Garage roof leaks often begin with the appearance of microcracks in the old roofing felt or swellings through which moisture easily penetrates into the concrete slabs. Laying technology allows you to solve the problem once and for all roofing felt or its modern analogues on a bitumen-polymer basis, such as Rubemast. This material is highly resilient and lasts up to 15 years, making it an ideal choice for flat garage roofs.
The process of restoring tightness requires strict adherence to the temperature regime and rules for preparing the base, since the final result depends on adhesion. Incorrect styling can lead to peeling of the canvas during the first frosts or, conversely, to bitumen draining in the summer heat. In this guide, we will analyze all stages of the work, from the purchase of materials to the final inspection of the seams, so that you can complete the repair efficiently and without the involvement of expensive teams.
Selection of material and calculation of the required quantity
Before starting work, you need to decide on the type of coating, since classic roofing felt on a cardboard basis is significantly inferior in durability to materials on fiberglass or fiberglass. Rubemast is a version where the base is thick cardboard or fiberglass impregnated with modified bitumen, which provides better frost resistance and flexibility. For the bottom layer of the substrate, RNP or RPP brands are usually used, and for the topcoat with a protective coating, RKP or RMK brands are used.
The number of rolls is calculated based on the roof area, with obligatory consideration of overlaps and allowance for parapets. The standard width of the web is 1 meter, and the length per roll varies from 10 to 15 meters depending on the density of the material. When calculating
In addition to the roll material itself, you will need bitumen mastic or a primer to ensure reliable adhesion to the base. Consumption primer is approximately 0.3-0.5 liters per square meter, and mastic consumption depends on the evenness of the surface and can reach 2-3 kg per square. An accurate calculation will help you avoid stopping work at the most inopportune moment due to a shortage of components.
Substrate preparation and tools
The quality of surface preparation directly affects the service life of the new roof, so special attention is paid to this stage. The old coating must be completely dismantled if it has multiple damages, or thoroughly cleaned and dried if it is decided to make repairs over the old layer. The base must be absolutely dry, free of debris, dust and oil stains, since any contamination reduces the adhesion of bitumen.
To work, you will need a specific set of tools, including a gas burner with a cylinder, a roofing knife, spatulas and a cleaning brush. It will also be an indispensable assistant roof hook, which allows you to roll out heavy rolls without constantly bending towards the ground. If the roof is concrete, cement mortar may be needed to seal cracks and smooth out slab joints.
⚠️ Attention: It is strictly forbidden to fuse the material onto a wet or frozen base. When heated, moisture will turn into steam and tear the waterproofing carpet from the inside, forming bubbles.
Before starting the main work, the surface is treated with a primer, which fills small pores and improves adhesion. It can be applied by brush, roller or spray, allowing time for complete drying, which usually takes several hours depending on the weather. Only after the surface stops sticking can you begin to fuse the first layer.
☑️ Checklist for preparing the foundation
First layer deposition technology
The first layer, often called the underlay, is installed using materials without a protective coating. The roll is rolled out over the surface, the positioning is checked and then, with one edge turned in, heating begins. The gas burner is held so that the flame simultaneously melts both the lower part of the roll and the base, forming a roll of molten bitumen in front of the edge.
The movement of the master should be smooth and progressive, while simultaneously rolling the laid area with a special roller or simply with his feet in soft shoes. It is important to squeeze out all the air from under the canvas so that there are no voids left that will become breaking points in the future. The overlap of adjacent strips should be at least 10-15 cm to ensure complete tightness of the joints.
Particular attention is paid to places adjacent to vertical surfaces, where the material must be placed on a wall or parapet to a height of 15-20 cm. Here, additional strips are often used or fillets are formed from cement mortar for a smooth transition of the corner. Qualitative fusing in these areas is critically important, since it is the corners that most often become the site of leaks.
Helpful advice: To understand that the bitumen is warmed up enough, watch for the appearance of a small roll of molten bitumen 1-2 cm wide in front of the edge of the roll. If the bitumen begins to smoke or drain too much, the flame must be reduced.
Laying the finishing layer of the roof
The second layer is laid after complete cooling and checking the quality of the first, and the direction of the strips should coincide or be perpendicular, which depends on the slope of the roof. For finishing, materials with coarse-grained topping are used, which protects the bitumen from ultraviolet radiation and mechanical damage. The laying technology is similar to the first layer, but requires greater care so as not to damage the protective layer when walking.
The seams between the top layer sheets are also carefully heated and rolled, ensuring the integrity of the coating. It is important to ensure that the joints of the upper and lower layers do not coincide, for which the second row begins with half a roll or an arbitrary indent. This is the rule seam spacing is mandatory to create a reliable waterproofing carpet.
After laying the entire canvas, it is necessary to conduct a visual inspection for bulges or poorly glued areas. All detected defects are eliminated immediately by local heating and pressing, since water bubbles left behind will sooner or later lead to rupture of the material. The finishing layer is also applied to vertical surfaces and secured with a metal clamping bar.
Comparison of methods: fusion and cold laying
The choice between the hot and cold method depends on the operating conditions of the garage and the availability of equipment. Fusion using a gas torch is the most common method, ensuring high reliability of seams due to the monolithic fusion of bitumen. However, this method requires an open flame, which is not always safe, especially near wooden structures or flammable materials.
The cold method involves the use of solvent- or water-based bitumen mastics, which are used to coat the base and edges of the canvases. This method is safer in terms of fire and allows you to work in confined spaces, but requires a longer drying time. In addition, the quality of adhesion during cold laying often depends on the cleanliness of the surface and the air temperature.
| Parameter | Fusion (hot) | For mastic (cold) |
|---|---|---|
| Work speed | High | Low (need to wait for drying) |
| Fire hazard | High | Low |
| Weather dependent | Medium (not possible in rain) | High (needs dry weather to dry) |
| Cost of work | Lower (less labor costs) | Higher (more consumables and time) |
Typical errors and coating service life
One of the most common mistakes is insufficient heating of the joints, which leads to the formation of “pockets” where water flows. Also, craftsmen often neglect to clean the base, believing that a thick layer of bitumen will hide the dust, but as a result, the entire carpet peels off from the slab. Another mistake is laying the material in cold weather, when bitumen becomes brittle and loses its elasticity when rolled out.
Service life of properly installed Rubemasta ranges from 10 to 15 years, which is 2-3 times longer than conventional roofing felt. Durability is affected not only by the quality of the material, but also by the presence of a protective coating that absorbs the impact of solar radiation. With regular inspection and timely elimination of minor defects, the roof can last longer.
⚠️ Attention: Do not walk on freshly laid roofing carpet in hot weather without special shoes with flat soles, so as not to leave dents and damage the integrity of the layer.
To extend its service life, it is recommended to inspect the roof once every 2-3 years for cracks in the places of bends and junctions. Minor damage can be repaired locally by applying a layer of bitumen mastic and gluing a patch of the same material. This preventive maintenance will help you avoid major repairs in the future.
Secrets of working with rubemast in windy weather
In strong winds, working with a gas burner is dangerous and difficult, since the flame is blown away and the canvas itself can flutter. In such cases, it is recommended to use windbreaks or switch to a cold installation method using quick-drying mastics. You can also heat the material not over its entire width at once, but in small segments, fixing them with weights until it cools.
Main conclusion: The success of repairing a garage roof depends 80% on the quality of preparation of the base and compliance with the temperature conditions during fusing, and not just on the brand of the selected material.
Frequently asked questions (FAQ)
Is it possible to glue rubemast over old roofing material?
Technically, this is possible if the old coating holds firmly, is not swollen and does not have multiple tears. However, experts still recommend removing the old layer in order to be able to inspect the condition of the concrete slabs and eliminate hidden defects in the base. Sticking a new layer over the old one increases the load on the structure and hides potential sources of destruction.
At what temperature can rubemast be laid?
The optimal air temperature for working with deposited materials is from +5°C to +25°C. At lower temperatures, bitumen becomes viscous and does not heat up well, and at too high temperatures there is a risk of overheating and dripping of the material. Work in winter is only possible with the use of hot tubs or special additives, but this is not economically feasible for a garage.
How does Rubemast differ from regular Ruberoid?
The main difference is the composition of the bitumen impregnation and the base. Rubemast contains polymer additives that increase the elasticity and heat resistance of the material, and also has a thicker bitumen layer on both sides of the base. Conventional cardboard-based roofing felt ages faster, cracks in the cold and has a shorter service life.
Is it necessary to sprinkle rubemast on top?
If you used material with a protective coating (marked “K” - coarse), then additional coating is not required. If the top layer is made of a smooth material, to protect it from ultraviolet radiation, it is recommended to apply a layer of bitumen mastic and sprinkle it with quartz sand or fine chips, or lay a layer of material with sprinkles.