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Mantel and supporting pipe

Shaken-n-stirred's picture

I would like to mount a heavy mantel to my fireplace.  I don't know exacly what the mantel will be but expect it to be large.  For the sake of argument, let us assume it will be 12 inches square and 8 feet long, which if larch would weight about 300 pounds.  That should be the high end of my load, as it will likely be a bit thinner and probably made of douglas fir which is lighter than larch. 

My fireplace is a Zero clearance unit, so the surround is stud framed. I am thinking of running two steal pipes in through the front of the fireplace surround and run it to the back of the surround (distance 33 inches).  These pipes would extend out the front by 8 to 10 inches.  On to these pipes I would slide wood timbers on which the matel beam would set (worse case another 30 pounds for each extension).  So the total load would be 300 to 360 pounds,which would mean each pipe would carry 150 to 180 pounds.

So the question is:  Can I use black gas pipe to carry this load with very close to zero bending or sagging?  If not what pipe should I use?  Or solid steal?

Any experienced advise?

 

Thank you.

No dubt that would work fine (post #215276, reply #1 of 8)

No dubt that would work fine but seems overly complicated to me. Drive a 12' long, 3/4" lag into a stud toward each end of the mantel. Cut the heads off, drill holes in the back of the mantel and slide it over the bolts. It will never move.

Florida Licensed Building Contractor, 50 years experience in commercial remodeling, new homes, home remodeling and repairs and all types building maintenance.

WTH (post #215276, reply #2 of 8)

WTH do you get a 12' lag bolt?

 

:)

I cut the 24 footers in half! (post #215276, reply #4 of 8)

I cut the 24 footers in half!

Florida Licensed Building Contractor, 50 years experience in commercial remodeling, new homes, home remodeling and repairs and all types building maintenance.

crush wood? (post #215276, reply #3 of 8)

So even with 150 to 180 pounds hanging on a lag bolt won't cause the lag bolt to crush the wood in the stud a bit to cuase the mantel to tip slightly forward?  If the lag bolt at the front of the stud crushes down under load even a 1/32 of and inch the front of the head of the lag / mantel would dip 3/8 of an inch (12 inch extension times 1/32).  Even 1/64 of a crush would result in 3/16 inch.

Then again I suppose a 3/4 inch diameter bolt is not likely to crush as much as a much smaller bolt.

I suppose I could use 4 bolts.  I have seen this on-line.  I just worry about lining up that many holes on teh back of the mantel.

Thanks for your suggestion.  Bolts would be easier than cutting two pipes to length. 

I doubt that would happen. I (post #215276, reply #5 of 8)

I doubt that would happen. I don't think I've ever hung one that heavy but I've never used 3/4 lags either. I usually use 1/2 and haven't had a callback. If your framing is still open stick in a couple of 4 x 4's for insurance. You could as you suggest use 4 and you could drill larger holes to make them easier to line up. Just fill the holes with epoxy and slide the mantal on.

Florida Licensed Building Contractor, 50 years experience in commercial remodeling, new homes, home remodeling and repairs and all types building maintenance.

Shake (post #215276, reply #6 of 8)

get two pcs of 1/4 x 3" steel plate like we use laid flat for a granite counter o-hang.  Mount (use lags) on edge to the sides of front and rear studs, extend how far you wish.  Cover that with your preferred wood Corbel.  Easy to level and fasten and it ain't going anywhere.

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French Cleat (post #215276, reply #7 of 8)

I'd think of a way to hang it on a french cleat and anchor the cleat to as many studs as you can.  nice load spread that way. Size the cleat appropraitley for the load, ie more weight = thicker cleat. 
You'll have to think about the drwyallw being curshed adn things looseing so the larger the area of the wall piece to spread the load, the less of an issue it will be.

Nice Drawing John. What (post #215276, reply #8 of 8)

Nice Drawing John. What software do you use or is this a standard detial that you found?