Every car owner sooner or later faces the need to repair a garage cover, especially when it is old roofing felt begins to crack and let moisture through. Traditional bitumen material has been the standard for many years, but modern technology offers more durable and easier-to-install solutions. The choice of alternative often depends on the type of roof structure, budget and skill of the roofer.
Replacing the cover is not just an expense on materials, but also an investment in the safety of the car and the tools stored inside. If you are looking for how to cover a garage roof instead of roofing felt inexpensively, it is worth paying attention to weld-on membranes, liquid rubber and modern polymer mastics. These materials provide better tightness and last much longer than classic cardboard with bitumen.
In this article we will analyze in detail the characteristics of popular budget materials, compare their costs and consider installation technology. You will learn how to prepare the foundation and what tools are needed for quality repairs so that you can forget about leaks for many years.
Why roofing felt is no longer an ideal choice
Classic roofing felt is made from roofing cardboard impregnated with bitumen. Its main disadvantage is hygroscopicity of the base: cardboard absorbs moisture, swells and breaks down when temperature changes occur. The service life of such coating rarely exceeds 5 years, after which complete dismantling and new installation is required.
Modern analogues do not have this drawback, since they are based on fiberglass, fiberglass or polyester. These materials do not rot, are highly elastic and better tolerate ultraviolet radiation. The use of outdated technologies often results in the roof requiring intervention again after two seasons.
⚠️ Attention: When choosing a material, be sure to take into account the angle of the slope. Flat roofs (less than 3 degrees) require materials with increased water resistance and the absence of joints, while for pitched structures appearance and wind resistance are important.
Another factor in abandoning the old roofing felt is the complexity of its installation. For high-quality installation, an open fire is required, which creates a fire risk, especially on wooden bases. New materials often make it possible to do without the use of gas burners, which simplifies the process and increases work safety.
Fused materials: glass insulation and uniflex
The closest and most logical replacement for conventional roofing felt are fiberglass-based materials, such as Stekloizol, Uniflex or Bikrost. They belong to the class of fused roofing, but differ radically in their service life, which can reach 15–20 years. The basis here is not cardboard, but fiberglass, which is not subject to rotting.
Installation of such canvases is carried out by fusing using a gas torch. The bottom layer of bitumen melts, providing monolithic adhesion to the base. This creates absolutely sealed carpet, which eliminates leaks even in places adjacent to walls. It is important to work carefully so as not to burn the material.
For a garage, the best choice would be material with markings K (coarse sprinkle on top) for the top layer and P (film) for the bottom layer of the lining. The use of a backing layer increases the overall thickness of the coating and its reliability.
- ✅ High tensile strength thanks to the glass base.
- ✅ Possibility of laying in one or two layers depending on the climate.
- ✅ Resistance to temperature changes from -40 to +80 degrees.
- ✅ Affordable price, comparable to high-quality roofing material.
Before fusing, be sure to heat the surface of the base with a gas burner to remove residual moisture and dust - this guarantees perfect adhesion of the first layer.
It is worth noting that working with deposited materials requires a certain skill. Overheating leads to bitumen dripping and loss of elasticity, and underheating leads to a lack of adhesion. Therefore, if you are taking on work for the first time, practice on a small area.
Liquid rubber and bitumen mastics
If your garage roof has a complex geometry, many pipes, antennas or connections, the best solution would be liquid rubber or polymer-bitumen mastic. This material is applied in liquid form and, after drying, forms a monolithic elastic coating that completely follows the contours of the surface.
The main advantage of the technology is the absence of seams. Traditional rolled materials always have joints, which over time can become a weak point. Liquid rubber fills all microcracks and pores, creating a “second skin” effect. It can be applied with a brush, roller or spray method.
For the garage, two-component compositions are often used, which are mixed immediately before use, or one-component, ready-to-use. Particular attention should be paid to preparing the base: it must be dry and grease-free.
| Parameter | Liquid rubber | Bitumen mastic | Ruberoid |
|---|---|---|---|
| Service life | up to 20 years | 10-15 years | 5-7 years |
| Installation | Application by brush/roller | Application with a spatula | Deposition |
| Tightness | 100% (monolith) | High | Depends on the joints |
| Difficulty | Low | Low | Average |
When working with liquid compounds, it is important to observe the temperature regime. Most mastics require an air temperature of at least +5 degrees and dry weather. A wet base will cause the coating to peel off within a short time.
☑️ Preparation for applying liquid rubber
Polymer membranes and PVC coatings
Polymer membranes are a more modern and technologically advanced class of materials, which are gradually replacing bitumen analogues. They are made from PVC (polyvinyl chloride), EPDM (synthetic rubber) or TPO (thermoplastic olefins). Such coatings are characterized by incredible durability and resistance to aggressive environments.
The main difference from roofing felt is the installation method. Membranes do not require open flame; their joints are welded with hot air using a special hair dryer or glued with double-sided tapes. This makes the process safe and allows you to work even in conditions where the use of fire is prohibited.
The materials are highly reflective, which helps reduce heat inside the garage in the summer. They are elastic, do not crack in the cold and can stretch without breaking, compensating for movements of the building structure.
Although the initial cost of a polymer membrane may seem higher than that of roofing felt, its service life (up to 50 years for some types) fully pays for the investment. For a co-op garage, this could be a great collective solution.
⚠️ Attention: When choosing a PVC membrane, avoid contact with bituminous materials and oils. Plasticizers contained in bitumen can react with PVC, destroying its structure. Use a separation layer.
Budget options: corrugated sheets and slate
If the pitched roof structure allows, rigid sheet materials will be an excellent alternative to a soft roof. Corrugated sheet (profiled sheet) is galvanized steel with a polymer coating. It is durable, easy to install and lasts for decades.
Slate (asbestos-cement or modern euro-slate Ondulin) also remains a popular choice. Classic slate is heavy and fragile, but cheap. Ondulin lighter, easier to cut and does not rust, although less resistant to fading in the sun.
When choosing hard coverings, you need to make sure that the rafter system can withstand the load, especially in winter, taking into account snow. For corrugated sheeting, the correct spacing of the sheathing and the use of special self-tapping screws with rubber washers are important.
- 🔨 Profiled sheeting does not require a continuous sheathing, rather sparse.
- 🔨 Slate perfectly absorbs the noise of rain, unlike metal.
- 🔨 Both materials allow you to organize natural ventilation of the under-roof space.
- 🔨 Installation is possible at any time of the year, regardless of temperature.
The secret to the durability of corrugated sheets
The most vulnerable point of corrugated sheeting is the places of cuts and holes for self-tapping screws. Be sure to treat them with a zinc-containing primer or special mastic immediately after installation to prevent corrosion at the ends.
Foundation preparation technology
Regardless of what you decide to cover your roof with instead of roofing felt, 80% of success depends on the quality of the preparation of the base. The old covering must be dismantled or, in the case of a soft roof, thoroughly cleaned and leveled. The presence of swelling and bubbles is unacceptable.
The surface must be smooth, dry and clean. To do this, use brooms, compressors to blow out dust and construction hair dryers to remove moisture from the pores of concrete. If the base is concrete, a device is often required cement-sand screed with a slope for drainage.
A mandatory step is priming the surface with a primer. This is a bitumen solution that removes dust from the base and improves the adhesion (adhesion) of the base material. Neglecting this step will lead to peeling of the coating in the first season.
Primer consumption: approximately 0.3-0.5 liters per 1 m² of surface.After the primer has dried (usually 2–4 hours), you can begin the main work. It is important to ensure that no dust or moisture gets on the prepared surface before laying the finishing layer.
High-quality preparation of the base is more important than the choice of expensive material. Laying a new coating over blisters or dust will negate all the effort and expense.
Comparative analysis of material costs
When planning your budget, it is important to take into account not only the price per square meter of material, but also the cost of related products: gas cylinders, primer, fasteners, as well as labor costs. Cheap material may require double installation or frequent repairs.
Welded materials type Bikrost remain leaders in terms of price-quality ratio for flat roofs. Liquid rubber offers ease of application on complex surfaces, but requires more expensive chemicals. Corrugated sheeting is more expensive to purchase, but lasts the longest.
It is worth saving wisely: using the cheapest cardboard with bitumen will lead to the fact that after 3 years the procedure will have to be repeated. Investment in glass-based material will pay off due to the absence of repairs.
What material is best to choose for a wooden garage roof?
For a wooden base (solid flooring made of boards or OSB), it is strictly forbidden to use weld-on materials with open fire. The best choice would be Ondulinwhich is nailed, or liquid rubber, applied cold. Corrugated sheeting is also suitable, but you will need a high-quality waterproofing substrate.
Is it possible to put new material directly on old roofing felt?
Technically, this is possible if the old coating holds firmly and does not have swelling or moisture underneath. However, experts recommend complete dismantling. A multi-layer “pie” creates excess load on the structure and hides base defects that may appear later. In addition, the adhesion of a new layer to old bitumen is always lower than to prepared concrete.
How to calculate the number of rolls per roof?
The area of one standard roll (10x1 m) is 10 m². However, when calculating, it is necessary to take into account overlaps (usually 8–10 cm in length and width). The actual useful area of the roll is reduced to 7.5–8 m². Also add 5-10% allowance for trimming and joining walls.
What to do if it rains during work?
If you use a built-up material, rain is fatal - water will get under the bitumen and when heated, it will turn into steam, creating bubbles. Work will have to be stopped and the surface dried. Liquid rubber and mastics should also not be applied to a wet base. The only option is to have thick plastic film on hand to quickly cover the area, but it is better to monitor the weather forecast.