Built up – Tar and Gravel Roofing vs EPDM Roofing Systems.

These photos were taken during  two home inspections conducted by my company, Magpie Property Inspections LLC in Denver Colorado. The photos above are of an mid century home with a low pitched  roof which has an older tar and gravel type roof installed. This type of roofing was typically used on flat and low slope roofing and on commercial installations. It is comprised of several layers of asphalt saturated felt which are layered in opposite directions, then covered with hot asphalt roof coating. While the asphalt is still hot, gravel is typically spread over the roof  to deflect heat and light and to protect the felt and asphalt which provides the actual water proofing.

This example shows the problems that may develop with this type of roofing. Cracking and wear around exposed areas of felt have occurred which may be allowing moisture penetration. The gravel layer has worn loose and the saturated felt is “Alligatoring” from heat and drying of the materials. Vent and stack openings have developed cracks which can leak.

The photo below is of a more modern, improved roofing type used on low slope and flat roofs. It is called EPDM, (ethylene propylene diene terpolymer) roofing.  It is a type of rubber material. As with most construction choices, there are good points as well as drawbacks to a rubber roof.  Low relative cost and the ability to patch and repair areas of roofing are a plus. The vast majority of EPDM roofs are black, but EPDM can also come with a white coating that can aid in heat reflection and thereby reduce energy costs.  EPDM roofs are also fully compatible with solar panels and even support rooftop gardens and decks well.  Another advantage is the material’s relatively light weight. It adapts to any shape or style of roof (not just flat roofs) with all of the same advantages.

As with any roofing system, there are also drawbacks to EPDM roofing. These roofs generally cannot be installed by the homeowner. Some professional installers who claim familiarity with the roofs may not have enough experience with it to install it correctly. Obviously this problem can be solved by using the trained and certified installers with a track record of experience successfully installing EPDM roofing.

It is also possible for small leaks to develop around vent pipes and other openings on a roof, especially if the installers are not as familiar with rubber roofs as they should be.  Punctures can also occur in a rubber roof, but all of these defects can be easily repaired by a roofer skilled in EPDM roofs.

If you are considering replacing an old tar and gravel roof, make sure to consult a qualified roofing contractor to explore your best options.