Building or renovating a garage is a process that requires careful attention to every detail, and the roof plays a key role here. It’s the quality roofing pie depends on whether your car will be protected from leaks, condensation and temperature changes. Many car owners prefer to do this work themselves, as this allows them to significantly save money and be confident in the materials used.
The modern market offers many solutions, from the classic roofing felt to long lasting corrugated sheets. The choice of a specific method depends on the design of the floor, the angle of inclination of the slope and financial capabilities. In this article we will analyze the main stages of work so that you can plan your project correctly.
Do not underestimate the preparatory stage, since it is this that determines the service life of the entire structure. The optimal slope for a flat roof should be at least 2-3 degrees to ensure natural water drainage. If you ignore this parameter, even the most expensive material will quickly become unusable due to moisture stagnation.
Choosing the optimal roofing material
The first thing a home master faces is choosing a coating. For garages, soft roofing on a bitumen basis or metal sheets are most often used. Ruberoid remains the most affordable option, proven over decades, but it requires frequent updating. More modern analogues, such as euroruberoid or stekloizol, last much longer and are easier to install.
If the garage has a pitched structure, an excellent choice would be corrugated sheet. This is a durable, lightweight and aesthetic material that is easy to install even alone. Metal sheets are resistant to mechanical damage and are not afraid of ultraviolet radiation, which makes them ideal for regions with harsh climates.
It is also worth paying attention to ondulin - wavy bitumen sheets that perfectly dampen the sound of rain. They are easier to process than metal and are not subject to corrosion. However, when choosing ondulin, it is important to strictly follow the lathing step specified in the manufacturer’s instructions.
- 🏗️ Ruberoid: low price, but requires laying in several layers and heating with a burner.
- 🏗️ Profiled sheeting: high strength, durability, but requires careful sealing of fasteners.
- 🏗️ Ondulin: ease of installation, noiselessness, but flammability and sensitivity to extreme temperatures.
Preparation of the base and calculation of materials
Before purchasing materials, you must carefully prepare the base. If you are replacing the coating on an old garage, you need to dismantle the deteriorated layer and clean the concrete slabs or wooden flooring of debris. The surface must be dry, level and free of dust to ensure adhesion of the bitumen mastic.
For a pitched metal roof, it is critical to install it correctly sheathing. The pitch of the beams depends on the angle of inclination and the type of corrugated board chosen. Lathing that is too sparse will lead to deformation of the sheets under the weight of snow, and lathing that is too frequent will lead to waste of wood.
⚠️ Attention: When working with open fire (fused roofing), be sure to have a fire extinguisher and a bucket of sand. Bitumen vapors are highly flammable if not handled carefully.
It is better to calculate the amount of materials with a margin of 10-15% for overlaps and trims. For a soft roof, it is important to consider the number of layers: usually two layers of underlying material are laid and one finishing layer with topping. For metal, the calculation is based on the usable area of the sheet, taking into account horizontal and vertical overlap.
Use a laser level or hydraulic level to check the level of the base before starting work - this will help avoid the formation of "pockets" of water.
Installation of sheathing and insulation
If you plan to insulate your garage, then work begins with laying thermal insulation between the floor beams or on top of the slabs. Most often used as insulation mineral wool or penoplex. It is important to leave a ventilation gap between the insulation and the roofing so that moisture can evaporate without destroying the structure of the materials.
The sheathing for a soft roof is continuous. To do this, boards are laid on top of the rafters or slabs with a gap of 1-2 cm, and sheets are placed on top OSB or moisture-resistant plywood. Such a base must be perfectly smooth, without sharp knots and burrs that can damage the roofing material.
For a metal roof, the sheathing is made sparse. The bars are attached across the slope with the step indicated in the table below. All wooden elements must be processed before installation antiseptic and fire retardants to protect against rotting and fire.
| Roof type | Base material | Lathing step | Requirements |
|---|---|---|---|
| Soft (roof felt) | Solid decking (OSB/Plywood) | 0 cm (solid) | The gap between the boards is 1-2 cm |
| Metal (corrugated sheeting) | Bar 50x50 mm | 300-500 mm | Antiseptic treatment |
| Ondulin | Bar 40x40 mm | Depends on slope | Strictly according to the manufacturer's instructions |
☑️ Checking the readiness of the base
Soft roofing technology
Installation of a bitumen roof begins with the application primer (bitumen primer) on the base. This improves the adhesion of the material to the surface and removes dust. After the primer has dried, you can begin fusing or gluing the first layer.
If you are using built-up roofing felt, the roll is rolled out and heated with a gas burner until a characteristic shine appears and the bitumen begins to boil slightly. The burner's movements should be progressive, simultaneously heating both the surface of the base and the material itself. It is important not to overheat the bitumen, otherwise it will lose its properties.
The second layer is laid with the seams offset from the first so that the joints do not coincide. The overlap of the strips should be at least 10 cm, and in places where they adjoin the walls, the material must be placed on a vertical surface to a height of 15-20 cm. For reliability, the edges can be pressed with a metal strip.
⚠️ Attention: Do not step on newly laid hot bitumen - this will disrupt the structure of the coating and leave dents in which water will accumulate.
Secrets of working with a burner
For high-quality surfacing, use a torch with wind protection. Hold the torch so that two rolls (base and roofing material) are heated at the same time at their meeting point. Avoid forming a “wave” in front of the bale – this is a sign that the roll is moving too fast or is not warming up enough.
Installation of metal corrugated sheets
Installation of profiled sheets begins with installation cornice strip, which protects the overhang from moisture getting under the roof. The sheets are laid from bottom to top, starting from the corner opposite to the prevailing wind direction. This will prevent rain from blowing under the joints.
Fastening is carried out with special self-tapping screws with EPDM washers that match the color of the coating. They need to be screwed strictly perpendicular to the surface into the lower wave of the profile. You cannot overtighten the screws, as this will lead to deformation of the washer and loss of tightness.
Additional elements are installed on the ridge and ends. The ridge strip is attached through the upper wave in increments of 20-30 cm. It is advisable to place a sealing tape under the ridge to prevent birds and leaves from entering, but to leave a ventilation gap.
- 🔩 The fastener is screwed into the bottom wave for a tight fit.
- 🔩 The consumption of self-tapping screws is about 6-8 pieces per square meter.
- 🔩 It is better to cut metal with electric scissors so as not to damage the zinc coating.
The main mistake when installing metal is using a grinder for cutting, since the burned-out zinc layer becomes a source of corrosion, reducing the service life of the roof to a minimum.
Sealing of joints and junctions
The most vulnerable places on any roof are the ventilation outlets, walls and gutters. To protect them they are used aprons made of galvanized steel or special bitumen tapes. Metal aprons are cut into the wall and secured with dowels, and the seam is filled with sealant.
A “tie” is installed around the ventilation pipes - an additional layer of waterproofing, which is inserted under the roofing from below and applied on top. For round pipes, ready-made ones are sold elastic penetrations, which are easily crimped with a clamp.
Don't skimp on quality sealant for roofing work. It should remain elastic at any temperature and not crack over time. Polyurethane or bitumen-rubber compounds are best suited for this.
How to properly seal the joint between a roof and a brick wall?
For reliable sealing, it is necessary to make a groove (groove) in the brickwork at a height of 10-15 cm from the roof level. The upper edge of the metal apron or pressure strip is inserted into the groove, and then fixed with dowels. The junction of the metal and the brick is generously coated with roofing sealant. The lower edge of the apron is glued or fused to the main roof covering with an overlap of at least 15 cm.
Do you need to remove snow from your garage in winter?
It is advisable to remove snow from a flat roof in order to reduce the load on the floors, but this must be done carefully, without using metal shovels, so as not to damage the coating. Snow melts off a pitched metal roof on its own when there is a thaw, but you need to make sure that the drainage system is not clogged with ice, otherwise water may go under the roof.
Is it possible to put a new roof on top of the old one?
Technically this is possible if the base (floor slabs) is in good condition and has no deflections. However, experts do not recommend doing this, since you will not be able to check the condition of the old waterproofing and insulation. Moisture remaining between the layers will cause the new coating to swell and the base to rot.
What is the service life of roofing felt in a garage?
An ordinary cardboard-based roofing material lasts about 5 years. Euroroofing felt on a glass base or fiberglass, when properly installed in two layers, can last 15-20 years or more. A metal roof with a high-quality polymer coating lasts up to 40-50 years.