Insulating the basement

[Dave Turpin]

So, I tore the basement "walls" down to discover that like much of the rest of the house, there is no insulation. So I have installed 2" polyisocyanate insulation on all the basement walls and am in the process of putting drywall back up.

My questions: Is it worthwhile to insulate the hip walls that lead to the crawlspace if the crawlspace is heated? Is it worthwhile (economically) to insulate the floor? It will cost as much to do the floors in 1/2" polyisocyanate as it did to do the walls in 2". Finally, what are good strategies to insulate the crawlspace? More foam or is fiberglass better? It would be cheaper.

Oh, one more. I was quoted $5100 for externally blowing Airkrete insulation into my above-grade exterior walls. (1300sf) Does that sound about right? They will be drilling through the brick facade to do it.

Thanks!

[Dale Sheler]

A vapor barrier is pretty important in an insulated basement wall application, you should use a vapor barrier between the heated space and the studs and insulation.
With no vapor barrier water vapor in the air will condense in the insulation against the cold basement walls, this will cause the insulation to hold water and rot studs and insulation, wet wood also draws termites.

[Dave Turpin]

Are you referring to the foam or the glass? The foam IS a vapor barrier, and code actually requires unfaced insulation in the crawl space.

I actually have one bit of basement wall to finish. There was a leaky crack... I think I sealed it but am waiting a few days to make sure.

http://i207.photobucket.com/albums/bb21/bpestilence/faae69fa.jpg

[Dale Sheler]

An actual vapor barrier would be plastic sheeting stapled to the studs behind the drywall, the idea is to keep all warm air and water vapor out of the stud spaces.

[Rob Beckers]

Dave, you mention they blow Airkrete in by drilling through the brick facade: Where does the insulation go? Is this between the facade and sheeting? Or is the idea to drill through the sheeting into the stud bays and fill those up? (Surely there was insulation in there already?) I wonder what happens if this gets between the facade and sheeting. Since it's a concrete-like product it would be porous to water, just like the brick facade. That would mean any moisture getting through the brick would make it to the sheeting and, I would think, rot out the sheeting eventually.

-RoB-

[Dale Sheler]

In spite of the name as far as I know airkrete is just a product name, is is a sprayed in foam insulation, is is intended to fill in stud spaces.
I don't know where Dave lives but there are a lot of areas in the US where houses were built with no insulation in the exterior walls.
We don't have perma frost in some places down here.:)

[Rob Beckers]

What? Your summer is longer than 4 weeks? Hard to image... :D

Actually, I would have thunk that even in the warmer parts of the US they used insulation to keep the heat out. No insulation will get really expensive with today's energy prices!

-RoB-

[Dale Sheler]

What? Your summer is longer than 4 weeks? Hard to image... :D

Actually, I would have thunk that even in the warmer parts of the US they used insulation to keep the heat out. No insulation will get really expensive with today's energy prices!

-RoB-

This house was built around 1889, the type of construction is called balloon construstion, they built the entire outside shell then add floors and walls later, during many remodeling projects we found the outer walls were just rough cut pine with the inside surface plastered with news paper.
Of course now days codes everywhere require a given R value of insulation, but there are still plenty of old farm houses with little or no insulation in the outside walls.

[Dave Turpin]

My house is 1947, and it was common not to have wall, or basement, or crawlspace insulation. The attic got a thin layer of newspaper insulation, and that was it.

The airkrete is a foam insulation, whose chief ingredient is mineral. So it is similar to polyiso spray foam in R-value but less flammable. Is it still an excellent vapor barrier. They will drill through the facade and fill the stud cavities. I had to wait to do this until I upgraded to modern wiring, because once the foam is in place there is no going back.

[SunFusion Energy]

I would say insulating the walls and the floors is a wise option. It restricts the heat inside the use. The use of energy consuming devices like air-conditions can be minimized.Overall an energy conservation method!:rolleyes: