Mounting a wiring panel on a chimney

[Dennis Brothers]

I need to place a wiring panel (2' X 4' 3/4" plywood) for mounting some 110 blocks, a couple of multi-zone communicating HVAC controllers, 24V transformers, a network switch, and who knows what else. The best place to mount it, from the standpoint of convenience and proximity to related stuff, is on the back of a fireplace in my basement.

The fireplace/chimney structure is about eight feet wide and three feet deep. Two gas boilers and a gas hotwater heater vent into a flue or flues on the right-hand side; the left-hand side has (on the opposite face) a fireplace (in a basement playroom). We never use this fireplace; we do occasionally use a living room fireplace which is directly above the basement one.

My thought is to attach two furring strips to the brickwork with small lag screws and lead shields and construction adhesive, then mount the plywood panel to the furring strips, thus leaving an air gap. Does this sound reasonable? What are the code implications, if any?

Thanks for any insight - - Dennis Brothers

[ameijers]

If the fireplace stack in the basement is brick, rather than block, I take it this is an older house? What you propose will probably work fine, but I'd probably take the non-invasive route. Build a 2-stud wall set back from the brickwork a couple of inches, tied into the joists above, and tied to spacer blocks or bricks between the studs and the brick at the bottom. Probably be plenty solid as is, but you could always adhesive the spacer blocks to the floor, and glue or nail the studs to them. Basically like a 2-post 19" rack, just made out of wood. Or, you could just get a commercial rack, if there is a used hardware place in your town.

aem sends...

[Dennis Brothers]

Exellent suggestion. Oddly enough, I've considered exactly that. Couple of problems - there's ancient ductwork up there that I'd have to remove to fasten 2X4s to the joists (the house was originally forced hot air). I've already removed all the "easy" ductwork (got _way_ more headroom in the basement now), but this particular bit will be difficult (things like conduit from the boilers fastened to it). It's doable, but I'd prefer not to have to. Secondarily (and relatively minor), there's a lot of wiring and piping running along the chimney just below the adjacent joists, and having a couple of 2X4s there will make any further modifications or improvements more difficult.

Fastening the panel to the chimney is by far the most "elegant" solution; as a practical matter that face will never get hot enough to be an issue (even if we do have a fire in the playroom fireplace); and there's wood in contact with the chimney/fireplace stack elsewhere. I'm just concerned about getting "busted" by an over-zealous building inspecter - is this really an issue?

BTW, yes it is brick. That's why I'm thinking _small_ lag screws plus construction adhesive.

- Dennis Brothers

[Bill]

From what I have read, you need to have a 2" air gap between a chimney and wood framing. So I would assume that would include a 2" air gap to any combustible material. And I would certainly not be drilling any holes in the chimney.

"Most codes require a 2" air space around the chimney"...

[Dennis Brothers]

Thanks for the link - interesting reading. As a practical matter, what I'm thinking of is probably safe, because the panel would be below the level of the actual fireplace flue, and there's over a foot of brick and mortar between the fireplace cavity and the surface I want to mount the panel on. But, as the article points out, the code doesn't take factors like that into consideration.

Time for Plan B.

- Dennis Brothers