Crawlspace encapsulation

[Grizzerbear]

So i had been contemplating this for the last couple of years. I got a couple quotes from some local companies 2 years ago and it was outrageous. 18000 bucks for a sump pump, crawlspace wall insulation, 20 mil liner, and a fancy entry door and a super duper dehumidifier and the hardware and labor of course. Also they were going to soda blast the whole crawl because of some black mold on the north rim joist that condenses in winter which is the whole reason for me doing this. I get that. Now mind you my furnace and pressure tanks are under my house which would have made it more difficult but 18000 is awful steep to me. So i priced the materials to do it myself. The liner was expensive....it was around 1500 dollars for enough 20 mil poly to cover the 1500ish sq ft foot print of the crawl but I wanted it thick enough and strong enough to walk on without damage. Had to buy butyl tape to hold the liner on the walls and piers and enough waterproof tape to seal seams which came ot to about 300. I bought a april aire dehumidifier for 1100. I dug and installed a sump basin and zoeller sump pump in my low spot. That was about 200 dollars. I dont have a groundwater problem but i wanted one in case of a water leak someday. I also pre drilled and screwed tapcons and fender washers in the liner every 16 inches where it terminates up the crawlspace wall. I installed the liner which was a chore by myself and a little help from my 10 year old daughter. Wrapping the piers was the worst part just because of the tedious cutting to make it fold around and look nice. One thing I didnt do is I didnt put insulation on the crawl wall simply because it is 80% underground and has never been a problem with condensation and I'm not trying to keep it from losing heat. I am waiting for more prolonged cold weather to see if the rim still condenses to decide if I should foam board or spray foam my rim joist. I'm hoping sealing the ground 100% with the liner, closing and sealing the vents, and the dehumidifier that maintains 55% humidity stops this from happening. As far as the mold....I just sprayed bleach liberally on the rim. I realize that isnt as good as soda blasting and that mold spores can easily spread through entire crawl and lay dormant but honestly it was one corner of the rim that it was visibly growing. I grew up in far worse and I think it will be fine and I just cant fork over that kind of cash.

Now that this is all done...I can say it is nice to not have to leave the vents open in the winter. I know, I know....you think I have it backwards. But if I kept my vents closed before during winter the rim condensed terribly. Leaving them open let drier air in and helped to some degree but not enough. It also made my floors cold as hell lol.

So I woke up this morning and walked to the kitchen. It got down to 40 last night so i wanted to see the difference it made with the vents sealed up. Toasty baby. I can finally walk barefoot again. Also the house dropped only 1 degree last night after the stove burned out whereas before it would have been reload time. If I have no problems with condensation on my rim after this winter I imagine I will go ahead and insulate it which should make a big difference in a colder temps.

So far im around 3500 in on this but I'm glad I finally did it.

Sorry for the long post but thought I should mention this here in case anyone else contemplated it.

 

[begreen]

We're fortunate to have a very dry, sandy soil underneath our house, so no humidity issues. I sealed up our crawlspace and turned it into a conditioned space in 2006 by closing off the vents and insulating the interior walls. The difference was immediately apparent. Our floors have been much warmer and the crawlspace stays around 60ºF for most of the year.

 

[Grizzerbear]

We're fortunate to have a very dry, sandy soil underneath our house, so no humidity issues. I sealed up our crawlspace and turned it into a conditioned space in 2006 by closing off the vents and insulating the interior walls. The difference was immediately apparent. Our floors have been much warmer and the crawlspace stays around 60ºF for most of the year.

Yeah at first I was going to insulate the walls before encapsulating but my crawl stays around 60 here as well without it. I definitely dont think it would have hurt but i didnt think I necessarily needed it in my situation. The ground here is all clay and it may look dry but it breathes a lot of moisture up into the air.

 

[ben94122]

Does the lack of ventilation make radon a problem at all? Or is that not an issue in your area? We don't have radon problems here, but my outside air kit vents from the crawlspace, which I think may help...

 

[Grizzerbear]

Does the lack of ventilation make radon a problem at all? Or is that not an issue in your area? We don't have radon problems here, but my outside air kit vents from the crawlspace, which I think may help...

Actually the two contractors I got quotes from did radon tests the day they were here and said I was good and i wouldn't need the mitigation vent so I didnt install one. But I did look into it and basically every state in us has areas that have high levels of radon in homes....which is considered to be 4.0 pCi/l. I think the average us house is around 1.3 and they suggest mitigation of anything above 2.0. Encapsulation helps to lower levels actually because it cuts off the main path for radon to escape into the air you breathe which is bare ground. Its for sure something you would want tested before you encapsulated and sealed it all up but honestly every one should test regardless. It's a relatively cheap fix.