Rim / band joist insulation
 

Hi Guys,
Just wanted to know if any of you have had this done. Right now, i have fiberglass insulation wedged in between the rim joists. These are really not that tight fitting and i can see some cobwebs around them (spiders make nests only where there is air flow). I had a guy come over and he wants to spray foam the rim joists for about $1000.

I know that is the best way but I dont think that i will be able to recoup that much in heat savings (do not have cooling).

I saw a video on you tube where a guy just does the same thing using a spray can (he does not fill the whole thing). I was thinking of doing the same.

Any ideas?

Thanks,
Ravi

Well, anything is better than nothing. Personally, I'd probably cut some 1-2" thick rigid foam to fit in each cavity and use the spray foam as an adhesive to keep it in there. You can throw fiberglass behind it for additional insulation, and the foams will block any air infiltration.

cut rigid insulation with 1/2" gap around the edges to make it easy to fit in then sprayfoam the gaps to seal it and hold the foam in. Cutting it to fit tight is harder and isn't going to seal as well.

The end result is functionally the same as a pro spraying foam.

There's a guy on youtube that shows you how to do it. It looks like a great technique. In fact I just used it to insulate under the floor of my Power Shed (every time I type that phrase I hear a booming announcer's voice and drums beating :D).

Wish I'd known about the gap thing, I squeezed everything in pretty tight and then the foam just sort of sat on the surface. Hope it holds. :o

Thanks a lot for the ideas, do you have a link for the video?

Never mind, I found it:

Rim Joist Insulation - YouTube

You just order a two part spray foam kit, then cut pieces of rigid insulation to within an inch or so of the size you your joist bays ( big long strips for the two sides of the house with no joist hangers and so on) tack them in, cover yourself in a biohazard suit and spray everything that even remotely looks like a crack or seam. EVERYTHING. Even though you think all of the area you are trying to seal is comprised of a facing band joist and vertical floor joists don't neglect to remember that air leaks around the top and bottom of the floor joists so foam those joints into the space further by 6 + inches. It's not too hard but spray foam is a petrochemical and thus is disgusting so get a respirator and a tyvek suit. Then take a vacation for a month or so somewhere biologically wholesome while you recover and your house outgasses.

I hired out the spray foam because we have an uneven sand stone foundation that needed to be foamed at the top to seal well, so blocks of foam would not have worked well.
Our bid called for 2" of foam and I found 20% of them to be done right, many of them had a quarter inch of foam or so, and some had none! there was even a spot in a hard to get to corner that I could stick my arm out in to open cold air, needless to say it took three trips back to get our house sealed up, but if I had not checked their work it would have been worthless!
So if you get a bid, make sure it has a depth on there and if it does not don't do it! if it does then check it with a thin wire with tape marking off that depth, if they don't do their job per spec, don't pay until it's done.

How many board Ft. was that Ryland and how much did it cost?

I don't remember the exact cost but I do remember that when we got the bid I compared it to the two part foam kits that you can buy online and figured that the cost would end up being about the same, only when I talked to contractors around here non of them liked the foam kits, saying that you never get all the foam out of them and they are fussy about tank temp.

This is all true in my experience. I have had great luck with heating them up for a day or so. The 600 board Ft. kit I used in my basement I heated for several days. That being said, I've had pretty good luck with the 2 part kits. But if bringing in the high density spray foam guys was the same price or only a little more I'd jump right on that. Spray foam sucks. I'm glad I don't have to work with it too much.

hi rav. thx for the video. it was actually better than the one I saw.

I'm looking for a 600 2part kit to do my bunkhouse ceiling. The roof is metal and when it rains it's so loud it drowns out the TV. :rolleyes:

Anybody care to add to S-Fs tip on getting the tanks warm? Or other tips.

S-F, was the smell really bad?

Re: 2 part spray foam kits
 

I have now used 3 of the 600 sf spray foam kits. Each kit covered very close to what I expected. About one room per kit in my case. Two exterior walls, floor to ceiling 2-3" thick (about 200sf x 3" = 600sf x1"). I am very happy with the results. Warming the tanks is important, 75-85 degrees F for at least 24 hours. A warm summer day is best. Last time I needed no artificial heating. You need plenty of fresh air and a good respirator. Still expect a nasty hangover headache the next day. There is some smell but I did not find it overpowering. In-fact until I used a tank in the attic (poor ventilation) I didn't really notice the smell.
Other tips: keep a wet rag handy, be ready to change tips as needed, wear a gloves and long pants.

The foam in these kits is not nearly as bad as the little cans. This foam cures in 45 seconds and dries brittle. You can pull it right off skin and most other surfaces once cured.

I will go this route for each of my remaining rooms as I can.

I watch my buddy P Allen Smith on PBS every once in awhile and I noticed when he spray foamed his "house" (more like a mansion) he used a soy based spray. Not sure how that stuff holds up or the price ($$$?), but you would think it would be a little greener. I have my rim joists just wedged with faced insulation, but plan on just insulating right in front of it with another layer when I build walls down there (build the walls from floor to ceiling). I only use that spray foam when I have to.

I actually saw a holmes on homes where he figured that spray foam of the rim joists and of foundation walls on the inside would become required by code "soon". Apparently putting rigid against the concrete on the inside wasn't good enough to stop moisture from condensing and leads to mold eventually.

If I was building new I'd definitely spray but man is it pricey to do an entire house that way.

I plan on framing walls and leaving a 1/2 inch gap between the the new wall and the basement wall. Then I will just fill the new walls with faced batts. Right now there is nothing and I'm guessing a lot of money is just going right out those cinder blocks.

The soy based foam is more expensive.

How much is a 600SF 2-part spray foam kit? Can these tanks be lowered into a 5 gallon bucket of hot water? When I needed to empty a 20lb propane tank I used the hottest water I could get out of the sink filled into a 5 gallon bucket and set the propane tank on top(since its too big to fit inside). You could use a 5 gallon bucket to get the final bit of foam out. If the last 1/4 or so was in there and if the cans can fit in 5 gallon buckets, boil some water ahead of time and when the cans start getting to cold to flow then drop the tanks in the buckets and keep going. I do the same thing when charging A/C systems, the can gets too cold for there to be pressure for the stuff to come out but dunk it in hot water and out it comes. Keep in mind you'll be putting it in boiling water but the tanks will probably be next to frozen by then so the temperature will equalize to something reasonable fast and you won't have to waste the foam.

I don't know what the kit costs. I have a contractors account so the prices are different. Just look at the price on the page and add $50 or so for shipping. The hot water idea isn't necessary. Just get them good and HOT for a couple days. Maybe three days. They won't cool down in the time it takes to spray the foam. It would take hours for them to cool down in a New England winter. I've experimented with the smaller 200' kits. The 600' kits will obviously keep their heat longer as there is smaller foam to surface area ratio.

I thought the reason why people weren't getting the foam out was because the expansion of the pressurized propellant in the cans would get cold when expanding causing their pressure to diminish and then you don't get it all out. If you heat the cans by immersing them in water you can fight the expansion cooling and get more out.

If that isn't why people aren't getting it all out, then what is keeping them from mostly emptying the tanks? There are thread post upon thread post of people saying they didn't get the full amount out.

You aren't able to change the temperature of the foam in the tanks with hot water or any short term heating. It takes days for the heat to reach the inside. The reason they aren't getting it all out is because they aren't heating it long enough and they aren't shaking it enough. I've never had a problem.

Oh ok, I didn't think there was that much of a barrier to the heat getting in, if the tank is still filled with liquid rather than foam its insulating quality in the tank could be minimal and keeping the tanks in boiling water could make a little bit of a difference. If you can get it all out of the tanks through a summer heat soak and shaking the tanks then I suppose my concern about it doesn't really exist so much. Thanks for clarifying.

I'm not exactly clear on your meaning here. Even in the summer I would still heat them for several days. What might work is to heat them at night and in the day keep them in a closed up car parked in the sun. I can't stress enough how difficult and important it is to heat these things thoroughly enough. Especially the larger kits. Most people don't use the larger kits. They just hire the work out to a spray foam company. I haven't priced the difference so I can't comment there. Most people build a box out of polyiso that can fit a 200' kit and put a bulb in there with a cheap domestic thermostat to keep the inside around 90° f. Set it in there and forget about it for a day or two. Then even in the dead of winter the tanks won't cool down before you use all the foam. I did this to an completely unconditioned rim joist last February. The space wasn't finished yet to there literally was 5° wind blowing on me the whole time. I got all of it out no problem.
Really these kits are over rated. It's extremely difficult to get the mix correct, even for people with $80K gear. There are glimmers of studies emerging showing that most 2 part foam installations aren't done correctly. In the lab I guess it's easier. If the mix isn't right you can get all kinds of issues, including but not limited to: foam that is hard and brittle, foam that will decompose and outgas, foam that is soupy and so on. The studies I have heard of are all based on the safety of the finished product as far as outgassing is concerned, not aout it's performance.

I suppose there is a good reason why I see professionals who talk about and demonstrate 1 part foam on Youtube when I'm searching for spray foam videos. I'm not sure what options are there. I'm currently looking at using 2" XPS and spraying the outer edge of the 'rectangle' of the rim joist, pushing the XPS into the foam and then foaming the XPS while its firmly held in place using some of the lesser expanding Great Stuff. Not sure if I should go for a pro kit but at this point it seems the cans are the best deal or I should have started with the pro stuff when I was foaming around the windows and doors when the bigger 'cost package' would have made more sense. Then again I'm not spraying a whole room so at this point it doesn't make so much sense to discuss it but I'm thinking ahead as far as 600bd ft kits go as far as making a small super insulated microhouse in the future.

This is the technique I usually use. It's much cheaper and does the same thing. Don't bother holding it up. Just hammer a single finish nail in the middle of each bay and jam the piece of foam onto it. And you might as well spring for a 200' kit for that. It'll work a lot better than 70 or 80 cans of great stuff. You could do that if all you are after is air sealing but if you want any kind of insulation you'll need so many cans that it would be ridiculous.

Oh, also, don't bother using the foam as a glue. sure you can do it but you ruin the R value of all the foam you just sprayed turning it into polyurethane glue. Just jam your board on a nail and foam around it. A good tip on this is to try to cut the blocks as close to the size of the bays as possible. At first I did it leaving more than an inch around and ended up spending more money on 2 part foam than I wanted to.

warmwxrules: I would not recommend using any fiberglass in a basement due to the potential for condensation (unless your foundation happens to be insulated already on the exterior). Also, insulation needs to be in contact with the surface it's insulating so leaving a gap will not result in good performance. Rigid foam is the way to go and it's really not necessary to construct full stud walls either. Here's a diagram I send out to my clients on a good way to insulate basements:

https://docs.google.com/open?id=0BxW...thkey=CMXjveQJ

This is relevant to the rim joist discussion because when you spray foam that area you can bring it down on top of the rigid foam and form a nice continuous layer of insulation.

Bang.
Continuous insulation from the top of the attic insulation to the slab broken only by plates and subfloor.Plates and subfloor are still a big issue but in a retrofit the odds are against you to begin with.

Well, I have seen Fibreglass insulated basemen using 6 mm Plastic sheeting as Vapor barrier that lasted over 30 years... being fully dry and still insulating very well. They also use non contiguous 6mm plastic sheeting under the ground line... on the inside of the concrete wall. (DIY, Insulation specialist and contractor jobs alike -- All following the Canadian recommendation by Energy, Mine and Resource Canada).

I have seen basemen insulated with expanse foam (White foam)... Completely ruined after only 6 years... and full of black mildew. (All DIY jobs)

I have seen wall with extruded foam that end-up full of mildew... With gypsum drywall completely wet and deteriorated... with paint pealing. (sometime build by DIY but often by 20$/hours man of all trade construction worker)

If your basement have water/condensation problems... call in the expert or investigate the cause. You likely need water proofing, better drainage around the house or better ventilation. If you are located in the north of USA or in Canada and you have a very well insulated house... you generally need mechanical ventilation (some stirring of the air) or a dehumidifier to prevent the condensation in the basemen -- especially in the spring and early summer when the heating demand is lower.

I never have seen any major problems with sprayed foam insulation... but the fact that all the jobs have been done by a single certified insulation company with a few engineers on payroll might have help tremendously. (all with proper mechanical ventilation mandated by the building code of Québec, Canada)

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Did I replace any fibreglass basemen insulation that was properly done... Actually, yes... following the flooding of a basement -- But, under these conditions, we replace all type of foams as well -- unless we can dry them very quickly (2 days maximum I think) -- and that we can ascertain that the water was not polluted/contaminated.

Essentially, if it get flooded by a river or the sewer, everything but the concrete foundation get replace. The concrete foundation get clean by an Enzyme treatment.

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Well, you will have to define touching: In cold climate, a spacing of 1/2 to 3/4 inch between some layers is often use. For example, if you use Aluminium foil insulation as vapour/radiant barrier over fibreglass insulation between 2x4 or 2x6.

Indeed, there is always more to the story. I absolutely agree that things can work out fine as long as there is no moisture problem in a basement. My generalized point was that rigid foam on the wall (not white expanded foam) is the least risky material to use in DIY applications. But if there is any kind of water/drainage problem get it fixed before using any insulation method.

The problems you cited were more to do with external water sources. The issues I've commonly seen are to do with condensation due to high moisture content on the interior condensing on the concrete wall, not being able to dry out due to the vapor barrier and then soaking the fiberglass. You see this all the time behind fiberglass in leaky sill boxes but in finished walls you usually only get to see it after it's too late.

As for the gap: it is appropriate if you can trap air completely so that it becomes part of the insulating assembly or if you are using some sort of radiant reflective coating on one side of foil-faced material. That said, the method of leaving a gap behind a framed wall with fiberglass so that it can dry out is not appropriate: the concrete wall is still cold and can cool the air in the gap, which is, well, not cool. Convective cycling through fiberglass = poor performance and risks condensation issues.

I'm beginning to enjoy this thread immensely!

When bringing a basement into the conditioned area it's always paramount that ALL moisture issues be ELIMINATED first. If it's not possible to properly deal with all outside moisture then one should remove the basement from the equation with extreme prejudice! Just fill it in! The condensation issue isn't unique to basements. In fact, the sheathing of a house here in NE will get much colder than any basement wall below grade ever will. So the dew point calcs are very similar.

Good thread here, much to ponder.

Don't want to change the direction, so if you'll bear with me...

On a related note, when I was running my test heat pump last winter, I was amazed by the amount of water that was condensing on the pipes that brought loop water into the basement, and that took the chilled loop water (that had been through the evaporator heat exchanger) and sent it back out to the loop.

Constantly condensing water, puddling on the floor, I couldn't figure out where it was coming from for quite a while.


My fix was to put foam pipe insulation on the pipe and to tie it on tight with nylon cable ties, so that high humidity basement air was not coming in contact with the cooler loop water, and especially, the chilled loop water.

In this same manner, it would seem that a gapless insulation application, like spray-on foam would work wonders in a basement. That way, high humidity basement air could not contact walls, and not condensation.

What do you guys think?

-AC_Hacker

Indeed. Why is it that we want to live in caves?

Closer to the Earth? It's peaceful down there? I don't know but I love to be below grade. Building a basement that isn't finished in a new house costs a lot more than building an extra story. Even a third story. But a finished basement is worth it to me. Maybe I'm part troglodyte on my Scottish side?

AC_Hacker, You make very interesting points which are thought and conversation provoking. Unfortunately I don't have a free minute to think about them much less respond as it's past my bedtime and I've already turned into a pumpkin. I will respond soon though. Thanks for participating all!

I sleep, watch TV and use my computer in the basemen.

Advantage: Quiet
Easy to keep cool in the Summer ( Like 1/2 tons per 1000 SF).

If my house didn't have a basement, both my heat load and cooling loads would be much higher. With having part of the house buried, it allows there to be less exposure to the sun, a geothermal cooling blanket in the summer and a space warmer than the outside in the winter. It was extremely helpful this summer, I could let the upstairs get to 85 degrees and then I could sleep on the level above the basement level at 76 while it was in the mid 80's outside and sunny. In the winter the house is getting geothermal heat when I'm not heating it beyond the soil temperature. Call me crazy but my November methane gas heating bill wasn't even $20 and I'm in Minnesota. Very little infiltration now with all of the retrofitting so humidity levels aren't really dropping even though I stopped boiling water for pasta and vent my bathroom until the mirror is clear after I take a shower. More heating with more temperature, pressure differential, and furnace make-up air would increase the fuel usage quite a lot. I'm comfy in the cold though. I'd imagine if I lived in the southern half of the country I'd probably never turn on the heat I was reading stories on hvac-talk where people in Virginia have estimated heating loads for a house smaller than mine having them install a furnace larger than the one I have in my much colder climate that came with my house and is over double the size it needs to be post-retrofit(or third the input if I put a 95% in).

I'm tempted to just insulate half the wall and leave the bottom half exposed (ground temp should be 50F even during the coldest time of year). I'm really poor right now (!) so the cheaper the option, the better at this point. I also don't want to create a mold factory (i would imagine leaving the bottom half exposed would allow moisture to move through the concrete without get trapped).

Not sure if I will finish the basement, so using something like polyiso might make sense for now.

Lot of basement insulation horror stories, don't want to create another one.

Outsulate. It's the best option. Use XPS and make sure it's at least 2' below grade. Then screw chicken wire to it and apply some stucco or something to about 5" below grade.

That is probably the best way to do it, but I've always been worried about termites. This past summer I pulled up some landscaping timbers out in the yard and the bottom was basically hollow! There use to be an old tree before I moved in and one day I was digging out the stump (that was rotten) and it was full of them.

Get the kind which is treated with borate specifically to prevent termite infestation and cap the boards with copper flashing so if they do get in there they can't get into the wooden parts of the house.