I’m in the process of insulating my basement. Without getting into the specifics of everything (outside of everyone is too busy to call back on a small job), I’m wondering what the cost differential would be to use blown in insulation for the exterior walls only vs. rolls of insulation? The finished portion of my basement is approximately 1600 square feet.

Thanks.

Is the basement currently unfinished?

What are the conditions of the basement?

Frankly, I would not put fiberglass or blown in in a basement. Either rock wool or foil faced foam.

I can't help on cost, I did my own, but it should be rigid foam against the foundation then roll insulation. Spray in foam is best but gets cost prohibitive.

quote:

Originally posted by arcwelder:
Is the basement currently unfinished?

What are the conditions of the basement?

Frankly, I would not put fiberglass or blown in in a basement. Either rock wool or foil faced foam.

Thanks Arc. I’m finishing my basement. My framing, electrical and plumbing are done but the building inspector is now saying we need fire stops along the top plate between each stud. In addition, every 10’ going horizontally, I need a fire plate from the bottom plate to the top plate. In addition, every 10’ I need to caulk ever hole in the studs from floor to ceiling. The inspector said blown in insulation would cover everything. Thus, I’m trying to figure out if it is cheaper to pay the extra cost of blown-in insulation vs. me taking the time to run a 2x2 or 2x4 plates between each stud and every ten feet along one stud from the bottom plate to the top plate. As for the insulation, I’m not married to anything particular other than than the cheapest easiest way to meet code. So any advice you have I’m all ears so to speak. I do want good sound insulation for the ceiling.

I hope this makes sense.

Thanks!
BB61

Three questions:

1. Is the basement below grade?
2. Are you planning on finishing it out with drywall etc?
3. What state do you live in?

quote:

Originally posted by smlsig:
Three questions:

1. Is the basement below grade?
2. Are you planning on finishing it out with drywall etc?
3. What state do you live in?

1. Yes.
2. Yes. Completely finishing it with bedrooms, bathroom, family room, etc.
3. Utah

We had the home built in 2002 and just decided to finish it this year.

THANKS!

quote:

I can't help on cost, I did my own, but it should be rigid foam against the foundation then roll insulation. Spray in foam is best but gets cost prohibitive.

That's how ours was done. Spray foamed the sill plate and rim joist after rigid foam was glued to the wall and sealed at the joints and the bottom. Framing with regular fiberglass up against the foam for the finished walls.

Nothing seals air gaps like spray foam. If you plan on staying there a long time, you might as well do it with the best insulation you can. You will recoup the costs in energy savings sooner than later...…..

Edited to say: Let me make a correction here. I'm talking about having the entire walls foamed with insulation that's sprayed on, not just using the stuff in the can found at HD.

This message has been edited. Last edited by: jimmy123x,

quote:

Originally posted by BB61:
My framing, electrical and plumbing are done but the building inspector is now saying we need fire stops along the top plate between each stud. In addition, every 10’ going horizontally, I need a fire plate from the bottom plate to the top plate. In addition, every 10’ I need to caulk ever hole in the studs from floor to ceiling.

What he/she is citing here is current IRC code and not a surprise.

Where the inspector deviates is by recommending "blown in."

The letter of the code doesn't prohibit it, but it isn't a best practice for this application.

A key point for modern insulation, is that there is a HUGE difference between "blown in" and dense pack cellulose.

"Blown in" does not belong in wall cavities of any kind. It is for loose fill in attics and other accessible spaces. In a wall cavity it will eventually settle creating voids and becoming ineffective.

Code is a "minimum building standard" in essence like "Milspec."

Blown in, either hopper or dense pack, will hold water, so will fiberglass, and open cell foam. Aside from closed cell sheet foams, or several types of spray foam, the only insulation that should go in a basement is mineral wool.

I need to back off of these threads, due to information presented, and other considerations. I'm happy to talk offline.

quote:

Originally posted by BB61:

quote:

Originally posted by smlsig:
Three questions:

1. Is the basement below grade?
2. Are you planning on finishing it out with drywall etc?
3. What state do you live in?

1. Yes.
2. Yes. Completely finishing it with bedrooms, bathroom, family room, etc.
3. Utah

We had the home built in 2002 and just decided to finish it this year.

THANKS!

OK.
The draft stopping the inspector is referring to is a fire control issue. You can use a spray foam product like this in each hole and along the top plate. I’m assuming that you have a small air gap between the back of the stud and the concrete wall unless you framed the wall with Pressure treated lumber.
https://www.lowes.com/pd/GREAT...nsulation/1000645183.

2. Once that has been done and inspected the least expensive way to install insulation is to use unbatted fiberglass roll insulation. This insulation doesn’t have any paper backing which minimizes the chance of mold. It is sized slightly wider and just pressure fits between the studs. You should be able to install this yourself if you want to.

3. The amount of insulation required will depend on where in Utah you live. Assuming Utah is still using the 2015 IRC code here is the insulation requirements for each county:

https://www.ase.org/sites/ase....s/utah_2015_iecc.pdf

This is all assuming that you have a properly installed foundation and don’t have any moisture issues but I wouldn’t think so being in Utah.

Good luck.

If you want to use a spray foam firestopping product, I'd ask your inspector before you do. It doesn't work the same as other firerstop, and some locales don't accept it.

I recommend this over the foam: https://www.drywalltooldepot.c...0029-p/jaco50029.htm

For larger gaps you can fill areas including the joist bays over the top plate with:

https://www.buyinsulationprodu...ool-firestop-safing/

Or a combination of that and solid wood.

Unfaced fiberglass is OK, but this is a superior product:

https://www.homedepot.com/p/Ow...-15-47-121/304633821

Easy to use, and less waste than fiberglass, and it is longer lasting, and a slightly different density than the safing insulation I already linked.