Basement vapor barrier, insulation, framing

[HotDoggin]

Hello Mr. Obvious, first time caller long time listener, Well just going to start finishing my basement which is a walkout and just want some input, ideas, and reminders so I don't have to go back and do too many things over again because I forgot. So here's the plan so far, going to put up foam board on all exterior concrete walls and tape seams, then frame and fiberglass insulate. Framing and everything should go well since I used to do it although it was 10 years ago, I'm hoping it will all come back to me as I get started. But mainly want tips and advice for insulation and eliminating any water issues in the future. Been in the house for 2 years, new build and haven't had water problems yet but shit does happen. Thanks in advance for any advice and pointers so I can hopefully avoid beating my head against a wall in the future.

HD

 

[jer79]

in the past I have ripped down inch and a half foam board to 12 1/2 inches and put that between 2x4 that were tapcon ed into the wall at 16 on center flat. just start with a board then put a piece of foam up, attach your next board etc/ that should work as a vapor barrior. u could run a quick bead of silicone (foam board friendly product) along the board if ur worried about air exchanging. it is kinda tricky I think because you don't want to end up with a "double vapor barrier". anyway if you put foam board up on a concrete wall, I think this could be the simplest and fastest method. use a table saw of course to rip the foam. this way the foam always fits tight in the cavity. maybe someone else has the hard and fast rule for vapor barriers and concrete.

 

[You]

Don't waste money foam boarding. Or 'vapor barriering'.

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Frame er up and staple some faced r13 the full height and ur golden. Then the rock. Ur not gonna 'waterproof' nothin.

green treat on the floor against concrete, regular two bys for the rest. Build ur walls, then 1/4" hammer drill thru green treat into the Crete, pound two 4" nails in hole wedge style. Done. Wall will never move.

water issues are addressed by building high in the first place, or building as near grade as u can and pushing dirt up to the foundation. a sump hole and tile around the house and tied to the sump is the best way to fight high water. I'll never own a home in which I have to babysit a wet/constantly running sump

 

[lunkerslayer]

Have you looked at using z channel steel studs, they come in 1,1.5, and 2" sizes they are very easy to work with

http://www.riversidesheetmetal.net/flashing-metal/masonry/z-furring-channel/

This works well for all wires or pipes you just cut the back of the foam to allow the wires to go through. Put cement fiber board on the first 4' and no more mold problems if your get moisture.

 

[Wild and Free]

Put in floor drain tile under the basement floor to make sure you have no issues going forward and then if you do develop water issues it will not cause headaches plus it will help in selling a home. I just recently learned this the hard way. If I ever do new construction or have to finish an unfinished basement it will definitely have under floor drain tile system under it.

 

[Obi-Wan]

You definitely need a vapor barrier but my option is that Kraft face insulation is a bad idea # 1 you can't see how well the insulation was installed especially the corners. # 2 the paper ( which is what the kraft face is ) tears easily and along with the ends gives you a very pour vapor barrier. A layer of 4 mil poly, tape, and caulk will give you a good vapor barrier with minimal cost. I am not a fan of mixing foam and fiberglass insulation as stated before you could end up with a double vaporer which could trap moisture in the wall cavity

 

[raider]

You definitely need a vapor barrier but my option is that Kraft face insulation is a bad idea # 1 you can't see how well the insulation was installed especially the corners. # 2 the paper ( which is what the kraft face is ) tears easily and along with the ends gives you a very pour vapor barrier. A layer of 4 mil poly, tape, and caulk will give you a good vapor barrier with minimal cost. I am not a fan of mixing foam and fiberglass insulation as stated before you could end up with a double vaporer which could trap moisture in the wall cavity

listen to this... i used to be a spray foam contractor and have seen it go terribly wrong...

i won't talk specs as it has been a couple years since i quit, and science never does... if you're going to go this route, carefully check the specs on the foam board and sealant... closed cell spray foam will give you a perm rating at under an inch... some builders like to use a hybrid system of spraying an inch of closed cell foam (r7), then putting up an r13 batt, then either a poly cover or not under the rock... either way, you have just built a petri dish as 2 coats of latex paint can be a vapor barrier...

with this system, you don't have enough r value to stop the intrusion of cold air through the basement wall and the foam, the foam will b cold... when warm moist air travels through the inside wall and reaches the face of the foam, which is cold, when the dew point is reached in the wall you create condensation and start growing mold...

in warmer climates to the south this will work... but up here it gets too cold... google "flash and batt"

please, for the sake of your family, don't try to save a buck here... talk to reputable people you trust...

if you can afford it - frame it, foam it - f it...

 

[lunkerslayer]

how much does spray foam cost by the square foot, can a person buy the stuff themselves, I am not talking about little cans

 

[jer79]

i hate kraft faced batting...it seems people that use that know just enough to be dangerous. lol

 

[raider]

how much does spray foam cost by the square foot, can a person buy the stuff themselves, I am not talking about little cans

do it yourself kits are sold as "froth packs"... my experience is that you can hire a pro to do it cheaper than the cost of the froth packs... quality compares to jb weld vs wire feed...

last i knew price would be around $1 per board foot which is 1 foot square x 1 inch thick... 1" closed cell foam is about r7, so 3" thick would run you about $3 per square foot for r21...



fwiw to the op, 2015 residential building code requires all rim joists to have an "air seal"... closed cell foam is the only way to do it... your city or county may not be using the 15 codes yet, but it is a great idea anyway...

have never heard anyone who was disappointed they had it done...

 

[jer79]

you can buy "froth packs" at lumber yards. I think that most kits cover 200 square feet per inch. and they are not cheap, but worth it possibly depending on what ur doing. to do a good job you need 3 inches minimum.. a spray foam contractor charges about 2.25 to 2.75 depending on the size of the job. they tell me that any more than 3 inches is a waste. its the beez kneez.

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he beat me to it

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and also r 21 with spray foam is better than r 45 fiberglass because closed cell foam is nearly 100 percent efficient. don't quote me... but it just does such a better job.

 

[HotDoggin]

Thinking maybe the Roxul insulation may be the way to go, The Homes on Homes guy really recommends it and looks like lowes carries it. Has anyone else used or heard of it?

 

[Wild and Free]

Raider, when and were is the best use for open cell and closed cell spray foam insulation? I had a kitchen remodel done on my home several years ago and did some wall and ceiling insulation in an add on entry way and the contractor wanted to use open cell on the whole job but I had reservations on that in one area with known moisture issues and made him do the entire job with closed cell and I couldn't be happier with the results.
Just wondering why he was not wanting to use closed cell at all until I requested it? He claimed he uses nothing but open cell on pretty much all jobs.

 

[raider]

open cell has really no good application north of kansas in my opinion...

it has an r value, depending on blend, of bout r3.5 per inch, while closed cell is bout r7... open cell gives no perm rating, or vapor barrier... in zones south of here you can hit building code standards with it in terms of r value, but not up here... r3.5 in a 4 (actually 3 1/2") wall cavity only gives you r14, when you need r21 to hit code... in a 2x6 wall (5 1/2") you can hit r19.5, which is still short even with a full cavity fill, which is how it is normally applied...

open cell is normally applied full cavity, and then shaved down to be even with the studs... it is like a sponge material you can easily pull out with your hands, and trims very easily... it will absorb water, and needs a vapor barrier...

closed cell is normally applied at 3", for r21, in wall cavities, and can be sprayed down on rock in ceilings to seal, with a layer of blow in to meet code, or applied directly to the roof sheeting (hot lid)... it cures very hard, giving a 400% increase in racking strength (structural strength), and has a perm rating (vapor barrier) usually at 1" or less...

the only thing open cell should be used for up here would b for sound deadening in interior walls such as bedroom or bathroom, or between floor joists, but fiberglass works just as well... for sound deadening, pack the fiberglass tight... in 6" walls, pack in a 5" (r19) unfaced batt...



i will say open cell finds it's way up her from time to time... some contractors up here from down south have tried to peddle it as "spray foam" instead of open or closed cell, and they normally will not tell you what it is... b careful... if the price seems too good to be true, it most likely is... open cell should cost bout 20% of closed cell...

 

[Wild and Free]

Thanks for the info Raider, I had talked to others and researched things before hiring the contractor I did which is one of the main local spray foam guys who advertises a lot here won't say the name here but as long as he has been around I would have thought he would know this, he was not impressed that I requested the whole job be done in closed cell but am very glad I forced his hand in it.

 

[eyexer]

In your situation the best method was stated above. Frame a 2x4 wall inside the concrete wall. But I would insulate with unfaced batts and install plastic sheeting on the inside. Run all your electrical before you insulate. The Z channels look tempting to people but the reality is that the foundations are never plumb nor straight. And have chunks you'll have to knock off to get it to sit decent on the concrete. And you have to hammer drill all them things in. And running electrical isn't any fun. Using steal studs is another option but then again you have to do the electrical a little different and there is a learning curve with steal studs if your not familiar with them. If your budget allows I'd do as Raider suggested and have a contractor come spray 3" of foam on the concrete wall then just build a stud frame wall inside. Just think all this could have been avoided if you had them use Insulated Concrete forms when they did your foundation lol

 

[Kurtr]

In your situation the best method was stated above. Frame a 2x4 wall inside the concrete wall. But I would insulate with unfaced batts and install plastic sheeting on the inside. Run all your electrical before you insulate. The Z channels look tempting to people but the reality is that the foundations are never plumb nor straight. And have chunks you'll have to knock off to get it to sit decent on the concrete. And you have to hammer drill all them things in. And running electrical isn't any fun. Using steal studs is another option but then again you have to do the electrical a little different and there is a learning curve with steal studs if your not familiar with them. If your budget allows I'd do as Raider suggested and have a contractor come spray 3" of foam on the concrete wall then just build a stud frame wall inside. Just think all this could have been avoided if you had them use Insulated Concrete forms when they did your foundation lol

Did my basement my self with them and if building new a person is a fool for not using them.

 

[deleted]

This might be better than the ICf....................http://www.compositepanelsystems.com/products/

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We have 2 in the ground in Fargo right now, one will be in parade of homes.

 

[eyexer]

This might be better than the ICf....................http://www.compositepanelsystems.com/products/

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We have 2 in the ground in Fargo right now, one will be in parade of homes.

rather interesting. most icfs systems are R25 but perform to R50. I'm not sure what the insulation is in the panels you linked to. What is the cost compared to icfs?

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Did my basement my self with them and if building new a person is a fool for not using them.

every house I've built had them. Easy sell to homeowners when they understand them or if you take them into a house with them. then put 1.5" styro under the floor and it's damn near too hot in the basement.

 

[DirtyMike]

Thinking maybe the Roxul insulation may be the way to go, The Homes on Homes guy really recommends it and looks like lowes carries it. Has anyone else used or heard of it?

I used the roxul in my garage and it's awesome but expensive.