Cold Crawl Space?

[GoddessKristie]

I was in our basement this afternoon and noticed a cold breeze coming in from an access to our crawl space. Only about 1/3 of our house has a basement beneath it and we've noticed that one of the areas with a crawl is cold at floor level. I'm wondering if there's anything that can be done to solve this. The cold air coming into the basement is only a problem if it can come up through the floor boards. The access to the basement is through an exterior door (the basement stairs have their own foyer-like area between two exterior-type doors-one leading to the house, one to the outside).
What would you do?

[Bearfootfarm]

Insulate underneath the floors and it should make a big difference

[crobar]

Doug Rye, radio personality, king of caulk & talk, would tell you insulate the foundation or skirting with 2"foam, lay plastic on ground to retard humidity. Might be easier than insulating floor.

[Ernie]

It might also be haunted.

I have spiders in my crawlspace. I don't go in there. Yet there's no cold breeze. One would imagine that if you blocked off one end of it (like I did) then no wind will blow into it. There will be cold air in there, of course, but it chills the spiders and slows them down.

[Macybaby]

If you insulate under the floor, use something that is going to stay put.

We've been doing some serious remodeling. When the two dens were built, fiberglass batt insulation was installed in the floor. This area did not have a crawl space.

When we removed the floor, all the insulation had fallen from between the joists into the dirt. It was wet and yukki and smelled bad. We didn't put anything in the floor, but did go around and seal up the perimiter as best we could. Floors are not cold, even with the nasty cold, windy weather we have.

We also have water pipes running under one area, and we need the heat from the floor to help keep that area a bit warmer. If I go into the cellar even on on a cold windy day, I don't feel any drafts coming from the opening for the pipes.

Plugging the holes helps to keep rodents out too.

Cathy

[wy_white_wolf]

Most crawl spaces have foundation vents for air circulation (getting rid of humidity). I replaced my foundation vents with ones that could be closed in the winter. Just have to make sure and open them again in the spring.

[meanwhile]

We have a similar set up: 1/3 the house has a full basement but the rest is just crawl space. There were two holes into the basement area from the crawl space. One has part of the return duct in it but the other was just there, probably from some plumber under there since water pipes are above it. The cold air from crawl space would sink into the basement. We took that solid foam insulation, cut pieces to fit over the holes, used duct tape and closed up the holes. Then we sealed double thick plastic over that too and stuck it good with duct tape. It works.

[Shinsan]

If the air is cold all year round, you could direct some of it to come up behind where your fridge is located. (Mesh covered holes in the floor.) That cold air passing over the condensing coils on the back of the fridge will bring down the cost of running it considerably.

[tiogacounty]

Google "conditioned crawl space". I'm a builder and that is the ONLY way I ever build or repair a crawl space. Keep the moisture out. Do not ventilate. Insulate the inside of the foundation wall. Introduce small amounts of conditioned (heated or cooled) air into the space. Lower utility costs, and a healthier indoor enviroment are the benefits. Crawl space vents and fiberglas floor insulation are a perfect storm in a lot of situations. The vents let wet air in, then the insulation soaks it up and keeps the wooden floor system wet until it's moldy. I have seen cases where people actually fall through a rotting floor due to a defectively designed and built crawl space. My first house had a crawl space. Twenty five years ago the owner tore the fiberglas batts out of the floor joists, poured a thin concrete slab over plastic, blocked the foundation vents shut with foam board, then added an inch thick layer of urethane spray foam on the walls and band joist. The house was a poorly built, low cost, vacation cabin, with no gutters and grades that sloped toward the foundation wall. The crawl space had been a wet mess. However, after the work was done, the crawl was bone dry, and decades ahead of it's time. This system really works, and now it's being accepted and encouraged by the building codes and inspectors in this area. good luck.

[tiogacounty]

Originally Posted by wy_white_wolf

Most crawl spaces have foundation vents for air circulation (getting rid of humidity). I replaced my foundation vents with ones that could be closed in the winter. Just have to make sure and open them again in the spring.

In anything BUT a very dry climate this can be the worst thing you could possibly do. In many locations, the warmer it gets, heading for summer, the higher the humidity climbs. Due to the design of most homes, (the chimney effect) open vents will draw air into the crawl space even without a breeze. The warm, wet air hits the cold masonary surfaces, condensates, then creates very, very humid conditions in the crawl. This ends up rotting the floor system. Probably a non-event where you live, but a disaster in the mid-atlantic, the southeast, the northwest etc....... In my area of PA. several firms make a good living doing nothing but crawl space repair. Smart realtors take the time to inspect crawl spaces on older properties before listing homes. This can prevent a lot of problems later. It's common for a home inspector to fail a home because it needs all the sills, band joist and a few dozen joists replaced. The seller is looking at a five thousand dollar repair, and didn't even know there was a problem. This can be a real deal breaker.

[SolarGary]

Hi,
I'd put in a 2nd vote for Tioga's conditioned crawl space.
I converted ours to this, and it seems to work quite well -- it was also less work than insulating the full floor, and it keeps all the pipes above freezing.

But, I would also monitor the humidity in the crawl space -- this is easy to do these days with all the cheap digital humidity sensors.

Gary

[crobar]

several years ago I insulated my kitchen floor with fiberglass batts, I used the stiff wire supports. A dirty, itchy, awful project. That house is now a rental, last night I cut out a section of floor to make some repairs. The mouse nest & tunnels were unbelievable. Do the outside foundation thing.

[Hooligan]

What are you experienced folks thoughts on using spray foam insulation instead of fiberglass batts to insulate the floor above the crawl space?

About half of our home is over a crawl space. Conditioning the crawl space would not be easy in this situation because there are no "walls" persay to insulate.

The part of the house over the crawl space is built on posts buried in the ground. The house is located on a hillside. At the high side there is less then a foot between grade and the sill plate. The grade slopes down from there and at the low side there is about 4 feet between grade and the sill plate. The low side has PT plywood as skirting while the high side is skirted by the board and batt siding extending a bit below the sill with the remaining space taken up with PT 2x6.

To condition this CS affectively I would have to dig out 3 or 4 feet around the perimeter and bury rigid insulation which would extend up to the sill.

The current set up has the floor above the CS insulated with fiberglass batts held in place with chicken wire stapled to the joists. There is definitely outside air getting into the CS. I keep a good eye on what's going on in there and there is no sign of any mositure problems. I keep the CS sealed as tightly as I can but I do open it up in the fall when the outside humidity is very low to try and dry up any moisture they may have condensed in there during the humid months of summer.

I have been pondering the idea of ripping out the fiberglass rodent nests/moisture trap insulation and replacing with rodent proof/bug proof/moisture proof spray foam insulation then reskirting the perimeter to tighten it ups as best I can.

Any thoughts?


I hope I am not stealing your thread Goddess. I figure the more info we can get about crawl space insulation the better.

[caberjim]

Hooligan - we're in the same situation. The house is on a pier foundation, no walls. I've been pondering making walls out of plywood or concrete block and then backing them with insulated board to keep the chill out of the floors.

[crobar]

I've never used spray on foam, I know it's available on the net. Fiberglass batts did make the floor warmer, the room easier to heat. If you have assess (enough room to manuever foam gun), foam should work. Expensive though $1.50+ @ sq.ft.

[tiogacounty]

Originally Posted by Hooligan

What are you experienced folks thoughts on using spray foam insulation instead of fiberglass batts to insulate the floor above the crawl space?.

Spray urethane performs exceptionally well, is expensive and may have fire code issues, if you are in an area with strict enforcement. In our area, if there are no inspections, it runs $1.25 sq. ft to have a pro spray an 1-1/2" layer, or roughly R-10. If it is new construction, it need to be covered with another layer of sprayed on fire rated paint, which is equally expensive. That said, I would be very careful about spraying it onto the underside of the subfloor unless you have a very, very low moisture enviroment. I once reviewed an absolute disaster that was caused by spray foaming. It was in a crawl space that had severe water problems. The customer had a spray foam installer spray incapsulate the floor joists and bottom of the subfloor. He did nothing to address the water problems at all, operating with the theory that he had sealed his problem below the foam. A few years later the floor literally failed, crumbling into the hole below. The floor joists and some of the plywood rotted inside the foam covering. There were small areas where the floor joists were missing, having rotted away completely, and just a foam "negative" remained. As a contractor who DID NOT take the repair job, I found it facinating. The owner was not nearly as impressed with his little experiment.

[GoddessKristie]

Originally Posted by Hooligan

I hope I am not stealing your thread Goddess. I figure the more info we can get about crawl space insulation the better.

No Sweat! I'm all for people expanding my threads to help everyone!
Right now our crawl is very dry, but we have very humid summers here, which makes me worry. I'll check out the crawl conditioning and post again when I have a better idea of what it is.
Thanks everyone and keep the ideas (and questions) flowing!

[TNHermit]

Originally Posted by tiogacounty

Google "conditioned crawl space". I'm a builder and that is the ONLY way I ever build or repair a crawl space. Keep the moisture out. Do not ventilate. Insulate the inside of the foundation wall. Introduce small amounts of conditioned (heated or cooled) air into the space. Lower utility costs, and a healthier indoor enviroment are the benefits. Crawl space vents and fiberglas floor insulation are a perfect storm in a lot of situations. The vents let wet air in, then the insulation soaks it up and keeps the wooden floor system wet until it's moldy. I have seen cases where people actually fall through a rotting floor due to a defectively designed and built crawl space. My first house had a crawl space. Twenty five years ago the owner tore the fiberglas batts out of the floor joists, poured a thin concrete slab over plastic, blocked the foundation vents shut with foam board, then added an inch thick layer of urethane spray foam on the walls and band joist. The house was a poorly built, low cost, vacation cabin, with no gutters and grades that sloped toward the foundation wall. The crawl space had been a wet mess. However, after the work was done, the crawl was bone dry, and decades ahead of it's time. This system really works, and now it's being accepted and encouraged by the building codes and inspectors in this area. good luck.

I totally agree with this. BUt i do have a question. Down here we have termites what do they recommend between the foam and the wall. Would a boric acid spray work ??

[homebirtha]

This board is so great!

The timing of this thread was phenomenal. We are just about to go for permits on an addition to our house and were going to go with the standard ventilated crawl space. Now I've emailed my contracted all this info, so he can look into doing it this way.

Thanks everyone!!

[crobar]

you might consider wall to wall carpet, I know this is probably almost heresy to suggest. We had room with a concrete floor(I realize other factors are involved there) that we carpeted because our feet could not stand the cold in the winter. We were absolutely astonished at the result 1/2"thick jute backed carpet made in the comfort level of the room. An auxiliary heater was no longer needed.