Platform supports settling

[Montanafront2012]

Good Afternoon,

I have had a 24 ft Yurt in Northern Vt since 2013. This Spring I have experienced some settling of the platform support posts into the ground.

The platform is supported by 4X4's sitting on poured concrete grade level bases. I did not have a level with me but I guessing the settle was 3-4 inches. (see attached pictures, the picture of the yurt itself is from years ago so you can see the terrain)

I am not sure why this happened after 7 years. The land to the south and west is higher elevation so I believe this is caused by moisture/freeze-thaw.

I was thinking that I would rent/buy a jack, jack up the platform post by post, then replace with a longer 4X4 post to account for the settle.

Any thoughts on this subject would be greatly appreciated.

If I can get the platform back to level I need to think about a way to keep

moisture

away from the area containing the supports.

Best Regards,


Peter M

[Ivan]

I guess “ Poured concrete grade level Bases” are just 4-5” into the ground, not down below frost line? If that is so, than i would get multiple jacks based on the worst case offenders.. I would also get a laser level as they are pretty cheap, to determine which legs have sunk the most. Instead of replacing the 4 x4, you may be able to shim some, worst case would be replacing the 4x4.. For me it would be important to lift a little with all the jacks , so you are not stressing the platform ..

[Montanafront2012]

Thanks for the information. The laser level is a great idea I will get one. The concrete bases are entirely above ground. For some reason they decided to settle this year. I guess it has to be

moisture

related.

Best,

Peter M

[Bob Rowlands]

You are in for some work. Jack the entire frame up until the entire platform is level. You'll likely have to 'stage' the lift in a few low spots if you have sagged 4". Whatever, get the entire platform level.

How to do this? Going post by post, jack and set a temp 2x between framing and a scrap of 2x6 on the ground. You might have to work your way up to level in the bad spots. The platform will tell you what it is gonna take as you jack it up.

Once the platform is level, check it for shifting. Just temp brace from the outside, not under the deck. You don't want the platform to shift and collapse while you are working to it.

I suggest 12" sonotube for piers. That's the standard and that's what I have under my platform. Set the new piers down into the ground a few inches instead of directly on top of the ground.

Cut sonotubes to whatever height that gives you a minimum of 4" thick, and set those in their location.

Figure what structural hardware is needed to attach the new 4x4 posts to the framing.

Measure from frame to sonotube, that is the new post length. Measure and cut your posts. Nail the structural hardware to attach the post to the frame, to the post. Plan on 4x4 standard concrete post anchors to attach post to piers.

Get the posts set and attached to the frame, dangling above the sonotube form and centered over it. Place concrete. Then get the conrete set. That way you don't fiddly fart around getting the mud in place. Get it in the form, level off. Done.

I'm very detail oriented. This is just a procedural overview. Hope this makes sense.

Lastly, beats me if this will last. You are on a hill and gravity ALWAYS wins. Normally you would want concrete piers to frost level, but that would impossible under an existing platform. Good luck.

[Bob Rowlands]

Another much simpler easier possibitys. It might be possible to jack up and level the frame, leaving the posts and piers in place. Brace platform so it can't collapse. Set temps under frame as described above. Leave the existing posts/piers dangling. Excavate under the base of where each pier sat on the ground. Form a new, bigger pier under that old pier. Place concrete. A WHOLE lot less work. Just might fly.

[Bob Rowlands]

Good morning. A few other points. I did the initial leveling of my 16' platform (before piers) with my 6'8" door hanging level.

Also, you can make a level with garden hose and a 'garden hose level kit', which is clear tubing with caps and hose fittings that goes onto the ends of a garden hose. I have used that before. Dead nuts accurate. When initially filling with water just keep smacking the hose until ALL air is out of the hose. Just look at the clear window and eventually you won't see any more bubbles. Using that hose level you can mark grade stakes around the perimeter of the platform.

Of course a lazer level is a whole lot nicer. My carpenter son has one but dragging a hose level around jobsite doesn't look too professional. lol

[Montanafront2012]

Bob,

Thanks for all of the information provided. Really helpful.

Once I jack the platform to level the temp 2X are around the perimeter of the platform only? The bracing would be between the 2X and the perimeter floor joist or between the 4X4 and floor joists?

Sorry if these are newby questions but just trying to visualize what I need to do.

Thanks again,


Peter M

[Bob Rowlands]

I would jack up every post that supports the deck (if necessary, and that is to level it only) not just the perimeter posts. There's 'no way' you will just lift the outside posts to level and not have the middle sag.

You CAN start level the outside posts and then work your way in with a level or whatever. If the cover is rolled up, just eyeball across. It would be REAL nice to have a buddy sight the floor while you are under there jacking it up to level. That would save you from repeatedly climbing under the platform.

I'd get a temp 2x support post adjacent to each existing post until the deck is level. The temp needs to butt into the same beam or framing that the existing post is attached to. And, far enough away so you can work. Also you should make some big wedges so you can just drive the temps up as you sneak up on level. Just make those from 2x ripped on an angle.


Yet more. I'd go for the post pier lift and repad under version instead of the removal version. Just add a new, larger pad under the existing pad. It would be helpful if you could get the ground dug out a bit under the new piers.

As for bracing, I would brace it if I felt there was any chance that the whole platform could shift and collapse once you have it jacked up to level. It might be wobbly and it might not. Just temp brace from the outside frame to a few stakes pounded into the earth, around the outside of the yurt, not under it. The existing bracing under the original posts should be good, once the new pads have cured. If the frame wobbles when you are done, rebrace it from underneath.

Lotta work but there you go. Have fun. BE CAREFUL!

[Montanafront2012]

Bob,

Thank you for all of the above posts. Really appreciate it.
You have given me a clear direction.

Hope to get up to the camp(7 hrs drive) within the next week to start the work. I just purchased two 12 ton bottle jacks for the jacking part.

I like the idea of keeping the existing posts and pouring a new, bigger pad underneath.



Best Regards,


Peter M

[Bob Rowlands]

You know it's a funny thing, I bet if I was there actually looking over your project, sizing up the job, I would have quickly thought of jacking up the platform leaving posts and piers in place. Looking at pics and looking with your eye are really two very different things.

Once you're in there working, if it gets kinda tough going, just keep in mind the scale of the work. In fact it is just a simple platform on posts, sitting on the ground. Not a house foundation 9 feet in the earth.

You'll get it. Those jacks are gonna kick butt. Good job. Think about your work as you are working. BE SAFE!!! Enjoy your work!!