What are Potential problems with a flat roof?

Answer 1

Where do you start? There are many types of roofs that cover flat roofs. There is modified bitumen, built up hot/cold tar, epdm, tpo, PVC and spray on membranes.

Mod bit is durable and has a good aggregate for slip-resistance. Dark colors give poor emissivity and reflectivity resulting in high energy bills. Membrane will eventually break down much like an asphalt shingle since they are much alike.

BUR roofs- are multiple layers of felt and tar. They can last 40-50 years if properly installed but, installation is dependent solely on the roofing contractor. The tar and asphalt WILL crack just like streets do due to the cold and heat expanses. Patching can be done but, regular inspections are necessary. BUR roofs have a high upfront cost and a very low reflectivity and emissivity causing even higher energy bills than a mod bit.

EPDM- is a thermoset membrane commonly referred to as "rubber" even though it really isn't. EPMD is made in a sheet and the seams are either adhered or taped, sometimes both. Bonding of these seams tend to break down every 5 years or so but, can be re-glued or taped. Membrane will break down anywhere from 13 years to 22 years if ballasted. Mostly made in black it also contributes to high energy bills if left exposed. Ballasted roofs and a white coating can help to reduce cooling and heating loads on a building greatly. Membrane when it breaks down causes aligatoring and cracking.

TPO- in Europe is a great product. In the US is garbage. TPO in Europe is a quality product and costs a considerable amount. TPO in the US is full of fillers and additives and is a commodity sheet. TPO membranes have proven to prematurely fail 4-7 years in their service life due to delamination, scrim wicking, crazing, cracking and premature curing. Formulations are not good enough to properly withstand UV degredation. Sheets are white and have a good reflectivity and emissivity but, only as good as long that it will last.

PVC- Proven to be the longest lasting single-ply on the market. Many roofs still on in Europe from applications in the 1960s and well over 30 years in the US. White membrane gives great energy savings. PVC is inherently fire-resistant unlike every other product out there. Hot-welded at the seams to prevent water penetration. Easily repairable should there be any patching needed. Price tends to be considerably higher than EPDM and TPO. Life expectancy is much greater.

Other problems include post-roof installation penetrations such as HVAC units, solar panels and anything else. Improper repairs can cause leaks.

Drains need to be clear of debris or seals around them can possibly leak.