Owners are often afraid to equip cold attic ventilation in their private homes, guided by the following assumptions.
- Heat escapes from the house through the ventilation grilles of the attic. It is believed that the building will cool down faster. But most often the problem lies in poor thermal insulation of walls or ceilings. By the way, humid warm air enters the attic through a poorly insulated ceiling. In what its danger we will tell in the next chapter;
- Ventilation of the cold attic of a hip roof or hip roof is necessary only in summer. According to many, ventilation grilles and windows in the attic are needed only for ventilation in the stuffy atmosphere. In fact, in winter, the ceiling of an unheated and unventilated attic will turn into a cave overgrown with ice stalactites;
- It doesn't matter what size the ventilation ducts are. The area of ventilation windows and air vents in the attic must be carefully calculated. How to do it right - read on.
Attic ventilation in a private house is the most important element of thermoregulation. Properly organized, it allows you to save money on heating or cooling the living space and preserve the structure itself intact. Ventilation of the attic above the attic is especially important.
An attic in a private house needs ventilation both in winter and in summer.
So, in the hot season, a hot roof heats the air in the attic to 150 degrees. Most of this heat is given off to the upper floor ceiling, and the air conditioner has to work with increased load to eliminate the excess heat. If there is no air conditioning, the owners are exhausted from the heat and stuffiness.
In winter, air exchange is necessary to remove excess moisture. According to the technical requirements, the temperature difference between the outside and the attic must be 4 degrees or less. Temperature fluctuations between the residential floor and the street contribute to the accumulation of condensation on the roof rafters. The moisture gradually freezes, creating whole cascades of icicles. In the thaw, they melt and moisture drips onto the floor of the attic. The supporting structures of the roof and ceiling are destroyed. Mold develops on wooden rafters.
By the way, high-quality ventilation of the cold attic prevents the accumulation of snow and ice on the roof of the house.
What is attic ventilation
Free air exchange between the roof space and the street is carried out through gaps and holes. Holes in the ridge and under the roof overhang work best. Placed in this way, they use the wind and heat pressure from the ceiling of the house.
If the ventilation of a cold attic in a private house is equipped correctly, in one hour the air doubles around the entire roof from the inside. The movement of flows is directed from the bottom of the vents under the cornices up to the ridge plates with special holes. If the roof is insulated, a gap of up to 5 cm is left for free air passage between the roofing material and the insulation.
The best ventilation is provided by a combination of ridge vents and sloping elements mounted near the ridge. For tiled roofs, tiles with air exchange vents are manufactured.
And another way to ventilate attics in private houses is to install deflectors (turbines for ventilation) that provide mechanical traction. The method is good for ventilation of the insulated attic above the attic.
The slight slope of the roof must also be considered when planning the ventilation of a cold attic. The vents in the ridge can be covered with snow, so they are replaced with pipes, the height of which should be higher than the snow cover.
The oldest ventilation method is the ventilation window in the attic. To ensure excellent air exchange in a cold attic, a combination of air vents under the cornice, in the ridge and dormer windows is quite enough.
The ventilation of the cold attic of houses with a hip roof differs in that the house does not have gables. Therefore, there is nowhere to install ventilation windows in the attic. Thus, cold attics under hip roofs are ventilated with ridge and cornice vents.
It is more difficult to equip the ventilation of the attic above the attic. Here, air vents are provided by cracks in the roofing cake and mechanical traction means. The ventilation outlet to the attic is hidden in the columns.
Ventilation of the attic through dormer windows
Only dormer windows can be used as ventilation in the attic, without equipping a system of air vents and vents. This option is not very effective, as air can stagnate under and above windows.
To improve air exchange and reduce the volume of stagnant places, the size of the dormer windows is made 60 cm x 80 cm. They are mounted in opposite gables. First, wooden frames are made, which are attached with racks to the rafters. The roofing material is attached to the frame. Windows with the same materials as the roof look better. Lining is well suited for finishing openings around windows. The window frame in the opening is installed last. All gaps between the window frame and the roof must be carefully closed.
Ventilation window placement rules:
- windows are placed at equal distances from the ridge, cornice and sides;
- there must be a distance of more than one meter between the windows;
- the design of the window should harmoniously fit into the general appearance of the building;
- a ventilation grill for the attic can be installed in the window, painting it to match the roof.
Air vents in the roof and roof
Air vents are openings in the roof for ventilation of a cold or warm attic. Air vents are ridge or cornice, depending on their location. Eaves are arranged on both sides of the eaves and represent gaps between the roof and the wall about 2 cm wide. They are called slotted. If the vents are made in the form of holes, they are called point. The smaller the slope of the slopes, the larger the diameter or width of the vents is made, but not more than 2.5 centimeters.
Ridge vents are made in the form of slots up to 5 cm wide or in the form of weather vane at intervals of up to 8 meters. Ridge vents are also installed in roofs with piece roofs, for example, tiled ones. Special tiles with holes are placed one row from the ridge.
Top roof vents are available as aerators, gable grill or retractable roof outlet. Ridge aerators and pitched outlets can be purchased with roofing material.
Perfume - this is the only way to ventilate the attic without skylights.
Ventilation aerators
Roofing aerator is a modern and convenient type of ventilation. It is a pipe covered with a cap on top. Aerators remove steam, moisture and stagnant air, providing ventilation to a cold attic in a private home. Aerators are installed on roof slopes, where air movement is provided by the difference in temperature and pressure, replacing the ridge vents. Aerators are continuous and point. Spot aerators are equipped with fans and guarantee good air movement.Outwardly, they resemble fungi.
Continuous aerators are a plate along the ridge with holes. Covered from above by a roof, they are practically invisible and provide intensive air movement due to their large openings.
Various types of aerators are created specifically for roofing from:
- bituminous tiles;
- flat roof;
- cermets;
- ceramics.
Aerators are installed only where eaves air vents are provided. There are other conditions for their installation:
- only roofs with a slope of 15 - 45 degrees are suitable;
- a distance of at least 30 cm is maintained from the chimney or wall;
- aerators protrude 25 cm above the slot at both ends of the ridge;
- point models are mounted no further than 50 cm from the ridge.
Calculation of ventilation attic
For those who decide to equip the ventilation of the attic with their own hands, before starting work, it is necessary to carry out calculations. Only a specialist can guarantee the best result. And for the most daring, we have prepared a hint:
The ratio of the area of the vents to the area of the attic is 1: 500.
500 sq. meters of the attic area should be 1 sq. meter of vents. As a last resort, you can be guided by a ratio of 1: 300, per 200 sq. meters of the attic should have a minimum of 0.4 sq. meter of air. The calculations take into account the area of true ventilation, that is, even the width of the grilles is excluded, the ribs of which interfere with the movement of air flows.
An excess of the area of the air is also undesirable, as well as a disadvantage. Holes that are too large can get snow and rain, because these are the most vulnerable spots of the roof, which must be remembered.
The area of the hood (ridge and pitched grates) should exceed the area of the inflow (cornice vents) by 12 - 15%.
Do-it-yourself cold attic ventilation
Many owners are thinking about how to make attic ventilation after a few years of living in the house. The musty smell and dampness in winter make you pick up your tools. We will tell you about the construction of ventilation of any attic with our own hands.
With a gable roof, the easiest way is to equip the ventilation of the attic with your own hands by making vents in the gables. The gables are usually made of wood and this greatly facilitates the work. Wind eaves on the sides of the roof are also covered with wood. All cracks must be made evenly, ensuring that the entire area of the attic is blown.
There are no gaps in the stone pediments, so you will have to arm yourself with a tool and drill two dormer windows. They are covered with bars and mosquito nets.
When equipping an attic ventilation with your own hands, the placement of air vents largely depends on the shape of the roof. Various options are suggested in the diagram above.
There is no need to worry about how you can make the ventilation of the attic if slate, tiles or ondulin are used as roofing material. The undulating shape provides enough voids for the passage of air. And the sheets are laid on the crate with gaps through which the air flows pass. The metal tile, although it has a wave-like shape, collects condensate during temperature drops, therefore, it is covered with a vapor barrier film from below.
Competent conclusion of ventilation to the attic is no less important than its installation. And special attention should be paid to pipe insulation.
Insulation of ventilation pipes
Ventilation pipes must be insulated in the attic and above the roof level. This procedure is performed to avoid the accumulation of condensate, which will accumulate on the inner walls and drain down. Since the joints of the ventilation pipes are not made airtight, moisture will penetrate the supporting structures, ruin the finish and lead to the gradual destruction of the building. And the ventilation ducts themselves suffer from contact with moisture if they are made of galvanized pipes.
In winter, the lumen of the ventilation duct is overgrown with frost and in just a month a standard pipe 15 cm in diameter will completely close.
The appearance of condensation in the ventilation ducts is inevitable: people exhale water vapor, wash dishes, bathe and wash. This releases moisture into the air. The humidity of the warm air of a residential building can reach 100%. In contact with the cool surface of the ventilation shafts, water settles on it.
To prevent this process, the ventilation pipes are insulated in the attic. Here is the border between the warm air of the house and the cold unheated attic.
The cheapest insulation option: mineral wool. It does not burn, but when it gets wet it completely loses its qualities. It is easier to mount a corrugation with mineral wool insulation.
Styrofoam in the form of special removable "shells" is very easy to install and inexpensive. But it burns well, emitting toxic smoke, therefore it is not recommended for residential buildings.
The best materials for insulation of ventilation ducts: polyurethane foam, polyethylene foam, polypropylene foam.
Professional recommendations
And, at the end of the day, a few important tips for those who are interested in how to properly ventilate the attic:
- All ventilation elements must be resistant to any weather conditions;
- Be very careful about the location of the ridge vents. They are installed as close to the ridge as possible;
- Continuous spotlights work effectively as eaves. The best materials for them are non-rusting aluminum or plastic. The surface of the spotlights is covered with a fine mesh;
- When equipping attic ventilation without dormer windows, special attention should be paid to the airflow between the rafters. It is important that during operation they are not clogged with debris and dust;
- To calculate the ventilation of the attic above the attic, involve a professional;
- Install decorative ventilation windows in the attic to add charm and style to your home;
- Equip the outlet of the supply ventilation to the attic in accordance with all the rules. The supply unit should be installed in the cleanest place, no closer than 8 meters from the exhaust pipe.
