Zone 3 Crawlspace Modifications
A little context…my home is a 1 story single family residence, built in 1957 (conventionally framed) located in Carlsbad, CA (Zone 3). 1350 sq ft. Post and beam foundation (approx 24″ vented crawl space). Subfloor is 2 x 6 T & G. 8 ft ceilings. The 2 x 4 walls are not insulated and the horizontal siding is attached directly to the studs (no wall sheathing) with the original WRB of the past.
My long term goal is to do an energy retrofit on the entire home as budget allows. I have been researching GBA/ building science techniques for a couple years now and would like to approach the retrofit so I have a tight home that is efficient and comfortable.
I am currently remodeling one of my bathrooms, which lead me into several other projects such as removing all of the blown in attic insulation as well as all of the cast iron waste/vent lines in the crawl space. Given I currently have a large opening to the crawlspace (because of the bathroom remodel) I thought it would be a good time to address this area.
The ground in the crawlspace is definitely moist, but I’ve never seen any standing water. I expect a lot of the moisture and dank air from this space migrates to the interior of the home and isn’t healthy. I’ve read several of GBA’s articles on possibly closing off vents and encapsulating, but given Zone 3, it seems like this could cause other potential issues. Any suggestions on what the best approach might be to air seal and insulate this crawlspace are appreciated.
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other issues such as what?
youll need (CRC 408.3) and want something down there to perform residial dehumidification. but that should be easy enough
Thanks for the response and reference, Luke. I have read several articles that note in Zone 3, due to the dry climate, encapsulation and blocking vents might not be necessary. But, now that you ask I don't see any direct references indicating what issues this will or could potentially cause. I guess if the encapsulation is done incorrectly, that is where the moisture issues would begin.
Do you think a full crawlspace encapsulation is overkill (or even unnecessary) for my situation? I want to invest funds towards improving my building envelope wisely, but am unsure if this project makes sense. Also, the idea of running a dehumidification system 24/7 also seems like it would work against my goal of running efficiently.
Thanks again, Ryan
unfortunately I won't be very helpful here since it all kind of depends. I think Joe lstibureks article on this is helpful for thinking about this-- crawlspaces should either be really open, or encapsulated. is it worthwhile to adjust your crawlspace accordingly? I dunno...
I think the least controversial next steps would be to make sure youve managed exterior moisture sources (e.g. do you have lots of irrigation around the perimeter of the house? consider eliminating those)
then you could lay down a vapor barrier on the ground. just a plastic sheeting from home improvement store.
as for insulating and air sealing., youve got to pick an approach and commit to it (either floor insulation, or encapsulation with wall insulation )
I sympathize with your situation . I've got a crawlspace down the road in missing valley and I've at least turned off the irrigation. haven't gotten to overcoming my claustrophobia and crawling around to layout that plastic sheet.
Thanks again for the referenced article and solid suggestions. Lots to think about. I was in my 'claustrophobic' crawlspace over the last couple days and observed that the west side is the 'moist side', which is the low side of my property. My property is also lower than both of my neighbors to the east and west (old house sandwiched between newer builds) so any rainwater essentially funnels to the west side of my property. Your suggestion about managing exterior moisture sources is likely what I need to address. Might have to go down another rabbit hole(s) on sump-pumps and french drains.