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Membrane Roofing Types

Types of Membrane Roofing Materials

Flat roofs have been around for ages. Old technology dates back thousands of years with respect to deflecting water. Old fashioned tar and pitch (asphalt compounds) were employed almost exclusively until 25 to 30 years ago. In fact, asphalt is still used today although its use is waning.

The new membrane products began to appear about 40 years ago. The explosion in the synthetic rubber industry and the plastics industry helped fuel this growth. The result are flat roofing products that enable you to basically "shrink-wrap" your roof! Prior to the advent of these products, you knew that if you bought a building with a flat roof, dealing with leaks would be inevitable. The new membranes allow you to be unconcerned with each rain cloud that floats over the horizon!

Three Basic Types

There are three major types of flexible roofing membranes. All of them are fairly complex and some have names that you can barely pronounce. I happen to like the products in the first group - those being the Thermoset types.

Thermoset Membranes

These materials are ones that chemically crosslink. What that means to you is that once seams cure you have one giant molecule of roofing over your head and possessions. That is a huge advantage. Many of the synthetic rubber roofs (EPDM) fall into this category. You also find the CSPE, CR, and ECR compounds/membranes in this group. These membranes are fairly thick and often you will find them in thicknesses between 30 and 60 mils. These roofing materials offer superior performance over a wide range of exposures. If applied according to manufacturers recommendations, they will give you leak free performance for many, many years.

Thermoplastic Membranes

These membranes are very similar to the Thermosets but there is no chemical cross-linking or vulcanization. Seams in the materials are welded together with solvents or heat. The welds - when done properly - are as strong as the material.

PVC plastic materials are part of this group as well as the following materials: CPA, CPE, EIP, NBP, PIB, and TPO. These are "code" acronyms you might hear the roofer talk about. Be sure to ask exactly what type of material you are getting so you can see which group it falls into!

Modified Bitumen Membranes

These membranes combine asphalt with modifiers and reinforcement materials. They are often a "sandwiched" roofing material. These materials can perform well in my opinion but they are not as advanced as the other two groups. These materials are often referred to as "torch-down" roofs because a large flame throwing torch melts the asphalt so that seams can be joined together. You might hear your roofer mention the names APP or SBS when referring to this membrane.

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13 Responses to Membrane Roofing Types

  1. Hi. Have metal R panel metal building. Where the roof meets the walls, a 'V' metal corner was put on. When the wind blows rain against the buliding, the building leaks at these junctions.

    Thinking of taking off 'V' panels, putting roofing membrane underneath, then putting 'V' panel back on. Do you think this would cure leaks, or do you have a better suggestion?

    Thank you.

  2. Have a Kalzip roof gutter overlayed with a TPO lining. The seams appear to be not sticking causing water ingress to one area. I have overlayed repaired the seams with TPO weld strips & then a coating of cromapol scrim coat for second defence.. Would you consider this to be a satisfactory remedy?

  3. Hey, we recently had a membrane roof installed on a 100 year old building. We also had them do 6 inches of iso right on top of it because we were going for the open rafter look where you can see the bottom side of the decking. Fast forward to the fall we had some leaks around the edges. The roofer said that is do to frost accumulating in the iso and then it warming up to moving the edges where there is a gap and coming out. He suggested I spray foam the one edge(about 15ft worth) and that should fix it. Not long after that winter struck and it hasnt warmed above 30 until yesterday. We have also had about 6 inches of snow in the last week. Yesterday I had more water in my building than when the original roof existed(it was bad). He came over and said I now need to spray foam the entire edges of the interior of the building.

    So I guess my question is if this is a reasonable explanation and fix to our problem? Im assuming that we do have some frost but yesterday when the snow started to melt off we had leaks we have never had before. He said it wasn't anything wrong with the roof but conceded that possibly the way he did the iso is allowing air in to it allowing it to freeze and thaw creating puddles that are now turning into falling water on my customers heads. He said he would spray some insulation in the 6 spots I had leaks yesterday but that I would need to do the rest myself. My assumption is that when he "fixes" these 6 leaks the water will simply go around them and find another place to come out.

    Thanks for your time.

    • Tyler, Sorry I'd have to be there to see everything and inspect the roof. Bottom Line is you got a BAD JOB. Call up three EXPERT roofers and have them come out to tell you what's wrong, even if you have to pay for their visit. Best $$$$ you can spend. How do you find the BEST roofer in your area? Easy. Use my Roofing Contractor Hiring Guide.

  4. Hello, I have some sort of roofing membrane covering my exposed upper deck. It gets a good beating from the weather as I live on the beach. It is likely 20 years old. Seams appear to have been likely heat sealed. It is perfect really for this application. No leaks thankfully. A few weeks ago I had a new roof installed and the workers damaged the membrane with a 6" tear. The contractor wants to fix it by NOT REMOVING THE DECKING, but covering it over with another membrane. Is that a good idea? Or, should the damaged roofing membrane be removed first.
    Thanks for any advice.
    Barbara Donaldson

  5. I have an 1100 sqft walkable flat roof. I live in the mountain at 7,000 feet so the freeze-thaw heat/cool occurs almost daily with a large variance in temperature. I need a really well priced solid roofing solution. Could you recommend?

  6. Is PVC roofing as good and long lasting as EDPM. I have a flat roof on my building and the roofer recommends PVC over EDPM because there is a restaurant in the building.

    • If the roof will support the weight there are many systems you can lay on top of the roof that lock together. Just call the manufacturer and ask what they recommend. or you can build a deck that just lays up there, no fasteners into the roof! Be sure to put a slipsheet under the deck.

  7. The EPDM system does not glue together molecularity and the seams are notorious for degrading and causing the entire roof system to fail. PVC and TPO seams are far suppirior to EPDM, just wanting to let you know the seams on EPDM are basically contact cemented together and then caulked to protect the contact cement from water. if the caulk is missing or even one spot comes off or has a hole in it then often water will degrade the contact cement.

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