Insulating under a house???

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Bigfoot

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I've only lived in two houses, in my adult life. I built both of them. The first one, a had insulation blown on the inside of the foundation. Electric company had a program going, where they actually paid for it (sorry Grit, I been sucking on the government tit my whole life). I never could tell it was doing anything. It might just be this cold snap, but it seems like this house is drafty. Thinking of insulating under this one. Which is better bats under the floor, or insulation sprayed on the blocks? I should say, I have 3 sump pumps under my house. Me and all my neighbors are setting on a crider soil.
 
Back in '71 I was appointed the official grunt while building my new family home. At the end of that project the last thing left was insulating under the floor. I spent 3 days crawling on my back stapling bats then chicken wire to the underside of the floor joists. Along in the early 80's I had the occasion to check on some plumbing and almost all the work I had previously done was on the ground. Can't say how spray will hold up, but staples from a staple gun won't.
 
slick4591":2i3p7x4q said:
Back in '71 I was appointed the official grunt while building my new family home. At the end of that project the last thing left was insulating under the floor. I spent 3 days crawling on my back stapling bats then chicken wire to the underside of the floor joists. Along in the early 80's I had the occasion to check on some plumbing and almost all the work I had previously done was on the ground. Can't say how spray will hold up, but staples from a staple gun won't.

Rolled would pose a challenge.
 
I have heard of people using the foam board up against the blocks, not sure how well it works.
 
When we lived in Michigan in a house trailer we had a deck porch that we enclosed and made into more living space.We came across some insulated door blanks similar to those insulated buildings you see. I cut them to size and put furring strips on bottom side of joists. It worked quite well.
 
I had the bats put in too, up between the joists.
Used some kind of wire things to hold it up and it's done pretty good since 2009, but beginning to fall down. My joists are 4'+ off the ground so it's not too bad working under there so I started putting up some kind of plastic mesh that's supposed to be better than chicken wire but never got it finished, (my fault) but either way, there's got to be something better than batting.
Bats are definitely the least expensive, but if I do have foam blown under there, I want the closed cell stuff. It won't absorb water and doesn't need a moisture barrier.

From what I was told, open cell foam runs about 45-65 cent/board foot and closed cell runs approx $1.25/board foot.
A board foot in this instance means 1 sq foot of coverage 1" thick.
I believe board footage = width in inches x length in feet x thickness in inches. It won't be cheap even for under my piddly little 35'x35' house.
 
do batts but use hangers.. just little wire things you can cut to joist spacing. use quite a few of them and it'll never sag. throw some staples in there too.

don't use faced insulation or the facing will mold.

if you don't have plastic on the ground under the house I would add that while I was under there.
 
When we remodeled the house that Mom and Dad live in, I had it spray foamed with 2" of closed cell. Good local contractor, and he wouldn't leave without going to the basement and doing the band board all the way around. No draft in the old house now, and you could heat it with a lightbulb.
 
If closed cell sprayed 2 inches thick is enough, I live in a 2 story house. That'd mean I only have about 1200 square feet to do. 2400 x $1.25= $3000. That's more than I'd really like to spend, but if it would pay for itself,then I'd be ok with it.
 
BF.
Best thing - so long as you don't have moisture issues under the house... and if so, you need to address that first and foremost... is to close those foundation vents and never open them again... cover the exposed dirt underneath with a plastic vapor barrier, and run that up at least 6" or so on the exterior walls, then have wet-blown cellulose or foam sprayed on the perimeter walls. You've essentially converted the crawlspace to a low basement. If your central ducts are in the crawlspace, any leakage will be contained and help to heat the floor.
If you just put batts under the floor, they don't do much to help hold heat in(it rises, remember?)... but might prevent any heat escaping from leaky ducts from making its way up to the living space.
 
Lucky_P":22r8xub1 said:
BF.
Best thing - so long as you don't have moisture issues under the house... and if so, you need to address that first and foremost... is to close those foundation vents and never open them again... cover the exposed dirt underneath with a plastic vapor barrier, and run that up at least 6" or so on the exterior walls, then have wet-blown cellulose or foam sprayed on the perimeter walls. You've essentially converted the crawlspace to a low basement. If your central ducts are in the crawlspace, any leakage will be contained and help to heat the floor.
If you just put batts under the floor, they don't do much to help hold heat in(it rises, remember?)... but might prevent any heat escaping from leaky ducts from making its way up to the living space.

Wet cellulose is what I had on the blocks of my old house. It was actually holding on pretty good. PRECC had a program, that paid for that back then. It would be cheaper than 3K for sure. I have plastic down. actually a little conveyer belt to. Makes it easier for me to access my sumps. I let the kids service those nowadays :D
 
For whatever reason, insulating floors is not a thing here. I worked for a carpenter crew about 25 years ago, and we would often work with other crews as well. Floors were never insulated when new houses were built. I've also never been under a house that was insulated. Insulating a floor seems logical to me, but it's not a big thing here.
 
I remodeled my old farm house and did the spray foam in the walls and along the foundation walls too. The guys doing it had a heat detecting camera and the before and after photos were amazing. Well worth the money spent.
I also own a rental and it had a freezing pipe problem. Tried everything to insulate the pipes and even heat tape, finally I went to menards and bought the spray foam diy kit and did that to the foundation walls myself, problem solved. Give it a shot.
 
Ours is insulated with regular wall insulation and held up by chicken wire. I don't know if it helps or not but it's a real pain when you have to work under there...or so the plumber tells me....it's too short for me. It's hanging down from diffrent people working under there over the years
 
Ohio Cowboy":2a049xay said:
I remodeled my old farm house and did the spray foam in the walls and along the foundation walls too. The guys doing it had a heat detecting camera and the before and after photos were amazing. Well worth the money spent.
I also own a rental and it had a freezing pipe problem. Tried everything to insulate the pipes and even heat tape, finally I went to menards and bought the spray foam diy kit and did that to the foundation walls myself, problem solved. Give it a shot.

We had pros come out finally and do the spray foam on the old farmhouse. The heat camera is kinda gimmicky but also kinda cool. We are kicking ourselves that we didn't have the insulation done the first day we bought the place. It's cut the utility costs (both heating and cooling way down). Think our fuel oil use went down by at least a third.
 
They came out. I have plastic down. They want to put a new thicker layer, and run it up the wall. Blow 1.5" of closed cell. $1370. In due time, that should pay for itself I'd think.
 
Bigfoot":2ar8ucd5 said:
They came out. I have plastic down. They want to put a new thicker layer, and run it up the wall. Blow 1.5" of closed cell. $1370. In due time, that should pay for itself I'd think.
Who did you get a quote from? Thinking about spray foam a garage.
 

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