my cabin is on leaning cement columns :/

[mrmarbles]

so, my newly acquired 22x24ft cabin was built on 9 columns of cinder blocks, they go 4 ft into the ground and are filled with cement and rebar, but they're leaning forward (there was a wall of earth pushing the place from behind, which i've since dug back).

I think in the spring I will replace the columns one by one, this time with 2 blocks per row. but I want it to make sure it survives the winter. it's the front 3 supports that worry me. I've put some jack posts behind them temporarily, just to reduce the weight a bit, but I'd like to do more. I'm thinking of making 2 stacked cradles of 6x6 hemlock timbers near the front, supporting a new beam that would run from 1 side to the other, and then put a jack post under each place where the new beam makes contact with the existing beams (see attached diagram -- the jack posts, new beam and hemlock cribs would be the addition i'm thinking of doing).

does that make sense? the hemlock cradles wouldn't be directly supporting the existing beams, but they would be supporting the new beam. I'm open to suggestions, but it can't be a huge job or involve a team of people.

by the way, don't tell me the place will fall any day, I know it looks bad but it's been like this for years, and with some extra supports it will surely survive until the spring! thanks.

 

[nealtw]

Welcome to the site, congrats on the new house I think.
Your plan for the cribing I think is good, get that done asap and then look at how best to fix it.

 

[bud16415]

The only thing I might question is what the winter frost might do. Right now all your support points are below the frost line. If you have a lot of temporary cribbing in tight resting on top of the ground and get an inch of lift from a frost I’m wondering if it will stress the other supports.

I don’t know for sure but tossing it out there Neal and some of the pros might have thoughts on that.

 

[inspectorD]

Well, the cribs could lift the structure off the columns, but they would go right back down with it when it settles. The biggest issue is the lean and lack of diagonal support, But with the way these columns are built with block, there is no real way to fix that. I would lean towards a wooded column like a pier post. (old telephone poles) Then attach them at the blocks at ground level with an anchor from Simpson Strongtie. That way you do not have to dig down again and disturb soils. Diagonal bracing is the key, because we see it is still standing straight up...for now.
just remember to have an exit strategy when your under there.. this is no place to be if your not experienced, or even comfortable being under there.
Good luck.

 

[bud16415]

Thanks for confirming my fear of the frost lifting the cabin. We don’t know the climate where it’s located but around here I would see movement at least a half dozen times thru the winter. Right now those stacked block columns have been in compression forever. I wouldn’t want to trust what loading and unloading with the lean and set they have might do to them.

I know the OP feels comfortable with them as historically they have worked but I would really error on the side of caution with that much weight and that much height and the columns built as they were. My fear would be a chain reaction failure. If one of the outer columns fail that weight would pull against the next one in and so on.

Given the OP wants to make it to spring I would do the cribbing but not the new beam and place 3 stacks of cribbing one under each of the existing beams. I feel that getting a big huge beam in under there would be a lot of work and one slip up with equipment could do damage to something. The cribbing could be put around the jack posts.

The question to me is do you crib it up tight or just have them under there just in case and held down a half an inch. Come spring the cribbing could then be jacked against as the columns are replaced one by one. The double stack filled and rebar sounds like it’s a lot better and DIY friendly.

Oh and I forgot welcome to the site.

 

[broadbill]

Instead of the crib idea (which sounds like alot of labor just to get through this winter), what about using a come-a-long system to pull the cabin back a few inches so it sits right on the piers? Leave the come-a-long in place for the winter.

Then in the spring build your temporary cribs on the outside of the foundation so that the cabin's weight is safely supported without you having to work underneath it until they are in place. Do your work under the cabin (better piers, diagonal bracing...all that has been suggested) and then remove the cribs.

 

[nealtw]

I would make no attempt to pull it back in place, something would break.

 

[broadbill]

I would make no attempt to pull it back in place, something would break.

Fair enough...then in that circumstance I wouldn't recommend he work under there at all; and should shore it up soundly from the outside first.

 

[bud16415]

Fair enough...then in that circumstance I wouldn't recommend he work under there at all; and should shore it up soundly from the outside first.

I agree. I understand photography pretty well and know about distortion in photos and such and for me those photos are pretty clearly showing bow and tilt as the new work he has added looks to be all plumb and provides a good reference. I know the OP is only moderately concerned and even went as far as to ask to not be told it could come down at any minute and maybe it won’t but I feel the prudent way to look at it as if it could. If not being under it is a concern then likewise not being inside it should be equally a concern.

The OP did say the problem was caused by the bank moving and pushing the building forward and he has removed the bank in contact. That is most likely a good thing but that could also be a destabilizing factor to my way of thinking as now the whole foundation is a series of parallelograms without any diagonal members in tension to keep things from hinging.

I wouldn’t rule out cables as you suggest but I wouldn’t want to do anything that causes movement until I knew things were supported against lateral shifting.

Looking at this more as the day goes on if there was ever a case to advise someone to get professional help this may just be the one. I know it’s a cabin and as such calls out for DIY engineering but how many times have I read where someone is questing a wall removal as maybe being load bearing and they are advised to get an engineer to confirm before doing anything.

 

[mrmarbles]

Thanks so much for all the input! I'm located in Quebec, where we get a lot of snow and very cold winters. I hadn't considered the possibility that frost could lift the cribs! Do you think that would happen? If so, at the very least, I should probably not make them too tight, based on this advice. Any significant lift could definitely stress the supports, since they are connected to the beams above them with a metal strap. Also, I guess lifting off the front supports would stress the rear supports.

One thing is that when I dug a few inches into the ground to make a flat surface for my jack posts, I discovered that there is a cement footing of sorts, which runs only from the front column to the middle column on either side of the cottage. This is what my jack posts on those sides are currently resting on (as seen in the attached photo of 1 side). So maybe I should rest my cribs on those (without adding beam running from 1 crib to the other), since that cement will not lift in the frost. It's only about a foot wide though, so the rest of the cribs would still be on the ground.

Also, inspectorD's suggestion of attaching a post to the bottom of the columns seems to me like a very good idea which I hadn't though of. Even if the top of the front columns were to continue to bend forward, there's a good chance that the base would stay in place and therefore keep the wooden post in place. I would probably use a 6x6 post for this. I'm not entirely clear on how I would attach that to the cement pillar though.

 

[bud16415]

From the little bit of searching I did I see Lally columns are rated around 14,000 lbs. They figure the weight of single story structures between 50 and 200 lbs per sq ft. So let’s guess in the middle your building is 50,000 lbs. and for safety sake the columns are good for 5000. That’s saying 1 lally is roughly good for about 1/10 of the weight and you have 9 of the block columns now so you are in the ball park I would say.

You are very lucky if you found the pads that go down to footer depth I would say.

Here is an idea I had the Lallys are no better than the blocks stacked up to resist things moving side to side they will carry load but nothing if things try and move.

What if you connected them both into these footings below and into the beam above and then rigged something to top to bottom and bottom to top with turn buckles in the center. This would carry load and also stop racking in the one direction. Maybe you could do something similar in the other direction also. I’m thinking maybe something welded top and bottom to the Lally to take a heavy cable or threaded rods.


PS

I still would advise you to talk to a structural expert and run the numbers.



On edit:
If you did a tension set up like that along with the X bracing I mentioned that would be in tension you would also need a beam / brace Lally to Lally across the bottom to act in compression. Reason being is you have no idea how secure those pads are into the earth. You can’t count on the ground acting as that member.

 

[slownsteady]

Looking at this last photo, I'm thinking the jack posts are enough - based as they are, on the piers. Trying to do too much could just add to the complexity.

That being said, it also occurred to me that diagonal or lateral bracing could be tied into the uphill side, just snug enough to prevent the bow from increasing. Not sure how exactly to do this though. And this is definitely not a professional opinion.

Edit: I didn't see Bud's last post when I wrote this, but it follows similar lines of thought, somewhat.

 

[nealtw]

Now I agree working under this might be a little dicy. The temp fix for it might better be to digg holes infront out about 12ft to frost depeth and install 6x6 lening back to the housr and bolted to it and put concrete in the hole to hold the post, maybe, still leaves him working in front of it.

I would investigate the pads between the posts, if they are footings or a bridge between posts I would build a block wall between the posts.

 

[bud16415]

I like the block wall if it runs across. I assumed they were just bases that never got used.

I wonder if bolting something to the front without tie rods or something running all the way to the back would work. Framing wasn't intended to hold a house sideways. If the bank was what pushed it out in the first place. Anchoring to it long term wouldn't be good. I know Neal said temp though.


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[nealtw]

It could be the hole thing slipping to the lake?????, around here it would be a maybe.

 

[mrmarbles]

You guys are good people, I'm glad I found this forum. About the hill... I think that if it weren't for the pressure that had pushed the house from behind, the cement columns would still be straight. The land in the front hasn't moved, and I don't think the columns under ground have moved. It's just that the house got pushed forward, and it brought the front columns with it, and because they're filled with rebar, they bent instead of collapsing.

Right now, based on InspectorD's suggestion, I'm thinking of putting 2 wooden posts in on either side, resting on the "footing" (after I check that it goes down a few feet into the ground and isn't just a 'bridge') and attached to the cement columns as pictured in the diagram below (brown = wood, grey = cement). The front post will stay held in place by the base of the front cement column, and then the diagonal support post will keep the middle cement column from moving forward. If I had that set up on either side, with jack posts helping out in the centre of the house, I think it could be pretty solid and much less expensive than the cribs.

 

[inspectorD]

This is what you need to do..and it is very easy to do. Crib support the areas you will work on and start to remove columns and use wood. metal columns will rust where the welds are ,and concrete cannot be diagonally braced. You need diagonal bracing or you will have the same issues.
Here are some pictures,

 

[oldognewtrick]

I fully understand budget restrictions, but don't confuse inexpensive with the cost if catastrophic failure occurs.

 

[nealtw]

I think inspector has it.

 

[mrmarbles]

Inspector, that looks like a good, easy enough, and relatively inexpensive solution. I can see that diagonal bracing is much easier to implement with wooden posts like that. Since my place is only 24 feet wide, I wonder if 9 wooden posts of treated 6x6s would do the job, or if I should put in 2 internal rows instead of 1.

At any rate, I will have to wait until the spring to do that since I think it's getting too cold up here to be pouring cement.