Worcester, MA · Member since 2012 · 145 posts · 6 votes
I am planning on adding more support to the main support beam in my two buildings. I am planning on using 6x6 wood beams that are graded for ground contact. I will put them on concrete supports. The support beams are currently sagging so I will jack it up some before putting in the new posts. I have two 30-ton jacks that I will be using.
I am wondering if there is a safety risk here and what I need to know to do this as safely as possible? The buildings are over 100 years old and there is some damage from powder post beetles.
Property Manager · DeLand FL · Member since 2012 · 860 posts · 243 votes
13y
You also cant simply put your new support post on the concrete floor, it wont hold the weight, you need to cut out a section and poor a deeper footer for the support.
If you only have a crawl space or on dirt, you still need to dig and put a footer there as well, the depth will depend on your area and conditions.
Real Estate Investor · Vancouver, WA · Member since 2012 · 78 posts · 22 votes
13y
Of course there always risk. I have jacked and leveled more than one house
Rule #1 Dont depend on the jack to hold beam in place while doing repairs
Have lots of blocks and shims. After you jack the beam in to position place blocks right next to the jack to help support the beam incase jack slips or leaks down.
Always place your jack on apeice of wood (with wide base like 2x12 or 4x12) to keep it from sinking into the ground.
Have a second person with you to help move stuff around plus if something bad does go wrong you have someone to help you or call 911
Just think 2 or 3 steps ahead of what your doing and be careful if you think it will take 2 hours plan for the whole day Things take a lot longer when you are on your back under a house
Investor · Sarasota, FL · Member since 2008 · 17k+ posts · 17k+ votes
13y
And hope that if the jack or the new support beam slips, you don't end up with a piece of wood through your chest or head.
In other words, if you don't know what you're doing, bring in someone who does. I've heard some horror stories about jacks slipping or giving out, and wood flying out an impaling things that would prefer not to be impaled.
Property Manager · DeLand FL · Member since 2012 · 860 posts · 243 votes
13y
You also cant simply put your new support post on the concrete floor, it wont hold the weight, you need to cut out a section and poor a deeper footer for the support.
If you only have a crawl space or on dirt, you still need to dig and put a footer there as well, the depth will depend on your area and conditions.
Massapequa Park, NY · Member since 2012 · 13 posts · 4 votes
13y
Are you using wood to support steel? this generally isn't acceptable. Also, have you consulted an engineer as to what type of soil you are landing on? Since you are adding support points, it is true you are unloading one area of soil and distributing the load to more area, but you may require the services of an engineer to properly size the footings.
Investor · Fort Worth, TX · Member since 2011 · 1k+ posts · 450 votes
13y
I'm an engineer (geotechnical) and can tell you this is not rocket science. It is, however, much harder work than one usually anticipates. It can be done though. You will hear very loud cracks and pops and it can be kind of scary. This is normal. I would recommend working with a helper and as Scott Williams said, have lots of supports for safety. Also, as J Scott said, there is a lot of pressure and wood shards could fly. Thnk about it - 60 tons of jack strength. An 18 wheeler weighs about 40 tons fully loaded.
As far as jack bases, I would prefer a larger "square" shaped footprint rather than what Scott desribed. The pros use steel plates, but you can double up some 3/4 plywood, too. Screw them together to increase shear strength.
One lesson I have learned is not to put the jack near an existing footing. I did this and ended up tilting the footing over from the pressure of the jack. Rather than jacking up the beam, the footing is now at an angle and the shims are there just to hold the beam where it was, rather than higher up as I had intended. You will also want something to spread out the jack footprint over the beam as well. If you don't, the jack will start pushing a hole into the relatively soft wood.
In the end, I found that it was not going to be a matter of just jacking up one spot. Several areas will need to be lifted to compensate for the new situation of the floor. That means more work. It is hard work dragging concrete blocks and wood members under a house - especially if you don't have a lot of space down there.
I ended up aborting the project. At my rent price, the tentants don't care that the floor is not level as water. If I ever decide to resell, I might at that point have it jacked up - by someone else. I was quoted about 1500 to level up a 750 SF pier and beam house. I would pay that just as readily as I would pay someone 2500 to replace the roof rather than DIY. Maybe I'm getting lazy...
Worcester, MA · Member since 2012 · 145 posts · 6 votes
13y
Was going to lay concrete square slabs to support the jacks and dig holes and use concrete footers for the 6x6 or lally columns, whichever I decide to use. I have someone who says they know how to do it and we were going to do it together with maybe one other guy but what you described with the cracks and pops has me freaked out. I think I will try to find someone else who can do this job.
One of my tenants complained to housing about the floor and I tried a temporary fix by leaving the two jacks in place but the building inspector was not satisfied and stressed the need for support every 4 feet.
Cincinnati, OH · Member since 2013 · 292 posts · 81 votes
13y
Definitely go belt and suspenders with these things - jack and posts. I also did as another experienced rehabber advised and also strapped the new beam to the joists during the process.
Shims, wide footprint steel plate, and take your time jacking it up (especially if you've got plaster in the house - if you don't give it time to adjust it /will/ crack.)
Worcester, MA · Member since 2012 · 145 posts · 6 votes
13y
What sort of footing should be placed under the new support beams? A 1 foot deep, 1 foot diameter concrete tube? A square footing? How deep will it need to go?