The metal tile guarantees reliable protection of the house from the influence of external adverse factors, it is easy to install. However, it also suffers from atmospheric water, condensation, and household fumes. Competently arranged roof ventilation for metal tiles will protect the roof from harmful effects for it.
You will learn all about the methods of removing moisture, destroying building materials, negatively affecting the microclimate, from the article we have presented. We will show you how to preserve the sandwich structure and support frame of the system. We will show you what needs to be done so that a roof with a metal-tiled roof lasts as long as possible.
The content of the article:
- Roof ventilation requirements
- Ventilation methods
- Installation of natural under-roof ventilation
- Elements for roof ventilation
- The procedure for installing the structure
- Conclusions and useful video on the topic
Roof ventilation requirements
The main purpose of roof ventilation is to drain the roofing cake and remove all types of moisture from under the roof, which reduces the insulating qualities and bearing capacity of building materials.
Ventilation provides the following benefits when properly installed:
- cools shingles in summer;
- creates conditions for uniform heating of all zones of the under-roof space in cold weather;
- removes accidentally trapped moisture from under the roof, which prevents the appearance of ice;
- improves the operating conditions of the truss and roofing system, excluding the appearance of corrosion and mold;
- creates comfortable conditions in a roofed attic or attic, which is relevant in the presence of equipped premises.
A roofing pie, mounted in violation of technology, even with the most advanced ventilation system, can cause ineffective ventilation and moisture accumulation inside. Air will not be able to circulate freely if at least one layer is laid in violation of the rules.
The circulation of air masses under the roof is not only a guarantee of the absence of condensation on the metal tile, but also a thermal layer. It does not allow cold to penetrate into the under-roof space when cooling the finishing material or heat when heated
The main thing is that proper roof ventilation ensures a long service life for all roofing materials.
Ventilation methods
There are two ways to create conditions for the unhindered circulation of air masses in the attic space: point and continuous. They differ in the different distribution of the outgoing air flow, which carries away all the vapors.
Continuous ventilation is laid even during the design of the roof or before the installation of metal tiles. Its essence lies in the equality of the outgoing and incoming flows, achieved due to the same ventilation gaps, vents. They begin at the cornice and end at the ridge, i.e. roof tops.
Correct installation assumes that gaps will be laid both between the roofing and the waterproofing layer and between the protective membranes and thermal insulation.
To exclude the possibility of clogging the holes, they are covered with overlays or gratings with small cells. An important nuance - the total area of the gaps should be at least 1% of the total roof area.
In order to ensure this condition, with the height of the timber for the device of the lathing and counter-lattice on top of the steam, heat and hydrosolation, it is necessary to decide in advance.
This method works effectively on simple gable roofs, where air can circulate freely in the under-roof space. If the circuit is done correctly, a natural, stove-like draft arises. It provides a constant supply of air.
Malfunctions in the functioning of the system lead to stagnation of moist air under the roof and, as a result, the appearance of fungus and rust. The point method, as an addition to the continuous one, is used on complex roofs and in the presence of an attic.
For roofs up to 60 m², one aerator is sufficient. If the house is large and the roof area is significant, it is necessary to install several point exits
"Dirty" air streams are discharged through a metal or plastic aerator, a device made in the form of a short pipe with a baffle or a flat tile with a grid. Aerators are installed in places that require active removal of moisture to the finished roof, taking into account the wind rose of the area.
In order not to damage the structure, more than one aerator must not be installed on one floor sheet. On a roof with complex geometry and with several ridges, ventilation outlets for metal tiles are made near each from the ridge with a distance of no more than 0.6 m from them.A point exit is recommended with a slight roof slope (up to 1/3).
Installation of natural under-roof ventilation
To organize a natural under-roof ventilation system, the following steps are taken:
- The crate is nailed to the inside of the rafters, a beam is attached to it. In the area of the valley, the timber should be solid. To create an additional gap in the gap between the lathing-timber, lay a ventilation lathing.
- Lay the vapor barrier on top of the lathing. An important detail: between the vapor barrier layer and the rafters, hollow ventilation ducts with a height of at least 5 cm with bar walls must remain. In the gap between the rafters, a heater is placed on top of the vapor barrier. When using a vapor barrier membrane, the gap is not necessary.
- Above the insulation, they arrange another tier of the crate and put waterproofing. This row of bar provides a distance between the thermal insulation and the waterproofing film. It may not be suitable if a specialized membrane is used as waterproofing. Then the insulation is covered with waterproofing without a ventilation gap.
- The counter-lattice is nailed to the outside of the rafters, and the lathing is on it. This is how ventilation ducts are formed between the waterproofing and the roof. In the case of laying metal tiles, this gap is required, it is necessary even if a waterproofing membrane is used.
- The metal tile is mounted, ventilation outlets are made in it in the inter-rafter spans.
The ends of the roofing cake are not covered with anything except gratings. With continuous natural ventilation, air will flow through the holes formed by the distance bar of the battens and counter battens.
For metal tiles, moisture from the inside causes more harm than dampness from the outside. Only a good air circulation in the under-roof space saves the day
The workout will come out through the vents and aerators in the area of the ridge, along which the slopes are not connected tightly. A gap of 3-5 cm remains between the planes of the roof along the ridge rib. It is overlapped ridge aerator, produced for equipping the ridge with tiles or a solid metal strip.
Elements for roof ventilation
For arranging the intersection of the roofing pie with a pipe of the internal ventilation system, coating manufacturers produce assembly kits.
When choosing them, you need to consider the following nuances:
- The profiles of the metal tiles and the aeration pads, as well as their color, must match.
- The properties of the material must be suitable for the climatic conditions of use.
- The kit requires instructions for installing the overlay, template, fasteners, pass-through element. In some kits, the last part is missing. high-quality installation of ventilation is impossible without it, you will have to purchase it separately.
- Some manufacturers equip ventilation outlets with additional functions that improve the ventilation process. It can be a fan - mechanical or electrical, spirit level, making it easier to install on the base.
Design ventilation outlet does not differ in complexity. It includes three main components: a ventilation pipe, a passage, an umbrella deflector. The first part is the main one, through it the air is discharged through the roof to the street.
The task of the second element is to ensure the tightness of the pipe to the roof. The last component acts as an umbrella that protects the hole from precipitation and debris.
The ventilation duct is available with or without a valve. In the first case, there is a damper with which the pipe is closed to stop the movement of air jets. Passages without a valve have a lower cost. The first is used for industrial premises, the second - in everyday life
There are insulated and non-insulated pass-through nodes. Passages with a layer of insulation neutralize the difference between external and internal temperatures. This prevents condensation from forming inside the bore. Elements without insulation are produced for use in regions with a mild climate.
The shape of the nodes of the wire can be round, oval, rectangular, square. The choice is carried out depending on the degree of humidity in the premises, the minimum and maximum temperature indicators inside the house. They are produced from plastic or metal. The best pipe aerators are aluminum, they are resistant to corrosion and high temperatures.
The height of the ventilation pipe on the roof under the metal tile on average reaches 0.5 m, the diameter ranges from 3 to 10.5 cm. The higher the pipe, the lower the wind resistance it has, but the thrust will be stronger. Usually, a small part of it is taken out, but in regions with heavy snowfalls, they try to install the pipe as high as possible - at least 65 cm.
The best solution - when buying a ventilation outlet for a roof made of metal, is to purchase it together with the roofing material. This will guarantee 100% match of the profile of the overlay and the color.
To ensure good traction on roofs with slopes longer than 6 m, abutments protruding by 0.4 m are used. In addition to the basic elements of the roof ventilation system, additional details play an important role.
These include:
- inspection hatches, with the help of which they inspect the condition of the channels and wiring;
- continuous outlets or ridge aerators;
- lattices with which overhangs are hemmed and used in other zones of the supply and exhaust system;
- fans;
- special deflectors designed for flat skates and roofs.
Based on the design, the following types of roof ventilators are distinguished:
- Point devices. They have a mushroom-like geometry and are equipped with a fan. Designed for installation in places with limited access. In turn, point aerators are divided into ridge, installed under the ridge, and pitched, which are mounted in areas requiring increased air circulation.
- Continuous. They are placed evenly over the entire roof surface to ventilate all layers of the roofing cake, attic and attic.
To enhance the outflow of air, both ventilation pipes and aerators are equipped with turbine devices. The turbine located at the wellhead can move independently or be powered by an electric drive.
The top of the continuous ventilation ducts, as with arrangement of a roof from a profiled sheet, most often closes the ridge fan. It is complemented by a moisture-resistant ventilation tape placed above the waterproofing layer.
The self-adhesive ventilation tape consists of three strips. The side corrugated aluminum strips are equipped with a self-adhesive strip. In the center there is a tape made of non-woven material that allows water vapor to pass through, but not water itself. It is high-quality protection against snow, slanting rain, insects, dust
Metal roof fan casing is made of materials resistant to corrosion, acidic environments, UV rays, high and low temperatures. The most suitable are stainless steel and polypropylene.
Aerators as part roof ventilation with metal tiles used in all regions, regardless of climate. They have good performance parameters, tolerate temperature changes within +90 / -50⁰.
It is recommended to locate the ventilation outlets directly above the duct so as not to bend the duct, otherwise the efficiency of the air flow will be reduced.
Plastic pipes are most often used. They compare favorably with galvanized counterparts not only in aesthetic appearance, but also in a long service life.
The procedure for installing the structure
The technology of the device for the passage of ventilation through the roof on the roof with metal tiles is simple. To get the job done, you need a set of simple tools: a pencil, metal scissors, a chisel, a building level, a screwdriver or screwdriver.
At the first stage, they decide the issue with the installation site. To do this, from the inside of the roof, using a plumb line, determine the point of passage of the ventilation outlet. Then the point is transferred to the roof by measuring its coordinates vertically and horizontally, starting from the rafters.
Next, the arrangement of the site begins. The contour for fixing the lining is marked using a template that is applied to the wave crest. An about 2.5 cm wide incision is made in the metal sheet using a chisel and a hammer. By marking with scissors for metal, cut out a contour, trying to make the edges at the hole even.
The second stage begins with gaining access to waterproofing by removing a sheet of metal tile with a cut out contour for the installation of the pipe passage unit. The contour of the sealing gasket is applied to the waterproofing sheet, after which a hole is cut out in the film.
The dimensions are adjusted, the back side of the gasket is covered with glue, it is applied to the waterproofing sheet and fixed to the crate with self-tapping screws. The insulating gasket is attached directly to the waterproofing layer with clips.
If the terminal rises 0.9-1.2 m above the roof, the structure will be rather loose; it may deform during snowfalls. You need to fix it at two points at least
Install the gasket from the inside. The removed sheet is set in place. Glue is applied to a rigid pad, intended for installation from the outside, and pressed to the installation site on the metal tile. Further, they are strengthened along the entire contour with self-tapping screws. Wrap the fasteners so that each subsequent point is diagonally relative to the previous one.
After the glue has dried, the outlet of the ventilation pipe is mounted. Its body is inserted into the pass-through unit, the edges of which are smeared with sealant. They achieve a stable position, align them necessarily according to the building level.
Alignment by eye is not suitable, even if the pipe appears to be in a strictly vertical position. The pipe is also fastened with self-tapping screws, and mounted on its cut deflector. The tightness of the passage of the pipe through the roof is an important condition.
It is necessary to press the base of the passage to the roof as tightly so that excess sealant comes out from under the gasket. Every carelessness made during installation will lead to leakage through the roof.
The outlet of the chimney must be connected to the indoor air duct. Most often, this is done using a corrugated pipe stretched through all layers of the cake - steam and waterproofing, insulation. Each intersection is sealed with adhesive tape, sealant, water-repellent material for hydro-barriers.
If the chimney is directly above the house hood, it is better to use plastic pipes for joining. When they are at a certain distance from each other, corrugated products are used.
If the penetration is done correctly, it is not afraid of temperature drops, vibration, pressure exerted by atmospheric precipitation. This element is made of materials that do not corrode, do not melt under the sun's rays, and resist moisture. Most often, rubber or silicone is such a reliable barrier.
Conclusions and useful video on the topic
By watching this video, you can get additional information about ventilation of metal roofing using aerators:
Video instruction on the installation of ventilation outlets:
Video about the installation of ventilation pipes on a metal roofing:
In order for a roof made of metal tiles to serve for a long time without repairs, it is imperative to install roof ventilation. Installation of ventilation equipment does not require huge material costs. And the desire to save money will lead to serious problems in the future.
Correction of errors made during installation will also be expensive, so it is so important to take into account every nuance of installation technology.
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