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I have a pretty large crawlspace under my house and I’m a “no vent” guy. (I have vents but will block them — the soil is bone dry under there.) My insulation guy wants to blow about 2″ of cellulose on the inside of the crawlspace walls. He adds a glue to his water spray and it sets up hard — does a lot of large metal buildings this way.
I’m inclined to do it and wait til winter to see if I really need to put insulation in the floor. Any experience with this? Concerns?
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Crusty,
IF the floor is soil, even if it's bone dry to the touch it can still be gassing off a lot of moisture. You should lay a small (say 2x2 ft) piece of plastic on the floor and weight the perimeter with sand. Leave it set for a few days and see if there is any condensation on the underside of the plastic. That'll tell if the soil is giving off any moisture.
Steve
*Oh, I'm sure when I put down my vapor barrier there will be lot's of condensation on the underside. But there is no infiltration of water from the outside. With hardwood floors, I think a vapor barrier over the soil is almost mandatory. (?) In the hot, humid south (did I mention humid?) I still think venting in the summer is silly.
*I'm with you completely, Crusty.Steve
*Be sure to check the local codes. May require a cementious covering over cellulose and foam. May not.
*There are some advantages to living in a semi-rural area of a backwards state like Arkansas. Since I'm out of the city limits, the only inspections I have to deal with are plumbing and septic. I can't imagine I'd need to cover the cellulose since it's treated and will not burn. It's not covered in attics is it? They sprayed it on the underside of my upstairs as "sound proofing" (jury is still out on that) and it didn't set up as hard as I thought it would. So I'm not sure now. Perhaps I'll have him spray a "test patch" and watch it for a while.
*I'm intrigued about this cellulose treatment. Do I understand correctly that nothing else is added to the cellulose--i.e. that it's not covered.I've been fussing for a couple of years about how to insulate the mortared stone foundation on the crawl space under half of my 140 y/o house in upstate NY. This glued/cellulose technique sounds ideal, maybe too ideal. Have others heard about it? used it?
*I have some doubts about durability, especially in the presence of much moisture. I wouldn't consider this at all if there is any penetration of moisture from the outside. My insulator says he's done it a few times, but I've not been to look at any yet. It is probably less expensive than most anything else you can do because it doesn't take much time for them to do it. But I don't know. I'm going to do some more checking.
*Are you thinking of using cellulose because of cost or because sprayed urethane foam isn't available? I've had foam sprayed on the underside of lofts over garages and metal roofs with good results. I'd think that it would work on a vertical wall too. The only drawback I know of is, like SIPs, you'd have to guard against carpenter ants.Nic
*Have you thought about spayed foam? I've used it under loft floors (over garages) and on the underside of metal roofs. It deadened sound, stopped floors squeaking (maybe they wouldn't have anyway..) and appeared to be more effective at stopping air infiltration. The only drawback I can think of might be carpenter ants.Nic
*Does anyone do cellulose in southern Calif any more? About 33 yr ago we had it put in the attic of our first house. It was great. Now I'm getting everything together to build our retirement home, and I can't find anyone to do cellulose. We are in rural Riverside county, near Nuevo.
*Hahahahahahahahahahahahahahahahahaha!Let me see. You are in the humid south and you want to glue cellulose insulation on the concrete stemwalls of your crawlspace? And you are also thinking about putting it on the uncovered ground in the crawlspace?Let me see. Termites eat wood. Wood is cellulose. Termites like warmth and moisture and cellulose. There are plenty of termites down south. You are sure that when you put down your vapor barrier there will be lot's of condensation on the underside. Some of the cellulose will probably be in contact with the soil. Cellulose insulation is made of ground cellulose and some borates for fire and pest protection. The borates interfere with digestion of bugs if they eat it. The borates are water soluble, like salt. Water soluble materials can slowly leach out of materials exposed to water or moisture transfer. Without protection of the borates you are gluing food and concealed passageways for termites all over the underside of your house.IMHO: Cellulose insulation should be kept free of soil just like it was wood. 6" minimum clearance. 12" or 18" recommended clearance in concealed spaces which are not expected to be inspected frequently.
*Gary, do you laugh a lot, or are you always hysterical? "And you are also thinking about putting it on the uncovered ground in the crawlspace?" .... why would ANYONE think of doing that? "Floor" is usually thought of as the floor of the house, as in constructed, versus the ground (i.e., unconstructed, dirt).I guess I wrongly assumed that anyone would know that you don't put ANY type of insulation in contact with the ground on a crawlspace wall -- how would you see the termite "trails" if you did. 6" clearance goes without saying.
*Stay away from blown cellulose on crawl walls. It falls off. The best is to spray urethane foam on the crawl walls. I've got experience on this one. In fact, my cellulose contractor won't even do it anymore.John
*John, I think you're right on this one. They sprayed it on the underside of my upstairs floor (as sound proofing) and it's staying pretty good, but still falls off in places.I think the foam is probably optimal, but probably a little expensive. Of course, it'd probably be cheaper than putting batts in the floor, and much easier since I wouldn't have to do it.I know where there are several stacks of what appear to be structural foam panels - I could probably get them cheap. What about sticking firring strips to the crawlspace wall with F-26 and then just screwing the panels in place?
*If you want to go foam panels, use at least 2" thick and you can skip the firring strips. I recommend spray foam if the budget allows. On the foam panels, nail to the sill plate with plastic capped nails and use foam safe construction adhesive to attach to walls. Also you can use some tapcons with some caps swiped from nails to help secure.For your cellulose that's falling out, put some mesh up underneath it. If you can't find insulation mesh, it's virtually the same as what we call septic cloth (a geo membrane that we use over the rock on septic systems).John
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I have a pretty large crawlspace under my house and I'm a "no vent" guy. (I have vents but will block them -- the soil is bone dry under there.) My insulation guy wants to blow about 2" of cellulose on the inside of the crawlspace walls. He adds a glue to his water spray and it sets up hard -- does a lot of large metal buildings this way.
I'm inclined to do it and wait til winter to see if I really need to put insulation in the floor. Any experience with this? Concerns?