# Insulating behind bathtub access panel



## brian0918 (Dec 28, 2016)

1950s brick ranch in Ohio

We have a room on the north side of the house that gets cold in winter. We have to keep the door shut, which is part of the problem. We put plastic up on the windows but that only helps so much.

There's a large access panel going to the adjacent bathroom, and that air space goes straight to a cold room in the basement, so I would like to insulate it. The access panel door is just a thin piece of wood paneling.

Do I just stick a thick piece of rigid foam insulation on the access panel door?

Could I fill the square gap to the basement with fiberglass insulation, or will that get wet from the pipes and cause mold?

Thanks in advance!


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## Windows on Wash (Aug 30, 2011)

My only concern would be if you stop roomside heat from getting down in that space, what is keeping those pipes above freezing at that point?


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## brian0918 (Dec 28, 2016)

Windows on Wash said:


> My only concern would be if you stop roomside heat from getting down in that space, what is keeping those pipes above freezing at that point?


Well, the basement is finished and partially conditioned at least. It's not freezing cold down there, but not warm either.


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## SeniorSitizen (Sep 10, 2012)

Consider doing a smoke stick test to check naturally occurring cold/warm air flow currents and then determine where and what will be needed as insulation, vapor barrier etc.


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## Gary in WA (Mar 11, 2009)

----------------------Welcome to the forums!-----------------------------

That open chase to below should be closed off with rated plywood or other fire blocking because your floor fire blocking has been compromised; 

"Openings around vents, ducts, pipes & cables at ceilings & floor" *pp. 4;* http://www.codecheck.com/cc/ccimages/PDFs/CCB3_sample.pdf

Add some closed cell pipe insulation to the pipes under the plywood level, seal with sheet metal around the pipes after adding plywood, fire-caulk the remaining smaller gaps. No insulation above the floor unless trying to keep the warm tub water warm...

Gary


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## SeniorSitizen (Sep 10, 2012)

Insulating pipes in this situation has no value.


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## Gary in WA (Mar 11, 2009)

I was going by "and that air space goes straight to a *cold room* in the basement," and this; basement is finished and partially conditioned at least. It's *not freezing cold* down there, but *not warm either*.' If the basement room never gets to freezing, at least insulating the hot water supply below the floor will keep it from losing heat- especially if the water heater is a distance away and the room below is unconditioned- storage room or such. Smoke pencil is not needed, with the opening left open -- the stack effect will add basement air to above. Same with a fire or fumes... close it off- if just for fire-blocking- same with a crawl space. 


Gary


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## brian0918 (Dec 28, 2016)

Thanks for the replies. Was the sheet metal layer intended as a vapor barrier, and does it go on the basement side, or the first floor side? I'm thinking first floor side, since that's warmer.


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## Gary in WA (Mar 11, 2009)

Yes, the side you are working from. It is easier to cut tighter fit with metal then wood, than you won't even need FR foam, but use caulking there. Also, put a bead around/under the metal on the wood to stop air. 

Hot water is 120* (or so) and cavity is at 60* or so, a 60*F difference,,, if you had that temp difference between exterior/interior; would you insulate your walls/ceiling/floor? The warmer the HW is in the pipe, the less money it costs you, especially if the supply run is long. 

Also, cc foam wrap stops/muffles sound. Most houses you can hear the water running through at least one wall area. If you insulated all water supply lines- conditioned spaces also- it would be much quieter. Add the pipe hold-downs over the insulation to the studs and stop direct sound through the wood to drywall in stud cavity there. I use FG batt in that interior cavity (pipes present and main drain line from upstairs so you don't hear the toilet flush- running joke on Archie Bunker show.

Gary


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## BryanWeaver (Jan 10, 2017)

Good try.


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