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Old 03-26-2019, 09:47 AM   #1
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Basement insulation - yes another thread asking this


Hello everyone, I am going be remodeling my basement starting hopefully within a week but had some questions. Let me first state some details on the basement:

-Size: 51’9” x 26’
-Cinder block walls
-Location: Southern NJ
-Furnace/hot water heater/ and water purifier located down in basement.
-No water issues minus a leak by Bilco doors but going get removed for a egress window or block it.
- efflorescence issue on 2 walls, getting yard regraded to help.
- Getting new furnace and hot water heater, Ned duct work also adding 2/3 vents in basement.

Ok so now that all that information is giving here goes the rest of thread. I am planning on taking a 1/4 to 1/3 the basement and making it a separate area from the rest (work spot rest is tv bar and so on). I was planning on using metal studs, and either carpet tile or LVT as flooring.

Now for insulation I want to redo the rimjoist insulation and from what I have read people suggested using EPS foam board, and also spray foam around the edges. They also stated leaving some spots with access for termite inspection. First question there is, is that the way to go for insulting the rim joist? How many spots should I leave without spray foaming the foam board in for termite inspection? How thick of a foam board do I go with?

Next is dealing with the walls. Also I read I should leave 1/2” gap from block to studs. Put a vapor barrier up behind studs, put batting insulation in between hoist, then vapor barrier over that again. I have also seen where people just use foam board and call it a day. What would be the best method of choice? Obviously it’s easy to just staple the vapor barrier to wooden studs but for metal what is recommended? Do I also put vapor barrier all the way up covering rim joist?

Lastly is for my concrete floor. Should I put a piece of roofing paper or something under the bottom metal track to prevent moisture if any to hit that?

If you guys need any additional information let me know.
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Old 03-26-2019, 10:19 AM   #2
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Re: Basement insulation - yes another thread asking this


I'm doing my basement in NY right now. well at work right now, but nights and weekends...

1) rim joist. I don't think there is any reason to leave some of the rim joist area for inspection if you're closing up the walls. I'd do the entire rim joist around the finished and unfinished areas.
1a) I did XPS foam board with canned foam it isn't hard, it is time consuming. If I were to do it again, I'd consider getting one of the foaming kits that are 200 board feet of spray foam.
2) Walls, I suggest using 2" XPS glued to the concrete and caulked/glued to the floor.
3) skip the vapor barrier=- the foam will work as a vapor retarder which is good. A vapor barrier will make things wet on one side and grow mold.

I had a waste pipe running halfway down my basement walls all the way around along with drops to worry about. doing the insulation board was a pain in the but.t If i were to do it over again, I'd consider hiring the work out. If you have nice bare walls without a lot of cut outs, It looks like it would be super easy to DIY.

Framing to foam, I'm not sure it makes a difference to leave a gap if you do 2"
I haven't done metal framing, so I don't know exactly about ground contact. I don't think it would hurt to use either tar paper or a sill gasket.
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Old 03-26-2019, 12:08 PM   #3
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Re: Basement insulation - yes another thread asking this


@Spyder
3) skip the vapor barrier=- the foam will work as a vapor retarder which is good. A vapor barrier will make things wet on one side and grow mold.

There are two reasons that would happen,
A leak on the outside which has nothing to do with the vapour barrier.

Cold air getting passed the insulation making the vapour barrier to a cold surface. That is poor insulation job and something causing air circulation behind the barrier.



So mold there is symptom of a problem, not the problem.
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Old 03-26-2019, 12:26 PM   #4
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Re: Basement insulation - yes another thread asking this


From time to time we do have to get to the rim joist so something that can be removed is not a bad idea. Foam board with caulk around the edge is as good as any.

Bat and VP there is a pain to do and can get very messy to work in.



If I was worried about termites would you not treat that wood with something for that before covering it up???



Which ever way you insulate there are just a few things you want right.

Enough insulation that the concrete stays cold and the warm side of the insulation stays warm enough that moisture will not condense on it.
A cavity between the concrete and the new wall needs to be blocked at the top for fire stop and air stop. So even if there is areas missing some insulation we don't want to supply it with warm moist air.


We have another thread here where they built the wall correctly but stopped at the furnace room, so warm moist air could get behind the wall and insulation and condense on the concrete.
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Old 03-26-2019, 12:59 PM   #5
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Re: Basement insulation - yes another thread asking this


Quote:
Originally Posted by Nealtw View Post
@Spyder
3) skip the vapor barrier=- the foam will work as a vapor retarder which is good. A vapor barrier will make things wet on one side and grow mold.

There are two reasons that would happen,
A leak on the outside which has nothing to do with the vapour barrier.

Cold air getting passed the insulation making the vapour barrier to a cold surface. That is poor insulation job and something causing air circulation behind the barrier.



So mold there is symptom of a problem, not the problem.
I'm not sure what you're advocating for here. Are you thinking there should be a vapor barrier?

I'm indicating your second item can happen if everything isn't perfect and realistically if you foam you've mitigated the need for a vapor barrier (when its working) and took away the negatives of a vapor barrier when its not, it allows some inward drying.

You indicate the mold is a symptom, not the problem... I feel you're half right. it may be a symptom of a construction failure, but it certainly ends up being more of a problem than a warm/cold air leak

This is a long article, but 3/4 of the way down they show vapor barriers installed in basement walls with mold growth then follow the discussion of foam.
https://www.buildingscience.com/docu...ding-basements

Last edited by Spyder; 03-26-2019 at 01:03 PM.
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Old 03-26-2019, 01:21 PM   #6
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Re: Basement insulation - yes another thread asking this


Quote:
Originally Posted by Spyder View Post
I'm not sure what you're advocating for here. Are you thinking there should be a vapor barrier?

I'm indicating your second item can happen if everything isn't perfect and realistically if you foam you've mitigated the need for a vapor barrier (when its working) and took away the negatives of a vapor barrier when its not, it allows some inward drying.

You indicate the mold is a symptom, not the problem... I feel you're half right. it may be a symptom of a construction failure, but it certainly ends up being more of a problem than a warm/cold air leak

This is a long article, but 3/4 of the way down they show vapor barriers installed in basement walls with mold growth then follow the discussion of foam.
https://www.buildingscience.com/docu...ding-basements
Code here is 6 mil poly vapour barrier, any time there is a problem it is about a problem with a leak from plumbing, roof or siding or insulation and barrier not done properly or completely.



So mold on or just wet vapour barrier is the symptom. You can remove the vapour barrier and it might stop the symptom , it does not solve the problem.


We see home owner that don't do it completely and air can flow in around outlets or gaps near the floor up thru the top of the wall into the floor system .



That can and will leave moisture and some times mold in the insulation around the outlet or on the concrete. The same home owner that discovers that may remove the VP as you might suggest. He has not solved the air movement problem, he has not solved a mold problem and now as it is allowed to dry to the basement side, he will have that musty basement smell.



The people that put down VB have never seen a house done properly to code. And code for is strict.
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Old 03-26-2019, 07:55 PM   #7
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For most part my walls are just perfect in the sense of nothing on them. One side I have my waste pipe exiting house that I’ll work around, and then another wall where my water comes in as well as my sump pumping exiting. Nothing to major to work around.

Nealtw, what do you recommend to treat the wood with? We have a company that comes out to do the termite treatment, but that isn’t something where they spray the wood once and call it a day forever. But if there is a product I can use to spray once on the wood and then I can fully seal it up and not have to touch it again I’m all for that. I just have read people saying to leave some spots accessible for termite treatment.

So I get both sides of Spyder saying use foam and that’s good, and also get the idea of using the VP, so I guess I’m on fence since I get both sides. As mentioned currently I have 0 water issues (knock on wood), only issue is the leak at bilco door but that’s getting resolved. Also only other issue is the efflorescence which I’m thinking the yard being graded away as well as downspouts discharged being pushed away from house will handle that. I will run a dehumidifier in basement do to fish tank in basement, but other wise all good.
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Old 03-26-2019, 09:33 PM   #8
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Re: Basement insulation - yes another thread asking this


Quote:
Originally Posted by EWC88 View Post
For most part my walls are just perfect in the sense of nothing on them. One side I have my waste pipe exiting house that Iíll work around, and then another wall where my water comes in as well as my sump pumping exiting. Nothing to major to work around.

Nealtw, what do you recommend to treat the wood with? We have a company that comes out to do the termite treatment, but that isnít something where they spray the wood once and call it a day forever. But if there is a product I can use to spray once on the wood and then I can fully seal it up and not have to touch it again Iím all for that. I just have read people saying to leave some spots accessible for termite treatment.

So I get both sides of Spyder saying use foam and thatís good, and also get the idea of using the VP, so I guess Iím on fence since I get both sides. As mentioned currently I have 0 water issues (knock on wood), only issue is the leak at bilco door but thatís getting resolved. Also only other issue is the efflorescence which Iím thinking the yard being graded away as well as downspouts discharged being pushed away from house will handle that. I will run a dehumidifier in basement do to fish tank in basement, but other wise all good.
We don't get the termites like that here so no real help. A foam board held in with caulk or foam might be the best if you have to get in it later for inspection. I guess any treatment would want to be on the outside.
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Old 03-27-2019, 06:39 PM   #9
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Let me ask you guys this, saw a contractor at my work today and figured bounce idea off him, he told me to use the Kraft insulation with backing and that’s all that is needed. Opinions with that idea?

As mentioned I get everyone’s ideas and to me all sounds right but I’m not expert hint why I’m here and just want to make sure it’s done proper.
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Old 03-27-2019, 06:54 PM   #10
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Re: Basement insulation - yes another thread asking this


Quote:
Originally Posted by EWC88 View Post
Let me ask you guys this, saw a contractor at my work today and figured bounce idea off him, he told me to use the Kraft insulation with backing and thatís all that is needed. Opinions with that idea?

As mentioned I get everyoneís ideas and to me all sounds right but Iím not expert hint why Iím here and just want to make sure itís done proper.

That would be my last choice, the biggest air leaks are around outlets and switches so not sure what the paper does there.

With a VB you can wrap the outlets or buy air sealed boxes
With out VB you need those air sealed boxes and be sure air can't get in or around anything.

It is all about getting the insulation to fit perfectly and stopping air flow at the warm surface.
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