Double checking clearances

[mattly1]

Hello everyone! I'll be installing my 3rd woodstove soon, but the first that will be in an alcove. I'd just like to double check the ceiling clearance for a Drolet 3000. The alcove height clearance is 74" in the manual, but it goes on to suggest that with a proper heat shield the ceiling clearance can be reduced 50%. My plan is to build a kind of drop ceiling into the alcove, using steel and cement board anywhere below 74", then to put a metal heat shield with spacers to be extra safe. I've attached a rough sketch to help illustrate. I'd appreciate input from you guys, thanks!

 

[EbS-P]

My math says you need a minimum stove to sheet metal shielded alcove ceiling of 22”. (74”-36(the stove height) times 50%.

This contradicts the table that says 18” minimum

https://www.drolet.ca/file/46109A_2022-10-11.pdf

 

[mattly1]

My math says you need a minimum stove to sheet metal shielded alcove ceiling of 22”. (74”-36(the stove height) times 50%.

This contradicts the table that says 18” minimum

https://www.drolet.ca/file/46109A_2022-10-11.pdf

View attachment 306458

Okay, either way I should be okay then since my 60" shielded opening gives me 24" of clearance to the top of the stove

 

[EbS-P]

My math says you need a minimum stove to sheet metal shielded alcove ceiling of 22”. (74”-36(the stove height) times 50%.

This contradicts the table that says 18” minimum

https://www.drolet.ca/file/46109A_2022-10-11.pdf

View attachment 306458

It does not say alcove ceiling clearance can’t be reduced by shielding. It’s worth an email to SBI to double check.

 

[begreen]

A stovepipe can not pass through a wall or ceiling, real or false.

Will the alcove ceiling be made completely non-combustible? (metal studs, cement board) If so, ask SBI if dropping it to 60" is permitted and clearances not applicable because it is non-combustible.

Otherwise, could there be no second, false ceiling and just a non-combustible, front wall extending down to 60"? It would be best to put a large grille on that front wall to vent trapped heat.

 

[mattly1]

It does not say alcove ceiling clearance can’t be reduced by shielding. It’s worth an email to SBI to double check.

I called them and after a long bit of conversation between techs they agreed that it was allowable to reduce alcove ceiling clearance. I'm still going to build with non-combustible material below 74" just to be safe.

 

[mattly1]

A stovepipe can not pass through a wall or ceiling, real or false.

Will the alcove ceiling be made completely non-combustible? (metal studs, cement board) If so, ask SBI if dropping it to 60" is permitted and clearances not applicable because it is non-combustible.

Otherwise, could there be no second, false ceiling and just a non-combustible, front wall extending down to 60"? It would be best to put a large grille on that front wall to vent trapped heat.

I'll use a ceiling box to transition to Class A at the false ceiling. The alcove ceiling will be steel and cement board, yes. I called them today and after a bit of discussion between technicians they agreed that it was allowable and per their manual would be okay with just shielding. I'm still going to go the non-combustible route with the drop ceiling and the enclosed space up to 74" just to be safe.

 

[EbS-P]

I'll use a ceiling box to transition to Class A at the false ceiling. The alcove ceiling will be steel and cement board, yes. I called them today and after a bit of discussion between technicians they agreed that it was allowable and per their manual would be okay with just shielding. I'm still going to go the non-combustible route with the drop ceiling and the enclosed space up to 74" just to be safe.

Try and do that with VC or Jotul. Not a chance. SBI customer service is great

 

[begreen]

I'll use a ceiling box to transition to Class A at the false ceiling. The alcove ceiling will be steel and cement board, yes. I called them today and after a bit of discussion between technicians they agreed that it was allowable and per their manual would be okay with just shielding. I'm still going to go the non-combustible route with the drop ceiling and the enclosed space up to 74" just to be safe.

It's great that you got a quick response. Be sure not to run stove pipe up past the drop ceiling or is that being eliminated now with the new ceiling height at 74"?

 

[mattly1]

It's great that you got a quick response. Be sure not to run stove pipe up past the drop ceiling or is that being eliminated now with the new ceiling height at 74"?

Yeah I am happy with their customer service so far, the Canadians seem to have a knack for that (I have a Woodland Mills sawmill as well and it's the same quality of service from Canada). My last message was a little confusing, there will still be a drop ceiling at 60" but made of non-combustibles inside and out up to at least 74". I'll transition to the Class A chimney pipe with a ceiling box at the 60" drop ceiling.

 

[begreen]

Yeah I am happy with their customer service so far, the Canadians seem to have a knack for that (I have a Woodland Mills sawmill as well and it's the same quality of service from Canada). My last message was a little confusing, there will still be a drop ceiling at 60" but made of non-combustibles inside and out up to at least 74". I'll transition to the Class A chimney pipe with a ceiling box at the 60" drop ceiling.

There should also be a firestop at the actual room ceiling height. What is above this room? Attic?

I would also be tempted to put a grille at the top of the alcove face to vent some extra heat into the room.

 

[mattly1]

There should also be a firestop at the actual room ceiling height. What is above this room? Attic?

I would also be tempted to put a grille at the top of the alcove face to vent some extra heat into the room.

Yes, attic space above. The room ceiling will be drywalled before the alcove is built, the only opening into the attic will be for the chimney pipe.

I thought about insulating the "drop ceiling" of the alcove with rockwool to keep the inside from becoming a heat trap, although a grille would probably still be beneficial.

 

[begreen]

Yes, attic space above. The room ceiling will be drywalled before the alcove is built, the only opening into the attic will be for the chimney pipe.

In this case, a firestop and attic insulation shield are required at the room ceiling (attic floor) level.

I thought about insulating the "drop ceiling" of the alcove with rockwool to keep the inside from becoming a heat trap, although a grille would probably still be beneficial.

Is there a room on the side or behind the alcove that might benefit from some extra heat? If so, the grille could be located in that area. For even better heat distribution, another grille down in the drop ceiling will improve convection.

 

[mattly1]

In this case, a firestop and attic insulation shield are required at the room ceiling (attic floor) level.

Is there a room on the side or behind the alcove that might benefit from some extra heat? If so, the grille could be located in that area. For even better heat distribution, another grille down in the drop ceiling will improve convection.

It's a conditioned attic so no insulation to worry about on the floor. The firestop here is just to stop the possible flue effect if a fire were to breakout, so it doesn't necessarily need to be anything besides the drywall closing the gap, correct?

The master bedroom is directly behind, so that is a definite possibility to put a grille in there. We'll also have a blower on the woodstove itself to help push the heat out of the alcove into the main living space.

 

[begreen]

Yes, the firestop is just a metal plate surrounding the chimney pipe. What brand of chimney is being used?

 

[begreen]

The master bedroom is directly behind, so that is a definite possibility to put a grille in there.

That might be a nice improvement. The grille should be large enough to support natural convection. Maybe 8x16?

 

[mattly1]

Yes, the firestop is just a metal plate surrounding the chimney pipe. What brand of chimney is being used?

Ah okay, to bridge the airspace required for clearances. It'll be Duravent.

 

[begreen]

Ah okay, to bridge the airspace required for clearances. It'll be Duravent.

For DuraTech chimney, their attic insulation shield 6DT-IS will work for this purpose. This is a firestop that also maintains the required 2" clearance from combustibles. The attic insulation shield is a good idea, even in a conditioned space. The collar on top prevents debris from falling alongside the chimney pipe, or boxes near it, and it keeps kids' little toys out too.

 

[mattly1]

For DuraTech chimney, their attic insulation shield 6DT-IS will work for this purpose. This is a firestop that also maintains the required 2" clearance from combustibles. The attic insulation shield is a good idea, even in a conditioned space. The collar on top prevents debris from falling alongside the chimney pipe, or boxes near it, and it keeps kids' little toys out too.

Perfect, thanks for your help, I appreciate it!