Never framed for a hearth before. How’s it done? Traditional, flush with the floor masonry hearth of some sort, probably bluestone, in front of a Rumford fireplace. Is the 2×6 floor framing in that space going to complicate things?
Also, how big is a hearth supposed to be?
Steve
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Is this a masonry fireplace? Must be if it's a Rumford. We used to head out for the hearth and the mason would cantilever a concrete base off the fireplace. Carpenters just put in a bottom piece of ply for a form. The concrete ended up tapered, about 6" to 4" I believe.
Hearth dimensions are about 20 inches, depending on local code. You might want to dimension based on your finish hearth material so that you have full pieces.
John
Minimum size should be 18" to front of openning and 12" to each side.
Yes, the 2x6 framing will complicate this. you frame just as tho it is a hole in the floor - with doubled joists and header surronding the hole. 2x6 floor joisting makes me presume old house and bouncy floor, so possibly two posts at corners.
we pour the concrete base of hearth as a one withthe hearth of the fireplace cantilvered over into the hole. Support the form under it by screwing to bottom of joists so you can pull form board back down after curing. Where inspectors expect to see decoupling of masonry and framing, line the hole with twin pack of hardiboard, or 1" foam that can easily be cut out later after curing
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This is new addition to old house, but because of issues matching floor thickness, and headroom issues, I've designed for 2x6 floor framing on the first floor. There will be posts at the corners of the masonry mass supporting beams that go past the masonry mass to the foundation wall that the (interior) fireplace mass is up against.O what you are saying is that the base of the fireplace masonry and the hearth are one piece, ie: if my masonry mass 3x7 feet, then the whole is framed at 4 1/2' x 7' and the the hearth concrete is really a cantilever out from the fireplace mass?If you have to decouple the hearth from the framing what supports it?Steve
The rebar in the crete supports it
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Here are some instructions from Rumford. Hope they are helpful.
http://www.rumford.com/insta.html
John
the ro is the total of the fireplace and the hearth
I started framing in the 70's and every house we did had a masonry fireplace back there in MI. I don't remember working on any house with 2x6 floor joist.
We would frame the rough opening using a doubled header and doubled beams. Sometimes, we'd triple the beams. After that, we'd line the inside of the rough opening with a 2x4 nailed flush to the bottom.
This ledger would then support "T irons". The t irons would be placed by the masons in between their courses of brick. T irons are a very common item in any builders yard in MI.
The 2x6 floor system is the result of a combination of errors on my part. That I'm still kicking myself for. I should have specified 9' walls on the cellar of this addition, but didn't. When we were replacing the septic system I was trying to get the tank low enough in the ground for a gravity-drained bathroom in the cellar. So we set it up with 8' walls to help facilitate that, but in the end, the septic engineer and the excavator ruled that out, so I wound up with 8' walls and still had to go with a sewage pump. After the footers were poured and the walls formed, at the last minute I realized that I had specified the height of the wall 4" too high. The part of the 1850 building we are adding on to is 7 inches out of level over 20 feet, which is no excuse for my mistake, but it happened. So I had the walls poured 4" shorter than the forms to make things work with flooring heights inside the old part of the house.Now the engineer insists we must have 7'6 headroom in the basement, finished floor to finished ceiling. The only way I can get to that is with 2x6 joists on a double sill plate. I can divide my floor platforms into (3) 8' spans with 2 intermediate beams and make that work. The footers are there for it. 2x6's are acceptable out to 9'4 (10'3 if I go with 12" OC) but it's going to complicate stuff like this hearth opening.Steve
That would not complicate the hearth situation at all. Instead of nailing on 2x4s as the ledger, I'd simply order 2x2 steel angles and lag them to the bottom of the joist. I'd then lay the t irons on them.
Here's the underside. Just as the other kids wrote, frame the opening in the floor as required. My mason used...I don't know it's proper name...but it's a corrugated "W"-type metal pan. Held up by scrap lumber tacked to the sides of the joists, the 'crete is poured, and once cured the support scraps are removed and concrete shelf is self-supporting.
This is my downstairs fireplace, a 48" wide firebox. I used a raised hearth to elevate the firebox off the floor for better viewing and enjoyment.
Yes, I actually do enjoy the snap crackle pop of a good old fashioned wood fire. BTU gain or loss be damned.
So from below:
View Image
From above:
View Image
Thanks everyone for your help. I have a much clearer picture of what's happening now.
not sure how progress on this thread has gone but did you ever look at http://www.gobrick.com/ to see if their Tech Notes have anything to offer?
Just looked. Not much there on the hearth. But I think I get the gist of it now. Not framing for a little while yet.Steve
mmoogie You can use old metal roofing instead of "pan decking" for pouring the hearth slab on. Screw it together with "stitcher screws" and brace it from below.
I have done it many times.
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