The flat roof dilemma

What happens when you have a flat roof and a slow leak? As you can tell from the picture, it can get rather ugly.

While remodeling our client's kitchen, they asked us to look at a water stain on the ceiling in a different room. When we removed the drywall to investigate, we discovered a significant amount of rot in the ceiling rafters. The rot was so significant that the only way to repair the damage was to remove and rebuild the entire roof.

You're wondering how so much damage could happen from one tiny leak? Well, there were a couple of things at work. First, there was a small leak that caused damage in a specific spot hence the stained ceiling. Then the roof system had a design flaw that may have been causing rot over time even if there hadn't been an actual hole in the roof.

Most houses have a pitched roof with a ventilated attic space. Homes with a flat roof don't have an attic space, allowing warm air to sit in the small space between the ceiling and the roof covering, causing moisture to condense. Eventually, this causes the roof framing to rot.

The best way to solve a situation where a roofing system suffers from inadequate ventilation is to use a different type of insulation. We recommend using a "closed-cell spray foam" Instead of regular fiberglass roofing insulation. The spray foam insulation eliminates the possibility of condensation and prevents moisture damage. After rebuilding the roof, we made sure to use the proper insulation so the client wouldn't have any more issues with moisture build-up in the future.