First, don't be fooled by the title. If your flat roof has slope, that is good design as is explained below. The other day a blog I wrote about mold received a lot of interest from the real estate community. I decided to give the details of an inspection I did at a property where significant mold was found. As far as I know, it had the most serious concealed mold issues of any home I have inspected. It also had a flat roof. The conducive conditions were present and, even though at no point did I see mold, I figured it likely that it would be present. My supposition, which turned out to be true, was based on clues.

Getting back to flat roofs. Flat roofs, such as we see in the photo below, should not really be flat but low sloped. Here in the wet northwest, the mention of a flat roof makes an inspector's antennae go up because we see so many problems with them. They are different surfaces or membranes: built-up, torch down, EPDM, PVC. Torch down is probably the most common here. What most people do not realize is that, ideally, even a flat roof should have some slope. Why? To drain the water off the roof. This is often done with drains or scuppers, often at corners, or the roof may gently slope back to a single gutter and downspouts. And, my least favorite and the case here, the roof might slope toward a central point and there one finds an integral drain system that, in theory, routes the water down through the attic area with a pipe and then turns and takes it on out of the building. No matter how this drainage is accomplished, if done right, the roof has some slope toward the drain(s). That is theory, in fact, often the roof was not done right in the first place or roofing materials have no slope for whatever reason. As a result, we see lots of roofs that are lakes. When that is the case, beware! Yes, this condition can be repaired for a fee by a good roofer who will, if necessary, rebuild the roof slope so water actually drains as it should.  That said, lets look at the problem below.

This was an addition. Someone decided it would be cheap to put on the flat roof. This roof had an integral drain in the center, as I described above. It was not only fully blocked by debris, but it was tarred in place and it had come loose from the roof. As a result, it was below the roof and the water was getting in around it and going down into the attic. One look at the flooded roof was enough to make me suspicious. When I went below, inside the home, I saw that there was a slight sag at the acoustic ceiling tiles. They were coming loose at the corners -- about center right under the drain.  I used a pinless moisture meter to compare this area to another area, on the same ceiling, which I was pretty sure was dry. Moisture readings on this ceiling area, near the sag below the drain, were extreme when compared to other ceiling areas in the same room. This strongly indicated that there was water or moisture over the living room ceiling. As an inspector does not remove material, that was what I knew and it made sense based on what was visible at the roof above. A water leak of this magnitude can lead to a number of serious conditions, including mold. I told the client that and recommended that the ceiling be removed, for further investigation, along with obviously getting the roof repaired. I later heard, from the realtor, that there was serious mold in the attic and the work required to repair it was extensive. The good news is that, based on the report, they knew that might be coming.

Drain in center, is loose and plugged too

44% moisture reading, reading at ceiling areas away from this leak were negligible

Thanks for looking.

Steven L. Smith

www.kingofthehouse.com

Bellingham WA home inspector