Bitumen Roof Shrinkage

Shrinkage of a membrane often damages base flashings or the roof edge assembly leading to water infiltration.

Bitumen roof shrinkage.

Its causes include aging of the material poor installation and uv exposure. The material is based on the same materials used in asphalt shingles. It is most common on epdm or modified bitumen roofs and is usually caused by aging of the material poor installation or excessive uv exposure. The swelling of the underside of the shingle is commonly due to the migration of excessive amounts of airborne moisture from the attic spaces through the roof deck and into the bottom surface of the shingle.

A few decades ago unreinforced rubber roof systems were plagued by shrinkage problems but thanks to technological advancements and improvements to epdm roofs the problems have diminished. An organic felt or fiberglass mat saturated with asphalt and faced with granular stone aggregate. The shrinkage of the top surface is commonly due to normal aging and weathering of the shingle over the years. While roof shrinkage technically involves parts of the roof shrinking to an extent it rarely makes your roof look visibly smaller.

Shrinkage is most common on epdm or modified bitumen roofs. The more obvious sign of roof shrinkage are highly visible gaps running along the seams where the roofing surface rolls were initially laid out. Thanks to technological advancements and improvements to epdm roofs though shrinkage has diminished significantly. Roof shrinkage is no easy matter to deal with.