When planning the installation of a pitched roof, you most likely wondered why ventilation of the roof ridge is needed. Surely they decided how best to do it. We found out whether the technology of the arrangement depends on the type of roofing.
Only properly arranged ventilation in the area of the ridge ridge will ensure complete drainage of the roofing cake. The air currents formed by it will divert fumes from the insulation, while maintaining the height of its insulating qualities. The blowing will prevent condensation on the wooden elements and their destruction.
In the article we will talk about what options for ventilation of the ridge exist. We will acquaint with the solutions offered by manufacturers, we will give examples of self-made structures.
The content of the article:
- What are the functions of ridge ventilation?
- Preparing to install a ventilated ridge
-
Ridge ventilation manufacturing options
- Installation of a ridge on corrugated roofs
- Installation of a ridge on a flexible tile
- Installation of ridge aerators
- Consequences of poor or no ventilation
- Conclusions and useful video on the topic
What are the functions of ridge ventilation?
A ridge is a horizontal element that connects two roof slopes at their top. Despite the apparent simplicity, in order to ensure a long service life of the roof, this element must perform two functions at once:
- Prevent the penetration of precipitation, insects and birds into the roof structure;
- Allow steam and humid air to escape freely from under the roof to the street.
If the task of protecting the roof from precipitation and foreign objects is obvious, and most developers perform it, then many manage to forget about the ventilation of the ridge.
Ignoring the requirement for ventilation of the ridge can lead to the most serious consequences, up to the need for a complete roof reconstruction.
The fact is that even with a well-executed vapor barrier of insulated slopes or an attic floor, warm air and steam gradually enter the under-roof space from the house. Further, warm air and steam rise up to the roof vault, which is covered with a ridge.
If, having reached the ridge, this air meets an obstacle and cannot go out into the street, then it will cool down and begin to collect in large drops. The water in the insulation halves its ability to resist heat waves. Puddles on the floor will at least turn into a favorable environment for mold and other putrefactive microorganisms.
Warm, moisture-laden air cannot leave the attic. Because of this, it condenses on the rafter system, causing it to get wet. Also, excess heat in the attic leads to melting snow on the roof and leaks.
This process will be repeated endlessly, and will lead to excessive moisture in the roofing system and in the space limited by the roof, its wooden structures and insulation getting wet.
The inevitable consequences of working in this mode is the defeat of wooden structures with blue rot and black mold, metal fasteners - with rust. The result will be a loss of bearing capacity and subsequent failure.
Even if you think that the ventilation of the roof in your house is done correctly, still periodically check the condition of the roof structures in order to take additional ventilation measures at the right time and avoid heavy consequences
To prevent such a scenario, the skate must provide free ventilation. To do this, it must have holes through which air from the roof space will be removed to the street.
If good ridge ventilation is provided for the roof, then the situation is quite different.
Two types of ventilation flows are unloaded through the ridge rib. Firstly, due to temperature changes, there is a constant movement of air inside the roof from the eaves to the ridge. Secondly, air and moisture from the room gradually penetrate the roof through the attic floor and also rise to the ridge.
Warm air currents that have entered the under-roof space in various ways rise into the very top to the ridge and without encountering resistance on their way, they freely go out, taking with them the excess moisture. Thus, a comfortable regime is provided for the roof, and the risk of the insulation getting wet and fungus contamination of the wood is minimized.
Preparing to install a ventilated ridge
There are several options for a ventilated ridge device, which will be discussed below. But in order for any of these methods to work, two important conditions must be fulfilled even at the stage of installing the roof slopes.
Firstly, no matter what material the roof is made of, to ensure ridge ventilation, it is necessary to leave a gap between the slopes with a width of 5-10 cm. This space is necessary for the free flow of air from the under-roof space to the ridge and ventilation openings.
In order to make the optimal gap between the slopes, read the instructions of the ridge element manufacturer. If the gap is made too large, then the ridge element may not cover it enough and precipitation will begin to enter the roof.
Secondly, if you used a waterproofing film when installing the roof, then in the area of the ridge this membrane should also have a longitudinal rupture with a width of 5-10 cm. It is not necessary to leave this gap when using a waterproofing membrane. this material is able to pass moisture out through the pores.
Air from the attic, through a gap in the waterproofing, enters under the ridge and through the holes with a seal goes out into the street. If there is no such gap, then the air will not be able to go out to the ridge and will remain in the attic.
Compliance with these two rules is a prerequisite for the operation of ridge ventilation.
Ridge ventilation manufacturing options
Roofing materials abound in variety. Each of them, be it metal, ceramic or soft tiles, corrugated board, slate or ondulin, have their own characteristics. The roof structures assembled for different materials differ from each other. Therefore, the design of the skates and the way of organizing their ventilation also differ.
Depending on the roofing material and the personal preferences of the developer, three types of ridge ventilation are usually used:
- Ventilated ridge on corrugated roofs;
- Ventilated roof ridge made of soft tiles;
- Ridge ventilation with universal aerators with conventional or pipe deflectors.
All of these ventilation methods work effectively. And even amateurs can perform any kind of ridge ventilation.
Installation of a ridge on corrugated roofs
This method of ridge ventilation is the simplest and cheapest.
The fact is that roofs made of metal profiles, metal and ceramic tiles, slate and ondulin have a wavy shape. Due to this, gaps are formed between the roofing material and the ridge strip, through which air from under the roof can freely escape.
By simply installing the ridge bar on metal or any other material with a wave-shaped cross-section, you will provide the necessary clearances for air to escape from the attic to the street.
Therefore, for a roof made of such materials, the installation of a ventilation ridge can be performed in just two stages:
- install a seal or special ridge tape;
- fix the ridge bar over the seal.
The sealant and tape keep snow, dry leaves, insects or birds out of the roof. This is especially true if the roof is flat, that is, it has a small angle of inclination or is located in an area with frequent winds.
Thanks to the wide range, today you can choose the right seal for any shape of roofing material. When choosing a seal, it is better to give preference to the profile type, since it adheres more tightly to the material and allows air to pass through better
Structurally, the tape and the seal are strips of porous materials that allow air to pass through well, but retain small objects. The seal and tape have an adhesive layer for firm attachment and elimination of gaps.
When buying a ribbon, make sure it is wide enough to fit your skate. When installing the tape, stick it securely to the roofing material to exclude the penetration of foreign objects
It should be noted that sealing roofing tapes began to be used in domestic individual construction relatively recently. However, their installation is not a prerequisite. However, they perfectly protect the under-roof space from dust, while at the same time they do not in any way affect the speed and volume of flows coming out through them.
In the case when the gap between the slopes overlaps with a wide ridge strip with a large margin, there is practically no probability of rain or snow falling under the ridge even without seals.
He will acquaint with all the intricacies of the roof ventilation device with a metal roofing next article, which we recommend to read to the owners of summer cottages and country estates.
Installation of a ridge on a flexible tile
The roof, made of shingles, is absolutely flat, therefore, if you simply fix the ridge elements on it, then there will be no ventilation gaps, as on corrugated roofs.
The process of making a blind, non-ventilated ridge on a roof made of soft tiles impresses with its simplicity. However, it is better to opt for a ventilated ridge. This will save you from serious problems in the future.
If the ridge tiles of the shingles hermetically close the gap that is left between the slopes for ventilation, ventilation outlets are chosen at the top of the pediment. Most often, these are small openings above the girders of the pitched roof or gable windows located below.
For the manufacture of a ventilated ridge on the roof of a flexible tile, it is necessary to install an aeration structure that forms a longitudinal gap between the plane of the slope and the ridge.
This small element will hardly increase the installation time of the roof. However, it will provide reliable ventilation and prevent harmful consequences.
There are two options for constructing a ventilated ridge structure:
- Installation on the ridge of a factory aerator;
- Making a ventilated skate with your own hands.
Both methods are simple and guarantee an excellent roof appearance with an equipped and beautifully designed roof. Installing a ridge aerator is a great way to save time on installation work and, by default, will provide protection against foreign objects falling under the roof.
There are many options for ridge aerators from various manufacturers on the construction market. However, the principle of their design is similar: the aerator is a plastic structure that creates a gap for air to escape. On the street side, the aerator is equipped with a mesh that prevents insects and birds from entering.
When choosing a ridge aerator for soft tiles, check the manufacturer's recommendations. This will help you find the width and height of the aerator suitable for your roof, prevent precipitation and foreign objects from entering the roof.
Depending on the needs of the developer, the ridge aerators provide a different level of protection against the penetration of foreign objects and precipitation under the roof. The smaller the cells in the mesh or grate of the aerator, the smaller the particle size they let through.
In some aerators, in addition to coarse meshes, sealing strips are also installed, which completely exclude the possibility of anything getting under the roof.
When performing work, ensure that the ridge is firmly attached to the roof, as it is exposed to strong wind loads
The installation of such a ridge aerator does not cause difficulties and takes place in three stages:
- Before laying the shingles along the ridge line, the sheathing is reinforced. Usually a board is used here if all the slopes are equipped with OSB boards. If the crate was made with a board, then it is placed along the ridge ridge without gaps. A waterproofing carpet is laid on top.
- The ridge on nails or self-tapping screws is fixed to a board laid along the slopes;
- Tiles are fixed on top of the ridge in the usual way.
The prefabricated ridge has a long service life and guarantees good ventilation.
You can make a ventilated ridge with your own hands, if for some reason you do not want to use a factory-made ridge aerator.
If you carefully treat the work, then from the ground it will be impossible to distinguish a homemade roofing aerator from a factory one.
For the independent manufacture of a ventilated ridge, you will need the same materials that were used in the construction of the roof itself:
- Lattices from a bar 50 × 50 mm;
- OSB or plywood;
- Flexible shingles designed for the construction of the ridge. You can buy it ready for installation or cut it yourself from ordinary shingles;
- Galvanized roofing nails.
If desired, to protect against snow, insects and birds, it is necessary to purchase a cornice or some other net.
If you decide to make a ventilated ridge yourself, then be sure to take into account the amount of materials required for it when calculating and ordering a roof
First of all, we fix the laths in the upper part of the slopes above the rafters. The length of the bar depends on the angle of inclination of the roof: the smaller the angle, the longer the lathing elements should be made to prevent rain from falling in bad weather. In normal cases, a length of 50 cm will be sufficient. Excessive increase in the length of the crate and ridge elements will impede air circulation.
We attach a cornice mesh of the appropriate height to the ends of the bar.
Next, on the block we install the base under the shingles made of OSB or plywood, on top of which we fix the shingles in the usual way.
Homemade ventilated roof ridge made of flexible tiles can be both double-sided and one-sided. If you want that the ventilation gap is not visible from the front side of the roof, then install a one-sided ridge with a ventilation gap on the opposite side
The ridge ventilation made in this way will harmoniously repeat the appearance of the roof and will not require serious skills and financial costs.
Installation of ridge aerators
There are situations when a ventilated ridge cannot be installed. For example, on roofs with a small angle of inclination, the snow cap does not come off and can overlap the ridge, completely stopping ventilation. In areas with snow and strong winds, snow can blow under the ventilated ridge.
Also, during operation, it may turn out that the ventilated ridge is not efficient enough. In these cases, the best option is to install universal deflector aerators on the ridge.
Do-it-yourself installation of roofing aerators is not difficult. You just need to follow the manufacturer's recommendations
The roof aerator can be installed in any type of ridge element. It can be used as the main element of the ridge ventilation (with a blind ridge), as well as in addition to the existing ridge ventilation.
The advantages of this solution are:
- It is excluded that precipitation and other foreign objects get under the roof;
- The ability to use on roofs with a slight slope, on which snow accumulates;
- Providing additional traction.
Unlike the ridge aerator, which expels air evenly along the entire length of the ridge, the ramp aerator provides spot ventilation. Therefore, when using it, it is necessary to ensure that there are no obstacles to the movement of air towards it along the ridge. This can be done by sawing the upper parts of the rafters 5-7 cm parallel to the ground.
If your roof has a long ridge and slopes of a large area, then it is better to install several ridge aerators so that there are no zones of stagnant air under the ridge.
Manufacturers offer an excellent selection of ridge aerators as well as turbine or conventional ventilation ducts. ventilation deflectors. They are suitable for all types of roofing, so choosing the right one for you is easy.
Consequences of poor or no ventilation
Concluding the topic, one cannot but touch upon the troubles that the absence or ineffective operation of ridge ventilation can lead to. At the beginning of this article, it was already mentioned that the consequences of improperly organized ventilation can be quite serious, up to a complete replacement of the roof.
Of course, in order to bring the situation to such a state, it is necessary to seriously violate the rules for constructing ceilings and roofs, or to ignore ventilation problems for a long time. However, the likelihood of running into trouble is still great.
First of all, problems with the ventilation of the roof lead to an increase in humidity and moisture condensation on the elements of the roof. In winter, moisture condenses on the roof structures and turns into frost, which, when it thaws, melts and turns into water.
Having melted, this frost will wet the rafter system and get into the insulation. The consequence will be a decrease in the effectiveness of thermal insulation and the resettlement of putrefactive microorganisms
The consequences of this phenomenon are the most unpleasant and destructive:
- Wet wooden structures are affected by a fungus and gradually collapse;
- Metal fasteners begin to rust and lose strength;
- Condensate dripping from the roof structures onto the insulation of the floor or attic penetrates into it, nullifying the thermal insulation properties.
The second common type of negative consequences from improper installation of the ridge bar or ridge aerator, or the absence of a sealant in them - this is the ingress of strangers into the roof structure items.
In windy weather, rain or snow can penetrate into the under-roof space, leading to wetting of the elements of the roof or insulation.
Install the ventilated ridge so that the ridge strip reliably and with a margin overlaps the gap between the slopes in the upper part of the roof
In the absence of a ridge seal or tape, birds can enter the attic. They can build nests there and annoy them with constant noises, or they can pick out and pull out insulation for the construction of their nests.
When deciding to install a ridge element without a seal or tape, observe or ask your neighbors about how many small birds are in this area
Another dangerous consequence of the lack of ridge ventilation can be the formation of an ice dam (congestion) on the roof. This phenomenon is inherent in poorly insulated roofs with a slight slope that traps snow on themselves, or in the presence of snow guards installed on the cornices.
The reasons for the formation of an ice block are too high air temperature under the roof due to heat leaks and lack of ventilation. As a result, the snow above the attic is constantly melting and rolling down. At the same time, on the eaves, under which there is no warm attic, the snow does not melt and retains the water coming from above. Gradually, a dangerous build-up of snow, water and ice forms on the cornice.
This phenomenon is especially dangerous if people walk under the cornice, because falling icicles and ice can cause irreparable harm.
It should also be noted that ridge ventilation is only an integral element in the ventilation of the roof and attic and, in fact, is an exhaust hood. Based on this, for its normal operation, it is required to ensure the flow of air under the roof, for example, through the eaves.
If we neglect this, then in the absence of the necessary air flow, even ideally made ridge ventilation there will simply be nothing to pull out into the street, and water vapor will continue to accumulate in the roof structure and destroy her.
In addition, when arranging ridge ventilation, one should not forget about installing a vapor barrier for the ceiling and insulated attic slopes, they will protect insulated structures from household vapors. In cold roofs, steam barriers are not used. Waterproofing is required to protect both insulated and cold roofs from atmospheric water.
Dormer and gable windows are also a mandatory component of roof ventilation. The first ones are built on hip and hip roof types, the second - on single-slope, gable and broken ones. In addition to them, as an addition, they mount ventilation valves with or without fans, vents and other devices.
Conclusions and useful video on the topic
The video shows how to independently make a ventilated roof ridge from flexible shingles:
Video of installing a ridge with a sealant on a metal tile:
Installation of a ridge aerator with a deflector:
Installing a blind ridge and ridge aerator on a shingle roof:
Video about the causes of condensation in the attic and the need for ventilation:
Ridge ventilation is an important element in extending the life of roof structures. At the same time, thanks to various design options and a wide selection of finished products, you can make or install ventilation yourself.
The main thing is to choose the right type of ridge ventilation for your roof.
Please write your comments in the form below. Tell us about how your roof is ventilated through the ridge. It is possible that your recommendations and the information you provide will be very useful to site visitors.
