Choosing a roofing covering for a garage is a task that requires a balanced approach, since the safety of your car and tools directly depends on the quality of the materials. The garage roof is constantly exposed to aggressive environmental influences: ultraviolet radiation, temperature changes, snow load and chemical reagents. The wrong choice can lead to leaks within a couple of years, which will require expensive repairs.
The modern construction market offers a wide range of solutions, from classic bitumen materials to modern polymer membranes. Durability of the design depends not only on the price, but also on the compliance of the type of roof with the angle of inclination of the slope and the quality of installation. In this article we will look in detail at the best way to cover the roof in order to forget about repairs for many years.
Criteria for choosing roofing material
Before purchasing materials, it is necessary to conduct a thorough analysis of operating conditions. Snow load Your region dictates strength requirements, and climatic conditions influence the choice of heat resistance. For example, in southern latitudes, resistance to ultraviolet radiation becomes a priority, and in northern latitudes, frost resistance and elasticity at low temperatures become a priority.
An equally important parameter is slope angle. For flat roofs with an angle of up to 5 degrees, only fused rolled materials forming a monolithic carpet are suitable. For steeper slopes, you can use sheet coverings such as metal tiles or slate, which effectively drain water by gravity.
Budget is also a factor, but skimping on waterproofing often ends up costing you double down the line. Leak repair may cost more than the initial installation of a high-quality, albeit more expensive, coating. Also take into account the weight of the structure if the garage is already built and is not designed for a heavy roof.
⚠️ Attention: Never use materials intended exclusively for flat roofs on slopes with a large angle without additional fixation, as there is a high risk of the coating slipping.
Rolled bitumen and polymer coatings
The traditional and most common answer to the question “how to cover a roof” remains bitumen-based roll materials. Ruberoid is a classic of the genre, affordable, but requires installation in several layers (usually 2-3) to ensure tightness. Modern analogues such as TechnoNIKOL or Linocrom, have a fiberglass or polyester base, which significantly increases their service life and elasticity.
Polymer membranes represent a more modern class of materials. They are characterized by high tensile strength and puncture resistance. Installation of overlay coating requires the use of a gas burner, which requires compliance with strict fire safety measures. It is important to carefully prepare the base, clearing it of debris and dust.
The service life of high-quality bitumen-polymer materials can reach 15-20 years, which makes them the optimal choice for garages with a flat roof. However, it is worth considering that at high temperatures bitumen can soften, and at extremely low temperatures it can become brittle.
Secrets of laying roofing felt
When laying roofing felt, it is important to maintain an overlap of at least 10 cm between the sheets. It is better to lay the bottom layer on mastic, and fuse the top layer, heating the surface with a burner until a characteristic shine appears.
Sheet metal coverings
Metal sheets are the choice of those who value installation speed and durability. Corrugated sheet (profile sheet) is a leader in this category due to its availability and variety of profiles. Galvanized steel with a polymer coating reliably protects the metal from corrosion for decades.
For garages, corrugated sheeting with a wave height of 20 mm or more is often used, as it has sufficient rigidity. Metal tiles it looks more aesthetically pleasing, but costs more and requires more complex lathing. The main advantage of the metal is its fire resistance and ability to withstand significant snow loads without deformation.
When installing metal roofs, choosing the right fasteners is critical. Self-tapping screws must be equipped EPDM gaskets, which prevent moisture from entering the holes. An incorrectly tightened screw (under-tightened or pinched) will become a leak point after the first rainy season.
- 🔩 Use only galvanized screws with a rubber washer matched to the color of the roof.
- 📏 Observe the fastening step: into the wave for corrugated sheets and into the deflection of the wave for metal tiles.
- 💧 Don't forget about the waterproofing film under the metal to avoid condensation formation.
Corrugated bitumen sheets and slate
Ondulin (Euro slate) and classic asbestos slate occupy their niche due to their good sound insulation properties. Unlike metal, rain drums on such roofs more quietly, which can be important if the garage is used as a workshop. Bitumen corrugated sheet easy to process: it can be cut with a regular hacksaw, which simplifies DIY installation.
Slate, despite its weight and fragility, remains popular due to its low price and non-flammability. However, asbestos-containing materials lose strength over time and may become covered in moss, requiring regular cleaning. Ondulin lacks these disadvantages, but has a shorter service life and can fade in the sun.
When choosing between these materials, it is worth considering the condition of the supporting structures. Slate is very heavy and requires a powerful rafter system, while ondulin can be mounted even on light frame buildings.
| Material | Weight 1 m² (kg) | Service life (years) | Difficulty of installation |
|---|---|---|---|
| Ruberoid | 4-5 | 5-10 | Average |
| Corrugated sheet | 5-7 | 20-40 | Low |
| Ondulin | 3-4 | 15-20 | Low |
| Slate | 10-14 | 20-30 | High |
Preparing the base and calculating the slope
The quality of the roof depends 80% on the preparation of the base. Soft roofs require a perfectly flat surface, usually a screed on concrete slabs or a solid plywood/OSB sheathing. Substrate moisture before fusing, it should not exceed 4-5%, otherwise the water will boil under the hot bitumen and form bubbles.
The roof slope determines the installation technology. On flat roofs (up to 5 degrees), the use of a backing layer and double overlap is mandatory. If the angle of the slope exceeds 15 degrees, sheet materials can be used, but then it is necessary to provide snow retainers so that an avalanche of snow does not damage the drain or people.
☑️ Checking the roof’s readiness for installation
Pay special attention to junctions with walls and ventilation pipes. These are the places where leaks most often occur. Use special metal flashings and UV-resistant sealants to create a reliable waterproofing line.
Installation technology and typical mistakes
The process of laying the roof requires adherence to technology. When working with surfaced materials, heating must be uniform: underheating will lead to a lack of adhesion, and overheating will lead to destruction of the bitumen structure. Laying direction usually chosen from bottom to top, so that the top sheets overlap the joints of the bottom ones.
When installing corrugated board or slate, it is important to follow the fastening diagram. Nails or screws are driven strictly into the crest of the wave (for slate) or into the deflection (for metal), but not at the highest point, so as not to deform the sheet. Sealing holes - a mandatory step, ignoring which negates all efforts.
⚠️ Attention: Working at height requires the use of a safety rope. Even when working on a pitched garage roof, the risk of falling is high, especially if the surface is wet or covered in dew.
A common mistake is to skimp on drainage elements. The lack of organized gutters leads to erosion of the foundation and walls of the garage. Water should be drained at least 30-50 cm from the base of the building.
Before starting work, lay the material on the ground to check the color and absence of defects. This is especially true for colored corrugated sheets and ondulin, since different batches may differ in shade.
Insulation and vapor barrier of a garage roof
If the garage is heated or used as a workshop all year round, insulating the roof becomes a necessity. Heat loss through an uninsulated roof can reach 25%. For garages, non-combustible materials such as basalt wool or expanded polystyrene with fire retardants.
The design of the “roofing pie” must include a vapor barrier on the room side. Warm, humid air from the garage, rising upward, condenses in the insulation, which leads to wetting and rotting of the structures. Hydro-windproof membrane laid on top of the insulation, protecting it from blowing and external moisture.
When using expanded polystyrene, it is important to ensure high-quality ventilation of the under-roof space, since this material can melt in a fire and release toxic substances. Ventilation gaps help remove excess moisture and equalize the temperature under the roof.
A properly assembled “roofing pie” with steam and waterproofing extends the life of the roof by 2 times and keeps the garage warm in winter.
FAQ: Frequently asked questions
What material should I choose for a flat garage roof to prevent leaking?
For a flat roof, the best choice would be fiberglass-based fused-on materials (for example, Technoelast or Uniflex). They create a monolithic carpet without seams. It is important to make at least two layers: a lower lining and a top one with a protective coating.
Is it possible to put new roofing felt on top of the old one?
Technically this is possible if the old layer is not swollen and holds tightly. However, professionals recommend completely dismantling the old coating in order to assess the condition of the screed and remove accumulated moisture. Laying a new layer on top of the old one can hide areas of rot.
Is ventilation needed under corrugated sheeting?
Yes, definitely. The metal gets very hot in the sun and cools down at night, which leads to the formation of condensation on the inside of the sheet. Without ventilation, water droplets will drip onto your vehicle or tools, causing corrosion.
What is the cheapest way to re-roof?
The most budget option remains the usual roofing material, laid in 2-3 layers on bitumen mastic. However, the service life of such a roof is limited to 5-7 years, after which repairs will be required.