Built-up Roof Systems / Hot Mop Applications

Built-up roof systems have been applied as far back as 1870. Back then, roof materials were crudely manufactured and not stable or consistent. Application specifications for the name brand materials were vague and not to todays standards. Roof materials have greatly improved since the 1960s and 70’s and so has the material specifications. Todays built-up roof systems can last and outlast other flat roof types, if applied to the manufacturers specifications. During our 42 years of contracting, rarely have we found built-up roofs that were applied even close to being correct. This is probably due to the many components needed to correctly apply a multiple layer roof system.

The phrase “built-up roof” simply refers to a multi-layer roof that is adhered together with cold application adhesives or the more common, hot asphalt. The more roof layers, the tougher and thicker it becomes. We currently have several 4-ply built-up rock roofs that are over 30 years old and still wearing well.

Today, most roofing companies prefer to apply single ply T.P.O., P.V.C. or EPDM roof systems. It’s easy to apply and because they have become so popular lately they are usually over-priced. At one time, Single Ply Torch down Modified Cap Sheet Roofs were thought of the same way in the 1980’s an 90’s. The only time tested proven roof is the built-up roof system. Wilson Pacific Roofing still receives many requests for built-up roof systems and we are continuing to apply manufacturer approved built-up roofs.