Thick or thin roofing membrane?

Which is better … thick or thin roofing membrane? That’s not an easy question to answer.

A debate is raging among the roofing industry about whether or not thicker single-ply roof membrane is better than a thinner one. Naturally, the manufacturers of the various types always have solid reasons why their product’s thickness is the best. Membranes generally come in the following thicknesses: 40-, 45-, 50-, 60-, 65-, 80-, or 90-mil membrane.

Step 1: Material Choices

Before you worry about the thickness of the roof membrane, the first step is really to choose your product, PVC, TPO or EPDM.

There are actually several questions you should be asking yourself about the product before you get into details about roofing membrane:

• Are you looking for a compromise between cost and long-term durability?
• Are you looking for an inexpensive solution to prepare before a sale of the property ?
• Are you in a damage-prone area – maybe some place that gets regular hail or high winds?
• Are you looking for energy efficiency?
• Do you need long-term durability?
• How much traffic will be on your roof?
• and more!

Step 2: Seams

There is no such thing as a solid piece of roofing material. They all have seams. The more seams and how they are sealed, the more possibilities of problems, since seams are always the most vulnerable areas of any roof. It’s silly to spend extra money on thicker membrane and wearing surface if your seams are going to cause problems from the get-go. Spending more time and money on reducing seams and planning for the best and most appropriate type of binding (i.e., glue, tape, heat-welding etc.) will go a long way.

Step 3: Wearing Surface

Next you need to think about the “wearing” surface of your roof. In layman’s terms, roofing membranes have a brace or reinforced area roughly midway through the material. The stuff above is the wearing surface. That surface can wear away over time due to foot traffic, natural aging, exposure to harsh weather, pollution and more. If too much of the wearing surface degrades, the roofing material no longer offers the protection you need. Naturally, the thicker the wearing surface, the more protection for a longer period of time. In short, how long do you want your roof to last?

Step 4: Cost

So now imagine you are comparing 45 mil thickness versus 80 mil thickness roofing membrance on a TPO roof. The 80 mil actually only adds about 17 (roughly 0.014 inches) of additional wearing surface. It also costs roughly twice as much. Is it worth that extra costs to have 17 mils of added protection?

Step 5: Ask the Experts

This is where the value of hiring a professional roofer can really come in handy. With more than 35 years of experience, we can help you select the right product and roofing membrane that best suits your roof and will be as cost effective as possible.