Insulate Walls or Floors?

[Boris]

I live in an elevated rancher built in 1978. I just removed carpeting and linoleum from my breakfast room, kitchen, dining room, and living room, all of which are open to each other. I had 3/4" red oak planking installed over the existing plywood subfloor.

Winter season has come, and it has been unseasonalbly cold, and I really notice it in the rooms mentioned above. I don't know if it's because the wood transfers hot/cold more than what was on the floors, or because of the really cold weather. I'm in the S.F. Bay area, where winters are normally mild (40 - 50), and my furnace usually heats the house fine, but now it takes an hour or so to heat the house (20 year old gas heater, forced air, below in the garage). When I wake in the morning, the house is 56 - 60, and overnight temps were mid-30's to low 40's.

I'm considering insulating the crawlspace under the house, under the new wood flooring. I have good access to all areas under the new wood flooring, and to all exterior walls. I can walk under the entire area. The floor joists are 2 x 10 (1 3/4 x 9), and the wall studs are 2 x 4 (1

3/4 x 3 1/2). I've been reading a lot about insulating crawlspaces, and some say just need to insulate between all the joists, and others say best to insultate just betwee the studs. Of course, doing just the studs would be much easier, since it's doesn't have to be 'hung', and less expensive, since the insulation wouldn't have to be as thick.

Any suggestions?

[Ralph Mowery]

YOu did not mention the insulation over head. If it is less than about 8 to 10 inches, start there. Then to the walls and last the floors.. Do be sure that the vents under the house are closed so the air does not just flow under it.

[Boris]

"Ralph Mowery" wrote in news: [e-mail]:

Over head? I think you mean what's in the attic...that blown in pink stuff, lots of it. So much so that you have to clear it away to find the ceiling joists.

I've closed up all the vents already.

[Ralph Mowery]

Yes, the attic. Not sure how large the joists are, but you need around 8 to

10 inches, more if in a cold area of the country. It is recommended from one to two feet in the attic of cold weather areas.

[Tony Hwang]

I'd use rigid high density styrofoam panels between joists under floor. You can use adhesive. Walls as well or batts.

[trader_4]

Access to exterior walls, usually that isn't the problem. The problem is the insulation would need to go in the walls and that doesn't have good access. Considering it was built in 78, the wall cavity should already have insulation, no?

I can walk under the entire area.

Assuming the studs you're talking about are the exterior wall studs, how are you going to get easy access to put that insulation in? Usually putting insulation between the joists in a crawlspace is trivial compared to getting insulation into wall cavities. No insulation in those exterior walls already?

[Eagle]

Ralph Mowery explained :

What if you don't have vents under the house, just a concrete slab?

[Eagle]

We need insulated concrete here in Cali. It got down to 29 last night, and is supposed to get down to 20 tonight. My poor palm trees are going to freeze again!

[Boris]

trader_4 wrote in news: [e-mail]:

Yes, the exterior of all living space is insulated. I'm talking about exterior walls of the crawlspace. It is defined as a crawlspace, but it's really tall. As a matter of fact, there's a standard size door that connects it to the garage, both of which are below the first floor. From the garage, I walk into the 'crawlspace'. It's a hoarder's paradise under there. (Me no hoarder.) Anyway, the foundation sill has the standard 2 x 4 on top of it, and on top of that are the 2 x 4 exterior wall studs, unfinished (no sheetrock). The exterior is stucco. In some places, these walls are 4' tall, and in others they are 8' tall. The house is built on a slope. From the sidewalk view, the left side is higher, and the land slopes down to the right. The right hand walls are the taller ones.

No, these are the unfinished (no sheetrock) exterior walls in the crawlspace

[Boris]

Tony Hwang wrote in news:8Djgy.66614$ [e-mail]:

Been looking at those, but the highest R factor I find is 5.89, and 2" thick.

[Boris]

"Eagle" wrote in news:n5sl75$q9k$ [e-mail]:

Are you built on a concrete slab?

[Boris]

"Eagle" [e-mail] wrote in news:n5sl3a$pr2$ [e-mail]:

Vents are to move air to control moisture in dirt crawlspaces. The moisture comes from the ground. You shouldn't have any moisture issues.

[Ed Pawlowski]

You want to insulate both walls and floor. I'd use foam board with adhesive to hold it on the floor above.

[thekmanrocks]

Heat's first propensity is to rise. Take care of that first. The United States of America remains in 2015 the most under and uninsulated country on earth - residentially.

[Terry Coombs]

Are there any water pipes in the crawl space ? If t'were me I'd insulate the walls with batts between studs then add a 1" layer of foam on top of that . I'd also lay down some poly sheet on the ground to help with moisture control . They make automatic crawl space vents that open when it gets hot , you might want to put some in while you're down there .

[mike]

Be clear about what you're trying to accomplish. You made no mention of heating cost. If your problem is that the floor is too cold and/or you'd like reduced heating cost, insulate under it. If you plan to inhabit the space, put something over it to contain the insulation dust. Look up the historical dewpoint. You wanna make sure that you don't condense moisture on the underside of the floor in summer. Vapor barrier may be required.

Now, you've just made the crawlspace colder. If there's anything in there that's sensitive to cold, like plumbing, you may need to address that with insulation or pipe tape or ???? Insulating the walls will help. I've lost track of the crawlspace floor, but you also may need insulation and vapor barrier there too. Depends on the ground temperature.

I'm in Oregon. If I close the air vents, the temperature under my house is 55F or thereabouts year round. My attic and crawlspace were insulated at the same time, so I don't have any individual measurements of the effect on heating costs. When I changed from carpet to fake wood floors, they felt colder, but I'm not sure it made any actual difference in the heat lost/gained. I fixed that problem with area rugs everywhere.

[Ed Pawlowski]

Wrong. Hot air rises. Heat energy travels to attempt equilibrium no matter the direction. If the floor is not insulated properly the heat will travel to it.

[Stormin Mormon]

How about Afghanistan, or Iraq? Where do they rate on blown up insullation?

IED = Installed Energy Dampening.

[burfordTjustice]

Source?

[CRNG]

On Mon, 28 Dec 2015 22:37:21 -0000 (UTC), Boris wrote in

The more insulation the better.