floor joist sagging

[fitnessguybill]

Hi,

I was hoping to get some advice/encouragement. I am in contract to purchase a new home.

The former owner was an older man that did a lot of home improvement projects.

It looks like he installed a swamp cooler, and it apparently sprung a leak. It looks like it was leaking for some time before it was noticed. I'm guessing he was away when it happened.

it looks like there is a sag in the floor where the leak puddled the worst. a 8 by 12 foot area.

My initial feeling is that this is a job beyond my knowledge, and I should run away quick. But it is a great house and ultimately would be worth doing the work.Here's my plan to fix the problem. And suggestions would be greatly appreciated.

1. I plan to pull up all the sub flooring in the affected area to expose the joists.

2. sister the joists that have a sag. (one side)

3. attach posts to the joists, and bury/cement into the ground (for stability)

4. Replace sub floors.

In my head this is a good solution. But I wanted to get as much input as I can before I begin.

Thanks,
Billy

[HayZee518]

how long are these joists? the ones affected. any long piece of lumber will have a crown in it that should be installed upward, not down. also the joists usually are supported on the ends either atop the bottom plate or sill or atop a wall plate as in floor/ceiling.

[fitnessguybill]

aprox 20 ft

[HayZee518]

normal new construction floor joists are 2x10x [whatever length] to keep from twisting X type bridging is installed between the joists every 8 feet of the span. The joists are installed 16 inches on center. The crown of the joist is installed upward so it there is any "sag" it will impart a downward and outward pressure from the center. It seems odd that a joist would sag - say - four feet from an end unless the joist was green and there were several knots in the board at that end. if you have access to the supporting beam, when you sister a joist, see if you can install a double wide joist hanger. this will support the ends and stop some of the twisting at the ends. Then use carriage bolts in a staggered pattern and bolt them up. Install bridging like I said above.

[fitnessguybill]

I will be opening up the floor after closing on the property on wed. I'm sure I will ba having more questions after that point.

[mrcaptainbob]

Same thing at my house. Did exactly as HayZee518 issuggesting you do. The worst part was unthreading the electrical and moving some hydronic plumbing out of the way. After sistering I still was forced into gluing leveling blocks to the sisters. For a subfloor I used double layer of 3/4 ply crisscrossed to each other and staggered seams. The floor is now solid as a rock. I anticipate it possibly lasting another 145 years!