# Insulating and Venting a Vaulted Bathroom Ceiling



## sbcontracting (Apr 22, 2010)

*Update and pics*

Hey there.

I ended up putting in a skylight after all. Went to the city and we both looked up snow loads for the roof, 5'6 span, 16" OC, according to code it's fine. And so is a skylight. I doubled up the joists on either side of the skylight and double-headered above as well.

Original post was about insulation.... I used spray foam to fill the cavity. What a mess cleaning it up! I ended up using a 41/2" metal brush grinder to get rid of the um... 2" excess :whistling I don't think I'll bother with that again...
I also vented the rafters that could be vented - used 1/2" strips and tacked a peice of 1/8" hardboard to it to have some venting up through the roof. Note: spray foam insulation doesnt stick well to hardboard!

Here's a pic of the finished product below.


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## sbcontracting (Apr 22, 2010)

OH and regarding the insulation. They had MUCH bigger problems than a 2x4 space in the roof. The bathroom is a shed dormer, and the walls of the exterior bathroom under the windows were open to the roof! So essentially they had cold air blowing in under their floor from the roof. I sealed that up and insulated below the floor as well. You can see it in the pic above.


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## SAH (May 6, 2010)

Sprayfoam insulation is a skilled job. Those with experience will not have issues with overfoaming. If the hardboard is smooth, yes you're going to have problems with it sticking.

As for the excess, why did you use a brush grinder? All you needed was an old hand rip saw, cuts it nice n neat between the joists/studs.

Saw the other pics you posted on the final job. Looks good. Glad you verified the specs on the ceiling joists with the building dept.


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## sbcontracting (Apr 22, 2010)

SAH said:


> As for the excess, why did you use a brush grinder? All you needed was an old hand rip saw, cuts it nice n neat between the joists/studs.


I tried a handsaw. Didnt work well. It was closed cell foam, not sure if that makes a difference, but it was damn near impossible. Would have been tough slogging.

The grinder was suggested on this board actually. I tried a few solutions, that was the one that worked. Just generated a good amount of dust 

There are specialty tools out there which I didn't have the time or the money to buy.

But you're right - it is a specialty and I ain't good at it. Doubt I'll do it again. Just sub it out if required.



> Saw the other pics you posted on the final job. Looks good. Glad you verified the specs on the ceiling joists with the building dept.


Thanks!


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## Morning Wood (Jan 12, 2008)

Closed cell, open cell makes no difference. Hand saw, pull saw, hack saw blade should have gone right through it like butter. are you sure there wasn't anything wrong with your foam? I've never had an issue with cutting it. I can't imagine grinding foam. That must have been an f'ing nightmare. Still going to say should have put rigid on the underside of the rafters. Plenty of room for an inch of it. would have put you way ahead in the insulation department.


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## Old Truck (Apr 19, 2010)

*could have been me*

I priced out a bathroom reno that was similar to this although it was 8x10. Sloped ceiling ,coldest room on the main floor and they didn't want to spend the money on an exhast fan. Saw some mould up in one corner didn't really want to see what was behind the tub wall when it came out and there was black mould in he basement below the tub.After I gave them the quote they told me the previous owner had built the house himself, one example of his workmanship was the roof sheathing didn't join on a rafter they just butted together in midair. They told me to go ahead with the reno , but it fell through for health reasons for one of them.


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## sbcontracting (Apr 22, 2010)

Morning Wood said:


> Closed cell, open cell makes no difference. Hand saw, pull saw, hack saw blade should have gone right through it like butter. are you sure there wasn't anything wrong with your foam? I've never had an issue with cutting it. I can't imagine grinding foam. That must have been an f'ing nightmare. Still going to say should have put rigid on the underside of the rafters. Plenty of room for an inch of it. would have put you way ahead in the insulation department.


There actually wasn't any room for rigid foam. Not for headroom, but because of the shower door that was installed. The tub was 24" high, and the door was about 39" long by 50" high - and it just fit when extended, under the ceiling. It's a MAAX tri-folding door that's mounted to the wall.

Not sure if there was something wrong with the foam. It might not have been warm enough. The brush grinder was messy but an easy/effective way to get rid of the excess. I'd really think hard about doing it again.

They can't have it all, and in the end wanted big tub over insulation with cheesy L-shaped shower rod or custom glass (spensive)... so in the end the extra insulation drew the short straw.


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## sbcontracting (Apr 22, 2010)

Old Truck said:


> I priced out a bathroom reno that was similar to this although it was 8x10. Sloped ceiling ,coldest room on the main floor and they didn't want to spend the money on an exhast fan. Saw some mould up in one corner didn't really want to see what was behind the tub wall when it came out and there was black mould in he basement below the tub.After I gave them the quote they told me the previous owner had built the house himself, one example of his workmanship was the roof sheathing didn't join on a rafter they just butted together in midair. They told me to go ahead with the reno , but it fell through for health reasons for one of them.


Were the health issues caused by mould by any chance arty:


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