Basement Insulation?? Advice??

[LD1]

I know this is probabally opening a can of worms, and I have done a TON of googleing and there is a bunch of conflicting information.

So Id like to hear your thoughts and what has/hasnt worked for you.

Backgroung...I want to finish the basement on a budget. It is heated/cooled but the cold walls seem to suck a lot of heat out of the house.

It seems the cheapest insulation per sq/ft is kraft faced R-11 23" wide stuff @ menards for $23 for a 70' roll. ~0.17/sq ft

12 rolls will do the whole basement. ~$300

But I started googleing things like Air gap vs No air gap, Plastic aginst the block vs no plastic, kraft facing out or in, etc and that is when it gets interesting.

It seems the "best" way is to put foam board directly aginst the wall and then put up studs/fiberglass/drywall.

I dont want to spend a fortune on foam board. Right now (this project is a ways off. Still in the planning stage). But currently, I am planning to build the wall ~1" off the block. So the fiberglass doesnt touch the wall. No foam board or plastic. Leaving the air gap. And insulating kraft face toward the interior.

Any suggestions? Comments? Thoughts? All are welcome:thumbsup:

 

[Deere Dude]

I know this is probabally opening a can of worms, and I have done a TON of googleing and there is a bunch of conflicting information.

So Id like to hear your thoughts and what has/hasnt worked for you.

Backgroung...I want to finish the basement on a budget. It is heated/cooled but the cold walls seem to suck a lot of heat out of the house.

It seems the cheapest insulation per sq/ft is kraft faced R-11 23" wide stuff @ menards for $23 for a 70' roll. ~0.17/sq ft

12 rolls will do the whole basement. ~$300

But I started googleing things like Air gap vs No air gap, Plastic aginst the block vs no plastic, kraft facing out or in, etc and that is when it gets interesting.

It seems the "best" way is to put foam board directly aginst the wall and then put up studs/fiberglass/drywall.

I dont want to spend a fortune on foam board. Right now (this project is a ways off. Still in the planning stage). But currently, I am planning to build the wall ~1" off the block. So the fiberglass doesnt touch the wall. No foam board or plastic. Leaving the air gap. And insulating kraft face toward the interior.

Any suggestions? Comments? Thoughts? All are welcome:thumbsup:

There are a bunch of ways to do that, but what I did and seems to work for me is to 2X4 stud the inside of the block walls and put fiberglass on the studs just like you do upstairs. The paper on the inside. The downside is you lose a little more floor space. The upside is running electricity is easy and you can drywall. I did this in 3 houses I lived in and have no complaints. I would use treated wood for the base plate just in case you get a little water.
On my first house I had a 12" block fully exposed on a 30+' section and the basement was impossible to heat. I put the wall up and a little insulation and it was like a night and day difference.
People put firing strips and Styrofoam in between quite often, but I like the stud method myself. I think the 1 inch Styrofoam only has an R-value of 5 and the 3-1/2" fiberglass has R-11 or 13 about. More insulation value with fiberglass. Skip the Styrofoam and just use fiberglass. No doubt others have different opinions on this but I like it done that way. Unless your wall has a history of leaking, I don't think I would try to leave it away from the wall.

 

[BrianDT]

When I finished my basement, I only used fiberglass insulation and nothing else. I can see how the foam boards could help, but is it worth the extra cost.

When I did the insulation, I put it in the studs with the paper against the drywall. I also stuffed insulation around the top of the studs so I did not get the cool air from the wall traveling up to the floor and cooling it. Most of my home is tile and it can be cold enough.

This has worked excellent for me. We have a gas fireplace down there that can heat it up in 5 minutes. (1850 square feet finished, 750 unfinished)

The tile I put on the basement concrete is always cool. My next home will have radiant heat in the basement. But it will also most likely be left unfinished.

 

[LD1]

I would use treated wood for the base plate just in case you get a little water.

I was actually planning on using treated for the studs too. They are a few pennies cheaper than non-treated....go figure.

But then the issue of the lumber will probabally eat the drywall screws:confused2:

Either way, I will definatally use treated anywhere it as to touch concrete:thumbsup:

How much "air-gap" did you leave between the stud wall and the block foundation?

 

[LD1]

When I finished my basement, I only used fiberglass insulation and nothing else. I can see how the foam boards could help, but is it worth the extra cost.

When I did the insulation, I put it in the studs with the paper against the drywall. I also stuffed insulation around the top of the studs so I did not get the cool air from the wall traveling up to the floor and cooling it. Most of my home is tile and it can be cold enough.

This has worked excellent for me. We have a gas fireplace down there that can heat it up in 5 minutes. (1850 square feet finished, 750 unfinished)

The tile I put on the basement concrete is always cool. My next home will have radiant heat in the basement. But it will also most likely be left unfinished.

Did you leave an air gap between the finished wall and the block? or are your studs/insulation actually touching the block?

 

[MrWhippy]

When we finished our basement, we used a sealing paint on the block, then shot up furring strips and attached board insulation, then made a standard framed wall. On the coldest walls, we put in fiberglass in the studded walls. It has worked great. But putting up framed walls, running electric is MUCH easier.

The sealing paint prevents water coming directly through the concrete block. Furring strips give an airspace for condensation to escape. The foamboard doesn't absorb water, so where there's fiberglass insulation, we don't worry about humidity making it wet.

 

[LD1]

I did just double check the fiberglass I am going to use...R-11 3 1/2"T x 23"W x 70.6'L Kraft-Faced Fiber Glass Rolls at Menards

And it says in the product description "basement walls"

And also says "will not settle, mildew, rod, or deteriorate" :thumbsup:

 

[Deere Dude]

I was actually planning on using treated for the studs too. They are a few pennies cheaper than non-treated....go figure.

But then the issue of the lumber will probabally eat the drywall screws:confused2:

Either way, I will definatally use treated anywhere it as to touch concrete:thumbsup:

How much "air-gap" did you leave between the stud wall and the block foundation?

I didn't use any air gap. The block wall wasn't perfectly level and flat and smooth so there ended up being maybe 1'4" to 1/2" in places. The 2x4s aren't perfectly straight either. I wouldn't worry about it unless your walls are damp and leak. But, an air gap wouldn't hurt anything either. It would be easier running electric wires.

 

[moeh1]

You may also wish to look into the foil air pocket insulation rolls to go on the wall before studding, they look pretty effective at a quick glance.

 

[Egon]

Leave whatever gap you want or is suitable for the insulation. Use metal studs and rails. Quicker & easier. Put 6 mil plastic on the room side of the studs. Use the proper screws for metal studs and also use them for fastening the plastic.:thumbsup:

Note: Metal rails and wooden studs will also work. Studs can be 2 x 3 wood or 2 5/8 metal. Use tapcons for holding the metal rail to the cement.

 

[LD1]

Leave whatever gap you want or is suitable for the insulation. Use metal studs and rails. Quicker & easier. Put 6 mil plastic on the room side of the studs. Use the proper screws for metal studs and also use them for fastening the plastic.:thumbsup:

Note: Metal rails and wooden studs will also work. Studs can be 2 x 3 wood or 2 5/8 metal. Use tapcons for holding the metal rail to the cement.

Metal studs is about 2x's the cost of wood. So I dont see that happening.

I like wood. Easier IMO with the tools I have to cut/fit/install, etc. Time is not important. This is just a project to tackle in my spare time. I dont care if it takes 3 years to finish. The basement isnt going anywhere

 

[tractchores]

I've also used regular studs and fiberglass just like you would upstairs. You do lose a little bit of space, but the insulation works well. For the floor you'll also want insulation. I've used the dry-lock panels (think that's what they're called). Basically its a subfloor you put together and it interlocks and has a fiber board like surface. The bottom is plastic and raised to create an air space that helps in case you get any water or moisture. So far they've worked really well.

 

[LD1]

I've also used regular studs and fiberglass just like you would upstairs. You do lose a little bit of space, but the insulation works well. For the floor you'll also want insulation. I've used the dry-lock panels (think that's what they're called). Basically its a subfloor you put together and it interlocks and has a fiber board like surface. The bottom is plastic and raised to create an air space that helps in case you get any water or moisture. So far they've worked really well.

For the floor I was just going to use some cheap ~50 cents/sq/ft carpet. Like an indoor-outdoor or cheap level loop berber. Just so it isnt cold to walk on

 

[BrianDT]

Did you leave an air gap between the finished wall and the block? or are your studs/insulation actually touching the block?

I left room so I could do anything back there if I needed. On one wall I left room to run a gasline down. I kept 2" away (minimum) at all times as it was what felt comfortable. I did not use treated as I assumed if I have a water issue, the carpet and other items would have to be torn out. My basement was unfinished for 4 years without leaks, so I was confident in it.

I have a 9' basement and my finished sidewalls are just under 8'. I ran the drywall vertical so I had no butt joints and also so it could be cut out and replaced easier if need be.

 

[65fl]

I'm getting ready to do the same thing and have been researching this subject extensively. From what I've read the key issues are sealing air leaks in the rim joist area, providing a thermal break and effective insulation and most importantly preventing mold growth.
This PDF explains it pretty well. http://www.eere.energy.gov/buildings/building_america/pdfs/db/35017.pdf

Gluing foam to the walls prevents warm moist air condensing on the cool basement walls and growing mold, it also adds a thermal break. Right now I'm leaning toward gluing 1" (or greater) XPS foam to the walls, sealing the rim joist area with foam then build a standard 2x4 stud wall on 24" centers 1/2" off the foam and insulating that with unfaced fiberglass bats and cover it all up with 1/2" drywall. This will be on the walls that are fully exposed on the exterior of my walk out basement. The rest of the walls which are mostly buried in the hillside I might just use 2" XPS foam with drywall attached directly to it and call it good.

Looking forward to hearing other folks opinions and experiences.

 

[forgeblast]

might want to think of using the mold reistant drywall.

 

[tractchores]

For the floor I was just going to use some cheap ~50 cents/sq/ft carpet. Like an indoor-outdoor or cheap level loop berber. Just so it isnt cold to walk on

You can always put in a subfloor later. I took the carpet only approach, but it was always very cold and if any water got in the carpet was soaked. The subfloor really made it feel like regular living space, but on the flip side the subfloor was the most expensive part of the install ($2.50 per 2'x2' tile).

 

[bp fick]

We've insulated 3 or 4 basements over our lives. Always just used wooden 2x studs and Kraft paper toward the living space, just as you would in most applications. Never have had an issue, and some of those installs are over 40 years old. Not a problem.

Sometimes, we use 2x4 and use an R-13 thick batt. If you use the R-11, a 2x3 is plenty big enough. It's not like you can "flush" the stud against the uneven wall. It's natural to hold the stud off the concrete wall by a 1/2 inch, just because you have to.

The R-11 at Menards is also cheaper than the R-13 at Home Depot.

 

[Egon]

Metal studs is about 2x's the cost of wood. So I dont see that happening.
/QUOTE]

At least use the metal railing with wooden studs. Makes it a lot easier.:thumbsup:

 

[LD1]

might want to think of using the mold reistant drywall.

Already planning on that. A few dollars a sheet more, but peice of mind.

You can always put in a subfloor later. I took the carpet only approach, but it was always very cold and if any water got in the carpet was soaked. The subfloor really made it feel like regular living space, but on the flip side the subfloor was the most expensive part of the install ($2.50 per 2'x2' tile).

Not sure what the sub-flooring is you are talking about?? Got any links? $2.50 per 2x2 is a little pricy but I'd want to know for sure what you are talking about before I decide.

What do you do "IF" you ever get a leak/flood?? I mentioned in another thread that I did used to work for a company that did basement restoration after flooding/water back-ups. And never seen anything like it. All I know is that if the carpet had pad, we had (mandated by the insurance companies) to yank up the carpet and toss the pad. And then the homeowner had to have the carpet re-installed. But with NO pad as I am planning, it was as simple as sucking the water out and drying it with blowers and de-humidifiers. MUCH cheaper and simpler than w/pad.

I'd imaging with a sub-flooring, in the event of water damage, the carpet would have to be removed, subfloor dried, and then carpet re-installed.

We've insulated 3 or 4 basements over our lives. Always just used wooden 2x studs and Kraft paper toward the living space, just as you would in most applications. Never have had an issue, and some of those installs are over 40 years old. Not a problem.

Sometimes, we use 2x4 and use an R-13 thick batt. If you use the R-11, a 2x3 is plenty big enough. It's not like you can "flush" the stud against the uneven wall. It's natural to hold the stud off the concrete wall by a 1/2 inch, just because you have to.

The R-11 at Menards is also cheaper than the R-13 at Home Depot.

Everything around me is cheaper @ menards vs HD or lowes. And the R-11 I linked is the cheapest of anything I have found per sq ft. comes in @ ~ .17 per sq/ft. R-13 is ~.29 for 23" and .22 for 15", but that savings is offset by having to buy more studs for the 15".

And I'll look into the 2x3's. They are 1.49 per 8' and the 2x4's are 1.99. I thought the R-11 had to have 2x4's because it says 3-1/2" thick like R13. But I guess that dont matter. I could go with a 2x2 if I wanted. Because if I leave an air-gap.......so what if the insulation sticks out into the "dead space" a bit. I could just space the wall a little farther out to begin with. :thumbsup: Thanks for the good idea. Figuring about ~120 studs and 50 cents a board savings is $60:thumbsup: