Metal tile or corrugated board is an excellent durable material that creates a reliable coating for any structure. But the metal roof has a drawback - it does not allow air to pass through, as shingles do. In this regard, it is necessary to provide measures for ventilation of the under-roof space: special ventilation outlets for metal tiles are made on the roof, resembling a short chimney. If we neglect these devices, condensation accumulates under the roof, destroying the rafters and deteriorating the properties of the insulation.
A competently constructed metal roofing will last for many years if moisture is removed from under it. But if the roofing sheet is laid correctly, where does the moisture come from?
Moisture under the roof
A person in the process of vital activity releases a lot of moisture in the form of vapors: when breathing, bathing, washing dishes and cooking. The vapors rush upward, penetrate the ceilings and linger in the insulation layer under the roof. Some owners cover the bottom of the insulation with a layer of plastic film, protecting the roof. So all the moisture remains in the living quarters, which is also very bad. Sometimes the problem is partially solved by venting through the wall.
Another source of moisture under the roof is condensation. In winter, warmth from the house penetrates into the attic, so warm air comes into contact with the icy metal surface and "dew" falls out.
Moisture in the under-roof space is dangerous:
- Wooden rafters, when wet, deform, mold and dry out. Stronger destructive effect if the rafter system is not covered with an antiseptic;
- The insulating layer ceases to insulate and perfectly conducts heat or moisture;
- In winter, the metal from below warms up and the snow on the roof melts, freezes and melts again. The load on timber structures is increasing;
- Moisture can cause metal to rust. After all, it is impossible to cover the roof without damaging the coating of the sheets.
All these troubles recede when roof ventilation is equipped with ventilation outlets.
Ventilation of the roof space
Roof ventilation is organized in a continuous or pointwise manner. With any of them, air enters under the roof from below, into the eaves, passes under the entire roof area and goes outside together with water vapor and heat.
In the first case, through the ridge duct (continuous ventilation outlets), in the second, through isolated ventilation outlets (point). Some owners fear that precipitation will fall on the walls and ceilings through the ventilation outlets. In vain, the design of point aerators completely eliminates this possibility.
Air movement in the under-roof space solves a number of problems:
- Water vapor is evacuated into the roofing cake from the house;
- The metal tile cools down, preventing snow melting in winter and the appearance of icicles and ice blocks;
- In summer, the roof does not overheat in the sun.
The advantage of using point ventilation outlets is that they can be installed on a completely finished roof. Whereas the cornice vents are equipped directly during the construction of the roof.
Insulated ventilation outlets are located as close to the roof edge as possible.There are several types of aerators, their size and number depends on the area and material of the roof.
Selection of ventilation outputs
If the roof area does not exceed 60 sq. meters, it has a hip or gable shape and is covered with metal tiles, a single ventilation outlet is enough.
The larger the roof area, the more ventilation outlets are needed.
With a complex roof shape with several ribs, ventilation outlets for metal tiles are installed at each rib. The location is determined by the owner of the house or the architect.
The basic rule: from the ridge to the ventilation outlet with a hood should be no more than 0.6 meters.
However, it is not advisable to install more than one ventilation outlet on each sheet of metal tile or corrugated board, so as not to unnecessarily damage the roofing.
There are many options for ventilation outlets for profiled sheet and metal tiles on sale. Although the principle of operation of all types of isolated ventilation outlets is the same, there are slight differences in designs from different manufacturers, fasteners and equipment.
When choosing a ventilation outlet for a profiled sheet or metal tile, you must consider:
- The profile of the ventilation outlet with the hood must match the profile of the roof covering;
- Temperature drops for which the ventilation output for corrugated board is designed;
- Equipment. The set should include: the point output itself, the installation manual, template, fasteners, overlays. It is also important to have a passage element, otherwise it will be very difficult to do the work accurately. Some manufacturers do not supply a pass-through;
- Diameter of the ventilation outlet with a hood. It is directly proportional to the roof area. To save money, on roofs of complex shapes with a large number of attics, ventilation outlets to the roof are made of pipes of the smallest diameter;
- The color of the spot element is selected depending on the color of the roof and the house;
- Availability of additional functions that enhance air exchange (fan) or facilitate installation (built-in level).
Ventilation outlet installation
Before installing ventilation outlets on a roof made of profiled sheet or metal tiles, purchase tools and consumables:
- scissors and a hacksaw for metal;
- drill and screwdriver;
- marker;
- construction level.
To make the ventilation outlet to the roof airtight, you need a silicone sealant.
Before starting work, make sure that there is a passage element again.
It is most convenient to purchase an already fully equipped ventilation outlet, for example, from Wirplast or TechnoNIKOL. Read the instructions for your model carefully.
Work progress
The first step is to make a hole in the roof. The passage through the roof is one of the most important moments in the installation of a ventilation outlet for corrugated board. The quality of the passage determines whether the roof leaks at the installation site of the Wirplast ventilation outlet, whether the factory coating of the metal is broken and whether rust appears.
Next, it is necessary to install the pipe tightly so that air only escapes through it, and moisture does not penetrate into the cracks. The device of the TechnoNIKOL d110 ventilation outlet is such that, with proper installation and assembly, a reliable structure is created that meets all the requirements.
- The kit includes a template that is applied to the roof in the place where the Wirplast ventilation outlet is planned. The template is outlined with a marker;
- With a drill, holes are made along the line as close to each other as possible;
- With metal scissors (you can use a hacksaw), a hole is cut out that matches the template. You cannot use a grinder! Sparks and heat destroy the polymer layer of the metal tile, creating places for corrosion;
- The passage element is installed in accordance with the instructions for it;
- The place where the pipe passes through the roof is coated with sealant, after which an O-ring is put on. It is screwed in with screws. The TechnoNIKOL ventilation outlet is inserted into the O-ring in accordance with the latches;
- In order for the upper casing of the passage element to rigidly hold the pipe, it is trimmed, leaving an opening one quarter smaller than the pipe diameter. Some manufacturers pre-assemble the pass-through, delivering it ready for installation;
- Before rigidly screwing the pipe, check the vertical with a building level;
- Decorative and protective elements are attached.
Now, from the bottom, from the attic, view the accuracy of the installation and seal all the broken layers of the roofing cake with a sealant.
When installing the TechnoNIKOL d110 ventilation outlet or any other model, do not forget:
- Carefully follow the sequence indicated in the instructions;
- Work carefully and do not rush.
Once you have installed a ventilation outlet through the roof, you can independently make a ventilation outlet for the metal tiles of the house and antennas through the walls. Do not forget that the duration of the roof operation depends, among other things, on the quality of installation of ventilation outlets and pipes.
A video about the installation of the passage element will help to make all the work without errors.
