Flat roof or low-slope homes look futuristic. However, the sturdy and dependable roofing materials behind these homes are still prone to some issues especially if it wasn’t reputable and dependable Edmonton AB roofers who performed its installation. In our experience with most flat-roof home or commercial property roof inspections, roof shrinkage is a common problem.

Roof shrinkage doesn’t mean your roof is getting smaller and smaller. Rather, we mean flat-roof membranes such as EPDM (rubber roofs) and modified bitumen shrinking in size. What causes roof shrinkage? Can you do anything about it? First, let’s get to know what really happens with roof shrinkage with The Original Roofing Company‘s informative post below.

Everything You Need to Know About Roof Shrinkage

Roof shrinkage affects roofs that rely on synthetic rubber membranes most commonly ethylene propylene diene monomer (EPDM). EPDM is a relatively sturdy rubber membrane and is often used to seal vehicles, windows, and (you guessed it) roofs. Despite its durability compared to other rubbers, EPDM naturally shrinks over time—several factors can speed up EPDM shrinkage.

EPDM is a commonly used because it is capable of protecting more vulnerable roofing materials. However, when EPDM shrinks those protected materials break; either because of the tension of shrinkage or from exposure to sun, rain, snow, etc.

Signs Your Roof Is Shrinking

The best way to keep yourself informed about your roof’s health is through regular maintenance by a roofing professional. While routine maintenance is ideal, there are a few tell tale signs of roof shrinkage. If your roof is leaking, cracked, or has visible separation deformities, they may be due to roof shrinkage. (Read more)

Next, can we do anything to prevent it? As with all roofing problems, the best installations will nip the small factors that contribute to roof shrinkage before they even grow big. This means investing in an experienced Edmonton AB contractor. In addition, excellent installations prevent any major roof repairs that can cost you money too.

DC Taylor Co has a great post on roof shrinkage and installing both EPDM and modified bitumen in the best way that prevents roof shrinkage significantly. Check it out below.

How to Prevent Roof Shrinkage

The primary concern with a roof that is shrinking is the way it pulls the flashings at curbs, penetrations, and walls; this often leads to splits and cracks that allow moisture in, which can result in leaks.

Prevent It

Proper installation is the best prevention. With modified bitumen, crews should lay out the material to relax for 45 minutes, then when installed, alternate/stagger end laps. On an EPDM roof, use of ballast or a coating can prevent UV from heating the membrane and causing shrinkage.

Repair It

Replace affected flashing and curbs and relieve pressure and pulling by cutting the flashing, securing the field sheet with a termination bar or russ strip, and installing a new flashing. (Read full post)

However, will using other types of flat roofing material on your low-slope residential roof help you avoid long-term EPDM and modified bitumen shrinkage? Yes, and in fact, it’s always better to choose a quality roofing material whenever possible. In doing so, you avoid costly repairs and frequent maintenance on your Edmonton AB flat roof.

For example, a great alternative to EPDM and modified bitumen is TPO or thermoplastic polyolefin. This roofing membrane has no risk of shrinkage. Buildings has a great explanation on why it can achieve such a feat.

Why TPO?

Cost considerations, ease of fabrication, and potential for improved performance come to mind. As compared to vulcanized EPDM rubber, TPOs can be welded and reprocessed like other thermoplastics. Yet by containing EP rubber within the TPO, low-temperature flexibility is very good. By not needing plasticizers (required by PVC and CPE), shrinkage and aging through plasticizer loss is less of a factor. The absence of chlorine in the polymer chain suggests that these membranes may be “greener” than those that contain chlorine.

ASTM Specifications 

ASTM Specification D6878-Specification for Thermoplastic Polyolefin Based Sheet Roofing has finally been published after years of trying. It is notable that ASTM recognized Paul Oliveira of Firestone with a Distinguished Leadership Award in December 2006 for his patience and guidance in resolving the many issues related to introducing this new roof membrane system specification.

Some of the TPO manufacturing facilities are brand new and are capable of producing sheet with widths up to 12 feet (this reduces the number of seams that must be field welded).

Common thicknesses for TPO are 45 and 60 mils, but 80 mils is also available when increased impact and puncture resistance is needed. As compared to PVC, the increased thickness does not necessarily relate to durability, whereas plasticizer loss in PVC is a surface-related phenomenon, and thicker is better. What is more important with TPO is the thickness of polymer film on top of the scrim. If the sheet has “hills and valleys” due to the texture of the reinforcement, abrasion (such as from rooftop traffic) will expose the fabric to the weather, resulting in water wicking into the fabric and possible delamination of the sheet. (Continued)

Remember, installation of any roofing material — even materials superior to EPDM and modified — require proper installation to maximize their lifespan and achieve long-term performance. DDCL is an exceptional residential roofing company with decades of experience in providing top-quality roofing services. Contact us today to learn more what we can do for you!