hearth construction plans concurrence

[fran35]

Hoping for some feedback from the community.

I am finishing up my sunroom and need to rough in my hearth area in order to finish the surround walls. I have attached a few photos of the area for your reference. I plan on putting insulation in the 2x4 wall shown. It is a non load bearing wall, second floor sitting on 2x6 walls, 16 oc and 2x12 joist, 16 OC. The hearth is outer corner of room. I plan to throw sheetrock over the insulation for air sealing purposes before I throw up my 1.5 inch air space and then concrete boards. Over the concrete boards I will attach stone veneer (concrete type). The stone veneer will run about 4.5 feet up, followed by mantel and then drywall above. The air gap cement board will be fastened to the studs with strips of .5 inch concrete boards, with air gap at top and bottom of cement board to allow constant air flow. The veneered and air gapped wall will have cement board strips or stones underneath to support the wall and maintain the bottom air vent. I feel that I am confident in my interpretation of nfpa wall construction, but am wondering if the wall can support the veneered hearth wall. The studs are closer than 16 oc and I think the load will be on the joists below, which rest on one side concrete block wall and the other the aforementioned 2x6 16 oc half wall (it's 4 foot of block, 4 foot of studs) I think the floor support is easily enough, but just want confirmation on the outside pictured wall and Stone veneer. See pics below:

 

[fran35]

A few more photos of the room and hearth area

 

[fran35]

If anyone has any input at all, I would be most appreciative. Is this better served being in a different section? BeGreen, I would really value your opinion. Thanks!

 

[begreen]

I see nothing wrong with the plan from a safety standpoint. Only 1" gap is needed behind the shield. It is very effective with just one inch space. I'm not sure about how much weight the veneer wall can carry, that is determined by the sheer strength of the screws. With a screw every 8" it should be pretty high. I think you will probably be fine, but ask a mason to be sure.

 

[HeavyMetalHippy]

Why not just attach cement board right to the studs then your rock veneer to the cement board, clearance issues with stove, just being safe?
Durarock is 1/2" and with 1/2" sheetrock it makes a nice transition. Then you just lay that stone covering the seams. Finishes nicely.

 

[fran35]

I see nothing wrong with the plan from a safety standpoint. Only 1" gap is needed behind the shield. It is very effective with just one inch space. I'm not sure about how much weight the veneer wall can carry, that is determined by the sheer strength of the screws. With a screw every 8" it should be pretty high. I think you will probably be fine, but ask a mason to be sure.

Thanks, I tend to overengineer as well as over analyze. I appreciate the input.

 

[fran35]

Tha

Why not just attach cement board right to the studs then your rock veneer to the cement board, clearance issues with stove, just being safe?
Durarock is 1/2" and with 1/2" sheetrock it makes a nice transition. Then you just lay that stone covering the seams. Finishes nicely.

Thanks for input. I wanted the 1 inch air gap just to reduce clearances. My stove is rated down to 3 inches clearance from combustibles when a rear heat shield is used in conjuction with the 1 inch air space. I do not plan to go anywhere close to 3 inches, but will probably keep it around 7 or so. Without the 1 inch air gap, I believe it would have to be 12 or so.

 

[HeavyMetalHippy]

I see. Should be cool either way. Looks like a cool room.

 

[fran35]

I see. Should be cool either way. Looks like a cool room.

Thanks! It's taken a long time and alot of my life in the last 6 months, but I could never have afforded to pay someone to do the room the way I wanted it. Hopefully I get to enjoy it before the Govt moves me! I will post some more pictures as the hearth comes along and I get the flooring in. I got a great deal from the Amish on some reclaimed 150 yd Heart Pine flooring out of Atlanta. The hand hewn beams came very cheap too when the Amish were taking down a barn nearby. I just had to really research killing powder post borers without the use of a kiln. Good times

 

[fran35]

I see nothing wrong with the plan from a safety standpoint. Only 1" gap is needed behind the shield. It is very effective with just one inch space. I'm not sure about how much weight the veneer wall can carry, that is determined by the sheer strength of the screws. With a screw every 8" it should be pretty high. I think you will probably be fine, but ask a mason to be sure.

BG- another question for you. When constructing this veneered hearth wall with a 1 inch air gap, I plan to leave the bottom of the wall gapped about 1 inch, with stone veneer discreetly hiding some of the gap. At the top of the veneer - about 4.5 feet up, I planned on ending the veneered part and 1 inch air gapped cement boards. I then plan on leaving the air flow slot open for about and 1 inch before the mantel is hung(which would break up the completely vertical airflow. Is this ok, or does the air need to have a straight vertical run? This probably sounds confusing and I can make a hand drawn illustration to upload if needed. Thx!

 

[begreen]

It's supposed to be open on top, but may be ok if there are adequate slots very near the top. Not sure about the mantel, will it be non-combustible? A sketch will help.

 

[fran35]

It's supposed to be open on top, but may be ok if there are adequate slots very near the top. Not sure about the mantel, will it be non-combustible? A sketch will help.

Ok, here is my sketch. The mantel is a very old hand hewn locust barn beam. The sketch is very rough, but should convey my plan adequately

 

[begreen]

That should work. You could also bring the cement board to the floor at the 1" shim points to create "feet" for the wall. Here are a couple possible visual cues. Equally important is to honor the clearances required for the wood mantel. This will depend on how far it projects and the stove requirements. Where are you getting your clearance reductions and top clearance distance from? Is this for the Englander 30NC or a different stove?

 

[fran35]

That should work. You could also bring the cement board to the floor at the 1" shim points to create "feet" for the wall. Here are a couple possible visual cues. Equally important is to honor the clearances required for the wood mantel. This will depend on how far it projects and the stove requirements. Where are you getting your clearance reductions and top clearance distance from? Is this for the Englander 30NC or a different stove?

No, this is for the Hearthstone Shelburne you gave me advice on a few weeks back. The mantel is required to be at least 28 inches from stove top, which I am observing. Do the side of the ventilated air space need opening, or just the top and bottoms? My code inspector came out to look at my framing and I was quizzing him....the guy was clueless. He said as long as I used cement board behind the stove, there was no combustible at all. I asked about the framing and he said the cement board zeroed it out. I didn't argue with him as I still needed his signature on my electrical work

 

[begreen]

OK, I forgot about the Shelburne. If you want to make the wall look a bit more built in you could do slots at the bottom to coincide with the stud spacing. Or you could do something like I show here on the top. The main thing is to allow a good volume of air to convect behind the wall shield.

 

[fran35]

OK, I forgot about the Shelburne. If you want to make the wall look a bit more built in you could do slots at the bottom to coincide with the stud spacing. Or you could do something like I show here on the top. The main thing is to allow a good volume of air to convect behind the wall shield.

View attachment 174502

Thank again for all the help, much appreciated

 

[ObuseMe]

Looks like a nice room, I like the wood beams across the ceiling.

 

[fran35]

Looks like a nice room, I like the wood beams across the ceiling.

Thanks

 

[begreen]

Yes, it should look great when done.