If you give it a place to go, water will go there. And water is THE killer of houses, inside and out.
You have all seen the rubber membrane roof product, particularly on flat or low-slope surfaces. That is an EPDM roof, or Ethylene Propylene Diene Monomer roof. Technically, it is a thermoset with high tear strength that can be cross-linked by both peroxides and sulfur (I learned that in Indianapolis!), but I digress.
If you look out a window at a small, flat front porch roof, you will probably see it.
It comes in different thicknesses, principally a 60 weight and a 90 weight, not getting too technical.
Which weight do you think builders will put on houses?
Hint: the 60 weight, called FM I-60, is thinner and cheaper.
Correct! They put on the cheaper product. No brainer there! It doesn't last very long if exposed to direct sunlight, maybe 15 years.
Being thinner it also expands and contracts more. This can cause the glue which adheres it to the substrate to come loose.
This particular house, and this front porch roof, is only 10 years old. The glue is already coming loose.
And what happens when it comes loose boys and girls?
Water damages the substrate. It loosens more. The substrate, being wood, will rot. As it does it will sag. More glue will come loose. And more water will get in.
When water gets in it sits.
And viiiioooola! (That's French) You get more damaaahhge. (That's French too) *
What's an inspector to do?
Observe and report.
My recommendation: When you see a rubber-membrane roof, check it carefully for evidence of previous pooling of water. You can see what such a stain looks like here. If you see staining, almost certainly there is a problem.
* And here you thought I only spoke Spanish!
Jay Markanich Real Estate Inspections, LLC
Based in Bristow, serving all of Northern Virginia.
Office (703) 330-6388 Cell (703) 585-7560