Hello!
I am planning to replace a sill (timber log about 15x15 cm) under a load-bearing interior wall in a two-story house with a crawl space foundation. The sill is 2 meters long and rests on foundation stones at both corners (one of which protrudes from the chimney). On the sill, there are three standing studs (10x10 cm), two of them located at each corner of the sill, the third one in the middle. The sill is quite rotten, so I guess not much weight can rest on the middle stud. The other two are placed over the foundation stones, so they can surely carry a lot of weight.
My idea is to attach two horizontal 45x220 boards on either side of the studs. Then I plan to use 4 20-ton jacks (one on each corner) to lift these, remove the old sill, and put in a new one. I will probably need to place something under the 220 boards to lift a bit away from the sill (since it's wider than the standing studs), I was thinking of placing a horizontal 45 mm thick board under each pair of jacks. I hope it's clear what I'm thinking of. Do you think this will work?
I think the jacks should handle the lift without any problem.
What I'm wondering is if the 220 boards can handle it?
I'm also considering what to fasten the 220 boards with to the studs. Lag screws? Since I have access to both sides of the wall, I could also use a through-threaded rod, would that be stronger than a lag screw? What dimension of screw/threaded rod would you choose?
Another consideration is whether the chimney could be a problem? One of the standing studs is right next to the chimney. Since I will only be lifting slightly (a few millimeters should suffice), I hope it won't be affected.
I am planning to replace a sill (timber log about 15x15 cm) under a load-bearing interior wall in a two-story house with a crawl space foundation. The sill is 2 meters long and rests on foundation stones at both corners (one of which protrudes from the chimney). On the sill, there are three standing studs (10x10 cm), two of them located at each corner of the sill, the third one in the middle. The sill is quite rotten, so I guess not much weight can rest on the middle stud. The other two are placed over the foundation stones, so they can surely carry a lot of weight.
My idea is to attach two horizontal 45x220 boards on either side of the studs. Then I plan to use 4 20-ton jacks (one on each corner) to lift these, remove the old sill, and put in a new one. I will probably need to place something under the 220 boards to lift a bit away from the sill (since it's wider than the standing studs), I was thinking of placing a horizontal 45 mm thick board under each pair of jacks. I hope it's clear what I'm thinking of. Do you think this will work?
I think the jacks should handle the lift without any problem.
What I'm wondering is if the 220 boards can handle it?
I'm also considering what to fasten the 220 boards with to the studs. Lag screws? Since I have access to both sides of the wall, I could also use a through-threaded rod, would that be stronger than a lag screw? What dimension of screw/threaded rod would you choose?
Another consideration is whether the chimney could be a problem? One of the standing studs is right next to the chimney. Since I will only be lifting slightly (a few millimeters should suffice), I hope it won't be affected.
Member
· Norrbotten
· 3 390 posts
Several French screws should work, or possibly a through M12 threaded rod, as tight as possible, of course. It's probably a substantial load that needs to be supported, and you don't want it to collapse in the middle of the work.
The capacity of the jacks seems ample. However, you should be very careful around the chimney stack. It doesn't take much movement around a masonry structure for it to start shifting in the joints.
Good luck.
The capacity of the jacks seems ample. However, you should be very careful around the chimney stack. It doesn't take much movement around a masonry structure for it to start shifting in the joints.
Good luck.
Nibbbottenstorpet is right in what he says, but I would make an extra case for threaded rod instead of French screw.
With a threaded rod, you get an incredibly much stronger "pinch" against the stud.
If I were to use screws, I would have taken 10-12 x 120 mm and a substantial washer (50x50mm) under the head. Pre-drill with an 8-10 mm drill bit to prevent cracking. Two to three per stud and side. Place the planks at different heights to avoid completely tearing apart the studs when 4-6 screws come in at the same place.
/Vojma
With a threaded rod, you get an incredibly much stronger "pinch" against the stud.
If I were to use screws, I would have taken 10-12 x 120 mm and a substantial washer (50x50mm) under the head. Pre-drill with an 8-10 mm drill bit to prevent cracking. Two to three per stud and side. Place the planks at different heights to avoid completely tearing apart the studs when 4-6 screws come in at the same place.
/Vojma