AC/Heat vent necessary in bathroom?

J Dougherty · 08-18-2011, 06:30 PM

We are redoing our bathroom and our contractor asked if we wanted to cap our AC/Heat vent. He told us it wasn't necessary, especially since we've opened up the space considerably. It is now capped and covered with the floor and we love it, especially since our front room seems to stay cooler now.

But is it necessary to have a vent in the bathroom (we live in NC). If we would like to sell the house one day, will we fail inspection now that it has been taken out?

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**Rick Cantrell** · 08-18-2011, 06:37 PM

There are no requirements to have an HVAC vent in a bathroom.
However it is good to have a vent in there.
Proper ventilation will not only keep the temperature at a comfortable level, but also reduce moisture, which causes mold and mildew.
Also when you go to sell your house most buyers will expect the bath to have an HVAC vent in it.

**Jerry Peck** · 08-18-2011, 06:55 PM

Something else to consider is "how" it was capped off and abandoned.

If not done correctly then the a/c may cause condensation on the underside of what is above it (the floor) which is your floor.

The heat may cause similar, but different, concerns.

J Dougherty · 08-18-2011, 08:04 PM

Originally Posted by Jerry Peck

Something else to consider is "how" it was capped off and abandoned.

If not done correctly then the a/c may cause condensation on the underside of what is above it (the floor) which is your floor.

The heat may cause similar, but different, concerns.

First, thanks, both, for getting back to me so quickly with great information.

Jerry, you bring up a really great point. Do you think the condensation could cause a problem through the floor which has 1/2" of (cement?) sub flooring over top what is originally there. Forgive me, I know very little about construction and the proper terms.

**Jerry Peck** · 08-18-2011, 08:13 PM

Originally Posted by J Dougherty

Jerry, you bring up a really great point. Do you think the condensation could cause a problem through the floor which has 1/2" of (cement?) sub flooring over top what is originally there. Forgive me, I know very little about construction and the proper terms.

It might long term.

The supply register opening should have been closed off with material and insulation suitable to match the type of ductwork supplying the supply register.

Properly sealing it off with ductboard (which is fiberglass insulation compressed to a rigid board material with a foil covering which acts as the air barrier, the fiberglass is just a thermal insulation barrier), taped and sealed with mastic and mesh tape to fully seal it off. Just one possible option.

If the floor were just laid over the supply register, especially if it was a/c, I can see potential long term problems. Concrete can draw moisture very long distances through capillary action.

**Eric Barker** · 08-19-2011, 05:12 AM

J - The only issue I take with that is when the bathroom has an outside wall. If surrounded by other rooms I am fine with it.

**Jerry Peck** · 08-19-2011, 05:06 PM

Originally Posted by J Dougherty

We are redoing our bathroom and our contractor asked if we wanted to cap our AC/Heat vent. He told us it wasn't necessary,

But is it necessary to have a vent in the bathroom (we live in NC).

Originally Posted by Eric Barker

J - The only issue I take with that is when the bathroom has an outside wall. If surrounded by other rooms I am fine with it.

Eric,

The key, though, is that the answer to his question "is it necessary" is "no", it is not "necessary" as in 'it is not required'.

It may, however, be 'necessary' to feel comfortable in that bathroom on a real hot or a real cold day.

So, I guess the answer is to ask him to define "necessary".

**John Kogel** · 08-22-2011, 12:20 PM

Hopefully the duct was capped back at the trunk. If the bathroom needs heat, you will find that out this winter. Or do you even have a winter down there?

The best heat for a bathroom up in my climate is dry heat - electric. It may not be needed, but dry heat helps to keep the walls dry and the room comfortable. You could have a wall-mounted fan heater installed if you need heat. There is a kickpanel electric heater that mounts in the bottom of the vanity, another choice that works good.

**Benjamin Thompson** · 08-22-2011, 08:43 PM

You mean like this?

P9200024.jpg
Doesn't a room need a register if it's over a certain size?

**Bruce Ramsey** · 08-23-2011, 06:27 AM

IRC only requires supplied heat to living space. Bathrooms are excluded from the definition of living space so are not required by code to be heated regardless of the size.

Comfort is an entirely different matter. The bathroom maybe be too cool or hot without a supply register depending on a number of factors including size, number of exterior walls, etc.