phenomena ventilation of the subroofing should fight with.
According to the laws of physics, warm and humid air tends to rise. It accumulates under the ceiling of the upper floor and from there penetrates into the attic. If the house has a residential attic and even worse - between the roof material and the living space there is only a layer of plastered drywall and insulation.
In contact with cold roofing material, moisture from the air condenses, enters the rafters and causes their damage. Water gets on insulating material (most often mineral wool) and worsens its properties. Further, moisture penetrates the attic ceiling and the owners find ugly smudges and spots. Gradually in wet places mold settles. All efforts to finish the room went down the drain. And residents begin to suffer from allergic diseases.
When the air temperature in the street reaches minus marks and snow falls, everything becomes even worse. Warm air from below causes the snow to melt, the roof does not withstand the meltwater backwater and begins to leak. In severe frosts, melt water freezes, icicles appear. By the way, it is they who indicate poor-quality under-roof ventilation or its absence.
And in the summer, the owners of such a roof live no easier. The sun heats the roofing material, if air exchange is not organized under it, all the heat is transferred to the air of the attic or attic, and from it to the residential floor. The load on air conditioners is increasing. If they are not, people suffer from heat. And an overheated roof quickly fails (especially for soft roofing materials).
Roof ventilation functions:
- removal of water vapor falling under the roof from living rooms;
- leveling the temperature of the roof to prevent icing;
- decrease in roof temperature in the summer.
High-quality ventilation of the roof made of metal is provided by the movement of air flow along the inner surface of the roofing material in the direction from the bottom (from the cornice) up (to the ridge). With a well-designed roof, ventilation will be carried out without mechanical appliances and electricity costs.
For unhindered movement of air, products are installed and a roofing cake is formed in a special way.
Roof ventilation methods
To ensure air exchange in the under-roof space using:
- roof vents;
- piece roofing with ventilation holes;
- roof fans;
- ventilation gap in the roofing cake;
- dormers.
The market offers a wide selection of ventilation roofing exits or products of continuous or spot type.
Continuous aerators include ridge and cornice products.
The maximum effect gives a combination of continuous ridge products and cornice.
Such a scheme works on the basis of wind and thermal pressure. If the roof ventilation is done correctly, in one hour the air flow passes twice under the entire roof surface.
Top vents are covered with roofing material, so they do not spoil the appearance and do not allow atmospheric precipitation.
The area of all ventilation openings must be calculated, since for the normal operation of the roof ventilation the following ratio must be fulfilled:
- the area of the upper vents is 15% larger than the area of the lower ones.
In this case, the traction will be good. The total product area can be calculated as follows:
- the attic area is multiplied by 0.03 - 0.05;
or so:
- per 100 square meters meters area of 20 square meters. see products.
If the roof length is more than 10 meters, it is advisable to use additional ventilation devices (aerators).
Roof cake ventilation gap
In order for air to freely pass under the roof, providing ventilation, he needs a corridor. The correct structure of the roofing cake consists of vapor barrier, waterproofing and insulation. It is very important to choose all the materials correctly, otherwise the roof structure will seriously suffer, which means that it will have to be repaired much earlier.
Waterproofing does not allow precipitation into the insulation layer. The best material for waterproofing is superdiffusive breathing membranes. They allow steam coming from the living quarters, but retain moisture from above. Lay waterproofing over the insulation. The photo shows the roof ventilation scheme by means of a properly laid roofing pie.
Vapor barrier is an equally important layer that protects the insulation from the penetration of steam. Often a plastic film is used as vapor barrier.
A clearance for ventilation of the under-roof space is left between the roofing material and the waterproofing. To do this, a 5 cm thick counter-lattice is nailed to the waterproofing film. A solid flooring or step crate is applied on top, depending on the selected roofing material.
The counter-lattice protects the waterproofing film from damage during the construction or repair of the roof. If there is no counter-lattice at all, or if it is made of thin rails, the roof ventilation will not work.
Between the waterproofing and the insulation, a lower ventilated gap is sometimes equipped. This is a way out for steam rising from the attic living rooms. This phenomenon is observed when using a poor vapor barrier film or improper installation. For example, the film adheres to the walls, it is not glued at the joints, not tight. For ventilation of the under-roof space of the metal tile, you can do with only one upper gap, if the vapor barrier is fastened according to the technology.
The width of the upper gap should be 40 - 50 mm. Its increase will not improve ventilation of the under-roof space of the metal-roof, and may even worsen. Turbulent flows occur that disrupt the direction of movement and increase resistance to air flow.
Eaves ventilation
Through the eaves, air enters under the roof, passes upward and through the ventilation ridge roof outlet goes into the atmosphere. When performing cornice work, often the functionality and beauty contradict each other. Designers do not favor lattices, spotlights and levels on eaves overhangs.Nevertheless, it is important to provide under-roof ventilation in the required amount. The movement of the air flow through the eaves during roof ventilation in the photo.
Eaves are equipped along the entire length of the eaves overhangs.
They may be:
- Slotted. Slit up to 25 mm wide between the wall and the roof;
- Pointed. If the slope of the roof is more than 15 degrees, the diameter of the duct is 1 cm. If the slope is less than 15 degrees, the diameter of one duct is 2.5 cm.
The overhang of the roof with slit-shaped products is covered with spotlights, dot lattices. It is most convenient to purchase ready-made gratings for curtain ducts. They are made in different colors, easily attached with screws or nails, and are corrosion resistant.
Difficulties with ventilation of the under-roof space under the metal tile can arise when the green facade is made of plants or external insulation, which can partially cover the air holes. In some cases, birds settle under the roof. But if you cover the gap with a ventilation tape, an overhang aero element and a decorative grille over it, no birds of roof ventilation under the metal profile are scary.
To prevent snow from blowing out, simply place the gutters directly above the ventilation gap. And even with powerful icing on the roof, the gap remains free.
Ridge ventilation products
Through the ridge vents, the air involved in roofing ventilation exits and mixes with atmospheric. The ridge vent can be a continuous 5 cm wide over the entire length of the ridge or in the form of frequent holes.
Special piece copies with vents are made for the tiled roof, which are installed one row after the ridge.
Both cornice and ridge products must be protected from clogging with natural debris and nesting birds. For this, special ventilation elements are installed, which can be purchased at construction stores.
For example, for a ridge there are sub-roof tiles with labyrinth channels, ventilation rolls and aero elements of the ridge. One example is the TechnoNICOL ridge aerator for roof ventilation. This device with labyrinth ventilation ducts copes with roof ventilation. TechnoNICOL is easy to install, does not allow leaks in the ridge. The TekhnoNIKOL ridge aerator is made of plastic, which ensures the durability of the roof ventilation system.
If the roof is made of soft shingle, use a plastic and metal profile for roof ventilation or form a ventilated ridge from the roof material.
Violations during the construction of the roof, worsening the work of the ridge vent:
- Sealing with special tapes without gaps or filling the ridge gap with mounting foam. This is the most common mistake made during the installation of the roof when ventilation of the roof made of metal is used. Ventilation of the under-roof space in this case does not work at all;
- Installation of an overlapping film with an overlap, without a ventilation gap. On the ridge, a gap of about 10 cm wide must be left.
Clearly mounting errors of the ridge, interfering with the roof ventilation in the photo.
Even the installation of aerators does not in all cases provide decent roof ventilation from a metal profile. Therefore, the roofs over the attic floors must be equipped with continuous ridge vents, regardless of the material of the roof.
Roofing aerators
Roofing aerators are used to remove steam from the subroofing space. Aerators are suitable for all types of coatings and roof shapes, even with almost no slope.
Functions of aerators:
- Drying the insulation layer;
- Removal of condensate from under the roof;
- Prevents rotting under the roof;
- Prevents possible leaks.
Devices are installed both on an already fully prepared roof, and during its erection.
The number of aerators on the roof depends on:
- roof area;
- roof shapes;
- roofing material;
- destination premises.
One of the main problems with soft roofs is bloating, which causes leaks. Water penetrates into the under-roof space and gradually destroys the roof. Roofing aerators remove moisture, keeping the roof intact.
One of the world's largest manufacturers of roofing ventilation elements is Vilpe. In addition to Vilpe aerators for roof ventilation, it produces:
- passage elements for ventilation;
- roof valves;
- antenna outputs;
- fire hatches on the roof;
- roof outlet seals.
Elements for roof ventilation Vilpe are produced from materials resistant to corrosion. A wide selection of colors allows you to choose the right elements for any roof.
Ventilation groove
From the point of view of erection, subsequent use and ventilation, a valley or gutter can be considered the most difficult element of the roof. It is strongly not recommended to make two ventilation gaps if the roof structure is complex, with a long groove and small cornice overhangs. In this case, it is very difficult to create air exchange in the insulation and the rafter system near the valley. Holes in the rafters do not work at all, which also reduce the strength of the structure.
In the under-roofing film, holes are made in each span or ready-made elements of the lower protective film are installed. You can also equip a continuous air channel along the groove.
Aerators or special ventilated tiles along the valley are placed on the roof.
These methods work only on roofs with a slope of 45 degrees. If the roof of the canopy, snow collects in the grooves, covering the ventilation holes.
Therefore, roof fans or nozzles are installed to prevent the penetration of snow.
Such a roof will cost significantly more. Many customers dwell on finely perforated films and subsequently incur losses due to condensation on the roof.
Joining the roof to pipes, walls and windows
Additional elements of roof ventilation are used if the usual natural system is not able to cope:
- in the presence of skylights;
- at the exits of the ventilation shaft, fireplace pipe or stove.
Ventilation may work poorly if the insulation is poorly laid. For example, heat from the chimney can completely disrupt the movement of air flow under the roof and moisture accumulates in this place. Similar is not uncommon on roofs of complex shape and gently sloping, with a small slope.
And a snack on a ventilated roof for a snack.
