Built-Up Roofing (BUR – “tar and gravel” – coal tar – asphalt and gravel) is one of the most classic roofing systems. Traditionally, BUR flat roofs have been installed by setting three to four layers of coal tar with coal tar saturated felts (tar-paper). Typically, the surfacing is gravel set in a flood-coat of hot asphalt.
Coal tar is a by-product of the coal manufacturing process and makes an excellent water and oil resistant material. An unusual feature of a coal tar roof is its ability to soften in warm temperatures and “heal” itself. The warmer the temperature the faster and easier the membrane adjusts to changing conditions sealing minor ruptures and abrasions helping to keep it resistant to leaks.
Care must be taken with a built-up roof if wide-open expanses of roof exist or if there is movement within the structure itself. In a traditional built-up roofing system, the ability to stretch and relax because of thermal or structural movement is limited to about 10 percent. Thus, where the building is very long, additional curbs must be built into the roof to keep the area of expansion and contraction within manageable limits. This may become a problem if these curbs must be positioned to not interfere with drainage.
If you think your built-up roof may need to be replaced or recovered, a thorough thermographic infrared roof inspection is always the first step. Due to the unique materials on a tar and gravel roof, it may be hard for a walk-on inspection to really tell you what is needed. An infrared inspection should be a priority before any work or planning begins.
If you have been having repeated issues with your built-up flat roof and have had unsuccessful attempts at repair, do not hesitate to call us. Improperly repairing a built-up roof can result in worse damage to your roof and can potentially create problems elsewhere.
Pros and Cons of Built-Up Roofing
- It provides excellent waterproofing protection
- Built-up Roofing provides ultra-violet protection
- Low- maintenance
- It lasts longer to weather inclemency
- Gravels or minerals can be used as surfacing material
- Low-life cost maintenance
- Slower Installation
- Hazardous fumes and vapors when installing it
- High installation costs
We value our clients and believe in 100% customer satisfaction. Call 416-855-0549 today for a free, no-obligation estimate on your next flat roofing project.