Using OSB for wall surface around furnace and hot water tank - DIY Chatroom

kandony · 07-02-2009, 01:28 PM

Hope I posted this in the right forum.

I had some extra OSB so I nailed it up around my furnace and hot water tank. Basically as some sort of wall instead of having bare studs showing. I've heard that this is not a good idea and I should cover it in drywall as a better fire stop just in case a fire starts in that area. Even heard rumors that if a fire did start that some insurance companies would deny coverage just because of this OSB.

Anyone know if this is true, if OSB is not to be used in such a way, breaks some major code, is a fire hazard, etc?

Thanks so much.

Kenny D

adpanko · 07-02-2009, 03:14 PM

I don't know about OSB vs drywall in terms of fire code issues (presumably drywall is more fire resistant though), but I know you can't build walls too close to your furnace and can't close it in completely. I believe there are space requirements around the furnace, especially with regards to combustible materials. And the furnace needs ample air around it to make and keep the flame. You can't build a small room around it use a solid door, because there wouldn't be enough airflow to the furnace. You'd have to use a louvre door, or cut holes in a solid door, to let air in. But I honestly don't know the specifics about space, airflow, or materials requirements. You should call your town and see what the inspector says to be safe. You don't want to void your homeowners insurance if you do something wrong and your house burns down.

**Scuba_Dave** · 07-02-2009, 03:54 PM

How far away from the furnace is the OSB ?
What type of water heater?
OSB is not on the ceiling above the furnace?
Mine has 5/8" sheetrock above the furnace

kandony · 07-02-2009, 04:16 PM

Wow - Thanks for the quick replies.

My furnace is a new 95% efficiency Carrier model.

The osb is only on the walls behind the furnace - about 6 inches away from the furnace and higher up 3 inches away from the main output ducting. Its about 9 inches away from the water heater.

The cieling is just open joists right now which is being spray foamed in about a week.

The water heater is a 50 gallon - 3 year old one from home depot.

I have only put the osb behind the furnace and on one side wall. The front of the room is made up of 3 - 24" closet doors and the other side is drywall. I was told the new high efficiency furnaces don't need as much room air as the mid efficiencies due to the 2" inch intake and output pipes they put out the side of the house - for condensation and air. (I think this last part of my post is starting to wonder into the hvac forum)

Daniel Holzman · 07-02-2009, 04:17 PM

My boiler has type X (fire resistant) sheet rock above the boiler attached to the floor joists. The walls are bare concrete in the basement, can't get much more fire resistant than that. I think there are pretty specific codes about fire resistant material near furnaces and boilers, makes sense when you think about, after all they are hot, and it is always possible for oil or gas to leak and catch fire outside the firebox.

GBR in WA · 07-02-2009, 08:43 PM

Look inside the removable door to the unit. The wall clearances will be listed there. Keep at least 6" to any flues, and seal the ceiling/attic penetration with sheet metal. Code requires a minimum on the sides and in front of the appliance. The doors need to be louvered for the H.W.T. if it is gas. OR.... you need two, a high and low, air supply's to the room. These cannot be in a bedroom closet.
The osb will eventually dry out and very possibly catch fire. I strongly urge you to remove it. Be safe, G

Ron6519 · 07-02-2009, 08:58 PM

Quote:

Originally Posted by kandony

Wow - Thanks for the quick replies.

My furnace is a new 95% efficiency Carrier model.

The osb is only on the walls behind the furnace - about 6 inches away from the furnace and higher up 3 inches away from the main output ducting. Its about 9 inches away from the water heater.

The cieling is just open joists right now which is being spray foamed in about a week.

The water heater is a 50 gallon - 3 year old one from home depot.

I have only put the osb behind the furnace and on one side wall. The front of the room is made up of 3 - 24" closet doors and the other side is drywall. I was told the new high efficiency furnaces don't need as much room air as the mid efficiencies due to the 2" inch intake and output pipes they put out the side of the house - for condensation and air. (I think this last part of my post is starting to wonder into the hvac forum)

OSB is totally inappropriate in this application. OSB is little chips of wood.
Wood burns. And when wood burns, thing in proximity to that wood burns.
That would be the house.
I hope you have a plan ,"B" or a lot of fire extinguishers at hand.
Ron

kandony · 07-02-2009, 09:38 PM

Yeah Plan B is to remove it and put in drywall. It was a pain orignally to put in but hey its less of a pain to remove it than burn my house down.

I didn't think anything about the OSB and fire when putting it in. But to be on the safe side I'll rip it all out and put something less flamable!

Cheers all - off to do some demolishing!