Why is roofing felt the best choice for a garage?

The garage roof is exposed to aggressive influences every day: temperature changes, precipitation, ultraviolet radiation and mechanical loads. Ruberoid remains one of the most popular materials for waterproofing due to its combination of availability, durability (with proper installation - up to 15 years) and ease of installation. Unlike metal sheets, it does not create noise during rain, and in comparison with bitumen shingles it is 2-3 times cheaper.

The key advantage of roofing material is versatility. It can be laid on flat and pitched roofs (slope up to 30°), on concrete slabs, wooden sheathing or old roofing material. However, it is important to take into account climatic features: in regions with extreme heat (above +40°C), ordinary roofing felt can melt, and in northern latitudes a frost-resistant version with modified bitumen is required.

This article will help you avoid common mistakes that can cause your roof to start leaking within a year or two. We'll sort it out all stages — from choosing the brand of roofing felt to finishing the seams, and we will also give advice on repairing the old coating. For clarity, we provide a comparative table of materials and a video with key installation points.

📊 What type of roof does your garage have?
Flat concrete
Flat wooden
Pitched (slope up to 15°)
Pitched (slope 15–30°)
I don't know

Choosing roofing material: markings and technical characteristics

There are more than 20 types of roofing felt on the market, but only 3-4 types are suitable for a garage. The main difference is basis and cover layer. Classic cardboard Roofing felt (brands RKP, RKK) is cheap, but lasts no more than 5–7 years. More durable options:

  • 🔹 Fiberglass based roofing felt (RST, RKS) - 2 times stronger than cardboard, resistant to rotting, service life 10–12 years.
  • 🔹 Euroroofing material (TKP, HKP) - with a polymer base and modified bitumen, withstands temperatures from -50°C to +120°C, warranty up to 25 years.
  • 🔹 Ruberoid with sprinkling (RKP-350, RKK-400) - the top layer of stone chips protects against UV rays and mechanical damage.

When choosing, pay attention to marking:

  • 📌 RKP-350 — roofing felt with dust coating, density 350 g/m² (for the lower layers).
  • 📌 RKK-400 — with coarse-grained topping, density 400 g/m² (for the top layer).
  • 📌 TCH — euroroofing felt with a polyester base (for regions with extreme climates).
Brand of roofing felt Base Density, g/m² Service life, years Price per roll (10 m²), ₽
RKP-350 Cardboard 350 5–7 300–450
RKK-400 Cardboard 400 8–10 400–600
PCT Fiberglass 300–350 10–12 500–800
TKP (euroruberoid) Polyester 400–500 15–25 1200–2000

Critical error: using roofing material marked “P” (lining) for the top layer. It does not have a protective coating and will collapse in 1-2 seasons. For a garage it is optimal to combine RKP-350 (bottom layer) + RKK-400 (top).

⚠️ Attention: Buy roofing felt with a margin of 10–15% for overlaps and trimming. A standard roll 1 m wide and 10 m long covers 9–9.5 m² of roof (including overlaps).

Preparing the garage roof for laying roofing felt

70% of success depends on the quality of preparation. Even the most expensive roofing felt will leak if it is laid on an uneven or dirty base. Preparation algorithm:

  1. Surface cleaning. Remove old roofing (if any), debris, moss and dust. For a concrete roof, use a metal brush or grinder with an attachment; for a wooden roof, use a spatula.
  2. Repair of cracks. On concrete, seal cracks with a cement-sand mixture (1:3) or sealant Soudal. Check the wooden sheathing for rot - replace damaged boards.
  3. Alignment. Height differences of more than 5 mm are unacceptable. For concrete, use a self-leveling mixture Vetonit, for wood - plywood or OSB.
  4. Primer. Apply a primer (bitumen or polymer) to improve adhesion. Consumption - 0.3–0.5 l/m².

If the roof pitched, make sure the rafter system is reliable. Deflections of more than 10 mm per 1 m require reinforcement with 50x50 mm timber. For flat roofs, check the slope (minimum 1-2° for water drainage). If it is not available, create a ramp from expanded clay or foam concrete.

All layers of old roof removed|

Cracks and chips repaired|

The surface is cleaned of dust and oil|

Primer applied (complete drying 2-4 hours)|

Roof slope checked (minimum 1°)

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⚠️ Attention: Don't ignore the primer! Without a primer, the bitumen in the roofing felt will not adhere to the base, and the coating will move during the first heavy rain.

Roofing felt laying technology: step-by-step instructions

To work you will need:

  • 🔧 Gas burner (or blowtorch) with a propane cylinder.
  • 🔧 Roofing knife and metal scissors.
  • 🔧 Roller or brush for rolling.
  • 🔧 Bitumen mastic TechnoNIKOL No. 24 (for the cold method).
  • 🔧 Gloves and a respirator (when working with a burner).

Installation order:

  1. Cut out the material. Roll out the roofing material on a flat surface and cut strips taking into account overlaps (10–15 cm on the sides and 20 cm on the ends). For pitched roofs, start from the bottom edge.
  2. Applying mastic (cold method). Cover the base with bitumen mastic with a layer of 1–2 mm using a roller. Lay the first sheet, smoothing from the center to the edges. At temperatures below +5°C, heat the mastic to 40–50°C to improve fluidity.
  3. Fusing (hot method). Heat the underside of the roofing material and the base of the roof with a burner. Press the sheet with a roller, moving in a herringbone pattern from the center. Do not overheat - the bitumen should not boil!
  4. Fixing overlaps. Heat the joints with a torch and press tightly. For reliability, coat the seams with mastic.

For a flat roof, lay roofing felt in 2-3 layers with joints spaced apart (like brickwork). On a pitched roof, 1–2 layers are sufficient, but with obligatory fastening with nails or slats around the perimeter (steps of 20–30 cm).

What to do if the roofing material bubbles?

Bubbles are caused by moisture underneath the material or uneven heating. To resolve:

1. Pierce the bubble crosswise with a knife.

2. Bend the edges and dry the base with a burner.

3. Apply mastic and press the roofing felt with a roller.

4. Melt the edges with a torch.

If there are a lot of bubbles, remove the coating and redo it with a base primer.

Installation video instructions:

📹 Watch on YouTube: "Fusing roofing felt with a gas burner" (duration 12:45, author Roofer PRO).

Treatment of seams and problem areas

Leaks in 90% of cases occur at joints, junctions with pipes and corners. To seal, use:

  • 🔹 Bitumen mastic — for seams between sheets (applied with a brush in 2 layers).
  • 🔹 Self-adhesive tape Nicoband - for connections to walls and pipes.
  • 🔹 Metal aprons - for chimneys and ventilation shafts.

Adjacency processing technology:

  1. Cut an “apron” 30–40 cm wide from roofing felt.
  2. Heat the bottom part with a burner and glue it to a vertical surface (wall, pipe).
  3. Secure the top edge with a metal strip on the dowels.
  4. Coat the seams with mastic or sealant Sika.
Problem area Sealing material Technology
Joints between sheets Bitumen mastic Apply with a brush in 2 layers and dry for 2–4 hours.
Connecting to a wall Self-adhesive tape + apron Heat with a burner, press with a roller, secure with a bar
Roof corners Euroruberoid + mastic Lay an additional layer with an overlap of 20 cm
Pipes and ventilation Metal apron + sealant Crimp with a clamp, lubricate SikaFlex
⚠️ Attention: Do not use polyurethane foam to seal seams! Under the influence of UV rays, it is destroyed in 1-2 seasons.

Repair of old roofing felt covering

If the roof is leaking, but the base as a whole is intact, you can get by partial renovation. Algorithm of actions:

  1. Localization of damage. Inspect the roof after rain - wet spots will indicate problem areas. Common defects:
    • 🔸 Cracks (from temperature changes).
    • 🔸 Bloating (due to condensation under the material).
    • 🔸 Mechanical breakdowns (from hail or falling branches).
  • Cleaning. Remove debris, moss and old mastic with a metal brush. Dry the surface with a torch.
  • Patches. For cracks up to 5 cm, use liquid rubber Gidroizol. For major damage, cut out a patch from new roofing felt (with a margin of 10 cm) and fuse it with a burner.
  • Gain. If the coating is 70%+ worn, lay a new layer of roofing material on top perpendicular to the old one.

    • Repair cost:

    • 💰 Local patch — 200–500 ₽ (materials + 1 hour of work).
    • 💰 Partial replacement of coating - 1000-3000 ₽ (depending on the area).
    • 💰 Complete relocation - 500–800 ₽/m² (including dismantling the old layer).
    💡

    For temporary repairs (for 1–2 seasons), use bitumen tape Titan. It glues without heating and can withstand temperatures from -30°C to +80°C.

    Tips for care and life extension

    To ensure that the roofing material lasts as long as possible:

    • 🔧 2 times a year (spring and fall) clear the roof of leaves and debris. Use a plastic scraper to avoid damaging the topping.
    • 🔧 Check the integrity of the coating after hail or strong wind. Fill small cracks with mastic immediately.
    • 🔧 Renew the protective layer every 3-4 years: apply bitumen varnish Bitumast with a brush.
    • 🔧 Do not walk on the roof in hot weather - the roofing material softens and becomes deformed.

    Service life of roofing felt depending on care:

    Type of care Service life, years
    No care 3–5
    Cleaning 2 times a year + minor repairs 8–10
    Cleaning + mastic renewal every 3 years 12–15
    Euroroofing material + complete care 20–25
    💡

    Regular cleaning of the roof from debris and timely repair of minor damage increases the service life of roofing felt by 2-3 times.

    FAQ: Frequently asked questions about laying roofing felt

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

    Yes, but only if the slate is intact and does not crumble. Preliminary:

    1. Clean the surface from moss and dust.
    2. Seal cracks with cement mortar or sealant.
    3. Apply primer to improve adhesion.
    4. Lay the roofing felt in 2 layers with the seams spaced apart.

    If the slate is wavy, use filler (for example, polyurethane foam) for leveling.

    Which roofing material is better - domestic or imported?

    Imported (for example, ICOPAL or Katepal) is more durable (service life up to 30 years), but costs 3–5 times more. Russian stamps (TechnoNIKOL, Bikrost) are optimal in terms of price/quality for the garage. The main thing is to check the production date (the shelf life of roofing felt is 1 year).

    What to do if the roofing material comes off at the edges?

    Reasons:

    • 🔹 Insufficient heating during styling.
    • 🔹 No primer.
    • 🔹 Temperature deformation.

    Solution:

    1. Fold back the loose edge.
    2. Clean and dry the base with a torch.
    3. Apply mastic and press with a roller.
    4. Secure the edges with battens or nails (for pitched roofs).
    Is it possible to paint roofing felt?

    Yes, but only acrylic or latex paints for bituminous surfaces (e.g. Dachbeschichtung from Alpina). Paint:

    • 🔸 Protects against UV rays.
    • 🔸 Extends service life by 3-5 years.
    • 🔸 Reduces roof heating in summer.

    Before painting, clean the surface and apply primer BitumenSoil.

    How much does it cost to cover a garage with turnkey roofing felt?

    Cost of work (without materials) in 2026:

    • 💰 Flat roof (up to 20 m²) - 3000–5000 ₽.
    • 💰 Pitched roof (up to 20 m²) - 5000–8000 ₽.
    • 💰 Dismantling the old coating - 500-1000 ₽/m².

    With material (TechnoNIKOL RKK-400 + mastic) the total price will be 8000–15000 ₽ for a standard garage 6×3 m.