Getting our bathrooms remodeled at the moment. The ventilation for heat and a/c will now go under the vanity cabinets (it was via floor vents before).

My builder has basically left a hole in the floor with the ductwork around it -- which the new vanity cabinets will then sit on top of. There will be a finished vent in the toekick of each vanity cabinet, but no ductwork inside the cabinet. The holes for the hvac are in the floor near the wall, so there would be this big open space the air would travel through to get out.

The builder said the air will have nowhere to go in the vanity cabinet, so it will be forced out the vent that's in the toekick at the front of the cabinet (there is a floor in the bottom of the cabinet). The cabinet space is about 3'x3' underneath. My concern is that this is not efficient and more importantly, not standard practice. It seems like there should be some hose or duct that leads the air OUT from the floor TO the front of the cabinet and out the vent...just like any other vent in a finished wall or floor. Or am I mistaken? How do builders/remodelers usually do this?

I'm afraid we'll lose our heat out through the wall (two of which are outside-facing walls), or we'll just be mostly heating and cooling the cabinets. And cold air falls, so the bathrooms won't be cool in summer.

Thanks for any input!

I've seen that done before. You won't lose heat or cooling as it will only go out the toe kick.

Alternatively your heating contractor can make a boot that sits on the floor under the cabinet if you think that would be more efficient.

Either way heating and cooling a bathroom is optional.

I wouldn't worry unless you're not getting what you are paying for.

They are using the cabinet base as ductwork.

Worst case I've seen is the metal ductwork not being fastened to the floor (or wall if that's the case).

Advantage to floor vent - crap doesn't have to get fished back out.


I have a radiator and fan under a split level bathroom floor ( same concept as the vanity space) .

Dis advantage is having to remove the vanity to get at it ( or if it is installed "wrong" like mine having to remove a box from the basement joists.

Allows me to have a separate zone and thermostat for the bathroom, though.

Mine is an 'under-vanity ' radiator .
Fan is fairly quiet.

I have the same setup in my kitchen. It works OK. A bit weird (to me) but it works.

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Plumbking
I've seen that done before. You won't lose heat or cooling as it will only go out the toe kick.

Alternatively your heating contractor can make a boot that sits on the floor under the cabinet if you think that would be more efficient.

Either way heating and cooling a bathroom is optional.

I wouldn't worry unless you're not getting what you are paying for.

Thanks for the input, all.

My big concern is that in the master, there is about a half-inch or so of gap where the subfloor meets the wall -- on three walls. You can see the basement underneath that, so not only are we potentially losing air to the two outside walls, we're losing it to the basement on 3 walls. And the cutout for this "vent" is in the corner right where the two outside walls meet.

Also, I've had the vents closed in these bathrooms before in winter and "optional" is not a word my wife enjoys hearing when it comes to that! (We get VERY cold winters here...20s down to zero are frequent.)

He could easily build a wooden duct and fasten it in place before putting in the vanity. I believe you would
get better flow that way. If it's being blown through a cabinet I see no reason it couldn't be blown through
a wooden duct. Is this job being inspected?

BTW: We've gone 4 weeks now without a Kitchen and man does that suck. I'd say it's half way there.
Sheetrock in and mudded, now the beaded board ceiling is going in. Next is $10K worth of cabinets.
We have yet to pick out our countertops.

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Grateful11




Edited 1 time(s). Last edit at 09/07/2010 04:26PM by Grateful11.

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SteveO
(We get VERY cold winters here...20s down to zero are frequent.)

Get a quote on heated floors, just for the bathroom (electric pads that go under the tile). Once you walk on one barefoot you'll never want to walk on a "regular" floor again.

Not sure if it's being inspected or not, I think not since no permit was pulled. Good idea on the heated floors, Plumbking. I will check that out. Is this costly? The bathrooms are not very big; they are each about 10-15 sq ft of open flooring area.

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Grateful11

BTW: We've gone 4 weeks now without a Kitchen and man does that suck. I'd say it's half way there.
Sheetrock in and mudded, now the beaded board ceiling is going in. Next is $10K worth of cabinets.
We have yet to pick out our countertops.

That's why I got a house with 2 full bathrooms and 2 full kitchens. I hate being inconvenienced.

You made the following statements in your two posts:

"The builder said the air will have nowhere to go in the vanity cabinet..."

"My big concern is that in the master, there is about a half-inch or so of gap where the subfloor meets the wall -- on three walls."

These are contradictory. And unless the duct from underneath is sealed to the subfloor, the airflow will create enough pressure under the cabinet to force air back around the ductwork.

I have the same concern as you: Loosing heat in the winter and cooling in the summer.

Building a duct under the cabinet takes time and labor, which your contractor seems reluctant to provide. What other parts of the job is he skimping on? Are you paying just to have the job done, or to have the job done properly?

If you don't want air loss through those gaps, fill them in.

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Ed (modelamac)

I think I will just put an OUT OF ORDER
sticker on my head and call it a day.

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SteveO
Not sure if it's being inspected or not, I think not since no permit was pulled. Good idea on the heated floors, Plumbking. I will check that out. Is this costly? The bathrooms are not very big; they are each about 10-15 sq ft of open flooring area.

My GC friend recommends SunTouch floor warming available at Home Depot [www.homedepot.com]

As far as permits go you should insist on it. Pull it yourself and man the inspections if necessary (even your wife can if you can't). The process is there to protect you the homeowner.

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SteveO
My concern is that this is not efficient and more importantly, not standard practice.

It may not be super efficient, but it works - and it is standard practice amongst most builders.

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SteveO
My big concern is that in the master, there is about a half-inch or so of gap where the subfloor meets the wall -- on three walls. You can see the basement underneath that, so not only are we potentially losing air to the two outside walls, we're losing it to the basement on 3 walls. And the cutout for this "vent" is in the corner right where the two outside walls meet.

Forget the heat loss - this is a huge fire spread risk and would not be allowed in my state.

"Forget the heat loss - this is a huge fire spread risk and would not be allowed in my state."

BINGO !

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Definitely go with the floor heating mesh. Inexpensive and oh so wonderful to walk on compared to an unheated tile floor.

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"In science it often happens that scientists say, 'You know that's a really good argument; my position is mistaken,' and then they would actually change their minds and you never hear that old view from them again. They really do it. It doesn't happen as often as it should, because scientists are human and change is sometimes painful. But it happens every day. I cannot recall the last time something like that happened in politics or religion." (1987) -- Carl Sagan

The fire risk with the subfloor has already been mentioned.

The issue that I have with using the vanity as ductwork is the exposure to the vanity. Most are made from plywood. Running hot, moist air along the underside creates an environmental difference between the top and bottom sides of the vanity bottom. This could lead to failure (separation of glued veneers, etc.) or warping of the vanity bottom and would not be covered by the manufacturer's warranty. Take a look at installation guidelines for engineered wood I-beams. They specifically state that they are not to be used to create ductwork as was done years ago with true dimensional lumber.

The ductwork to do this properly would only cost a few dollars and would be cheaper than the time to construct something out of wood.

I would definitely pull permits if the contractor didn't. It protects you and you might have to do it after the fact when you go to sell, especially if your jurisdiction requires an occupancy inspection prior to settlement.

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lafinfil
"Forget the heat loss - this is a huge fire spread risk and would not be allowed in my state."

BINGO !

Tell me more, please...what is the risk..because there's a gap in the subfloor?

UPDATE: Okay, no worries, I emailed the contractor last night and he went out and grabbed the proper metal ductwork. All good.