Thread: Mechanical Room in Garage

Just got back from inspecting a home built in 2006. The garage is on the lower level and has all of the appropriate fire rated drywall, steel doors etc to the adjacent family room and the bedrooms above which I usually don't see. In the garage is a mechanical room with the gas water heater and the gas furnace. It is separated from the garage by a 2x4 framed wall with fire rated drywall on one side only (towards the garage). THe mech room has no ceiling drywall. The door from the garage to the mechanical room is hollow core Masonite. There is no door or opening from the mechanical room to the living areas of the house.

Should the mechanical room be separated from the garage by the same fire rated barriers as to the living areas of the house?

Is the Masonite door acceptable separation of the room from the garage? If it were not there then the water heater and furnace would have to be 18" above the floor. It certainly provides minimal fire protection and no barrier to spilled flammable liquids.

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As long as the separation wall (which is not fire-rated wall) goes around behind the mechanical room, the mechanical room could actually be open to the garage (no door needed in the doorway).

You description did not address the wall between the mechanical room and the house, was it open studs as well (a no-no) or did it have drywall on it?

Jerry: The wall between the mechanical room and the house is drywalled on the living area side but not on the mechanical room side.

Are you saying that the water heater and furnace would not have to be 18" above the garage floor if there is just an opening, no door, between the mechanical room and the garage?

Originally Posted by Bob Hunt

Jerry: The wall between the mechanical room and the house is drywalled on the living area side but not on the mechanical room side.

There needs to be at least one wall which meets the separate requirements between the house and the garage.

If that wall was between the mechanical closet and the garage, then the mechanical closet could be open to the garage.

If the wall between the mechanical closet and the garage is open on one side, then the wall around the mechanical closet and the garage would need to meet the requirements AND the door to the mechanical closet would need to meet the door requirements.

Are you saying that the water heater and furnace would not have to be 18" above the garage floor if there is just an opening, no door, between the mechanical room and the garage?

Nope.

If the wall between the mechanical closet and the garage is open on one side, then the wall around the mechanical closet and the garage would need to meet the requirements AND the door to the mechanical closet would need to meet the door requirements.

Jerry: This was what the I thought the situation should be. I guess that I did not describe it very well

I don't agree, You are saying that an opening directly from the garage into the mech room is allowed? Gas fumes can enter through that opening correct? and if the combustion unit is below 18" "boom"
Or is it a loophole in the code. If you are not separating the combustion units from the garage, they must be above 18"

Originally Posted by wayne soper

I don't agree, You are saying that an opening directly from the garage into the mech room is allowed? Gas fumes can enter through that opening correct? and if the combustion unit is below 18" "boom"
Or is it a loophole in the code. If you are not separating the combustion units from the garage, they must be above 18"

Wayne,

I'm trying to figure out what you are replying to.

If my post, I said no to the water heater NOT being 18" above the garage floor (actually 'the ignition point', but we commonly just say 'the water heater', is what must be 18" up).

If not my post, ... I am lost and have no idea what you are asking?

Jerry, what I was trying to say is that unless you separate the combustion units from the garage in a closed room with fire door, they must be at least 18" above the floor. The mech room would also have to have it's own exterior air supply, oh yeah, and BOOM

Originally Posted by wayne soper

Jerry, what I was trying to say is that unless you separate the combustion units from the garage in a closed room with fire door,

Huh? No "fire door" required.

I wish HIs would get off that "fire door" and "fire-rated door" mis-direction ... that is not a requirement.

they must be at least 18" above the floor.

It does not matter what kind of door is separating that mechanical room from the garage, the water heater would STILL need to be raised to 18" because the mechanical room is NOT PART OF the living space and it COMMUNICATED DIRECTLY to the garage through that door - and is thus still considered as part of the garage.

The mech room would also have to have it's own exterior air supply, oh yeah, and BOOM

Huh? The mechanical room could get combustion air from the garage with no problems.

Please explain that part.

They way I get folks to understand the 18" rule is fairly simplistic, I think!

I use the following:

Think of where you might be able to place a gas can in the garage or storage room. If you can place that can in the garage or storage room, then you need to have the mechanical equipment raised 18" or more above the floor.

When you think about the gas can and the location you might keep one, it makes sense as to where you need to follow the 18" rule.

Originally Posted by Scott Patterson

They way I get folks to understand the 18" rule is fairly simplistic, I think!

I use the following:

Think of where you might be able to place a gas can in the garage or storage room. If you can place that can in the garage or storage room, then you need to have the mechanical equipment raised 18" or more above the floor.

When you think about the gas can and the location you might keep one, it makes sense as to where you need to follow the 18" rule.

Every time you pull your car, motorcycle, lawn mower, etc., into the garage you ARE placing that gas can in your garage.

That reasoning "Think of where you might be able to place a gas can in the garage or storage room." is possibly behind the code requirement that if a storage room, mechanical room, etc., opens to the living space there is no problem, yet if that same room opens to the garage then the ignition source needs to be raised.

If that storage room, mechanical room, etc., opens to the house it is unlikely you will store gas in it, but if it opens to the garage you may.

However, that is not fully behind the code requirement (I did say "possibly") as in that storage room, mechanical room, etc., the ignition source only needs to be raised 18" above the GARAGE floor, not the storage room, mechanical room, etc., floor.

Of course, though, if the storage room floor is raised up higher than the garage floor, then the vapors can spill out and DOWN TO the garage floor, reducing any problem in that storage room.

re: the 18" - M1307.3 Elevation of ignition source. Appliances having an ignition source shall be elevated such that the source of ignition is not less than 18 inches above the floor in garages. For the purpose of this section, rooms or spaces that are not part of the living space of a dwelling unit and that communicate with a private garage through openings shall be considered to be part of the garage.

from the 2003 IRC Commentary [the only one I have on disk]: An appliance installed in a closet or room that is accessible only from the garage must be considered as part of the garage for application of this section. Even though the room may be separated from the garage by walls and a door, there are no practical means of making the door vapor-tight nor is there any assurance the door will remain closed during normal use. An appliance room that is accessed only from the outdoors of from the living space would not be considered as part of the garage. Rooms such as utility rooms or laundry rooms that communicate both with the garage and the living space are considered as part of the living space and not part of the garage.

So then, am I correct in seeing this as two distinctly different discussions?

One pertaining to the storage of flammable fluids and the need to have ignition sources elevated 18" or more above the garage floor. In this case the mechanical room, as it's described, has to be considered as part of the garage, and the appliances located in it need to be elevated to meet the 18" minimum requirement.

The second discussion is about the requirement for a firewall and fire resistant door(s) separating the garage from the living areas of the house. If I'm interpreting this correctly, as far as this second requirement is concerned, the mechanical room could be considered to be separate from the garage (and part of the living area) as long as there is a firewall and appropriate door in place between them.

If that is indeed true, it has already been stated that there is a firewall between the garage and the mechanical room, but the door is not fire rated. Installing a proper fire rated door would therefore be the least costly way to bring this second discussion into compliance. The only other alternative would be to extend the firewall (including the ceiling) to include the mechanical room as part of the garage, and I don't see the need to do that.

Originally Posted by Michael Chambers

So then, am I correct in seeing this as two distinctly different discussions?

Yes.

[If that is indeed true, it has already been stated that there is a firewall between the garage and the mechanical room, but the door is not fire rated.[/quote]

Actually, it was stated just the opposite - the the wall between the garage and the mechanical room DOES NOT meet the requirements for a separation wall, and that the wall between the mechanical room and the living space DOES NOT meet those requirements either.

Therefore the door has no effect on the discussion, not until the separation wall is defined and constructed to meet the requirements for the separation wall, and then the door STILL will not matter with regard to the 18" elevation of the ignition source (the door only matter with regard to the separation wall).

Yes, 2 separate issues: the garage/living space separation AND raising the ignition source 18" above the garage floor level.
Garage/living space separation, horizontal and vertical: Here in NY we require a 3/4 hour fire-resistance rating [not a "firewall"], same on the door which must be self-closing.
IF there is an ignition source in the garage, even if it's in it's own room with a door, consider it to be IN the garage and raise it 18". Remember, there are 2 conditions for the 18" rise, and BOTH must be present- the ignition source is in a space that communicates with the garage AND the space is not part of the living space of the dwelling unit.
Just to complicate things a bit more [sorry] a few other things to keep in mind: there are no requirements to enclose equipment but there are "clearance to combustibles" and prohibited locations; don't forget impact protection on equipment in the garage; and these are not retroactive requirements- you need to apply the code in effect when the house was constructed or when alterations were made.