Car fumes in the coach house
hull187
| Posted in General Questions on
Hey there – I have a design question. My company is renovating a detached coach house which will have 2 cars parked on the main floor and a living space above. It will have radiant heating in the main floor slab, which will be the coach house’s only heat source. Any suggestions on how to air seal the main floor “garage” area from the living space but still allow heat to transfer up? Is there a spray foam with no R value that still air seals?
Cheers,
Steve
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Search and download construction details
Replies
Dan - this is no different than having an attached garage. It may not be a great idea, but it is pretty damn common. I'm trying to find a safe(r) way of doing it.
This is so unlikely to be a good arrangement in any way whatsoever. Radiant heating is just that - if you're not in the direct range of the radiant surface in the garage floor you will get zero heating effect in a totally separate room above. Insulate and airseal the floor above the garage. Put a minisplit in the living area. Done.
Steve,
If you're going to heat the garage, you'll obviously have a problem air-sealing the garage doors, as Dan correctly pointed out.
You'll need to do a very careful job air sealing the garage ceiling. I would insist on a blower door test, using a theatrical fog machine, to test the integrity of the barrier between the two spaces.
And once the house is occupied and the garage is in use, I would install an exhaust fan in the garage that turns on every time the garage door is opened. The fan control should keep the fan running for at least 15 minutes after the garage door closes.
Finally, James is right. You don't want to heat the second floor with a radiant-floor loop installed in a leaky garage. You want to install a heating system for the second floor that is independent of the garage heating system. And if you insist on heating the garage, please keep the thermostat at 40 degrees F, unless you are actively working on your vehicles.
Steve - no, it's absolutely not like having an attached garage. It's more like parking your car in your living room. How many attached garages have you been in where the garage slab is the heat source for the rest of the building?
And while we're at it, how are you going to insulate the toe of the slab? Otherwise you're heating the driveway too.
This sounds like a terrible idea on so many levels. For starters - how are you going to make garage doors that do even a half-way decent job air sealing?
As you've implied, there is a rather dangerous trade-off between retaining heat and killing the occupants. Hope you get it right.