Need advice on a foundation replacement

[AK fisherman]

Greetings,
I live in CA and work summers in Alaska as a commercial fisherman. After spending 5 seasons living in a 25' travel trailer, we decided last spring to buy a small cabin near where we fish.

The place had been vacant for nearly 10years, had a 24 x 36 cabin on 1.75 acres. The asking price 6 yrs ago was 90K and had recently dropped to 35K. We offered 25k and it was ours. Unfortunetly, due to the snow on the ground, my buddy in AK was unable to get under the home to check things out. According the realtor, it was on a "block" foundation.

Well, it has a block foundation alright, 2x6 floor joists sitting on a perimeter of loose stacked 8x16 blocks, 2 high sitting on gravel. One edge of the building has now settled 3" with the wall leaning out, sheet rock cracked and a visually sloping floor. Mid floor supports are cinder blocks under 2x6 girders!

The property is primarily gravel with good drainage. Frost in the winter is a potential issue although the cabin is not occupied in the winter.

Before doing any further remodeling, I need to address the foundation. There are no building codes to deal with or insurance inspections since I don't have a loan on the home. What would be the easiest way to correct the foundation? I have never done anything in terms of jacking up a building so am unsure where to begin. While raising the cabin and doing a full perimeter foundation would be nice, I don't feel that going that far is needed due to the limited use of the cabin. Any suggestions?

[John Raabe]

That whole floor system seems undersized. 2x6 joists spanning 12' and then landing on a 2x6 "girder"?

You might consider jacking it up and doing a pier and beam foundation with leveling jacks or some way to shim the beams if you have settlement issues in the future. You could probably build the piers from the block you already have. (Reinforce them with poured cores.)

[AK fisherman]

I should have said something different than "mid span" as there are 2 rows of 2x6 "girders" breaking the 24' span up into 8' sections. Yes, I agree, the framing is substandard but now its a matter of figuring out how to correct to some degree, the lack of structural integrity.

What are options for jacking the cabin up? Wouldn't I have to have a dozen jacks or more to lift it all at once? How do people do this?

[John Raabe]

Sorry, I can't help on the jacking up part. The only times I've done this for a remodel it was a specialty subcontractor job involving big timbers, big jacks, big forces and subtle movements - not my expertise!

The 2x6 should be OK for a 8' span.

[JRR]

I would consider using the existing foundation ... just jack the floor level and shim accordingly.  You might consider bonding the blocks with surface cement ... but expect the foundation to continue to move as long as it can get wet.  Even though there is good drainage, a "french drain" outside the foundation would probably help.  Be sure to divert roof water away from the foundation in the design.

One jack is all that is "needed" .... more jacks just makes the job easier.  Good sized timbers are a must.  Make small movements, then place shims to hold in place.  Sears often has good deals on hydraulic jacks that would be helpful in a crawl space.  I once corrected a leaning masonry chimney that was about to fall in through the house. Because of water damage there was little structural resistance from the house framing.  Two small pot jacks used ... and there were many fearfull moments, before the beast was vertical and could be secured with reinforcing steel wire and surface cement.... and a huge "roof saddle" was added that helps to keep the chimney in place.  Most of the framing structure was repaired, dld roofing replaced, and a lot of care given to diverting rain water properly.

[John Raabe]

Thanks JRR

There you go!

[AK fisherman]

sounds good! I envision some long 6x6's, 3-4 jacks and then slowly moving the floor up, shimming over the top of the existing blocks and then adding more blocks/piers after I get the floor up where I want it.

The water issue could be substancial as there is very little roof overhang and the surrounding ground appears to be a bit higher than the cabin. Raising the entire cabin 6-12" would be ideal

Lance

[Don_P]

Do keep the weight on plenty of well cribbed timbers not on block as you move. Block has a tendancy to crumble under high point loads like you might get from a shifting building. It is possible to drop a building a full 8" when that happens... or so I've heard  .

[AK fisherman]

what should be the jacking proceedure on this? Jack up one side/wall an inch or two, block, then move the jacks toward the center of the cabin and do the same? or do I need to have jacks "everywhere" and jack it up everywhere one or two pumps at a time?

Lance

[JRR]

what should be the jacking proceedure on this? Jack up one side/wall an inch or two, block, then move the jacks toward the center of the cabin and do the same? or do I need to have jacks "everywhere" and jack it up everywhere one or two pumps at a time?

The method always depends on the situation ... but you should make very small movements.  First you need to establish some benchmarks at several locations, so that you never lose track of how much a particular spot has moved ... perhaps a set of horizontal markings on all current walls and piers ... all at the same elevation would be handy.  Or, a different plan might be to have two markings ... one over the other ... at each jack point .... all markings to be spaced the same initially, say 12".   I would think in terms of moving only 1/8", or even 1/16" at a time.  Depends on the structure. Tapered shims are going to be very handy.

Are you in a windy area?  If so, you also have to have adjustable tie-downs.

[AK fisherman]

Ok, I can see that this will take quite a while to raise. I need to pick up one wall about 3" just to get it plumb with the rest of the floor. I'd then like to raise the entire cabin about 24" as the floor level is even with grade level and there is water damage on the flooring due to snow melt. I guess I'll buy about 10 jacks from Harbor freight, ship them up to AK with the rest of my spring fishing gear shipment and start jacking!

Lance

[hedspase]

I just completed something similar to this during the summer.

I bought 30 acres with a 100 yr old 2 story farmhouse on it in Wisconsin.  The "foundation" was 4 large boulders, 1 at each corner, and some 2 foot diameter logs on end between the corners.  The house is 25 x 15, and one side had sunk around 3" over the years.  The perimiter beam that the house is setting on is 8x8 with 6" dia logs every 36" as floor joists.

I dug 12" dia holes every 5' around the perimeter, under the beam, and placed 12" sonotubes 4" deep, with another foot at the bottom belled out to 24" dia.  I had to dig the holes at an angle, and tip them up under the beam before pouring the concrete.

Once all the piers were in place, I was able to jack the house near each pier, and shim with green treat 2x6 boards.  I also bought a bunch of different thicknesses, including some 1/4" and 3/8" GT plywood for shims.  I just used a single 20 ton jack from HF, and worked my way around.  I would equate jacking the house like lifting a mattress.  it only moves near where you are jacking, and maybe 5' on either side. 

I used a water level (a bucket of water, and a length of clear tubing) to get the entire house level within 1/8".  The hard part was digging and pouring all that concrete, jacking the house and leveling was easy.

[JRR]

Great post, Hedspase.  I like your comparison "to lifting a mattress".

[AK fisherman]

hedspase,
yes, good info. What did you do for the interior supports? Just some pier blocks?

Lance