Here is what I am trying to resolve. Our bathroom is over an insulated crawl space, yet the bathroom is always colder than the rest of the house. The room is also far from the forced hot air furnace. The bottom of the tub is exposed to the cold in the crwal space and I am thinking that the tub is transfering the cold from the crawl space into the bathroom. Could this happen? Can the bottom of the tub be sprayed with foam to cut down on the cold? Or am I just way off base with the tub and need another solution to keep the bathroom warmer? Thanks, Hugh
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While it certainly won't hurt
While it certainly won't hurt to seal the tub (cast or acrylic?) from the cooler air of the crawl, you probably will have to do more to achieve the results you are after.
Close off the subfloor cut for the waste/drain would be one. Tempering the air flow to other 'warmer' rooms to hopefully boost your bath duct flow. Add an inline blower to bring more air to that duct when the blower motor comes on (use the blower to switch the inline fan on.
Sometimes something simple like undercutting the bath door just a bit more so the air return wants to "pull" more air while the furnace is running.
Thanks for the suggestions I am going to look into those fixes.
Hugh
Don't listen to the next
Don't listen to the next post.
He's Clueless.
Insulated crawl, yet you say the tub is exposed. Seems contradictory. If the tub is cast iron, you will have a HUGE thermal leak to your crawl which will contribute to the cold. A bathroom is filled with thermal problems due to all the plumbing. Insulate the floor ... but take care of air leakage first by caulking/foaming the penetrations of the floor/walls.
The other poster gave hints about the ducts and returns. Personally, I'd prefer a bathroom say 5++ deg warmer than the rest of the house. Being at the end of the run can be problematic. Particularly if you have no balancing dampers in the system (which generally isn't normal for residential anyway).
When we were building the house I shoved scraps of FG insulation inside the bodies of our tubs (the tubs are one-piece fiberglass units). It makes a huge difference in heat retention. The kids will play in the tub for up to an hour.
Another suggestion that might help is some under-tile heat.
If the bottom of the tub is exposed to the crawl you also have a bunch of air leaks into the bathroom. In addition to insulating the bottom of the tub (I think I'd enclose the bottom somehow and insulate with sheet foam), you need to seal all of the pipe penetrations so that cold air doesn't blow in around the faucet and control and showerhead. Also, you likely need to seal pipes feeding the sink, so that cold air doesn't blow up into the vanity.