Drying In
Posted on May 19th, 2009 by Doug Marsh VP, CR, CAPS, GBP | 2 Comments
I grew up hearing this phrase and have used it so many times but now that I am learning about building science in hot humid climates I am going to start saying drying in. After building for 35 years I am really comfortable with a building wrap on the outside of my buildings but I must admit I have always thought about it more from a "keep the water out" mentality: let the house breathe. Of course that is paramount - drainage plane etc. However moisture moves from high humidity to low humidity and in our area that means drying in. If the humidity level is high outside (ah... May to October!) then that humidity is trying to get into our buildings: steam pressure anyone? It still amazes me to think that after a good rain that our wet rock, brick, and stucco exteriors are all being slammed by the pressure created by the sun coming out after a good rain and pushing vapor through the veneer and into our buildings. Our drainage planes need to be applied in a shingle fashion, over flashing's, over window and door flanges and flashing's etc to drain the water and moisture out and away. I just can't help but notice all over town the peel n stick stuck on top of the flashing onto the building wrap. I like to cut the wrap a little short of the bottom of the flashing bend and then peel n stick it to the wrap. So keep the rain and humidity out. I never thought that I might be in favor of foam sheathing with taped seams but I guess it is time to rethink it.
Vented attics and crawl spaces are major issues in this drying in category. These are large areas immediately against our cool, low humidity (if your AC is working right) living spaces and that humidity is dying to get in the house. I have written about unvented attics and will be tackling crawl spaces soon.
ck out the guru on this topic. Note this was published in 1997!
Comments
On May 28th, 2009 Ricardo said:
Thanks for this information Doug.
On May 28th, 2009 Ricardo said:
Thanks for the info