Blisters In Built-Up Roofing: When Are Professional Repairs Necessary?
Built-up roofing is one of the most popular and widely used flat roofing systems and for good reason. When properly constructed by a reputable contractor, built-up roofs are highly durable, cost-effective, and less likely to leak than single-ply membranes and other alternative materials.
Unfortunately, built-up roofing (BUR) is not indestructible, and a phenomenon known as blistering may be a sign that your building's built-up roof is badly damaged. While blistering can sometimes be safely ignored, in many cases, blisters are a warning sign that a built-up roof needs urgent, professional repairs.
What Causes Blistering In Built-Up Roofing?
Built-up roofing consists of multiple layers of roofing felt, which are sandwiched between layers of bituminous asphalt, and topped with a protective substrate. This multi-layered structure provides durability and redundancy, but only if the individual layers tightly adhere to one another. If gaps are formed between layers of felt and asphalt, they can become filled with trapped air and/or water. When outdoor temperatures rise, the air in these gaps expands, causing the layers above the gap to balloon upwards and outwards. This process forms the characteristic domed shape of roof blisters.
Age is a common cause of blistering in built-up roofs. Built-up roofs that have been in use for many years will naturally start to degrade and delaminate, allowing air and moisture to seep between the roofing layers.
Do Blisters Require Professional Repairs?
If your building's built-up roof was installed years ago, a certain, limited amount of blistering can be expected. If these blisters are relatively small, the surface of the roofing over the blisters is not visibly damaged, and your roof is not suffering from any leaks, it may be safe to ignore them. It is still a good idea to inspect them regularly, as they may need to be repaired if they grow any larger.
If the surface of the blister is cracked, or the blister is particularly large, it will almost certainly need to be repaired by flat roofing repair specialists. Large and/or cracked blisters can allow moisture to seep deep into the roof's multi-layered structure and frequently cause leaks and damp problems in the building beneath. Blisters in relatively high-traffic areas of your roof will also need to be repaired. If personnel regularly use your roof to clean out air vents or inspect roof-mounted air conditioners, they may accidentally step on blisters, causing them to burst. Burst blisters are very likely to leak.
If your building's built-up roof is suffering from blistering, the safest course of action is to call in a flat roof repair service to inspect the blisters. These services will be able to determine whether blisters can be safely left alone, and can repair blistered roofing quickly by cutting out and replacing the affected sections.
Contact a local commercial roof repair service to learn more.
