History of Mod-Bit
In the early 1970’s, the Mod-Bit (modified bitumen) was developed in Europe. Shortly after, it was brought to the North American market. The use of thermoplastic elastomers in combination with suitable asphalt allowed developers to create a roofing compound with improved flexibility and a wider functional temperature window.
The polyester, glass, or composite reinforcement is web-coated with the modified bitumen to form a sheet. This sheet is then surfaced with a granular material. These sheets are then installed in a multi-ply system with hot asphalt, cold process adhesives, or torched together.
What Happens to Mod-Bit as it Ages
An ideal roofing system offers durability and a long-term waterproofing solution. As your roof ages it will degrade over time. Exposed mod-bit sheet will become more common from loss of granular material. The key factors that degrade the roof over time are heat, ultraviolet exposure, freeze-thaw cycling, and time.
Exposed Mod-bit will age due to the forces of nature. As it is exposed longer and longer the rubber will begin to get stiffer. As it continues to be exposed this will result in the membrane sheet cracking, and if not repaired, potential for system leaks. Areas prone to cracking are around edge details, flashings, drains, and roof penetrations.This aging process is not rapid and can take 10-20 years to develop.
How to extend the Life of your Mod-Bit (SBS) Roof
Catching the early warning signs is pertinent to maximize the roof system life. Some easily observed indications are:
- Exposed Mod-Bit
- Granular loss
- Small cracks/tears around details
- Clean roof drains
- Removing debris from roof
A qualified roofing professional can reveal additional areas needing attention to ensure the roof system remains waterproof.
Always review manufacturer and installer warranties before taking the next steps. Manufacturers provide warranties against rapid aging of their products. Contractors typically have warranty for products not applied properly. If there was work performed on your roof that was unauthorized by the contractor and/or manufacturer your warranty may be voided.
If the roof system is left unattended for too long, leaks can develop. Leaks will cause problems in the roof system that can only be repaired by removing the old roof to perform the repair. From saturating insulation and losing all R-Value, destroying the roof deck from the roof down, to causing mold issues. Staying on top of small repairs and maintenance can extend the life of your roof ~30%.
Re-Roofing your Mod-Bit roof
When the life cycle is coming to the end for your existing Mod-Bit roof, a professional roofing contractor can assess the extent of the damage in the roofing system from previous leaks. Using infrared scans, core analysis, and moisture metering, they can determine whether the existing roof needs to be removed and replaced.
If the roof was maintained and kept leak free, a new layer of granulated cap sheet can be installed onto the aged one. This Re-Roofing is significantly cheaper than a roof removal and installation. Installing a new layer of Cap Sheet is typically 25%-30% the cost of a new roof.
Each time a Re-Roof is done on an aged Mod-Bit roof, you can expect another 20-25 year life span. This Re-Roof can be done two times before it is recommended to remove the roof system entirely. Between proper maintenance and re-roofing you can expect to have a roof system that lasts between 60-75 years.