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JoulesWinfield 01-03-2007 08:39 AM

An interesting problem...sagging chimney.
I have been contemplating how to address this issue since I bought this house and discovered it.

The floor in front of my fire place is raised slightly. When I went into the basement to see what could be causing this I found that the fireplace was simply placed on perpendicular floor joists.
It appears that where the fireplace supporting joists tie in to the other floor joists they are lifted where the metal brackets are that attach them.

My guess is that they added the fireplace to the design after the basement was poured, therefore the need to push out that part of the floor.

The question is how to lower this part of the floor and permenantly, properly support it so it doesnt happen again.

What do you guys think? Should I dig a pit outside the basement put some type of footing for a jack and just lift it using some type of header?
Should I go from the inside and try to pull it back down into place?

One part of the quandry is that there is a vent window directly under the chimney, (great planning on that one). It would be a bummer to loose the little bit of light that lets in. But I would accept that for a level floor.

Any ideas at all are much appreciated.

harleysilo 01-03-2007 08:56 AM

Are you replaceing the floor in the room with the fireplace?

If so, could you not pull up the subfloor, and then plane down the floor joist till they are level with the others?

You might want to sister the joists you plane.

I would be hesitant to jack the fireplace, as you could crack the brick or stone work.

glennjanie 01-03-2007 11:27 AM

Is your fireplace built on top of the main floor? Is it a full masonry fireplace or a zero-clearance metal unit with a wood enclosure covered with artifical stone or thin (3/8") bricks?

JoulesWinfield 01-04-2007 05:16 AM

Glenn, strange to see your reply. lol

You hit it on the head. The inside of the fireplace is a couple of peices of some fake stone fire stop stuff, and the chimney is just wood and vinyl siding with a pipe going up through it.

@harleysilo- Im not replacing the floor yet. Later on I plan to rip up the laminate and put down some kind of dark hardwod flooring.

glennjanie 01-04-2007 01:05 PM

O K Joules, with that kind of fireplace you should be able to prop it up with 4 legs of steel pipe, take the metal joist brackets loose and lower them to level the floor. I lean toward keeping the posts under the fireplace to keep it stabilized; it can weigh an awful lot even though it is hollow.
If the movement should crack any mortar joints you could use caulking to match the mortar to fill the cracks.

JoulesWinfield 01-05-2007 06:02 AM

So are you just saying to temporarilly lift it from the out side, disconnect the steel brackets, level the floor, reattach the brackets and then I could remove the "jacks"? That would be nice to not have anything permenently installed under the chimney.

What do you mean by 4 legs of steel pipe? Are you talking about floor jacks? I have two new ones that I was thinking I would use to support it.

What capacity should that lifting jack be?

glennjanie 01-05-2007 12:02 PM

Yes, that should work just fine, unless the fireplace begins to sag again after you level it.
My statement about 4 legs? I was thinking the fireplace was inside the wall line. My mistake.
The floor jacks you have should be of sufficient capacity, all you will be doing is taking the strain off while you make the correction.

JoulesWinfield 01-06-2007 03:18 PM

Cool, thanks for all your help Glenn.
I may actually get this done before the snow flies.
Still gotta finish that bedroom project though.

JoulesWinfield 04-17-2007 09:59 AM

I know this is an old thread but I didnt want to start a new one for the same thing.

I was just wondering what type of setup I should use to lift the floor of the fireplace on the outside of the house.

What I mean is, the underside of the chimney is a couple of feet off the ground outside. Also I think all that is above the wood sheet on the bottom is the floor joists.

Should I make a lifting header and just try to use my 3 ton mechanics floor jack? Or will I need something stronger?

glennjanie 04-17-2007 10:47 AM

I would recommend two jacks placed under a 4 X 6 so you can keep a balance on the fireplace. Each jack should have a capicity of 10 tons. I know that sounds like overkill but I have seen several jacks fail in a row like a zipper because the load was blowing out the seals in the jacks.
I wouldn't want to raise the floor more than 1/2" for fear of cracking the covering masonry or causing the nails to fail in the framework.

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