hi, this is my first post. I'm a Brit in New York, and getting close to net zero energy for my 1963 house.
As part of my project I've closed a crawl space.

Here is what I've done:
Close crawl space vents.
Insulate crawl space walls with 2" R10 foam board (will add one more layer later).
Covered dirt floor with plastic.

Now here's my problem, rather than using 6 mil polythene to cover the dirt floor, I was bothered of tears, so I put down a pool mat and then a 20 mil pool liner. The trouble is that the pool liner is vinyl and off gases.

So to avoid the off gassing I could:
1) Rip out the vinyl liner and replace with polyethene? -- a big waste, and I've glued it to the insulation (with low VOC glue)
2) Cover / seal liner with a layer of polyethene.
3) Cover liner with thin concrete slab (I only have 24" height, so a max 2" slab / cap)
4) Vent the crawl space using the energy recovery ventilator that I already have (just fit an extra 4" duct).
5) Combination of above.
6) Wait and hope that off gassing reduces.

I could do a combination, like 2 then 3, and 4.

If I add a thin concrete slab (it does not need to take a load) then how thin could I get away with, and how thick insulation should I use under it. I'm thinking about 1.5" of concrete with some re-enforcing. Remember I've only got 24" total height.

Any advice please??


FYI: to get to net zero, so far I have 13KW of PV, 2 stage ground source heat pump, window upgrades next month (www.apleninc.com - mostly fiber glass), upgraded insulation, still to replace doors, and insulate basement. So far I'm able to cover my energy usage for 10 out of 12 months including heating. Also crawlspaces.org is useful for tips.

Tony, thanks

The crawl space is now opened to the house basement (conditioned space). So one could considered it vented to the inside of the house. It is within the thermal barrier. No insulation between it and the house.

I'll do as you advise. What I need is about 1 gallon of patience, but I haven't found anywhere that stocks that ;-)
The vinyl has been in there for about 3 weeks, and the smell is definitely less, I'll fit the duct to forcibly ventilate via the energy recovery ventilator and reassess it in a few months.