Crawl Space Insulation: Posting #1


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Old 01-07-16, 04:40 PM
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Crawl Space Insulation: Posting #1

We have a complicated insulation issue in my daughter's crawl space. Overall, I'll be posting about a dozen emails and would appreciate your thoughts.

My daughter's house has an above ground enclosed space under the master bath, best described as a crawl space. It is unconditioned and ventilated (due to construction rather than actual vents). Here's an exterior picture. Note the lower level of the extension:

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The issues are
  • Exposed pipes in the crawl space may freeze in freezing weather.
  • The bathroom is difficult to heat properly.
The space is only 8' by 9', making professional solutions somewhat cost prohibitive.

Here's interior photos:

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As of now, the solution is using a space heater to control the temperature. This keeps pipes from freezing but does nothing for the bathroom issue.

We cannot (in my view) use fiberglass in the crawl space ceiling because of moisture issues but are considering cellulose or denim.

Thoughts, please.
 
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Old 01-07-16, 05:47 PM
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Who's idea was that ?

That floor under the bathroom needs to be closed in. That space under the bathroom needs to be treated like a cantilevered addition.

I wouldn't call that a crawlspace..... more of a shed.
 
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Old 01-08-16, 04:00 AM
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Thanks for your comments. That section's not my favorite thing about the house. I agree with your comment on encapsulating.
 
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Old 01-08-16, 04:19 AM
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Hi Tony,
Is it a dirt floor or a concrete slab?
How are those walls constructed and does this sit on a foundation.

I hope the other 11 problems are easier than this one .

Bud
 
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Old 01-08-16, 08:43 AM
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The floor is concrete and not noticeably damp. There is no foundation.

Bud, on your other point, this is the only problem I'll be addressing. I have a series of questions on this I'll be posting. I plan to do this in individual threads because the specifics vary.
 
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Old 01-08-16, 09:39 AM
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Just kidding about the other 11 problems as I was laughing about this being your daughters house. I'm working on my daughter's home as well, but I do enjoy it and glad I can help. She swings a mean hammer, but does let me do some of it.

No foundation so that wood goes right to or into the soil?

My first instincts would be to do as PJ said "That space under the bathroom needs to be treated like a cantilevered addition." That would mean air sealing and insulating the floor above. The question would be, are there any pipes or other issues down there that must be kept above freezing?

Note, in winter the cold air enters low and flows up through a house, thus the cold room above.

I see some pipes so I'm thinking you might want to move the ceiling and insulation down to protect them.

More pictures if possible. I want to see if insulating the walls is an option.

Bud
 
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Old 01-08-16, 09:49 AM
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It's sometimes better to keep one topic in a single thread. If you start splitting it up then you'll be answering all the questions that were covered here.
 
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Old 01-08-16, 10:31 AM
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Bud, everything rests on the slab. I agree with the cantilevered treatment, which I've done before. However, the pipes create a complication and is probably a no-no in a cantilevered situation.

I believe standard procedure is to begin by gluing rigid foam board (perhaps 2") to the subflooring and seal. However, doing so will leave my daughter's plumbing in the cold.

How do I deal with that? Should I, instead, use faced fiberglass and skip the foam? (I hope not because I believe cellulose is a better option. here)

Also, my original post contained photos.
 
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Old 01-08-16, 10:35 AM
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Original post contained photos but we need to see more. I'm thinking the same way Bud is in that I'm wondering if insulating and heating the lower level is the way to go.
 
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Old 01-08-16, 10:39 AM
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Bud, regarding insulating the walls, we've done that with rigid foam and there's a heater inside to protect the plumbing. The problem is that really does nothing to substantively insulate the floor above. I don't think encapsulating is a cost effective option.
 
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Old 01-08-16, 11:27 AM
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By insulating the walls, we're looking to create a heated space below which would negate the need to insulate the ceiling/floor above.
 
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Old 01-08-16, 12:52 PM
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Thanks for all the input. I'll get some additional photo's over the weekend. In the interim, here's an additional photo I had.

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I was at the same spot as you and started out working on this by making the lower area a conditioned space. We have (as a recall) at least 2" of rigid insulation around the exterior, including the doors. (See new photo.) A space heater was put in to protect the plumbing and did so effectively. (This issue goes back to last winter.)

Outside of creating a mouse resort, the plumbing risk issue was resolved. However, the bathroom is brutally cold. I believe cold air from underneath is being sucked up into the bath and out, into the bedroom. You can stand at the bathroom door and feel the draft. This constant flow of air keeps the bathroom from warming.

Tony
 
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Old 01-08-16, 01:02 PM
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OK, so finding and sealing those air leaks should be your priority, IMO.
 
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Old 01-08-16, 01:06 PM
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"OK, so finding and sealing those air leaks should be your priority, IMO."

Are you suggesting sealing the subflooring?
 
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Old 01-08-16, 01:08 PM
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Where is the air leaking from outside into the bathroom? Those are the leaks I'm proposing you seal.
 
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Old 01-08-16, 01:24 PM
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Here's a link on air sealing from Efficiency Vermont that may help you identify where to air seal. I just picked up a bunch of caulking and can foam to do my daughter's house, wide open basement. I'll start at the rim joist and seal every hole I can identify, wires, plumbing, bathtub, vent stacks, anything. Where openings are too large for just caulking I will cut and fit flashing and finish it with caulking. I'll use fire rated caulk where the path is a potential fire risk (vertical).

Once the space below is well air sealed and insulated it will take minimal heat to keep it toasty. Then if the room above is still cold, the problem is part of that room.

SS has you on the right track.
http://www.efficiencyvermont.com/ste...ide_062507.pdf

Bud
 
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Old 01-08-16, 01:29 PM
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"Where is the air leaking from outside into the bathroom? Those are the leaks I'm proposing you seal."

I don't disagree that sealing the bathroom must be done and will improve the situation. However, isn't the primary problem that floors should have R-30 insulation in Connecticut and we have nothing beyond subflooring and tile?

That's the logic behind my thinking as I started the thread that sealing, then insulating the floor (including plumbing) was my solution. Is that just not practical?
 
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Old 01-08-16, 02:37 PM
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isn't the primary problem that floors should have R-30 insulation in Connecticut and we have nothing beyond subflooring and tile?
No and you proved that by heating the space below and still having cold infiltrating into the space above.

Insulation goes in outside facing surfaces - outside walls, the lowest floor and the highest ceiling in the conditioned space. If you have heat in the lower unit, you don't need to insulate the ceiling above if there is conditioned space above that. Were you to leave the lower space unheated, then insulating the ceiling would be in order but you appear to have already ruled that out in post #8.
 
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Old 01-08-16, 02:48 PM
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Fair enough. Given that I have to seal the bathroom whether I insulate or not, sealing first is a reasonable way to go. If the problem continues, I'll seek further guidance.

Thanks to all!

Tony P.
 
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Old 01-08-16, 02:57 PM
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Absolutely, sealing is always easier done before insulating.
 
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Old 01-08-16, 03:15 PM
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One of the reasons for cold floors when a living space is located over a cold area is the natural movement of warm and cold air. In that bathroom above, even a small flow of cold air will sink right to the floor so whatever warm air is in there is pushed up and your feet freeze. Setting energy efficiency aside, you can install some heat directly below those floors and then add your r-30 insulation and they WILL be warm.

But air sealing first as ss suggested is #1 for all reasons.

Note, given the height of that addition, there is more than one seam for the plywood sheathing and doubtful they sealed them before the siding went up. Thus there is cold air flowing into every wall cavity and looking for a way into the house. In addition to sealing the lower air leaks, seal anything you find up high, like around electrical boxes or exhaust fans. If the air has fewer places to exit, less comes in.

Bud
 
 

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