The Ultimate Guide to Modified Bitumen Roof Replacement
Modified Bitumen (MB) roofing systems are a cost-effective option for low-slope or flat roofs. However, they have a lifespan, as does any other roofing material. Knowing when and how to replace your MB roof is critical to protecting your property.
What is Modified Bitumen?
Modified bitumen is an asphalt-based roofing material that is enhanced with polymers like rubber or plastic to improve its strength, flexibility, and durability.
Signs It’s Time for a Replacement
Extensive Cracking and Alligatoring: The surface resembles dry, cracked mud, indicating that the membrane is brittle and deteriorating as a result of ultraviolet exposure.
Widespread blisters and bubbles: These are generated by trapped moisture or air behind the membrane and can cause tears.
Ponding Water: Areas where water remains for more than 48 hours can hasten deterioration.
Frequent Leaks: If repairs do not hold, a full replacement is the most cost-effective long-term option.
The Modified Bitumen Roof Replacement Process
A professional MB roof replacement follows several critical stages to ensure a watertight and long-lasting system.
Step 1: Preparation and Inspection (The Tear-Off)
Complete Removal: The old MB membrane, flashing, and any wet or damaged insulation are all removed down to the roof deck.
Deck Inspection: The exposed roof deck (often wood, concrete, or metal) is thoroughly examined for damage, rot, and corrosion. Any essential repairs are completed to guarantee a solid foundation for the new roof.
Step 2: Installing the Substrate and Insulation
Insulation: A rigid insulation board (such as polyisocyanurate) is installed. This step is critical for achieving energy standards and lowering heating and cooling expenditures. Tapered insulation can be used to form slopes and enhance drainage.
Step 3: Laying the Base Sheets
Attachment: Base sheets are mechanically fastened or glued, depending on the technology.
Step 4: Applying the Modified Bitumen Membrane
Torch-Applied (APP-Modified): The underside of the roll is heated with a torch, causing the asphalt to melt and bond directly to the foundation sheet. This method necessitates highly skilled staff and poses a greater fire risk.
Hot-Applied/Asphalt Mopping: Spread molten asphalt and roll the MB sheet into it.
Cold-Applied (Adhesive): The layers are bonded together using a solvent-based adhesive. This is frequently the favored option in situations where open flames are prohibited.
Self-Adhering (SA): The membrane has a factory-applied adhesive backing that is covered by a release film that is peeled off after installation.
Step 5: Flashing and Detailing
Detail Work: Membrane strips are fitted and sealed around vents, pipelines, HVAC units, skylights, and perimeter walls (parapets) to ensure a continuous, waterproof seal.
Step 6: Final Surfacing and Inspection
Granules: Many MB sheets include a factory-applied ceramic granule surface (similar to shingles) that provides UV protection and fire rating.
Coating: A protective reflecting coating (typically white or light-colored) is commonly used. This phase is critical because it reflects UV rays, greatly lowering surface temperature, increasing roof life, and saving building cooling expenses.
Conclusion
At Blue Sky Roofing, we understand that your roof is a significant investment. Whether your building requires a torch-applied system or a cold-adhesive solution, our team ensures the job is done safely and correctly the first time.