Roofing felt for the garage roof: which one to choose and how to lay it correctly

The garage roof is not just a protective element, but a barrier between your car and the aggressive external environment: rain, snow, ultraviolet radiation and temperature changes. Ruberoid remains one of the most popular materials for waterproofing garage roofs due to its affordable price, ease of installation and proven reliability. However, not everyone knows that the wrong choice of brand or violation of installation technology can lead to leaks within 2-3 years.

In this article we will look at which roofing material is best suited for a garage (compare RKK-350, RKP-350, RKM-350 and euroroofing felt), how to prepare the base, avoid installation errors and extend the service life of the coating to 10-15 years. You will also find step-by-step instructions with photos, a comparison table of materials and answers to frequently asked questions about repairing leaks.

Types of roofing felt for the garage: which one to choose

Roofing felt is divided into several types depending on its purpose, density and composition. Suitable for garage roof roofing and lining brands, but their properties are very different. Let's look at the main options:

• 📌 RKK-350 — roofing felt with coarse-grained topping (stone chips). Optimal for the top layer due to its resistance to UV rays and mechanical damage. Service life: 8-12 years.
• 📌 RKP-350 - roofing with dust coating. Cheaper RKK-350, but less resistant to abrasion. Suitable for temporary coating or undercoats.
• 📌 RKM-350 — with fine-grained topping (sand). Used for low load base layers or flat roofs.
• 📌 Euroroofing material (CCI, HPP) - a modern analogue with modified bitumen and polymer additives. Service life: 15-20 years, but the price is 2-3 times higher.

Ideal for a garage with a flat or pitched roof RKK-350 as a top layer and RKP-350 or RKM-350 - for lining. If your budget allows, choose euroroofing felt Chamber of Commerce and Industry (with talcum powder) or HPP (with flake mica) - they do not crack due to temperature changes and can withstand snow loads of up to 200 kg/m².

⚠️ Attention: Do not use roofing felt RPP-300 (lining) for the top layer! Its thin base and dusty coating are destroyed under the sun in 1-2 seasons.

Comparison of roofing felt: characteristics table

Brand	Density, g/m²	Sprinkle type	Service life, years	Price per roll (2026), ₽	Application
RKK-350	350	Coarse grain (granite)	8-12	450-600	Top layer
RKP-350	350	Dust-like	5-7	350-500	Bottom layers, temporary coating
RKM-350	350	Fine grain (sand)	6-8	400-550	Lining, flat roofs
TPP (euroruberoid)	400-500	Talc/mica	15-20	1200-1800	Any roof, durable coating

Euroroofing material Chamber of Commerce and Industry with the index "EPP" (elastic) is suitable for garages in regions with frosts below -30°C - it does not burst under temperature changes. If your garage is located in a risk zone (for example, the Far East or Siberia), overpaying for polymer-bitumen material will be justified.

Preparing the garage roof for laying roofing felt

70% of success depends on the quality of foundation preparation. Even the most expensive roofing felt will not last long if it is laid on an uneven, dirty or wet surface. Follow the algorithm:

1. Cleaning. Remove debris, old paint, rust (if the roof is metal) and old coating residue. Use a wire brush or grinder with a grinding wheel.
2. Alignment. Fill cracks in concrete with cement mortar (ratio 1:3), and cavities more than 5 mm deep with metal putty (for iron roofs).
3. Primer. Apply a bitumen primer (e.g. TechnoNIKOL No. 01) to improve adhesion. Consumption: 0.3-0.5 l/m².
4. Drying. The base must be absolutely dry. If the humidity is above 4% (check with a moisture meter), the roofing material will not stick.

For concrete roofs, be sure to use leveling screed 2-3 cm thick with a slope of 1-2° for water drainage. On metal roofs, remove rust to bare metal and treat with an anti-corrosion compound (e.g. Tsinkor-Auto).

⚠️ Attention: If there are old layers of roofing felt on the garage roof, they must be completely removed. Laying new material on top of old material leads to the formation of “air pockets” and rotting of the base.

Clean the surface of debris and old coating|

Fill cracks and level the base|

Apply bitumen primer and wait until dry|

Check the moisture content of the base (maximum 4%)|

Prepare tools: gas torch, roller, knife-->

Step-by-step instructions for laying roofing felt

The installation technology depends on the type of roof (flat or pitched) and the number of layers. For a garage, 2-3 layers are enough: one lining and one or two roofing layers. Consider the process for a flat concrete roof:

1. Marking and cutting the material

Unfold the roll of roofing felt on a flat surface and measure the strips with a margin of 10-15 cm at the edges (for overlap). For a 3x6 m roof you will need 2 strips 1 m wide with an overlap of 10 cm. Cut the material with a sharp knife along a ruler.

2. Applying mastic

Cover the base with bitumen mastic (for example, Technomast No. 21) in a layer of 1-2 mm using a roller or spatula. Consumption: 1-1.5 kg/m². The mastic should be hot (60-80°C) for better adhesion.

3. Laying the first layer

Lay the lining roofing felt (RKP-350 or RKM-350) from bottom to top, smoothing with a roller from the center to the edges. The overlap between the strips is 10 cm; at the joints, coat with mastic. For flat roofs, use the "fusing" method using a gas torch:

1. Heat the underside of the roofing material and the base with a burner (flame at a distance of 20-30 cm).
2. Press the material with a roller, moving in a herringbone pattern from the center.
3. Be careful not to form bubbles - if necessary, puncture them and press.

4. Laying the top layer

Repeat the process with roofing felt (RKK-350 or euroroofing felt), shifting the seams relative to the first layer by 30-50 cm. For pitched roofs (slope >15°), one layer is sufficient RKK-350, but lay the strips perpendicular to the slope.

After installation, check the tightness: pour water on the roof and inspect the joints from inside the garage. If you find leaks, heat the problem areas with a torch and press with a roller.

Common mistakes and how to avoid them

Even experienced craftsmen make mistakes that shorten the service life of roofing felt. Here are the most critical ones:

• 🔥 Burner overheating. If you hold the flame too close, the bitumen will burn out and the material will become brittle. The optimal distance is 20-30 cm.
• 💧 Laying on a damp base. Bituminous mastic does not adhere to a wet surface. Use a hair dryer to dry.
• 📏 Insufficient overlap. The minimum overlap is 10 cm for flat roofs and 15 cm for pitched roofs. Apply additional mastic at the joints.
• ❄️ Ignoring temperature. Roofing felt can be laid at temperatures from +5°C to +25°C. In cold weather, bitumen becomes brittle, and in hot weather it becomes too fluid.

Most common problem - swelling of the coating. It occurs due to air remaining under the roofing felt. To avoid this, roll each layer with a 50-70 kg roller or pierce the bubbles and press.

⚠️ Attention: If it rains after installation, do not cover the roof with film - this will create a greenhouse effect. Wait for natural drying (1-2 days) and inspect the seams.

What to do if the roofing felt peels off after a month?

Peeling is usually caused by poor substrate preparation or poor-quality mastic. Solution:

1. Lift up the peeling edge and dry the base with a hair dryer.

2. Apply fresh mastic (Bitumast or TechnoNIKOL No. 27*).

3. Press the roofing material with a roller and heat it with a burner.

4. Sandbag the repaired area for 12 hours.

*Do not use cheap solvent-based mastic - it destroys bitumen!

Leak repair: temporary and capital solutions

Even well-laid roofing felt can leak over time. Causes: mechanical damage, aging of bitumen or installation errors. Let's consider repair methods depending on the scale of the problem:

1. Pinpoint damage (cracks, punctures)

To repair small defects (up to 10 cm):

1. Clean the damaged area from dirt and dry it.
2. Apply bitumen mastic or sealant (Soudal Bitumast).
3. Cover with a roofing felt patch (5 cm larger than the damage) and heat with a burner.

2. Seams coming apart

If the seams come apart at the joints:

1. Lift the edges of the roofing material and dry the base.
2. Apply mastic TechnoNIKOL No. 24* (frost-resistant).
3. Press the seam with a roller and heat it up.
4. For reliability, stick tape on top Wakaflex (self-vulcanizing).

3. Major repairs (damage area >30%)

If the roofing material is delaminated or covered with cracks over the entire area, a complete replacement is required:

1. Remove the old coating with a scraper or grinder.
2. Inspect the substrate for corrosion (for metal) or cracks (for concrete).
3. Lay new roofing felt using the technology described above, but increasing the number of layers to 3-4.

For temporary repairs (for 1-2 seasons) you can use liquid rubber (for example, Elastopaz). It is applied with a brush and forms an elastic coating, but does not replace a full replacement of roofing felt.

Service life and how to extend it

Average service life of roofing felt on a garage roof:

• 📅 RKP-350: 5-7 years.
• 📅 RKK-350: 8-12 years.
• 📅 Euroruberoid: 15-20 years.

To extend the life of the coating:

1. Clean the roof from leaves and debris 2 times a year (spring and autumn). Stagnant water accelerates the destruction of bitumen.
2. Paint the roofing felt after 3-4 years with acrylic paint for roofs (for example, Roof-Lux). This will protect against UV rays.
3. Avoid mechanical stress. Do not walk on the roof in shoes with hard soles.
4. Control the snow load. If the snow layer is >30 cm, carefully clear the roof with a plastic shovel.

Euroroofing felt with copper foil (for example, Icopal Ultra) lasts up to 25 years due to UV reflection and oxidation resistance. If your garage is in direct sunlight most of the day, paying extra for this material will be worth it.

FAQ: Frequently asked questions about garage roofing felt

Is it possible to install roofing felt on an old slate roof?

Yes, but only after preparation: clean the slate of moss, seal the cracks with foam or sealant, and then cover with a bitumen primer. Lay roofing material in 2 layers with an overlap of 15 cm.

Which roofing felt is best for a garage in Siberia?

For regions with frosts below -30°C, choose euroroofing felt CCI EPP (elastic) or HPP with polymer additives. They do not crack due to temperature changes.

How many layers of roofing felt are needed for a garage?

For a flat roof: 2-3 layers (1 lining + 1-2 roofing layers). For pitched (slope >15°): 1 layer is enough RKK-350 or euroroofing felt.

How to glue roofing felt to metal?

Use bitumen mastic TechnoNIKOL No. 21 or Bitumast. For better adhesion, treat the metal with anti-corrosion primer (Tsinkor-Auto).

Is it possible to paint roofing felt?

Yes, but only 1-2 years after installation (when the excess bitumen evaporates). Use acrylic paint for roofs (Roof-Lux, Tikkurila Kivi*). Do not use oil paints - they destroy bitumen.