I’m putting a deck and deck covers off the back of my house and had a question about the footings for it. The area that the deck will be on is on top of one enormous rock, So can’t dig the standard 3 foot hole. Has anyone ever dealt with this situation before?
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First impression: that "rock" is one humongous footing for your short deck piers. Assuming the rock goes down more than your required three feet (presumed correct for your climate), what is a much smaller "footing" going to provide that the rock won't? If there is much slope to the rock where a short pier will go, bore a hole and use a piece of rebar there to anchor it against slippage.
Is that rock exposed everywhere the deck is going? Can you tell how deep it is?
It's one solid rock that covers most of the foot print of the house and the backyard. I'm not sure exactly how far down it goes but I know it is at lest 6 feet. I don't think I can skip this rock.I was think the same thing you are about the boring a hole I just wanted to get a second opinion
Where the piers will go, is the rock surface steeply sloped? I did a deck some years ago, 22x24, over a rock face. Six piers. Back two were shallow, with rock face maybe 15 degrees of slope; no pins. Middle two were perhaps 20 degrees; no pins. Front two were probably 45 degrees; on those, the BI wanted holes and pins. The concrete bonds fairly well to clean rock, and the deck never moved.
I would bore holes for all the piers.
But I wouldn't use rebar. And I wouldn't make a large hole.
I would use saddles. I'd drill a hole just big enough for the pin of the saddle, and set the pin in the hole with some epoxy.
There are saddles available where the saddle rides on the pin, instead of having to adjust pin and saddle and all, for height adjustments.
Life is what happens when you would rather be finishing your own house.
I'll second Luka.
JimNever underestimate the value of a sharp pencil or good light.
I'll third Luka.
Did exactly that on a very large deck and entry walk/stair. The BI really liked it, and so he should because he had instructed me that I should do it this way.
Call your building dept, explain the situation and ask if they will approve using the rock in lieu of poured footings. I had a similar situation, building a freestanding porch next to a rubblestone foundation, ran into a large rock that was part of the foundation, but the BI would not let me tie into it. I had to take a jack hammer and break it up to where I could pour a footing.
"I am the master of my fate, I am the captain of my soul." Invictus, by Henley.
Check ouy the RCPS in this link.
You could drill plumb then pack around the low side with grout
http://www.strongtie.com/products/categories/post_bases.html
NAIL IT !!!
I have run into this and we were able to pin the rock then set our post on the pin as long as the rock is deep enough past the frost line.
I build over ledge a lot. Drill a 1" hole 8" deep in the rock and set 3/4" allthread in masonry epoxy from Simpson. Then large heavy washers and double nuts to support 4x4s with a 3/4" hole drilled in the bottom. The nuts let you adjust the elevation a bit.
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Want some photos of your idea in action?
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All but the bracket saddle.I also sleeved the allthread ( on this it looks like it was full 1" bar" with ABS scrap so the frost would not be hooking the threads.
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Thank you.=0)
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I've never seen that done. It's a good idea. The only thing wrong with it is it looks like it shouldn't be able to support the deck.
all the load is vertical. We have had four feet of wet snow and ice on that deck. We also had a staging tower set up on it of steel pipe staging for roofing and rebuilding a chimney. The masons had it loaded pretty good!
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Practically it's fine. I was more thinking of a past client who had delicate sensibilities (and was ummm... a good 300lbs!) Probably guided by legitimate instincts for self-preservation, she was very particular where she stepped. I can see having to put up dummy posts to sooth people like her's fears that it is too flimsy.
I think it is a very elegant solution. Can't wait to find some more rock to build on.
Did you buy my Mothers summer place in NH? :-)
That place had a rock with a deck, stairs, and landings on it that if crushed into 3/4 stone, (what was showing next to the house) would have easily filled 5, 30 yrd trailer dumps. The rest of it went all the way to lake, about another 45 feet down. It was a great set of stairs and landings but removed all the enjoyment of going "down to the water". It really was easier to walk around it down the side.
She had nothing else to spend her money on.
Pin a footing to it and build off of that. Of course with the Pope coming to America, he will need to bless it along with your building department..