When examining leaky roofs from bitumen shingles, as it is not surprising, it often turns out that most problems are not a consequence of wear or other operational damage, but the result of errors in the installation of a soft roof. Some of these flaws are difficult to correct, while others can be corrected even several years after the roof is installed.
When a customer reports a leaking roof, he often has his own (not always correct) ideas about the causes of the leaks. After listening carefully, we begin our examination with a series of clarifying questions. How long does it take for a roof to leak? Have there been leaks in this location before? How long has the roof been in use?
If a leak comes and goes over a long period, the cause is most likely due to design flaws or poor choice of materials. If the roof is 20 years old, the problem is most likely due to its disrepair. If the house is new (2-3 years), then the reason usually lies in roof installation errors. First of all, we ask you to show traces of water in the house and try to determine whether the roof is to blame. Sometimes leaks that appear to be related to the roof turn out to be problems with the sheathing of walls or windows.
Having examined the house from the inside, we go to the roof, where we narrow the search to an area with a radius of 3-4 m with the center in the area where the leak appears inside the house. Then we check the coating - assess its condition, look for punctures from nails or tree branches.
Inaccurately installed ventilation risers and chimneys, cable entries, satellite dish mounts - all this may be among the possible reasons leak. We especially carefully check valleys that are prone to leaks. If the problems lie in the valley, we replace it entirely, without even trying to do minor patching of holes.
Poorly secured flooring
The most common problem I encounter when inspecting a building. If the flooring sags, the fasteners “pull out on their own”, as a result of which protruding nail heads damage the plates soft tiles and cause leaks. However, pushing out nails is quite possible over time and on a well-made roof. When I find the problem nail, I pull it out and then replace the damaged plate.
The first row of bitumen shingles is not laid correctly
It's amazing how often I find leaks because the plate joints in the starter and first rows match. This arrangement will certainly cause leakage along the lower edge of the slope and lead to rotting of the ends of the rafters and other structural elements.
If the structure is not damaged, then the repair in this situation is simple: you need to pull out a few nails and insert them between the roof plates of the starting and first rows metal inserts, covering unprotected joints. These plates can be secured with nails or drops of sealant.
Of course, if the decking is damaged, you will first have to remove several rows of roofing plates and replace the damaged ones wooden parts, lay a waterproof membrane covering and only then restore the roof rows.
If the roofing plates are not securely fastened, the wind will lift the edges, allowing water to penetrate under the roofing. Cases of improper fastening include a lack of fasteners, their location on the plate being too high or low, and other defects. Always follow the recommended fastening pattern for the plates and fasten them “storm style” on all roofs in windy areas and on roofs with a slope greater than 10:12.
Place nails correctly. They should pass through the fastening strip directly under the adhesive strip, where they will be covered by the tabs of the next row of plates. Exposed nails are a sure way for water to enter the roof.
Leaks are often caused by defects in the roof structure, which usually arise at the design stage. Project errors include incorrect placement of gutters or valleys directing water to the walls, poor location dormer windows, illiterate choice of location for the chimney, which obstructs the flow of water, and unnecessarily intricate outlines of the roof.
It is almost impossible to correct such design flaws, since the house has already been built, but you should definitely pay close attention to areas where leaks are likely due to this.
It may seem strange, but sheets with a continuous adhesive strip can themselves cause leaks. Water, having got under a plate with a continuous adhesive strip on the side, will not be able to flow down and will move to the side until it finds an exit point, which is usually at the junction between the plates. This is where the leak starts. Valleys, chimneys, internal drains, vents are the most vulnerable places for water, allowing water to penetrate under the roof. Such leaks are very difficult to detect and eliminate their cause. Therefore, it is better not to take risks and use plates with an intermittent adhesive strip. If you must use continuous adhesive strips, make sure that the valley and chimney flashings do not direct water into areas where it can find its way under the covering.
Avoid using plates with a continuous adhesive strip. Water that gets under the plate from the side has no way out. Intermittent adhesive strips allow water to drain at each interval.
"Fracture" of the package
Some roofers do big mistake, loading the package of plates onto the roof, laying it with the bend of the package on the ridge. This can cause the plates to fracture and separate their layers, which will certainly affect the service life of the new roof.
Always place packages on a flat roof surface. And further. Because cold plates are more prone to cracking, try to avoid roofing work in cold weather except in an emergency.
Do not bend the roofing plates over the ridge. This can damage the base material and reduce the lifespan of the roof. Place packages on flat roof, and to prevent them from slipping, use a stop.
Errors in arranging connections
One of the reasons for leaks may be incorrect installed elements adjacencies. For example, if the apron covers the adhesive strip of the roofing plate, then the plate of the next (upper, above the junction, row) will not be glued to the bottom one.
|
The flashing, when a nail is driven into its top edge, lifts the bottom edge of the next row of roofing plates. An additional nail securing the bottom edge of the apron is a potential leak point |
The flashing should be positioned flush with the top edge of the roofing plate and secured with only one nail in top corner. The adjoining elements should overlap each other by approximately 5 cm |
Sometimes they try to solve this problem by moving the apron slightly upward so that its upper edge is higher than the edge of the roofing plate. When a nail is driven into the junction element, the upper edge of the roofing plate becomes a fulcrum. This causes the flashing to lift the bottom edge of the next row of roofing plate, creating a gap where water can penetrate. The roofer tries to fix this by driving a nail into the bottom edge of the flashing piece, which will not close. next row, which can also cause a leak.
The cause of many leaks is poor waterproofing chimneys. However, before fixing this problem, check the condition of the masonry and make sure that there are no loose bricks. The most common mistake when waterproofing chimneys is that roofers do not seal the apron flanges into the masonry.
The junction here should be made only from a strip curved on the machine sheet metal, strictly L-shaped in profile, carefully embedding the apron into the mortar between the rows of masonry. An abutment made without the use of bending machine, is a serious signal indicating the master’s inattention to detail. If you find a roof with poorly executed chimney insulation, immediately look for other defects nearby.
Waterproofing a chimney is a job for a professional. The interface between chimneys and roofs are potential areas for leaks. If the masons did not embed the aprons in the mortar between the rows of masonry, and the junction was made using nails and putty, this is very bad. The seams must be grooved with an angle grinder so that the apron can be securely sealed between the rows of masonry.
Leaks can easily occur due to operational damage to the roof. Television or satellite antennas, skylights and ventilation hatches cannot be installed at random, but this happens quite often.
Overgrown tree branches can also destroy the integrity of the coating, and excessive shading of the roof promotes the growth of moss on its surface, which also leads to damage to the roof.
Careless covering of valleys
One can only be surprised that most valleys do not leak, given the widespread use in roofing practice of self-adhesive waterproof films as coverings in valleys. Some inexpensive films have guarantee period Service is only 5 years. Roofing plates with a service life of 50 years on top of a film with a service life of 5 years are nonsense. The only one reliable way eliminate the leak in the valley - completely block this problem area. When repairing valleys, always use not only a waterproof film, but also a metal apron.
Repairing a valley usually means completely covering it. Starting at the top, remove one entire roofing plate from each side of the valley. Accuracy here is extremely important, since the thoroughness of dismantling the roof determines how well it can be reassembled.
Roofing with undercut plates in valleys is often done incorrectly (left). Valleys with a metal apron are reliable (right).
Removing a damaged plate without harming its undamaged neighbors is not an easy task. This work is best done when the plates are cold enough so that they do not bend underfoot, and at the same time warm enough so that they do not crack during the work. In summer, it is better to do such repairs early in the morning. In winter, such work should be avoided, except in urgent cases.
 |
Separate the glued plates in the row below and two rows above the plate to be removed. It may turn out not an easy task. Roofing plates, whose service life is up to 50 years, are glued together very firmly. In such cases, the adhesive strip will have to be cut. |
 |
Once the plates are separated from each other, the nails holding the damaged plate can be removed. |
 |
Before removing the plate, you need to pull out four more nails in a row |
 |
Now you can pull out the damaged plate, slip a new one in its place and re-fasten the previously released plates with nails. |
When attaching the repair plate, you should not drive new nails into the holes from previously pulled out ones - they will most likely be squeezed out. Hammer nails next to the old holes, and drop a little sealant into the last ones. Also seal all torn edges of the plates with sealant.
07.01.2016
If the soft roof comes in waves, this is a sure sign of a violation of the installation technology. The reason for this is a violation of the technology for laying tiles or those located under them. thermal insulation boards. The problem cannot be fixed simple repair roofing: it is necessary to completely cut off the damaged area and re-tile the tiles.
Causes of malfunctions
The cause of waves and swellings should not be sought in the tiles - they just perform the functions of a covering. Problems usually arise from the sheathing, thermal insulation or vapor barrier. For example, a common case is when the side edges and ends of insulation boards covered only on one side are damaged. Difficulties can also appear in difficult places - where the sheathing forms corners or transitions. Improper cutting of heat and vapor barrier materials can lead to the roof losing its shape.
The fact that it is broken is also indicated by swellings with a diameter of more than 1 meter. The occurrence of such air or water “bags” occurs due to the fact that the heat flow lifts water vapor to the roof, where it condenses on the materials and is absorbed into them. In winter, this is especially dangerous, because during the cold season the insulation repeatedly thaws and freezes again, as a result of which the moisture alternates between liquid and solid states, destroying the roofing carpet. Blocks of ice formed in the insulation tear it off from the base, and at the same time increase the size of the pores in the materials included in its composition.
In summer, roofing with low-quality vapor barrier is also at risk. On hot sunny days, the roof surface heats up to 80 degrees. The enclosed space, where the water droplets absorbed by the roofing carpet are located, warms up even more, so that the water turns into a vapor state. The volume of water vapor is 15-40 times greater than the volume of liquid. This is the reason for the formation of “bags” in those places where the vapor barrier is broken.
Solving roof problems
If waves on the roof are associated with damage to the insulation, it is necessary local repair roofs. To do this, the tiles are removed along with the thermal insulation and re-laid, but not on the entire roof, but only on the damaged area. The base for re-sticking the materials is thoroughly cleaned, and the thermal insulation is installed in 1 or 2 layers. The same applies to the difficulties associated with improper cutting of vapor barrier and insulation materials.
The “bags” are removed in another way: they are cut with an envelope, the corners are turned away and dried. Internal sides The corners are cleaned of dirt, greased with mastic and glued back. The cuts are wiped with a comb and covered with a patch, it is puttied and covered with a layer of mastic. Sometimes an incision is not needed: if there is only air in the “bag”, it is enough to puncture the swelling, inject 20 g of kerosene or white spirit inside, and then press the damaged area tightly.
Installation of soft bitumen shingles must be carried out in accordance with the manufacturer's instructions.
Inattentive study of technical documentation, errors when choosing materials for roofing pie, haste and the desire to save money lead to various problems, including: leaks, visual defects, and reduced service life of the coating.
Knowing the most common mistakes will help you avoid unforeseen situations and serious costs for urgent repairs.
Use of wet lumber. During the operation of the house, the board used for sheathing dries out and becomes deformed. The slope becomes uneven, which leads to shingles peeling off, water flowing in, and reduced resistance to wind loads. For need to use edged board coniferous species with humidity no more than 20%.
Laying OSB without gaps. This leads to deformation of soft tiles at the joints of OSB sheets and the formation of elevations that spoil appearance roofs. Compensation gaps prevent the sheets from pressing against each other as the temperature rises or humidity increases. The installation instructions say: “a gap of 2-3 mm should be left between the OSB sheets.”
Improper storage of underlay carpet. Bends and folds, dents and creases form on the material. As a result, the laid underlay carpet loses its ideal surface geometry. becomes more complex, it becomes more difficult to select a pattern, on the surface finished roof waves are formed. The lining carpet should be stored in an upright position at normal humidity and a temperature not exceeding +30ºС.
Laying underlay carpet at low temperatures. As the temperature rises, there is a natural change linear dimensions OSB sheets. This leads to the formation of waves on the roof made of flexible tiles. The defect is more cosmetic and may go away over time. But is it worth the risk? Manufacturers recommend at a temperature not lower than +5ºС.
Error in selection of material: thick carpet, thin tiles. This combination “reveals” all the shortcomings and flaws in the installation of the base and underlayment. Irregularities and waves appear, resulting in a decrease in the resistance of the coating to wind and mechanical loads. It is better to use soft tiles and carpet from the same manufacturer, and the thickness of the tiles should be greater.
Errors when installing wind slats. These provide a tight connection between the roof and gables of the building. Improper installation leads to water flowing under the tiles and into. The pediment planks begin to be laid from the eaves, making an overlap between adjacent elements of at least 5 cm. The planks are nailed with roofing nails in a checkerboard pattern.
Use fewer nails for fastening or nails without notches. Saving on fasteners or using nails that are not intended for fixing the roof leads to a decrease in the reliability of the roof. In this case, the shingles are easily torn off strong wind. For installation of soft tiles, 25-30 mm long with a wide head are used. There are 4 - 6 nails per shingle (depending on the angle of the roof).
Installation without using markings. Laying shingles “by eye” leads to the formation of a crooked pattern. The markings act as guides, horizontal lines applied using construction laces or using a stretched rope.
Use shingles from only one pack. This leads to the formation of a “zebra effect”, which will negatively affect the appearance of the roof. Manufacturers recommend taking one shingle from 5-6 different packs to avoid variations in color.
Installation in hot weather. At temperatures above +25ºС, the bitumen in the flexible tiles softens. This makes it difficult to move on already installed shingles, and there is a risk of damaging the shingles with shoes. Roofing It is better to carry out at a temperature of +5 - +20ºС in dry weather.
When installing flexible tiles, the use of low-quality, cheap component materials that do not comply with GOST leads to unpleasant consequences. For example, “blowing of the roof” or “appearance of waves.” In this article we would like to take a closer look at the reasons for this effect.
Example 1. Flexible bitumen shingles from European manufacturer. 3TAB shingle shape. Photo taken from a large Russian construction portal.
This problem and methods for dealing with it are well known to professionals, and we would like to once again focus on this topic in order to prevent errors during installation.
Example 2. Flexible bitumen shingles from a European manufacturer. Shingle shape Hexagon. Photo taken from a large Russian construction portal.
It is no secret that the real reason for this problem is the quality of the materials of the solid base and compliance with the technology of its installation. This conclusion is clearly confirmed by the results of studies of similar objects, as well as tests of base and roofing materials conducted by our company, studies conducted by our colleagues from the Unikma company (), as well as many foreign studies.
The most common material for making a solid base today is OSB-3.
This is due to the manufacturability of this material, attractive price and tall performance characteristics, declared by the manufacturing companies. However, it is the actual properties of this material that are the source of the problems that arise.
The reason for the formation of waves is the linear expansion of the OSB board (see Fig. 1 and Fig. 2). When delivered to the site in its original packaging, the OSB board has minimal humidity due to its manufacturing technology. Material moisture new slab significantly lower than the ambient humidity. During operation, the moisture content in the slab and the surrounding air comes into equilibrium, which leads to moistening of the OSB and linear expansion (swelling). The edges of the slab, thanks to the gaps of 3-5 mm left between the slabs, have the ability to move, which leads to the formation of “waves” on the shingles of asphalt shingles along the short (to a greater extent) and long sides of the OSB slabs.
Rice. 1 Factory humidity of OSB during installation without preliminary exposure.
Rice. 2 Actual humidity of OSB during operation.
If you doubt the quality of the product, ask the distributor for a quality certificate for the OSB board, which indicates the actual characteristics for a specific batch of products.
Installation conditions.
The formation of “waves” is less common on roofs installed in warm and humid seasons, since in such conditions OSB boards have time to acquire “equilibrium” moisture content even before installation roofing– during storage on site and installation of the base.Waves most often appear on roofs installed in cold weather (less than +5 °C), when air humidity is minimal. But they appear when the outside temperature rises along with air humidity.
When installing a roof in cold weather, we recommend pre-conditioning (conditioning) the OSB panels before installation. OSB panels should be stored outdoors for 1-2 weeks, exposed to atmospheric air, in this case it is necessary to cover the OSB panels from precipitation, and lay gaskets (slats) between the sheets to allow air access to all parts of the sheet.
The problem is aggravated by the fact that the quality of OSB boards leaves much to be desired. For example, at some sites where waves appeared, samples of OSB boards from leading manufacturers were taken and sent to an independent laboratory to be tested for the indicator “thickness swelling in 24 hours” (GOST 32567-2013 clause 5.8 table 5).
Example 3. Flexible bitumen shingles from an American manufacturer. 3TAB shingle shape. Photo taken from the American Construction Forum.
According to the test results, at least half of these samples did not comply with GOST for this indicator, and, as a result, they were unsuitable for use as a solid base. Unfortunately, absolutely all manufacturers of flexible tiles, both domestic and foreign, are faced with this phenomenon, regardless of the shape of the tile or the type of bitumen. And this once again confirms that the reason for the occurrence of “waves” lies in the foundation.
Some customers mistakenly believe that this effect is due to the quality of the shingles or underlayment themselves, blaming the manufacturer. They base their guesses on the fact that when the OSB roof is opened, the slab looks normal, i.e. it does not delaminate, does not warp, and even some of the gaps remain (only they become much smaller, but no one pays attention to this). This gives the impression quality product. But, as shown above, this is not at all the case, and it is the OSB board that is the root cause of the formation of folds on the roof.
However, there is also positive news: from the experience of observing similar roofs on which waves formed, it was noticed that these deformations disappear over time. The time period ranges from several weeks to one year and depends on the quality of the OSB board, air humidity and the organization of ventilation of the under-roof space. In addition, do not forget that this effect exclusively affects the aesthetic perception of the installed material and cannot in any way worsen the waterproofing characteristics of flexible bitumen shingles.
Example 4. Multilayer flexible bitumen shingles from Russian manufacturer. Shingle shape Dragon tooth. Photo taken from the Russian construction forum
Below we would like to present measures that will reduce the risk of waves on tiles:
- Pre-conditioning (conditioning) of OSB panels before installation. OSB panels should be stored outdoors for 1-2 weeks, exposed to atmospheric air, while it is necessary to cover the OSB panels from precipitation, and lay gaskets (slats) between the sheets to allow air access to all parts of the sheet.
- Cutting OSB sheets according to long side(2500 mm) into 0.5 meter pieces, which will reduce the linear expansion of each individual piece and reduce the formation of waves.
List of common mistakes and frequently encountered problems when installing flexible tiles
1. Laying bitumen shingles on a roof with a slope less than the maximum permissible
Such cases are characterized by frequent occurrence of leaks. They occur due to increased rain and wind loads on the joints of the shingles.
2. The length of the roofing nails is less than the thickness of the wooden base
Short nails that do not penetrate through the boardwalk gradually come out due to the natural deformation of wood under the influence of humidity and temperature.
3. Fastening with staples
– soft material, so some believe that it can be attached to the slope using construction stapler. However, this tool is not suitable for this operation. The depth and uniformity of driving staples will depend on the hardness and uniformity of the wood layers, which may differ significantly depending on the different areas. Because of this, according to the experience of Stroymet engineers, it is impossible to ensure a tight, uniform fit of the tiles to the base.
4. Low level ventilation of the under-roof space
Accumulation of water vapor and condensation on wood and metal structures leads to their gradual destruction.
5. No vapor barrier
It causes moisture to enter other elements of the roofing pie, significantly worsening their performance characteristics.
6. Laying a solid base is done without gaps
Due to the swelling of wood in wet weather, the surface of the flooring becomes uneven and can be damaged. This not only reduces the level of tightness of the flexible tiles and the roof as a whole, but also deteriorates the appearance of the roof.
7. Shingles will not stick to underlayment or valley carpet.
This causes serious leaks of flexible tiles during rains and during snow melting.
8. The solid base is made of boards or sheet materials of insufficient thickness. There are no supports under the joint lines of the boards
It is dangerous to move along the slope; the base may not support the weight of workers installing flexible tiles, as well as the snow load.
9. Leaky connections to vertical elements(for example, chimneys)
Lead to regular occurrence of leaks.
10. The shingles are secured with roofing nails along the top edge
This prevents the fastener from reaching the previous shingle below. The joint area becomes especially vulnerable to wind loads.
Common misconceptions when installing soft roofs
- Roofing nails should not be pierced wooden base through.
- A solid base should be installed without gaps.
- For normal ventilation of the under-roof space, the gaps in the eaves overhang area are sufficient.
- The use of vapor barrier materials when installing a soft roof is not mandatory.
- Soft roofing can be used on roofs with any slope.
ALL OF THE STATEMENTS LISTED ARE ERRORAL!
