Trying to sort out my basement/crawl space

[Kirkf]

Howdy people. So I'm trying to come up with a strategy for taming our crawl space below the house. The goal is to improve air quality, cover the 4 vents for more energy efficiency, and keep any moisture out. We're not super flush with cash at this time so trying to do as much d.i.y. as possible. Has anybody around here tackled a project like this? Any advice or tips on this would be received gratefully. Should I put down a vapor barrier first thing? I'm anxious to seal the vents because the house and floors get super cold in Winter and I suspect this is a big part of it. Where should I insulate and what kind? These are the kind of questions I'm trying to figure out. Thanks.

 

[Snoonyb]

Welcome.
Interestingly, there is evidence of several improvement, some more recent than others.

You'll find that, throughout the LA basin, and surrounding counties, crawl spaces and basement utility areas seldom, if ever, have vapor barriers.

The building code also requires underfloor ventilation.

If you have aesthetic flooring products, other than carpet, they will naturally be cold.

After you've secured the loose and displaced cables you can install R-19, Kraft-backed batt insulation in the floor joist bays, with the Kraft backing against the floor sheating. There are wire supports used to retain it in the joist bays.

Given that LA is subject to tectonic activity, I would add connectors, where they are missing, where the post intersect the girders.

You should also excavate around the base of the post, and expose about 6" of concrete.

 

[Kirkf]

Welcome.
Interestingly, there is evidence of several improvement, some more recent than others.

You'll find that, throughout the LA basin, and surrounding counties, crawl spaces and basement utility areas seldom, if ever, have vapor barriers.

The building code also requires underfloor ventilation.

If you have aesthetic flooring products, other than carpet, they will naturally be cold.

After you've secured the loose and displaced cables you can install R-19, Kraft-backed batt insulation in the floor joist bays, with the Kraft backing against the floor sheating. There are wire supports used to retain it in the joist bays.

Given that LA is subject to tectonic activity, I would add connectors, where they are missing, where the post intersect the girders.

You should also excavate around the base of the post, and expose about 6" of concrete.

Hey Snoonyb, thanks for the reply. Very interesting, you obviously have a good knowledge of the subject. So you are saying I shouldn't cover the vents or cover the dirt floor with the heavy plastic? And yes, we had some work done under there when we moved in about 10 years ago. The drainage was not good and water got under there so a lot of the wood was replaced and it was tied down for earthquakes. The drainage issues were also corrected to not go under the house. There is a mother-in-law apartment that runs along the North side of the first floor. When it gets tot this time of year the apartment gets pretty cold, it's usually warmer outside. That actually goes for the whole first floor actually, warmer outside in the cooler month if no heat is on. Thanks for the info, if there's anything to add after that extra bit of info I gave, feel free and thanks a lot! Cheers, Kirk

 

[Snoonyb]

Thanks and yes I noticed the bottom of the post are connected, yet I'd also connect them at the top, to the girders, and absolute excavate around the base.

The standard 6" of exposure is recommend to mitigate termite intrusion, because the subterranean need to return to earth moisture every 24hrs.

I've seen 4' long termite tubes, in some of the older LA residences.

Happy DIY, and update us on the progress, as well as difficulties you encounter, and how they were resolved.

 

[slownsteady]

Do a search on this site for crawl space projects. There are some good discussions going back a few years.

But more importantly.....what's that organ doing down there between the water heaters????

 

[Sparky617]

Given your mild and dry climate I'm not sure a conditioned crawlspace is needed. Here in NC vented crawlspaces are common, but many are going to an insulated, sealed, and conditioned crawlspace.

This article might be of some use. The site is very good, and if you poke around you might find some good information based on your region. What works here in NC, isn't necessarily what will work in seismically active CA with a much different climate. Nor would what works here be good 300 miles north of me where colder winters and snow are much more common.

BSI-137: Carole King Does Foundations | buildingscience.com

buildingscience.com

 

[PJB12]

Part of our house is over a craw space instead of the basement. Since hydronic pipes & air conditioning ducts pass through, I didn't want it vented in Michigan winters. I made it a "conditioned" space to eliminate the need for vents. Below is what I did. It may or may not be up to codes, but it works and the rooms above are warmer in winter and cooler in summer.

GROUND-
FLOOR: Level the dirt (And remove the tree that the builder left in there decades ago!)
VAPOR: 6 Mil Poly Sheeting- Seams overlapped 8" and taped with vapor barrier tape.
RADIANT BARRIER: Laid perforated radiant barrier on the vapor barrier (Critical = Perforated)
SLEEPER STRIPS: Using 2 x 2 lumber, built a box and lined it 16" on center with more "mini joists" (Critical = Minimum of
19 mm space "radiant gap" between top of strip and face of radiant barrier.)
DECK: Aspenite, waxed side up. (I think OSB is what it's called now.)

WALLS-
Draped R-19 basement insulation batting down from the subfloor above. Ended it 24" onto the new Aspenite deck.
Covered it with perforated radiant barrier.
Note- Beyond the perimeter 24", it is said that the ground itself is sufficient insulation. Adding radiant barrier helps.
I'd imagine that distance from the wall changes by climate.

CEILING-
Nothing because it's now a conditioned space. (Same temperature and humidity as the rooms above)

I hope this provides inspiration for doing your project and, be sure to enjoy your project and the results!
Paul