Bubbles on a roof made of rolled materials: how to eliminate and prevent them

The problem of swelling and bubbles on rolled roofing is familiar to many owners of garages, private houses and outbuildings. At first glance, the defect seems insignificant - but over time it leads to leaks, destruction of waterproofing and expensive repairs. In this article we will analyze reasons for the formation of bubbles, ways to eliminate them and preventive measures that will extend the life of the roof by 30-50%.

A special feature of rolled materials (roofing felt, bikrost, waterproofing) is their multilayer structure, where bitumen impregnation alternates with a reinforcing base. If the installation or operation technology is violated, moisture or air accumulates under the top layer, which leads to swelling. It is important to understand: bubbles are not a cosmetic defect, but roof leakage signal. It cannot be ignored, especially when it comes to the roof of a garage, where valuables or a car are often stored.

Why bubbles appear on rolled roofing: 5 main reasons

Blisters on the surface of rolled materials never appear just like that. Their formation is associated with errors during the installation stage, improper operation or natural wear and tear. Let's take a closer look at the key reasons.

1. Violation of installation technology. The most common mistake is insufficient heating the bitumen layer during fusion. If the temperature of the gas burner is too low or the technician is in a hurry, the adhesive layer will not melt evenly. As a result, air pockets remain under the roll, which expand over time. Bubbles also form when laying on a damp base - even microscopic drops of water, when heated, turn into steam and “undermine” the roof from the inside.

2. Use of low-quality materials. Cheap roofing felt or bikrost often has uneven impregnation with bitumen, which leads to delamination of the layers. It is especially risky to buy materials without certificates - they may contain recycled bitumen with low adhesion. Such a roof begins to bubble after 1-2 seasons.

3. Temperature changes. Roll materials are sensitive to sudden temperature changes. During the day, under the sun, bitumen softens, at night it contracts. If the roof is laid without taking into account expansion joints or without expansion gaps, internal stress leads to bulges. This is especially true for regions with a continental climate (for example, Siberia, the Urals), where the difference between day and night can reach 30°C.

4. Mechanical damage. Falling branches, hail, or careless shoveling of snow can damage the integrity of the top layer. Moisture penetrates through microcracks, which expands and forms bubbles when frozen. This often happens at the joints of rolls, where the material is thinner.

5. Lack of ventilation. If the under-roof space is not ventilated, condensation accumulates on the inside of the rolled covering. Over time, this leads to peeling of the material and the formation of blisters. This is especially critical for garages with metal doors - they heat up in the sun and aggravate the problem.

• 🔥 Burner too close: when fusing, the optimal distance is 15-20 cm. Closer - there is a risk of burning the material, further - the bitumen will not warm up.
• 💧 Moisture under the roll: Even if the base seems dry, check it with a moisture meter. The norm is no more than 4-5%.
• ☀️ Styling in the heat: At temperatures above +30°C, bitumen becomes too fluid, which leads to uneven adhesion.
• ❄️ Winter installation: at sub-zero temperatures, rolled materials lose elasticity and do not adhere well to the base.

How to determine the extent of damage: when to repair and when to replace the roof

Before you begin repairs, you need to assess the scale of the problem. Not all bubbles are equally dangerous: some can be eliminated locally, others require a complete replacement of the coating.

1. Size and number of bubbles:

• 🟢 Small (up to 5 cm): As a rule, not critical. They can be pierced and sealed with mastic.
• 🟡 Medium (5-20 cm): require opening and gluing. If there are a lot of them, this is a signal of a systemic problem (for example, poor ventilation).
• 🔴 Large (more than 20 cm) or multiple: Often indicate separation of material from the base. In this case, partial or complete roof replacement may be necessary.

2. Condition of the material around the bubble:

• 🔍 If the bubble “crunches” when pressed, moisture has accumulated inside. This is the worst option, since water has already penetrated into the roof layers.
• 🔍 If the bubble is soft and gives in when pressed, it is most likely air. Such a defect is easier to eliminate.
• 🔍 Cracks or delamination around bloating is a sign of aging material. Local repairs are ineffective here.

3. Age of the roof:

The service life of rolled materials is 5-15 years (depending on the type). If the roof is more than 10 years old, and bubbles have appeared en masse, it is more advisable to consider the option of a complete replacement. Otherwise, the repair will become a “patch on a leaky bucket.”

Sign	Probable Cause	Recommendation
Bubbles are small, single, soft	Air pockets during installation	Local repair (piercing + mastic)
Bubbles are large, hard, with water inside	Leak or condensation	Opening, drying, re-sizing
Multiple swellings over the entire area	Violation of laying technology or aging of the material	Partial or complete roof replacement
Bubbles at roll joints	Poor seam sealing	Sealing joints with bitumen tape or mastic

⚠️ Attention: If bubbles appear on the roof of the garage where the car is stored, do not delay repairs! Moisture and gasoline vapors accelerate the corrosion of bituminous materials. In advanced cases, this can lead to the collapse of a section of the roof.

Step-by-step instructions: how to eliminate bubbles on rolled roofing

If the defects are local and the roof is generally in good condition, you can get by with spot repairs. Let's consider two methods: for bubbles with air and with water inside.

Method 1: Air Bubble Repair (No Moisture)

1. Preparation: Clean the surface of the bubble from dirt and dust. If necessary, wash the area with water and dry.
2. Piercing: Using a sharp knife, make a cross-shaped cut in the center of the bubble. Don't cut all the way through - just the top layer.
3. Alignment: Press the roll against the base, squeezing out the air. For better adhesion, warm up the repair area with a hair dryer (temperature ~60-80°C).
4. Sealing: fill the cut bitumen mastic (for example, TechnoNIKOL No. 21 or Gidroizol MGH-4). Level with a spatula.
5. Strengthening: stick a patch of the same material on top (5-10 cm larger than the bubble). Heat with a torch and press with a roller.

Method 2: Repairing Water Blisters

If moisture has accumulated inside, simply piercing the bubble is not enough - you need to dry the base.

Sharp knife or scalpel|Hair dryer or gas torch|Bitumen mastic (cold or hot)|Asphalt/bicrost patch|Roller or spatula|Cleaning rag|Gloves and protective equipment-->

1. Bubble opening: Carefully cut the top layer of material in a cross, bending the edges. If there is water inside, blot it with a rag.
2. Drying: Direct the heat gun into the cavity for 10-15 minutes. Temperature - no higher than 100°C, so as not to damage the bitumen. Alternative: Leave the area open for a day in sunny weather.
3. Substrate treatment: if there is a damp concrete or wooden base under the roll, treat it deep penetration primer (for example, Ceresit CT 17).
4. Restoring layers:
   • Apply a layer of bitumen mastic to the base.
   • Lay the patch, heating it with a torch.
   • Roll carefully from the center to the edges.

Sealing seams: glue the edges of the patch bitumen tape (for example, Nicoband) for added protection.

For large blisters (more than 30 cm) or massive swelling, it is better to use cut-and-re-glue method:

1. Cut out the damaged area with a knife with a margin of 10-15 cm.
2. Remove old material, clean the base from bitumen residues.
3. Lay a new piece of roofing felt/bikrost with an overlap of 10 cm, heating it with a burner.
4. Glue the joints with mastic and press with a weight (for example, a bag of sand) for 12-24 hours.
💡

For repairs in cold weather (below +5°C) use cold mastic (for example, TechnoNIKOL No. 33) - it does not require heating and retains elasticity at sub-zero temperatures.

Prevention of bubbles: how to extend the life of rolled roofing

The best repair is preventing the problem. By following simple rules, you can avoid swelling and leaks by 80-90%.

1. Correct installation is the key to durability:

• 🔥 Temperature: lay roll materials at temperatures between +5°C and +25°C. In hot weather, bitumen melts too quickly; in cold weather, it does not provide the necessary adhesion.
• 💨 Dry base: Before laying, check the moisture content of the screed or wood flooring. Use vapor barrier membrane (for example, Izospan B), if the roof is laid on insulation.
• 🔧 Tool: for fusing use gas burner with piezo ignition and flame regulator. The optimal distance from the burner to the material is 15-20 cm.

2. Selection of materials:

Don’t skimp on rolled roofing - cheap roofing felt will last a maximum of 3-5 years. Optimal options for a garage or home:

• 🏆 Bikrost: reinforced with fiberglass, service life - 7-10 years. Suitable for flat and low-slope roofs.
• 🛡️ Gidroizol: more elastic, resistant to temperature changes. Serves up to 15 years.
• 🔥 Technoelast: premium class from TechnoNIKOL. Withstands heating up to +120°C, warranty - 20 years.

3. Regular maintenance:

Even the best quality roof requires maintenance. Twice a year (spring and autumn) inspect:

• 🧹 Remove debris, leaves and branches - they retain moisture.
• ❄️ Remove snow in winter plastic shovelso as not to damage the top layer.
• 🔍 Check the joints of the rolls and the places where they join pipes/walls - this is where leaks most often begin.
• 🎨 Renew the protective layer every 2-3 years bitumen varnish or aluminum paint (for example, Serebrol). This will protect the roof from UV rays.

4. Ventilation of the under-roof space:

If a garage or outbuilding is not ventilated, condensation is inevitable. Solutions:

• 🪟 Install supply grilles at the bottom of the walls and exhaust deflectors on the roof.
• 💨 For metal garages use ridge aerators (for example, Vilpe).
• 🌡️ In regions with high humidity (for example, Leningrad region), add additional diffusion membrane for roll material.

⚠️ Attention: Never use to repair roll roofing silicone sealant or polyurethane foam! These materials are incompatible with bitumen and will cause further delamination. Only bitumen mastic or special tapes are suitable for sealing joints.

What are the dangers of ignoring bubbles on the roof?

Many garage owners ignore the swelling for years until it starts leaking. However, the consequences can be much more serious:

1. Destruction of the supporting structure. Water penetrating through the bubbles saturates concrete slabs or wooden beams. In winter it freezes and expands, causing cracks. In advanced cases it will be necessary strengthening or replacing the ceiling - and this is 5-10 times more expensive than timely roof repairs.

2. Car corrosion. If the garage is not sealed, moisture from the roof gets onto the car body. It is especially dangerous for cars that sit idle - rust appears within 1-2 years. According to statistics, 30% of body damage in garage cars is caused by roof leaks.

3. Mold and mildew. A humid environment is ideal for the proliferation of microorganisms. Mold spoils not only building materials, but also things stored in the garage (tools, spare parts, furniture). Some types of fungus (eg. Aspergillus) are hazardous to health - their spores can cause allergies and breathing problems.

4. Fire danger. Bituminous materials are flammable, and if enough air accumulates under the roof, the risk of fire increases. This is especially true for garages where fuels and lubricants are stored or welding work is carried out.

5. Financial losses. The longer you delay repairs, the more expensive they will be:

- Local repair of 1-2 bubbles - from 500 to 2000 rubles.

- Partial replacement of the roof (30-50% of the area) - 10,000–30,000 rubles.

- Complete replacement with dismantling of the old coating - 50,000–150,000 rubles. (depending on area and material).

What to do if bubbles appear on a new roof?

If swelling occurs in the first year after installation, this is a warranty case! Contact your contractor to request free repairs. According to the law (Article 755 of the Civil Code of the Russian Federation), the contractor is obliged to eliminate defects that arose through his fault. Save photos of the defects and the work acceptance certificate - this will help prove the claim.

Comparison of repair materials: what to choose

Not all bitumen mastics and patches are equally effective. Let's look at the pros and cons of popular solutions.

Material	Pros	Cons	Service life	Price (per unit)
Bitumen mastic TechnoNIKOL No. 21	Cold application, high adhesion, water resistance	Takes a long time to dry (24 hours), not suitable for sub-zero temperatures	5-7 years	300-500 rub./bucket 3 kg
Hot mastic Gidroizol MGH-4	Fast setting, can be applied at -10°C	Requires heating, fire hazard	8-10 years	400-600 rub./bucket 5 kg
Self-adhesive tape Nikobend	Easy to install, no heating required	Low resistance to UV rays, suitable for local repairs only	3-5 years	150-300 rub./roll 10 m
Liquid rubber (Polykrov)	Elasticity, seamless coating, resistance to temperature changes	High price, requires special equipment for application	10-15 years	1500-3000 rub./bucket 20 kg

Suitable for temporary repairs (for example, before winter) bitumen mastic or self-adhesive tape. For major repairs it is better to use hot mastic or liquid rubber - they provide better waterproofing.

When to call professionals: 5 signs

Some roofing defects can be fixed on your own, but in some cases it is better to trust the specialists. Contact a roofer if:

1. Bubbles occupy more than 30% of the roof area. This indicates a systemic problem (for example, a violation of laying technology or wear of the base).
2. The roof is leaking in several places. Local repairs will not help here - a full diagnosis is needed.
3. Blisters appeared at the joints with vertical surfaces (pipes, walls). These areas are difficult to seal without experience.
4. Roof over 10 years old. In this case, it is more advisable to consider the option of a complete replacement rather than “patching holes.”
5. You are not sure about the cause of the defects. For example, if blisters reappear after repairs, there may be a problem with the ventilation or waterproofing of the foundation.

Cost of professional roll roofing repair:

• 🔧 Local repair (1-2 m²) - from 1000 to 3000 rubles.
• 🏗️ Partial replacement (up to 50% of the area) - 500-1000 rubles/m².
• 🆕 Complete replacement with dismantling of the old coating - 800-1500 rubles/m².

When choosing a contractor, pay attention to:

• 📄 Availability agreement with warranty (minimum 2 years).
• 🛠️ Experience working with roll materials (ask for portfolio).
• 🔍 Use certified materials (for example, TechnoNIKOL, Icopal).

⚠️ Attention: before concluding a contract, check whether it is included in the estimate recycling of old coating. Dismantling roofing felt or bikrost belongs to hazard class 4 (according to FKKO), and its removal to a landfill can cost 5,000-10,000 rubles.

FAQ: Frequently asked questions about bubbles on rolled roofing

Is it possible to just puncture the bubble and fill it with mastic?

It is possible, but this is a temporary solution. If moisture has accumulated inside, it must be removed, otherwise the bubble will appear again. For air swellings (without water), this method is suitable, but only for small defect sizes (up to 5 cm).

Why do bubbles appear again after repair?

The reasons may be different:

• Poor cleaning of the base before repair (moisture or dirt remains).
• Using low-quality mastic (for example, expired).
• Lack of ventilation of the under-roof space.
• Violation of technology (for example, mastic is applied in too thin a layer).

If blisters reappear, contact a professional for diagnosis.

What tools are needed to repair roll roofing?

Minimum set:

• Sharp knife or cutter.
• Construction hair dryer or gas burner (for built-up materials).
• Spatula and roller for mastic.
• Protective gloves and glasses.
• Cleaning rag.

Major repairs may require bitumen boiler (to warm up the mastic) and skating rink for rolling rolls.

Is it possible to paint roll roofing to protect it from bubbles?

Yes, but not with any paint. Suitable:

• Aluminum paint (for example, Serebrol) - reflects UV rays and reduces heat.
• Bitumen varnish — restores the elasticity of the material.
• Rubber paint (for example, Super Decor) - creates an elastic coating.

Regular acrylic or oil paints are not suitable - they crack and peel.

How much does it cost to repair a turnkey garage roof?

The price depends on the area, material and complexity of the work:

• Local repair (1-2 bubbles) - 1000-3000 rubles.
• Partial replacement (up to 50% of the area) - 5,000-20,000 rubles.
• Complete replacement (including dismantling the old coating) - RUB 30,000–100,000.

Advice: if the garage is in a cooperative, agree with your neighbors about collective repair — many teams give a discount when ordering from 3-5 objects.