Sealing an old foundation

Our home is 150+ years old. Our walls are filled with urea-formaldahyde foam appx. 5 to 6 inches thick. Its currently 3 degrees here with a chill of -24. All exterior walls are warm, but where the floors meet the foundation they are drafty. We don't have any insulation in the floors between the basement and first floor. I can't for the life of me figure out how to stop or seal those drafts. The old basement walls are about 2 feet thick of boulders. The construction is weird because the homes floor joists are built in quadrants. Some run north to south and others run east to west. I think where the air is coming in is where the joists run into the beams on the foundation. I have looked over this multiple times and can't come up something to stop it. Everything else has been updated, windows and ductwork.

I have considered using urethane foam in the cans. Where all the joists meet the beams, there are blocks that were cut and put in place tightly. I would assume that these were used in the day to help stop some of the air. I have thought about removing those blocks, or drilling into them and injecting foam. One of my other thoughts where the air is coming in just under the siding at the base of the foundation. We have the original dutchlap and a layer of tar paper and asbestos shingles on the outer layer. Seems like no matter what I do I can't stop the drafts. This summer I will button up the home and add insulation in some places that need it. We are at 75 now, but the house will quickly cool w/o heat. I would like to see it hold heat a little better. It is pretty efficient for its age, actually cheaper to heat than my grandmas trailer.

froth-pak 12 may be a decent, low cost option that may work out for smaller spray areas
http://www.ncssupply.com/prodlist.html

That stuff looks like a nice solution to the problems alot of us with 100+ year old houses have with drafts..
Have you ever used it before?

Another forum member recommended it, I plan on ordering when it gets a little warmer out and post update

. ... pretty sure it is the same polyurethane product as the one time use Great Stuff cans at HD/Lowes, I went
thru 3 cans of that sealing a couple spots last year, that's $18 right there and I ended up wasting a lot of it

Supposedly froth paks are good for 30 days once opened . . ., found more info. at http://www.dow.com/buildingproducts/frothpak/fp_12kit.htm

You might want to look at Tiger Foam: http://www.tigerfoam.com/ It is a similar system to the froth pak 180 (200 board ft / 16 cubic ft coverage, two part polyurethane foam) but unlike most foams, it is fire rated. You may not be required to have fire rated foam a rim joist application (maybe someone with more code experience could weigh in on this...), but I tend to think safer is better. On the green side, it also is CFC, VOC and formaldehyde free. I don't see a price on the froth pak system, so I don't know how the price compares. Tiger Foam is $335 for the 200 ft. coverage tanks, gun and hose system.

I thought I noticed that tigerfoam was fire rated, good to know thanks . .. the froth pak prices are on ncssupply.com . . they haven't been updated in a little while, another price source is abcsupply.com

I guess I have to get in the swing of things and look at costs for stuff like foam boards. The price on this stuff, which I know seals irregular surfaces well, etc, sure seems expensive. Maybe everything is expensive, what do I know.

break it down to the cost per board foot, Owens Corning Formular comes in around 40 cents for R7.5, the spray foam products can be 1 to 2dollars per bd ft. The canned products (great stuff, insta seal) probably are v. expensive per bd. ft. and not worth costing that way b/c they are meant to fill smaller gaps (1-3 inches)

... so IMHO a combination of rigid, spray foam kit, and point of use foam in cans would probably be a good economical way to approach things . .

They also make "great stuff" in a maximum expanding version. For many of us with stacked stone foundations, anything rigid just doesnt work. I have a friend who has had the spray foam professionally done in his old house and crawlspace and it made a world of difference. Very pricey though! Unfortunately it is a problem that doesn't have an inexpensive solution.

When I lived in NH I had an old house with a stone foundation. Alas, during Spring it would leak like a sieve. Wouldn't the hydrostatic pressure just eat holes through the insulation?

suggestion...before using foam in exposed areas, I'd suggest a termite treatment you spary on the wood joists using a pesticide type sprayer. Reason is that once the foam is in place it's hard to inspect for termites in the future. If they're there now (or ants in the wood that you can't see) spraying foam guarantees that you'll probably never gain access to the wood for inspection. I used Boracare (got it on the internet)...it's a clear, syrup-like liquid that you mix with hot water and spray on the joists. It penetrates both sides of the wood and kills termites, beetles, ants, etc already in the wood, it stops new infestations and it preserves the wood. I sprayed all the joists, underside of the sub-floor and all box headers and sill plates in my crawlspace before I put up R-19 fiberglass. It was a real PITA but I have peace of mind knowing I don't have termites in the wood.