Grassroots Garage sill replacement

What's up hive, looking for some advice on replacing the sills in the garage I'll soon be taking over. During the inspection and all times we were at the house, the garage was dry even when it was raining. After getting into the house, I started digging back the dirt that was above the slab. I've clearly opened a can of worms, as now there's water in the garage. Ha!

Anyway, clearly they need to be replaced. What I'm a little worried about is that I think the current slab is sitting on top of another, and the sill plates are based on that lower slab. I'm not too scared of digging out and jacking up the garage, but in replacing the sills I don't want to immediately set them back down on/in the dirt. Is there anything I can do (other than get gutters)? The garage is about 20'x19'.

Any other tips or tricks to getting this done? I'm more of a novice around wood, with limited fear of failure and a need for this to be done in the next week or two so i can move my garage from the current rental house to our new house.

I'll try to get more pictures in the next day or two.

Could you raise the structure 1', and pour a concrete "foundation" wall around the bottom?

I have no idea if this is even logical; I'm talking out of my bum.

So...just to be clear....you're getting water intrusion at the bottom of the wall where it sits on the slab, right?

Dig a trench a few feet deep along the wall and fill it with gravel for drainage.

The sill itself should not be holding water back. That’s a recipe for disaster. You need to keep water from being up against the sill in the first place. Either through excavating and improving the slope around the garage or improving the gutters or something. 914s idea about the gravel is a good one and gives you a logical place to keep weeds away from the building. 

...and won't splash mud on the building.

ultraclyde said:

So...just to be clear....you're getting water intrusion at the bottom of the wall where it sits on the slab, right?

I believe so - I haven't been there when it's rained to see where the water comes in, but it only started coming after I dug out the outside and probably nicked the wood in a few spots. 

In reply to 914Driver :

Gravel is a good idea. The yard is high in a few spots, probably related to the two huge trees in the yard and the last owner being there ~50 years. We had planned to dig back some anyway, so adding gravel would be a good measure to try and keep water draining. 

When I was digging back on the outside, I did find concrete ~6" down, and 6" out from the current edge - that's what is leading me to think there's a lower slab that all of this is sitting on.

One more question, since I'll be doubling up on 2x4's to get the right height, does the stagger matter? The garage is ~20' deep, so I had thought I would do an 8' and 12' length to stagger the joints. 

If your going to install a sill board I would go two layers of 2X4's of the lengths you mentions and overlap the joints so the sill becomes one piece if you nail them together before you install it. And you are planning on using "treated" wood?

There's always the option of lifting the garage, running a couple of courses of block, and setting the garage back down onto the new knee wall.

Have you looked at the sill - is it rotten? Just water coming in is not a sign of needing a new sill, at all. Water should not be there. If the existing sill is rotten, yes you need a new one, but if the water problem isn't fixed you'll be facing replacing it again in a few years.

I'm with the other guys - water shouldn't be getting TO the sill in the first place. Exterior walls should be built at the outside edge of the slab and then siding should cover the transition from wall/sill down over the slab. I think what you really have is a drainage problem that has caused soil to stack up against the shop, effectively putting it below grade. If it were deeper I'd think about lifting the wall and putting a block run under the sill, but you're not that deep. I think that analyzing the water flow on the property and then installing french drains to carry the water away to the correct drain point is a better answer. Along with some reshaping (digging out) of the grades around the shop. Of course, this is speculation without really seeing the property.

Hopefully adding a few pictures here will help elaborate. 

I believe the sill is sitting outside the "outside edge" of the garage - on a slab beneath the slab I am seeing/standing on. I'm looking at the gap between the sill plate and the edge of the visible slab in this picture - you can see where water is coming up/in on the left edge.

Next pic shows the oustide of the garage - you can see that the "upper" of the 2 2x4's here is the one that's visible in the garage (different spot along the wall but still), and the lower one is sitting on concrete with the shovel, to show depth. 

and for good measure, a picture of the grade

I do think French drains would be the way to go, I just don't know where to have them drain to - people usually tie them into sewer/wastewater lines, no? We just had the yard dug up to run the power feed to the garage, and we had planned on trying to remove the topsoil anyway to lower the yard as much as possible on the side/back of the garage at least.

The sill is not meant to hold back water at all, and it sounds like the walls are set on a foundation with a poured slab inside of it ( I can't see the pics for some reason) that's fairly normal.

If the sill is rotten replacing it with pressure treated is a good idea. If it's not just regrade as much as possible away from the garage with gravel in a trench around the outside. 

My bad, I need to make the album public.

I do plan to regrade some and do pressure treated, just didn't know if I was missing a better way. Sounds like adding gravel or a French drain is the better way!

classicJackets said:

ultraclyde said:

So...just to be clear....you're getting water intrusion at the bottom of the wall where it sits on the slab, right?

I believe so - I haven't been there when it's rained to see where the water comes in, but it only started coming after I dug out the outside and probably nicked the wood in a few spots. 

In reply to 914Driver :

Gravel is a good idea. The yard is high in a few spots, probably related to the two huge trees in the yard and the last owner being there ~50 years. We had planned to dig back some anyway, so adding gravel would be a good measure to try and keep water draining. 

When I was digging back on the outside, I did find concrete ~6" down, and 6" out from the current edge - that's what is leading me to think there's a lower slab that all of this is sitting on.

 

One more question, since I'll be doubling up on 2x4's to get the right height, does the stagger matter? The garage is ~20' deep, so I had thought I would do an 8' and 12' length to stagger the joints. 

That concrete out and below is your footing, not another slab

I'm gonna bring this back up cause I actually have time to try and fix this this year.  I do need to put gravel down along the outside edges of the garage, but I think the next step will be replacing the (even more rotted) sills.

Are there any "easy" ways to do this? Or is it legit just jack up the walls and get the new PT 2x4s under?

I'm also hoping add some shelves along the back wall, width of the garage. I imagined running a 2x4 the width of the back wall on top of the header, a 2nd spaced out one Joist, and framed up to the joists in the meantime. Pictured below.. Anyone have better ways to do this? Since the garage isn't finished, tying these things in at 10' high shouldn't be too bad. I do need to add studs, as some of them are currently up to 32" on center. Wild.

Oh Boy...  Looks like a shed was built with a dirt floor.  Then at a much later date they poured a concrete floor.  Meanwhile, outside some little trees grew up to be very big.  That effected the drainage and soil accumulated over a long time up along the walls.

There are always threads here where folks complain about contractors doing site surveys and then going away and not ever hearing from them again.  As a contractor, if I drove up to this... I would be tempted to run.  Why? because the effort to solve all the problems could far outweigh the value of the building.  And, I wouldn't want to upset the owner with an estimate.  Easier to just drive away...

The big trees are the problem.  They were not a problem 50 years ago, but they grew up.  They changed the original drainage  situation.  French drains are going to be hard to install with massive tree roots all around the site.  To save the old structure as is you would have to eliminate the trees and re-sculpture the terrain to drain properly.    Else, its brace the structure and jack it up and run a few courses of blocks to set the building back down on.  Then try to waterproof the exterior of that block stem wall.    

As a contractor, i glance at it and say put the old building in a rollback and start over and it will be cheaper.  It's not like the structure is built close to any modern codes.  That solution totally freaks out the owner.  But at current labor costs, its realistic.

As the homeowner who is on a budget... you may want to invest some sweat into the project.  You could try digging away all around.  Improve the runoff.  Put gutters on to direct the roof water far away.  And replace the sills with PT lumber and rock on.

Didn't mean to rain on your parade.   YMMV.

My dad and I did this exact thing years ago on my first house. This was a fixer-upper house with a very poorly built garage that had termites in the bottom sill plate. Since I didn't have a lot of money I had to save the garage instead of rebuilding.

My dad was a jack of all trades and this is actually the second time he did something like this. First order was to reinforce the corners with plywood. Then we got four floor jacks together and with four by fours on the Jack we raise the garage by lifting on the upper wall plate (I think that's what you call it). 
 

Once the garage was up in the air we cut off the sill plate and some of the 2 x 4 walls that were damaged put another block underneath it ( it was sitting under grade so no wonder it had termites.) and a new sill plate and replace the two by fours set it back down and squared it back up.

I had to modify the garage door opening to make up for the difference in height but I can't remember exactly what I did. 
 

The garage is still standing some 25 years later but no surprise the new owners did replace the garage door.

I fully appreciate both responses! Always nice to hear experiences and what should be okay enough to "get by", as the space we have would never be worth the cost of a new garage and we love the trees..

Brought home some PT for the worse sides sill plate today, and a small stack of 2x4s to get something closer to 16" on center for the back wall.. may do some parts of the wall that needs the sill replaced as well, to try and add some structure!

Other next steps are going to be to get a few yards of gravel delivered so that I can lay that around the garage instead of attempting a French drain - hopefully lots of gravel + sand will give a good enough drainage path for water to stay away from the garage!