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what R insulation to use in a basement ceiling

11 years ago

we live in the Ct/Mass/Ny border so winters are cold.
I deduced that the insulation to the basement ceiling is the reason why the above room is always cold. I have had the HVAC people look at the vents and blower to this room.
As we surveyed the basement ceiling I could see substrate, missing insulation and areas where the insulation has a huge gap between it and the substrate.
The insulation gentleman says that I need to replace the R11 with at least an R 19.
Would it be better to do a R 25/30 or just install the R 19 product. This part of the basement has no heat, three walls of concrete and two small basement windows..
The present insulation does not sit flush with the substrate. When I walk in socks on the above room which has a wood floor the floor is cold.
So Do I install a higher R factor or go with the R 19
The installer says it will cost a dollar a sq foot to increase the R factor. I am looking at 1100 sq ft .
R 19 would cost 2800 so an R 25/30 would cost 3900
Thank you in advance

Featured Answer

randy427

11 years ago

More R, of course, means slower heat loss, as does an intact insulation system. I'd go with R30.
Is it within your budget to put in radient floor heat?

Comments (7)

brickeyee
11 years ago
How is the basement going to be heated?

Any water lines down there?
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I'm going to respond to something you weren't looking for - fiberglass batts on basement walls are not ideal. Yes - it is done all the time but foam is better. I'm not up on all the arguments but the basics are that moisture comes out of the concrete and will cause mold/mildew in the fiberglass. Far better to use rigid foamboard and I am pretty sure that you would be fine with R-8 - which would be 2 sheets thick. You can then put fiberglass on that if you want. Code here would be insulate the floor. Anytime you have unconditioned space next to conditioned, you need to insulate. Even if the basement is always going to be mild temp. I see what you are thinking - get some climate control from the ducting but that isn't allowed. And then maybe some more from the floor above. Fiberglass is cheap. Insulating the floor is the right answer. My builder always insulates the basement floor even on a conditioned walkout basement. The reasons are sound (minimal) and if you don't want to heat the basement at different times then your 1st floor won't suffer.
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Dr. Lstiburek's rule of thumb is a minimum R20 in basement walls north of the Mason-Dixon Line. (Of course, he doesn't always follow his own rules.) I've used R13 dense fg batts and 1" of XPS in basements plus spf in the rim joist area. That yields a nominal R18. However, in your colder climate (very cold on climate maps) I would be concerned that the 1" board (R5) would not be enough to keep the wall free from condensation on the above grade portion. What's more important than the nominal R value is the tightness of the wall to air penetration. That's why the tape, t&g, caulking and polyurethane spray is so important. BTW, since I live in my own homes, I can say the basement comfort in homes with the XPS/fg combo is noticeably greater than the previous standard fg. Plus there's less need for supplementary heating.
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snoonyb
11 years ago
There is a rule in insulation application; The vapor barrier faces the conditioned space.
If the comfort heating appliance is in the basement, there should be a register someplace in the ducting to maintain some level ambient heat.

Were I you, I would fill in the gaps with a similar faced product and add unfaced R-19to the joist bays, add storm windows too the windows and make adjustments to the ambient heating source.
This is about a day and a half for a DIY.
chickadee4
Original Author
11 years ago
deleted double post

This post was edited by chickadee4 on Tue, Mar 12, 13 at 13:15
chickadee4
Original Author
11 years ago
You are good!!!
Never considered installing radiant heat .
I did googled R factor for my zone and nothing appeared in my web searches.
I did find a website saying that crawl spaces and basement ceilings should have R19 when I googled is it dangerous to install fiberglass. A DIY website explained the R factors for each time zone . Code for this ceiling is now R19 . I agree that R 25 is a better choice.

I am not heating this side of the basement. The basement is already divided in three sections with the other two having sheet rock. The side I am having issues with is cold in the above room
I have a cold room and was trying to figure out if this space needed the ducts turned off or maybe the duct was blocked.
I pulled back the insulation and there is no kraft paper/there is no vapor barrier.

This is a simple DIY with googles, mask and long sleeves but I weigh under a buck and for my size am getting so tired of handling all the repairs. I am a handywoman deadly with my vice grips.
Not planning on using this side of the basement , just want to contain the heat and block the cold.
I will rip out the old insulation since there is no vapor barrier, install R25 and reuse the R11 over it.
Appreciate your opinions.TY
Please chime in if reusing the R11 is a bad idea. I would apply a vapor barrier R25 and leave the R11 over this.
snoonyb
11 years ago
If the existing product is faced, the facing is the vapor barrier and that is why I suggested filling in the voids and adding the unfaced R-19, equaling R-30.

Often these sites, when speaking about the old insulation, are considering other circumstance than in a basement where the product does not suffer the lose of its ability to retain air, caused by compression.

While I would use the raw, unfaced product, there is an encapsulated product which reduces the fiber exposure, however, because the loose product tends to lend itself to retention in place, the encapsulated will require some ty-wire to facilitate that.
chickadee4
Original Author
11 years ago
There is no vapor barrier/no paper/no kraft paper.
What i have is R11 held by stringers.
I found a website that says in my zone R 19 is needed.
I plan on removing the old R 11 since there in no paper.
I will install R 25 and reuse the R11 .

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