Repairing a realllly old building
Across the street from where I’m working is a very old pole-frame shed. It’s apparently from about 1880, which would make it among the oldest buildings here. It’s about 10×18 and built with ~4″ dia. vertical peeled poles ~2′ O.C. around the perimeter. Short pieces of siding are toenailed in between the poles. It’s very nicely done for 140 years ago.
Many of the post bottoms are rotting out. Some of them are set on a wooden sill on grade, and others are buried. The owner wants to lift the building a little, repair the bottoms of the posts, and set it back down.
But, on what? He talked about putting in a pressure treated sill on grade and setting the building back down on that, but it seems to me like a water trap… water sitting on the sill wicking into the bottoms of the posts.
What I need is a way of terminating the posts to the sill, maybe some sort of stand-off post base (for round posts!) or something else. I also need a way to repair the bottoms of some of the posts, which are too rotten to fill with epoxy (about 1/3 of them need new wood added). What’s a good detail for this?
Replies
I've built pressure treated foundations under existing houses. I could see if I could find the book. It was inspected and approved in Denver. Each building is going to be different and I agree that trapping water needs to be avoided. Let me know if want to know what we did. Caution--never did get fully paid for that job. But that's another story. Tyr
David,
How about setting the sill on a drained, gravel filled trench footing?
Then pray you gets no bad winds.
Alt, pour a footer and bolt down the sill.
SamT
Cover the sill with Vycor- that'll isolate the sill from the posts and prevent wicking.
Sure sounds like a candidate for a bulldozer though- does the owner know how much he's gonna spend to "repair" a 180 SF garage?
Bob
Sure sounds like a candidate for a bulldozer though- does the owner know how much he's gonna spend to "repair" a 180 SF garage?
I agree to a point. Maybe disassemble it and build it again on top of a poured footer. Or reuse the siding/posts as a decorative trim detail over a modern frame.
Seems to me the structure that old/rotted would just fall apart when you jacked it up.
I also need a way to repair the bottoms of some of the posts, which are too rotten to fill with epoxy (about 1/3 of them need new wood added). What's a good detail for this?
I've cut a tenon in the sound part of posts and fit a new bottom section with a mortise. Kinda picky, but works. Short tenon is fine.
Depending on how many need new lower areas, I'd be thinking about changing over to a square base, which could sit on your choice of ventilated feet. That would make them uniform, less like a patch.
I guess you don't figure you need the posts in the ground to prevent racking? Once lost a whole building over that, so I'm sensitive.
A low cost alternative would be to fabricate steel feet for the posts, high enough to find sound wood on all of them. Think 4" id pipe with a flange on the bottom. Much better would be 4" od and trim the posts to a tenon.
PAHS Designer/Builder- Bury it!
the HO is looking at a pricey fixer up. You will need quite a bit of cribbing for jacking up the shed. About 3 or 4 bottle jacks.....you probably know what materials but anyway.....jack up the building about 3 feet or so, cut away the rotten bottoms of the original studs (poles) and sister them up on each side and fill in the gap underneath. re: if you cut 2' off the bottom, replace it w/ another 2' piece and sister both sides as high as you can go, maybe 8'.
if the inside is all bare as far as 1x stock (whatever they used for walls) try not to remove too much of the siding on the outside....take only what you need to crib and replace rotten post bottoms.....you should install temp. cross braces inside.
after the building is elevated pour a 2' sill plate maybe half below ground level.....it doesn't sound like the HO is too crazy about minor freeze thaw effects where you would want to dig and pour footings to 42" (code here in NY) but if you do, leave footings at ground level and then pour a 2 sill on top of them...the footings seem like they would be ok 6 or 7' OC.
I don't want to ramble on too much, then nobody will bother reading this post. but if you do need more input or i should say anymore of my advice you can email me.
Good luck and be careful, it may be a small shed but it can still cause some damage.....
Dave