Experience with spray foam insulation?

[quicksandfarmer]

Part of my house is built on the fieldstone foundation of an old barn, circa 1850. It's very solid -- the stones are the size of desks, put there with oxen and manpower. But it lets dampness through and is uninsulated. The outside is buried so it needs to insulated from the inside. From what I've read the best way is foam sprayed on the inside.

I have about 300 square feet that I want to do. I've been looking at DIY kits. They are expensive but not unreasonably so. They're sold by the board foot of capacity, one square foot, one inch thick. A 600 board foot kit runs about $700. That would give me 2" of thickness, at R7 per inch that's R14 which would thrill me. Apparently it takes about 40 minutes to spray out one of the kits, so it's not a huge job (and you don't really want to stop once you start or it risks clogging the sprayer). So most of the work is probably in prep and cleanup, particularly arranging things so it can be done in one shot.

Now, every time I read a review of one of these kits (there are several brands) there's always a reviewer saying that if you hire it out a pro can do it for less than the cost of DIY materials. OK, that sounds good too. But my non-exhaustive search so far finds there aren't a lot of guys interested in small jobs, and that the spray foam business seems to have a fair number of people with mixed reputations in terms of customer satisfaction.

So I'm interested if anyone has experience with spray foam, either hiring it out or doing it yourself. What was putting it in like, what did it cost, and how is the result?

Thanks.

 

[joeu235]

I hired it out and it cost me $1 per bd foot. I had 2400 sq ft sprayed 2 inches thick in new construction. Three guys took about 8 hours to finish the job. The results are great. It's so tight I definitely see for a ventilation exchange system.

 

[RNeumann]

Spray foam isn’t a cure for dampness. Without solving the dampness issue first you are only putting lipstick on the pig and will end up with a moisture, mold mess between the field stone and the insulation. The spray foam could also “pop” off the stone. What’s the local contractors or DYI reps saying about spraying over the stone that has hydraulic pressure on it? They may have some tips.

Also note most basement heat loss is at the rim joist. Very little is below that level. I’m not sure the end goal but you may be doing a lot of work for marginal gain.

 

[EddieWalker]

I have no personal experience, but I have quite a few clients who have had their homes spray foamed and one who tried to do it himself. From what I understand, the challenge with the DIY kits is keeping the nozzle clear. They tend to plug up before you are done, and cleaning them is very difficult. Easier to buy extra nozzles. Of the clients who had their homes sprayed, open cell is considerably cheaper, and easier for a guy like me to come in and remove what's in my way when doing electrical work. Everything I've read on open cell is that it holds water and it will destroy whatever it's up against. It's especially bad against metal. The R value on open cell isn't anywhere near as good as closed cell.

Closed cell is what they use to build floating docks. It's what is used when lifting foundations. Every little bubble is air tight, so it does not absorb water or moisture from the air. A couple inches will make a huge difference.

For what you are describing, it sounds like closed cell foam might be a good solution. The only concern is if the moisture behind it will work it's way around the foam and become a problem somewhere else? I also worry that if there is any movement in the soil or rocks, will it crack the foam and allow moisture in?

Since it sounds like you are just trying to insulate the crawlspace under your house, it might not matter is you have a small amount of moisture get through when you are stopping 90% of it or more.

I also think the air temperature needs to be above a certain point for it to cure properly. Most things need to be 50F for best results, but I'm not sure about spray foam.

 

[quicksandfarmer]

Let me clarify what I mean about dampness.

The original structure was what they call a "bank barn." The floor of the basement was at grade level. The stone foundation was built above grade, and then dirt was piled around it ("banked"). It was used for keeping dairy cows. They would drive wagons through the upper part to bring in hay for the cows and drive wagons into the basement to catch and haul out the manure. So the house is up on top of a hill that is about 8' higher than the surrounding land.

I don't have a problem with liquid water coming in. The problem with dampness is that we are right next to the ocean. The air is very humid, and if the weather is much above 60F the basement walls get condensation. Also, the house is about 15 feet above sea level and the water table never drops below sea level. The soil tends to be moist all the time, even during droughts. The stone walls are mortared but they aren't moisture-proof, the dampness from the soil comes through.

I run a dehumidifier which helps a lot, but the part of the basement that is stone stays noticeably more humid than the newer part which is poured concrete.

 

[frugalangler]

Might be a little costly, but what about excavating the piled dirt bank from the stone foundation, and applying a waterproofing like a concrete foundation sub-terrain would have, then insulate the insde w/ foam - that would I'd think stop any moisture seepage from eh outside into the basement.

Whatever you choose, if you do the spray yourself, please do some documentation pictures and post, I think a number of us would be interested in the process and outcome.

 

[forgeblast]

I did a kit from foam it green .com. I prepped everything to spray one day and be done. They give you a lot of tips. If you stop spraying for 30 seconds-1 min throw the tip out. Its that easy. I had a lot left over. The biggest thing I had happen was splatter, I had one spot where my tarp did not cover the floor and when I was changing a tip the foam on the tip of the tip fell and hit the tile. I also had my tyvek coveralls push up on my arm and I lost a bit of hair on my arm when a drop of foam hit my arm.
Other then that it was like having two propane tanks, easy to use and not bad a all.

 

[jrepp44]

Good advise to address the moisture issues first. From my DIY experience spraying a 30 x 60 metal shop. Hire a pro if at all possible!! Don't expect to get anywhere near the claimed coverage - maybe 2/3 fill at best. Most miserable job I have ever done - you will need full coverage Tyvek overalls, full face mask(s), high quality air mask, clothes/shoes you don't mind destroying, several spare nozzles, maybe even a spare hose. The over-spray goes everywhere, expect to spend a LOT of time on cleanup. You will be left with empty tanks that may be hard to dispose of. Temperature and humidity MUST be as recommend by the mfg. Surface needs to be clean. If you stop spraying for more than 30 seconds, the nozzle WILL clog. -- Good luck if you decide to DIY it.

 

[RNeumann]

The issue with closed cell foam isn’t the foam itself absorbing or moving water. It’s in between the wall and the foam. I’m guessing the foam will “pop” off the rock leaving an air gap with moisture coming in from the rock side and no air movement on the foam side. I’m still thinking their is a better solution- which may be why contractors, who do this every day, are avoiding it.

 

[hawkeye08]

The moisture on the stone would be from moist air hitting the colder stone surface. If it is insulated, how would the air get to the stone? I doubt that the moisture from outside is coming through the rock.