MY MISTAKE 

We’re back at our brownstone renovation project in the Back Bay. In a previous episode, I talked about how we were going to apply a coating on top of the subfloor in the lower level to prevent moisture from making its way up through the wood floor and into the living space. But I missed a critical detail.

Underneath the subfloor is soil. My main concern was installing a new subfloor and applying the blue moisture guard on top. But what I failed to think about—and what the viewers caught—was that the soil underneath will not always be dry; it will get wet and create moisture. If we had sealed up the subfloor, not having anything on top of the soil, we would be creating a micro climate—moisture would have crept up, hit the wood, found the insulation and a nice warm place to hang out, and slowly rot that wood over time. 

A MUCH BETTER SOLUTION 

So, we hit pause and brainstormed for a better solution. We spread 6-mil poly underneath the floor, covering as much area as possible (these floors are partially wood and partially concrete). Of course, if the situation had allowed, we would have gutted the entire space and started from scratch, but in a brownstone like this with common areas, that’s just not feasible. Therefore, we concentrated on covering as much of the soil as possible to prevent the moisture from coming up from the ground and into the wood floor and framing. 

In addition, we discussed ways to ventilate or circulate the air in the crawl space. This can be done either by allowing it to ventilate directly outside (using a mechanical venting fan) or to encapsulate it within the envelope (basically pumping one end of the crawl space with conditioned air and letting that passively come across and then out of a vent).    

Thanks to the feedback and suggestions and consulting with my friend Steve Baczek, my mistake was caught in time. We were able to walk through other options and found the best approach moving forward.   

It’s time to discover what NS Builders can intentionally design and build for you! Contact us today to get started on your custom dream home. Together, we can make it happen. 

—Nick Schiffer