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Heat loss over shower stall

12K views 20 replies 6 participants last post by  John_W 
#1 ·
You can see, from the snow melt picture, that there is heat loss through the ceiling and roof. This snow melt spot is directly above the shower stall - not the ceiling outside the stall.

This was a 7" snowfall, last weekend, which is very unusual for northern Alabama.

The house was built in 1963. In 1985, roughly, we had some blown-in fiberglass insulation added, in the attic, on top of the original 5 inches of rock wool. That got us to a total of about R35.

I have never been to the part of the attic above the shower - so I don't know how the shower stall was framed, whether it has a vapor barrier above it or whether there is any insulation above it.

There is no vapor barrier in the attic, in the areas that I have access to, such as the one in the attic picture. There are no HVAC ducts in the attic.

This bathroom is not vented, but we don't get mold problems - maybe because we leave the door open to the bedroom while showering.

This is not a new issue. Whenever we get frost on the roof, the same spot is the first part of the roof to get defrosted.

What could be causing this heat loss - and is it something that should be fixed?
 

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#2 ·
#1 is always AIR sealing. You'll have to get in there and see why so much air is passing from the shower up to the roof, and, no, that is not good at all and, yes, that should be fixed. Insulate while you are in there air sealing. Moving air carries heat and moisture into the attic. A vapor barrier is probably not necessary in Ala, but air barriers are. No fan? You should install a fan asap, if at all possible.
 
#3 ·
There is only one noticeable possibility of an air leak inside the house. It's a crack in the gout between the tiles of two walls inside the shower. I did a smoke test and there was no air being pulled into that crack.

Could it be that the tiles of the shower are conducting heat into the attic - and - if there is no insulation, or 'failed' insulation, above the shower, the heat goes quickly to the roof?
 
#6 ·
You may have to cut into the Gypsum above the entrance of the shower to get a good peek. Plus it would allow you to see how hard it will be in getting the fan up there. There are remote fan units, where you would place the vent in the shower, but the fan would be away, so as not to make so much noise in the shower area. Unless you can find a midget or a small kid to crawl over that way with a camera, it will be hard to see from the attic space.

To the left, is that the ductwork for the Furnace, or just a Soffit that was built in that section?
 
#7 ·
Good idea about cutting through the wall above the shower to see what's 'going on' up there. I agree about it being hard to get to that spot through the attic. Very difficult and messy.

The pipe to the left is a plumbing pipe. Its connects, down in the crawl space, to the toilet discharge pipes. Probably something about keeping sewer gases out of the interior of the house.
 
#11 ·
RoxWool would be the best. I would right now look at it as the aspect of investigation. Get the hole cut, and take some pictures. Now also, where the pipes are for the shower, even just blocking the convection process on that side with Roxwool would be a plus first, then see from there. Humidity rises through air movement process, heat through the convection process.

Also, if you can get to where the shower is and take photos up in the attic of the wood sheathing, that would show everyone if there are other problems in that area. Even if you can get a vent fan into the bathroom and either vent through the side of the house, or through the roof, that would be a start and something to put on the list for Summer.
 
#12 ·
Is that plumbing access or some sort of medicine cabinet in the third picture? Can you use that to get a look up through the wall?

It is likely that the soffit above the shower is open to the attic and to the inside of the neighboring walls between the studs. Air is heated within those walls or leaks into those walls and rises up to the soffit and into the attic.
 
#13 ·
It's where we accessed the pipes in the wall behind the shower, to fix a leak, but it's not easily opened. I didn't like the flimsy snap in approach to covering the hole so I put sheet rock in and framed the resulting cut lines with the molding you see.

Thanks for the air heating theory. That's what I think too.

I will probably open the soffit above the shower for the best possible view - and as a way to make any needed fixes.

I'm still not clear on what to do - assuming it's just hot air rising from inside the walls and the top side of the shower - into an open, unobstructed, uninsulated part of the attic. I want to stop the airflow, insulate to slow heat transfer and do it without creating a moisture problem of some kind.
 
#15 ·
OK. The bathroom vent would suck all the moist air from the shower out. So, with that installed, the worry about moisture rising from the shower into the attic goes away.

Then, to deal with daylong heat rise from the interior of the shower stall cavity, I can just shove some insulation into the soffit over the shower, with no air barrier? Or, do I need to install an air barrier above the shower stall, and put the insulation on top of the air barrier?
 
#17 ·
Being a rank amateur, I don't understand some things that are obvious to experts. That's why I'm here looking for advice.

In this case, I have no conception of how a shower stall is framed, or whether the sheet rock of the bathroom ceiling also extends into the space over the shower stall.
 
#19 ·
Please Help Im Having The Same Problem

Hello, i have just bought a home in central wisconsin and i am having the same problem. I have a 2 peice shower/tub (tub and shower walls one piece and has a top cap as a second piece. This are is lower than the rest of the bath ceiling so i guess you could say i have that soffit thing on top. I have been messing around in the attic and have added a buch of insulation but still keep on getting a melted spot on roof above the shower. When in the attick i noticed that there is some blue foam board over the area where the shower is and i have been putting the insualtion over this. Do you think the heat is comeing from around the foam board? There are 2 larger holes cut in the floor under the tub due to leaky tub jets in the past for them to fix and these holes are in the area of the furnace. Do you think the heat generated by the furnace is going through these holes up the walls of the shower and out from the foam board around the shower? I was going to seal the holes in the floor with some foam board from the basement to keep the heat out from the furnace. Im just stumped i cant seem to get the spot from melting on my roof. And i dont want to cause a problem in the future.
 
#20 ·
That looks like a very localized bare spot on the roof. It's either caused by conduction or convection, but I'd find a simple way to get a look at the area directly above the shower and below the roof in that spot. Could you rent one of those cameras that you could snake in there?
 
#21 ·
Well, it's been a while since my last post on that warm spot.

We have had extensive repair done since then: to the wood siding, new roof and - most pertinently, added some soffit vents.

The hole for one of the new vents gave me access to the attic directly above the shower. I stuck my camera up through that hole and got some snaps. The insulation looks the same depth and color there as it does everywhere else.

I checked every soffit vent the same way, just to make sure there were no blockages. Two were partially blocked by insulation which I corrected with a leaf blower.

The heat is still rising up from the shower area, whether or not we have recently used it. I have not cut into the wall above the shower to see what is going on there.

Since the insulation in the attic looked okay above the shower, and since the house has been untouched in that area for 32 years, I'm not very concerned about whatever is going on.

Maybe I should be but life is too short.

:)
 
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