Non combustible 2x4 replacement? Chimney install

[hack]

Not sure if this is in the right place, but is there lumber replacement product that is non combustable that you can use in the vicinity of the chimney?

Looking at installing an 8" Selkirk class a at my parents house and I would like to make the ceiling support box out of a synthetic non combustable material for piece of mind.

 

[mellow]

You could get steel studs from Home Depot, but why not buy the premade support box?

 

[oconnor]

Not sure that the steel studs are intended for horizontal use. I'd just use the Selkirk support box, it's designed and tested to be safe.

 

[hack]

Sorry about the terminology, but I need to build a box that the ceiling support fastens to. This box will be the closest combustable at 2 inches. I know that is per spec but if it were metal or synthetic, the next closest combustable is over 6 inches.

Thanks

 

[arbutus]

Steel angle iron frame. A local welding shop can fabricate it for you if you have a good sketch.

 

[Highbeam]

The ceiling support box is supposed to be screwed to wood. That is why the dimensions of the box provide the required clearance. You are trying to go above and beyond which is fine but other readers should know that the box is designed to mount directly to combustibles. Tested, approved, safe.

Structural and non-combustible means either concrete or metal so as arbutus said, see a fab shop.

 

[DougA]

Steel studs are also made for ceiling use. They are slightly different than steel wall studs and will work just fine. Remember that you cannot put normal drywall on them as drywall is a combustible.

 

[begreen]

Sorry about the terminology, but I need to build a box that the ceiling support fastens to. This box will be the closest combustable at 2 inches. I know that is per spec but if it were metal or synthetic, the next closest combustable is over 6 inches.

Thanks

If you use the manufacturer's support box it will be all metal and is designed to keep the required clearances from wood. You can frame it in with wood studs without worry.

Provide us more details and pics if possible and we can review your plan.

 

[hack]

The ceiling support box is supposed to be screwed to wood. That is why the dimensions of the box provide the required clearance. You are trying to go above and beyond which is fine but other readers should know that the box is designed to mount directly to combustibles. Tested, approved, safe.

Structural and non-combustible means either concrete or metal so as arbutus said, see a fab shop.

Correct, 2" meets specs and I can use regular lumber to achieve this.

 

[hack]

If you use the manufacturer's support box it will be all metal and is designed to keep the required clearances from wood. You can frame it in with wood studs without worry.

Provide us more details and pics if possible and we can review your plan.

Here are the components that support the selkirk class A. I know I don't need to and probably can't, but If I use a noncombustible structure to create the box that the ceiling support attaches to (the round item with 4 tabs) it will be extra safe. I know I'm grasping at straws and will probably just use lumber as that is what I did with my own install.

Thanks

 

[cableman]

Frame the support box bigger and fill it in with durarock. 2" bigger will give you 4" clearance.

 

[oconnor]

Your assumption that it will be extra safe is based on your solution being as structurally sound as the solution Selkirk tested. It can be done, but it depends on your skill and aptitude. There are likely other areas in the install were you can gain better safety for the work involved.

 

[hack]

Your assumption that it will be extra safe is based on your solution being as structurally sound as the solution Selkirk tested. It can be done, but it depends on your skill and aptitude. There are likely other areas in the install were you can gain better safety for the work involved.

Point taken. Not trying to get creative. Just thought I'd ask the question in case there is an easy solution/product. In my case, this is the only wood/combustable that would be close to the chimney. I realize this would need to bear the full load of the chimney.

 

[Highbeam]

Frame the support box bigger and fill it in with durarock. 2" bigger will give you 4" clearance.

This is scary, I worry that the whole dang thing could fall down. The screws would have to run through 2" of durock before biting into lumber. The load of the chimney will be able to bend/twist/pivot the screws. Normally, the screws bite into wood immediately outside of the metal box and the screws are in shear. Much stronger.

 

[begreen]

Here are the components that support the selkirk class A. I know I don't need to and probably can't, but If I use a noncombustible structure to create the box that the ceiling support attaches to (the round item with 4 tabs) it will be extra safe. I know I'm grasping at straws and will probably just use lumber as that is what I did with my own install.

Thanks

This is the same setup that we have. It is designed and tested for fire safety. Just follow directions and ask questions when unsure. The system is designed to be very safe as long as installation follows the book. The main thing you can do to keep things safe is to honor or exceed clearances all the way, don't cut corners, and vacuum clean everything before installing the insulation shield and pipe.

 

[hack]

This is the same setup that we have. It is designed and tested for fire safety. Just follow directions and ask questions when unsure. The system is designed to be very safe as long as installation follows the book. The main thing you can do to keep things safe is to honor or exceed clearances all the way, don't cut corners, and vacuum clean everything before installing the insulation shield and pipe.

Thanks for the input. I'll go ahead and install per instructions like I did with previous install. At least I now know there isn't a synthetic wood substitute that the pros use.

 

[begreen]

Our support box is screwed to 2x4" framing. Tip: use long decking screws to screw the 2x4 braces in place instead of nails. You are less likely to pop sheet rock nails that way or to crack it.

 

[Highbeam]

Tip: use long decking screws to screw the 2x4 braces in place instead of nails. You are less likely to pop sheet rock nails that way or to crack it.

This is weight bearing structure. If you are using engineered brackets to hold the framing lumber you need to use what is specified which is usually nails but sometimes they allow a special screw. The old days of just popping nails into existing framing are gone. You can see in my photo, I used simpson structural hangers. Mine was inspected and I sure don't want the ceiling to fall down.

 

[begreen]

I am referring to existing ceilings, not new construction. FWIW, ours was inspected too. Not that he gave it any more than a casual glance.

 

[cableman]

This is scary, I worry that the whole dang thing could fall down. The screws would have to run through 2" of durock before biting into lumber. The load of the chimney will be able to bend/twist/pivot the screws. Normally, the screws bite into wood immediately outside of the metal box and the screws are in shear. Much stronger.

Well if i was to do it i would go 1" on each side and use some lags which would be overkill but it would extend the clearances! I bet 4" screws 3 on each side would hold no problem!
How many lengths are we talking here?

 

[Highbeam]

I am referring to existing ceilings, not new construction. FWIW, ours was inspected too. Not that he gave it any more than a casual glance.

Existing ceilings are not exempt from proper structural requirements. You're supposed to use the hangers and the hangers work fine with existing ceilings as well. Maybe another topic eh?

I agree that the inspectors aren't very thorough. Often, a good DIY guy will be vastly more knowledgable.

 

[begreen]

Key word being "structural". This is not.