Understanding Roof Bubbles: What Causes Air Bubbles in EPDM Rubber Roofs?

Rubber EPDM roofing has become a favorite in construction for its toughness and low prices, but its flexibility sets it apart. Like every roofing option, it does have challenges, including air bubbles developing under the membrane. This blog will identify the most common causes of roof bubbling in EPDM systems, what risks it poses to the roof’s performance, and the best ways to repair and prevent it. With this knowledge, contractors and property owners will be better informed when taking preventative measures that extend the longevity and effectiveness of EPDM rubber roofing.

What causes air bubbles in EPDM?

Unofficial Free and Open Source Software (FOSS) EPDM roofing systems are primarily caused by improper installation techniques, gas vaporization, or moisture getting stuck. During installation, if the adhesive is not applied correctly or the membrane is not smoothed out, air pockets can exist below the surface. Moisture is trapped below the roof deck, and the membrane can evaporate when it is warmed underneath, leading to bubbles forming above the surface over time. Furthermore, certain materials below the EPDM layer may off-gas, which can become trapped vapor and lift the membrane. Addressing and identifying these problems is essential to prevent significant and costly damage inside a roofing system.

What Role Does the Roof Structure Play?

From my experience and research, the roof structure is the primary basis for support for the entire roofing assembly. It affects the life span and stability of the roof by ensuring that it can endure environmental factors such as wind loads, snow coverage, and temperature changes. An adequately designed structure minimizes the stress the roofing materials would be subjected to, such as wear and tear, warping, or sagging. Moreover, proper ventilation within the structure helps in moisture control, which is key to preserving the EPDM membrane without compromising the building’s structure and avoiding problems like bubbling or lifting. Even the highest quality roofing materials will deteriorate in value if unsupported by a reliable roof structure over time.

How Can Trapped Air Lead to Blisters?

The trapped air underneath an EPDM membrane can cause blisters due to the pressure differences created by varying temperatures. When air is trapped, it can expand because of solar light or environmental factors, which increases internal pressure. This occurs because air expands with rising temperatures and exerts force on the membrane. Blistering is likely to occur if the adhesive bond or the membrane cannot provide sufficient support.

Key Technical Parameters:

• Temperature Range: The inflation of air pockets is especially noticeable between 86°F (30°C) and 140°F (60°C), which relates to the usual temperature of roof surfaces in direct sunlight.
• Adhesive Tensile Strength: Forming a strong adhesive bond with a tensile strength of over 10 psi greatly reduces the potential for blistering.
• Membrane Elasticity: Projects to these materials can be done without any tears, while those flexible enough to have an elongation rating of 300% are stressed.
• Air Volume: Volume pockets more excellent than five cubic inches are more susceptible to significant blistering under expansion caused by heat.

Long-term membrane performance can be qualified while upholding the issue by limiting the use of air pockets, preparing the substrate, and, most importantly, using adequate amounts of adhesive.

Are Roof Bubbles Indicative of Installation Errors?

Roof bubbles, also referred to as membrane blistering, is formed due to mistakes during installation, however, there might be other reasons too. The bubble is created because there is air or moisture that gets trapped below the membrane and then is exposed to temperature changes. Bubbles are usually caused during the installation process, such as not using enough adhesive, substrate not being prepared properly, or not getting rid of the air pockets in the space in the cabin. Other serious issues to note include the surface moisture content of the membrane’s structure, which should be kept at under 5% for installation, and the adhesive application’s standard, which averages 1.5-2 gallons every 100 square feet. Adequate installation rolling should also be followed by post-installation rolling to ensure the membrane is preempted from getting detached and blister formation, including moving the structure with functional weights of at least 75 pounds.

How Does Adhesive Affect the Formation of Bubbles or Blisters?

The adhesive is essential in ensuring bonding between surfaces. Proper measuring of the adhesive ensures that no bubbles or blisters are formed. Inadequate application of the adhesive will result in air or moisture being trapped in the surfaces. Also, using the wrong type of adhesive or not complying with the manufacturer’s guidelines, for example, the spreading rate or how long it can stay open, will worsen the problem. When the correct type of adhesive is used, it will ensure uniform application, manage thermal expansion, and reduce the chances of blisters or bubbles appearing.

Is Contact Bonding Adhesive Effective in Preventing Bubbles?

Contact bonding adhesives effectively eliminate bubbles, provided they are executed correctly and under the right conditions. Their suitability stems from their ability to form a uniform bond when pressure is applied after the adhesive has sufficiently dried to a tacky state. Proper surface preparation, along with the type of adhesive used and the application technique, also plays a vital role in determining the contact bonding adhesive’s effectiveness.

Technical Parameters for Effective Use:

• Spread Rate: When applied to the surface, both substrates must be ensured foam from 2.5–4.0 oz/ft² to eliminate under or over-application.
• Open Time: Under the provided ambient conditions, foam needs to be kept for 10-40 minutes to ensure the proper degree of stickiness.
• Pressure Application: A force of 40 psi must be applied to the surface using a roller or similar tool. Combined with the open time, this will ensure complete contact with the glue and the foam, preventing any trapped air between the two surfaces.
• Ambient Conditions: It is important to note that the adhesive will be effective only between 65°F and 85°F with a humidity level of under 50%.

Foam is required to properly execute all technical parameters, eliminating shrinkage, bubbles, or voids in contact bonding adhesive. This ensures that the bonds created are strong and durable, achievable with the right application.

Can Poor Adhesive Quality Cause the Rubber Membrane to Fail?

There are holes where the adhesive was applied poorly, which will cause the rubber membrane to stretch and break. Blisters can be caused when the adhesive is set at low temperatures. According to specialists and industry rules, blisters are generally caused when an adhesive does not have a sufficient bond. This problem leads to the membrane losing its durability and functionality. Blisters appearing directly affect the covering’s strength. To achieve these goals, high-strength adhesives must be used carefully while following the proper application.

How Do Weather Conditions Impact EPDM Roofs?

Weather elements can considerably affect the effectiveness and durability of an EPDM roof. Severe temperature changes may result in stretching, contraction, and stress at the seams and adhesive bonds. While the membrane UV radiation may degrade it over time, the structural makeup of an EPDM roof enables it to surpass other forms of roofing in terms of being withstanding over time. Moreover, heavy snowfalls and rainy seasons may result in excessive moisture or weight stress, meaning there is a need for drainage and proper direction design. These factors must be customarily managed for an EPDM roof to achieve long-term durability under various environmental shifts.

What Effects Do Temperature Changes Have on Flat Roof Bubbles?

Fluctuations in temperature can significantly affect the development and stamina of bubbles in flat membrane roofs, especially in the EPDM or TPO membrane styles. When the temperature is high, these materials stretch and cause air or vapor pockets to get trapped under the roof membrane, appearing as bubbles. The materials contract at low temperatures, which stresses already bonded seams and exacerbates already-formed bubbles.

The key technical parameters of the phenomenon include:

• Thermal Expansion Coefficient. The average EPDM expansion rate is built on the 160 µm/m°C m coefficient. This means that expansion and contraction are visible even with slight temperature changes.
• Temperature Tolerance. Every EPDM membrane works effectively at -40°F to 300°F. Extreme temperatures without appropriate insulation or bubble control affect the membrane harshly.
• Vapor Pressure. The vapor pressure of moisture trapped under the roof membrane can rise significantly at high temperatures. For example, water vapor pressure climbs steeply at 120 degrees Fahrenheit, causing the bubbles to expand further.

To mitigate the effects of temperature range variations on flat roof bubbles, following the proper installation methods, ensuring sound ventilation systems are in place, and following the manufacturer’s guidelines and requirements all aid significantly.

How Does Moisture Contribute to Blisters?

For roofs that are flat in structure, moisture was one of the main reasons for blisters on roofs. Water sits trapped between different layers once it seeps in through small cracks or punctures in the roofing membrane. If heated, water produces vapor pressure capable of separating the membrane from the underlying substrate, which is the leading cause of concern. Additionally, the bond-weakening cycle of bacterial feeding and mold growth deteriorated over time. Similarly, the complete and idle expansion and contraction temperate actively acts against the bond. To improve the problem, I suggest managing proper drainage and a compelling installation that can effectively cater to moist resistance.

What Are the Solutions for Remedying Roof Bubbles in New Roof Installations?

Solving issues such as roof bubbles that show up in new installations can yield some options to promote the long-term durability and maintenance of the membrane.

A. Ensure Proper Installation Techniques—It is crucial to use skilled personnel and adhere to the manufacturers’ specifications. This includes the proper installation of the membrane on the substrate, which involves correct application techniques that remove any possibility of air getting trapped in pockets within the membrane.

B. Choose Quality Materials that are Compatible—Installing roofing systems that incorporate materials fabricated for the local building’s climate and requirements helps mitigate the chances of moisture ingress and thermal expansion problems.

C. Improve the Design of the Drainage System—A well-constructed and thought-out drainage system is required to eliminate water pooling, which reduces the chances of moisture infiltration that can lead to roofing bubbles.

D. Conduct Regular and Thorough Inspections—Detailed inspections during and after installations, such as seams, punctures, and debris trapping inspections, should be conducted to identify and rectify defects before they progress further.

E. Apply Limits on the Penetration of Moisture using Barriers – Barriers must be deployed around the site where moisture penetration into the substrate needs to be limited, especially on sites with high humidity.

Utilizing these procedures cooperatively assists in reducing the number of problematic roof bubbles while extending the waterproofing system’s life cycle. Just as critical is the period of time after the installation to turn the structure into use so that the intended functionality of the structure is preserved.

How Can Proper Roof Design Prevent Future Blisters?

Effective roof design focuses on reducing the potential factors contributing to blisters, making maintenance practically effortless. The main points to be achieved include the following:

1. Sufficient drainage design—Set the minimum slope for spreading water at a quarter inch for every foot of the blisters. The slope should be standard to promote water runoff on the walls and roofs of buildings. This would undoubtedly minimize moisture absorption and prevent blistering altogether.
2. Movement of Heat—Adequate thermal movement maintenance joints and/or expansion joints should be incorporated where required to aid in thermal strain management. Flexible membranes with a high coefficient of expansion that matches the substrate are also less helpful for restraining heat movement.
3. Venting of Structures – Floating head drip, hatches, or vents should be infused to remove accumulating moisture and pressurized vapor from underneath the determined roof membrane or epdm. This should undoubtedly be applied to areas with a lot of moisture.
4. Material Use – If epdm sheets need to be applied on top of an excessive water vapor barrier membrane, the cement type, such an epoxy, also needs to be used. Such combinations greatly limit the likelihood of interface stress due to temperature and humidity changes.
5. Insulation—Determine insulation with rigid foam boards, minimum 20 PSI compressive strength, and low water absorption to ease stability against pressure and mitigate ingress water.

Resolving these technological conditions prevents blister formation, ensuring encapsulated roof systems will be durable and fully functional over long periods.

What Steps Should Be Taken During New Construction?

With new builds, I ensure all roofing elements are appropriately designed and implemented to avoid common problems like blisters. First, I ensure the substrate is clean and dry and prepared according to manufacturer instructions by removing any debris or moisture that could interfere with adhesion. I then select appropriate adhesives, membranes, and insulation that will meet the project’s thermal and moisture performance requirements. For instance, to minimize moisture trapping, I specify insulation with a compressive strength of at least 20 psi and water vapor permeability rates under 0.25 perms.

I also pay careful attention to the surrounding environmental conditions and do not apply when temperatures fall below 40 degrees or during high humidity to reduce the risk of curing issues. Seam overlaps are checked to ensure they meet the minimum manufacturer’s specifications, which, without fail, range from 2 to 4 inches. Finally, during and after the installation process, a properly conducted inspection is used to determine if any defects will compromise the structural integrity and performance in the long term. These techniques reduce weaknesses and provide a more vigorous and better-performing roofing system.

Are Bubbles on EPDM Roofs a Serious Problem?

Bubbles, commonly known to many as blisters on EPDM roofs, signify air or moisture trapped underneath the membrane. Even though small blisters may not immediately negatively impact the roof’s function, they can pose various problems in the future, like membrane strain and ultimate failure. The proportions of the blisters determine the severity. Inspections and installation methods, as with most issues, are essential and, if not taken carefully, can significantly exacerbate the roof’s performance. If the blisters are proportionally more significant than minor, or if they are unsightly and continuing to develop, then a check-up from a professional is warranted for better roof maintenance.

Are Small Bubbles Typically Harmful?

Tiny bubbles in an EPDM membrane do not pose significant issues if they are less than one inch wide and do not inhibit membrane adhesion and overall usage. These bubbles are usually attributed to slightly trapped air due to poor workmanship during installation or expansion of the membrane due to temperature fluctuation. However, while the bubble count or size staying in proportion may not have any negative repercussions, enlarged bubbles increase the chances of introducing stressed membranes, leading to tearing or pulling away from the underlying structure.

The phenomenon must be observed to determine what measures should be implemented to ensure they do not surpass critical thresholds, such as noticeable membrane lifting or reaching sizes larger than 2-3 inches wide. Small-scale bubbles larger than 1 inch can be regularly monitored through biannual inspections, especially following severe weather, to ensure that remedial measures are implemented. The prevention of substantial blistering and other negative repercussions on the membrane is ensured by maintaining a stronger than 2.0 psi bond on the initial adhesive. Blistering of the membrane can be controlled to a great extent, allowing the roof to do its function.

When Do Bubbles or Blisters Become a Concern?

Blisters and bubbles become problematic if they affect the membrane’s performance, integrity, or life span. Some indicators are more expansive than 2 to 3 inches in diameter, blistering over a wide area or lifting blisters that separate from the membrane. These can also undermine waterproofing ability and become stress points that, when exposed to thermal cycling or mechanical stress, can tear apart or detach. Blisters filled with water or vapor that suggest prolonged moisture infiltration are especially detrimental because they compromise the substrate materials and worsen structural issues. Inspect regularly and make timely repairs to ensure little blisters do not aggravate large-scale roofing damages.

How Can a Roofer Assess Damage to the EPDM Membrane?

Roofers can diagnose damage to the EPDM membrane using visual assessments and testing. During the visual inspection, one should look for areas with cuts, rips, pooling water, material shrinkage, and seam separation. These areas can be accompanied by discolorations or patches that suggest trapped moisture and a change in freshness.

Key technical parameters to evaluate include:

1. Seam Integrity:

• • • Ensure seams are correctly adhered to without separation. Use a seam probe to test the strength of adhesive or taped seams.
    • Industry-standard guidelines recommend a minimum seam overlap of 2–3 inches for proper performance.

2. Thickness Tolerance:

• • • Measure the membrane thickness using a caliper to ensure it has not thinned or worn down. Standard EPDM membranes are typically available in 45 mil (1.1 mm), 60 mil (1.5 mm), or 90 mil (2.3 mm) thicknesses.

3. Puncture Resistance:

• • • Check for punctures or mechanical damage caused by external impacts. Ensure no sharp protrusions compromise the substrate beneath.

4. Moisture Testing:

• • • Use infrared thermography or electrical impedance testing to detect moisture accumulation beneath the surface. This prevents undetected deterioration from further compromising the structure.

Document any findings and use this data to determine the appropriate course of action, whether it involves patching, re-sealing, or replacing membrane sections. Consistent preventive maintenance can prolong the EPDM membrane’s service life and help avoid costly repairs in the future.

References

1. Why Are There Bubbles Or Blisters On My EPDM Rubber Roof?
2. Blisters & Trapped Air within The Roof Structure
3. EPDM Rubber Flat Roof Bubbles Appearing

Frequently Asked Questions (FAQ)

Q: What causes air bubbles in a rubber roof, specifically EPDM roofs?

A: Air bubbles in EPDM rubber roofs can be caused by various factors, including moist air trapped beneath the roofing material. This air expands when the sun warms the roof, leading to blisters or bubbles forming in the EPDM membrane.

Q: Are bubbles or blisters on a one-piece EPDM roof a serious problem?

A: Whilst bubbles or blisters on a one-piece EPDM roof can be unsightly, they are often not severe. However, if the affected area is extensive, it might compromise the roof’s integrity over time.

Q: How can the roof’s perimeter affect the formation of air bubbles?

A: The roof’s perimeter can influence air bubble formation because if the EPDM membrane is not securely attached here, moist air can enter, causing bubbles or blisters when the sun heats the roof.

Q: Can the EPDM membrane being partially breathable lead to bubbles?

A: Yes, if the EPDM membrane is partially breathable, it may allow some moisture to pass through, which can become trapped beneath the roofing, leading to bubbles appearing as temperatures rise.

Q: What should be done if blisters or bubbles appear beneath the roofing material?

A: If blisters or bubbles are appearing, the affected area may need to be peeled back, the underlying moisture addressed, and the membrane re-bonded to the roof deck to prevent future issues.

Q: How does water-based adhesive impact the formation of bubbles in EPDM roofs?

A: Water-based adhesives can sometimes lead to bubbles if not correctly applied or if the roof deck is not sufficiently dry, as any residual moisture can cause the adhesive to lose its bond, creating blisters.

Q: What role do upstands play in the occurrence of bubbles on EPDM roofs?

A: Upstands, which are vertical components of the roof, can trap moist air if not properly sealed, contributing to the formation of bubbles as the air expands when heated.

Q: Why might the EPDM membrane need to be peeled and re-bonded?

A: The membrane may need to be peeled and re-bonded if the roofing material has lost adhesion due to moisture intrusion or improper installation, leading to persistent bubbles or leaks.

Q: Can rubber sheets beneath the roofing contribute to bubble formation?

A: Yes, rubber sheets beneath the roofing that are not correctly installed or that trap moisture can expand and cause the EPDM membrane to bubble or blister.

Q: What preventive measures can be taken to avoid bubbles in EPDM rubber roofs?

A: To prevent bubbles, ensure proper installation with dry surfaces, use appropriate adhesives, and ensure that all seams, edges, and the perimeter are tightly sealed to avoid moisture ingress.