A DRY BUILDING IS A HAPPY BUILDING
Our office has been working remotely now for almost 2 months, and that also means that a lot of interesting webinars and opportunities for continuing education have been surfacing. Since I’m really interested in building science and have also been working on several projects lately that involve a high level of moisture mitigation, what better way to earn my AIA continuing education credits than to learn more about keeping exterior building envelopes dry?
Between “Foundations, Keeping Your Bottom Dry” with Dr. Jon Straube and “Drainage & Drying in the Exterior Wall” with Will Maley, I became more familiar with the strategies that help keep moisture out of our buildings and wall cavities. I’m not going to bore you with all the little details, so here are some of the more important considerations that can be implemented on pretty much every building.
KEEP WATER AWAY FROM THE BUILDING
1. Implement roof eaves that overhang far enough to deflect driving rain.
2. Proper use of gutters and downspouts; connect downspouts to an underground storm sewer, or discharge at grade several feet away from the building using concrete splash blocks (or something that won’t get trampled over easily).
3. Slope the site AWAY from the building and make sure that your finish material is at least 8” above grade.
PROTECT THE FOUNDATION
1. Provide base drainage or damp proofing on concrete foundation walls to act as a vapor barrier and capillary break.
2. Use a drainage mat w/ termination bar at the top to control the flow of underground moisture downward towards perimeter drain tile.
3. Locate perimeter drain tile at the lowest practical point along footing base and below any basement slabs. Discharge drain tile to daylight using gravity, or a pump if needed.
LET THE EXTERIOR ENVELOPE “BREATHE”
1. Give water a place to exit should it get past the exterior cladding ( a.k.a. siding material).
2. Provide an air gap using a rain screen system or drainable house wrap.
3. Use a Weather Resistive Barrier (WRB) that is resistant to water, yet vapor permeable to allow moisture trapped in the exterior wall to escape.
These simple techniques could prolong the life of any type of building, and create a healthier environment for the occupants. Remember, water will ALWAYS find its way into a building, but allowing it to escape properly is the key to keeping it under control.
Thanks for reading!
Alex Parulis | Architect
08 May 2020