I bought a vacation home in the Stockholm archipelago some time ago. I've now discovered that one of the joists on one of the house's long sides, specifically the outermost joist the house rests on, where the floor beams are attached, is very close to the edge of the foundation on almost all the posts on that row. On one foundation, the joist has slipped down off the foundation. How can I fix this in the simplest way? See pictures.
There are three rows of foundations under the house. The one in the middle is lower with a beam. On the other two foundation rows, that is the middle and the house's other long side, the framework is correctly placed on the posts.
You might be able to jack up the house as well as excavate at the pillar row and adjust them. Probably the ground has shifted that pillar row.
What are the ground conditions?
Are the other footings the house rests on in the right place? Or has the whole house moved? Or is it the ground that's pushed the footings away?
Do you have a sketch of how the house looks and where the footings are positioned?
Unfortunately, no sketch.
I believe the other footings are in the right place. The footings could have moved, but it's strange if they all moved in roughly the same way? It's about 8 footings, I think. Now I looked at a picture from the other long side, and the beam also lies quite far out on that footing, which means the footings were probably cast too close together? See picture of the other long side:
You might be able to jack up the house and dig out at the post line and adjust them. The ground has probably shifted that post line.
What are the ground conditions like?
It's soil right there but I would guess there's rock underneath, rock everywhere on the property, exposed rock right next to the house on all sides.
Strange if they built the house so far out on the plinths. But it certainly looks that way...
However, it looks like the tar paper has slipped off on one plinth. Unless the plinths have slid inward under the house on both sides.
If you want to be sure that the house isn't moving or slipping off the plinths, I would cast new ones, but that's probably not entirely easy.
Have you noticed any changes since you bought it?
Strange if the house has been built so far out on the pillars. But it certainly looks like it..
However, it looks like the tar paper has slipped off on one pillar. Unless the pillars have slid inward toward the house on both sides.
If you want to be sure the house isn’t moving or sliding off the pillars, I would cast new ones, but it's probably not that easy.
Have you noticed any changes since you bought it?
Yes, indeed! I've only owned the house for a few months and haven't noticed anything =). The pillars might have slid inward on both sides, of course. But the paper still sits quite well on many of the pillars, sure one looks a bit suspiciously like it's slipping, but as mentioned, on many it still sits well.
I've never cast pillars myself, and currently, I'm not keen on shelling out a lot of money to cast new pillars. The dream is actually to demolish this house, a rather flimsy west coast cottage from 1980, and build a new sturdy house that's also slightly larger, but I don't have the money for it at the moment + it feels a bit luxurious to demolish a functioning (well..) house. But maybe I'll afford it in a few years, and then it feels unnecessary to spend a lot of money hiring a firm to do it properly if I can save it myself, even if it’s not as good. It becomes a bit more expensive as this house is on a car-free island.
My thoughts:
1. I read in another thread that you could cast a rim and place concrete blocks on it, then fine-tune the last bit with construction plywood or similar, maybe that could be something?
2. The house is on bedrock on each long side, as I said. Could you take a solid beam, attach it to the rock with a post anchor, and then attach the beam to the existing pillar with bolts? Maybe not enough load-bearing capacity in the bolts? Where the beam rule has slipped off the pillar, there is also a porch with pillars outside the house, where you could then attach a beam to one of the porch pillars and then to the existing pillar.
Other ideas? Preferably easy to do yourself... I've never cast pillars or retaining walls (although I did raise the floor in a basement with EPS concrete and self-leveling compound with okay results) but I'm quite handy and fairly quick to learn.
Edit:
3. Thought of another idea. You could attach a beam on the outside of the pillars running along the house. But would it be an uneven load for the pillar if, like today, the outer edge of the house rests a little bit outside the plinth or as today very far out on the pillar?
4. Alternatively, then, cast new pillars myself - how hard is this? I estimate that there is bedrock maybe 30 cm under the soil cover.
It's very easy to cast plinths. The trickier part is digging out the rock and anchoring it if space is tight. But if you have such close proximity to the rock, I think you can handle it quite easily!
Are your plinths currently sliding on the rock?
Lift the house and dig for new plinths that you anchor to the rock. Then you cast. You can get it done over a weekend if it's not too cramped and difficult to dig.
It's very easy to cast plinths. What can be a bit trickier is excavating the rock and anchoring it if the space is tight. But if you're so close to the rock, I think you'll manage it quite easily!
Are your plinths currently sliding on the rock?
Jack up the house and dig for new plinths that you anchor to the rock. Then you cast them.
You can handle that over a weekend if it's not too cramped and difficult to dig.
Thanks for the answer! Sounds hopeful!
"Anchor" = drill holes in the rock for reinforcement bars?
"Jack up the house" = Support the house with garden slabs, beams, logs, while I cast the plinths?
The height is at least a meter, I would guess. I can walk crouched (though quite a bit crouched in some areas) under most parts of the house.
How do I pour the concrete when the casting pipe will be almost directly under the house, since I can't jack up the house much higher than the existing plinths (unless I jack up the ENTIRE house higher, but that seems difficult, though I might have to lift the whole house including the patio that goes around almost the entire house to get access?)
It probably does. You can always scoop the concrete instead of pouring it. Takes longer but is just as good
Great! So then I prop/pump up the house, say in one corner, remove the old post. Dowels and cast a new post which then ends up about 1 dm below the correct level so I can pour in concrete. I place spacers on the post when it has set. Remove the propping/jack. Then I prop/pump up the house near the next post to be replaced and do the same thing. ?
Any tips on good spacers?
How do I remove the old post in a good way? Sledgehammer?
I think that sounds good, but you might need to jack up the entire side of the house at the same time. So make sure to have some jacks on hand just in case.
Rotary hammers work well to break away the old foundation if a sledgehammer doesn't do the job.
An alternative would be to cast a base and then build up with something like leca. That way you don't need to cast so high.
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