Rotted Sill Plate Options

[Fortress68]

Bottom Line Up Front: I am wondering if I should simply replace what exist with Pressure treated, cut studs shorter and then lay a course of block and replace plates on top, or lift the garage laying block and replacing plates then sitting garage back down on top.

Long version:
I have termite/water damage that has ruined the sill plates on my 1950s garage that was extended backward in what I assume was the 1970s.

The spaces have since been joined together under a single refinished roof with a small yet livable mismatch in slab height. The newer set of sill plates are 2x4s n the rear space, and the older sills up front are a true 4x4”. Both are installed in direct contact to their corresponding slabs, which lie about even with grade, the older portion in front terminating with a 8’ garage door at the same grade as our concrete driveway.

I know I can simply cut out and replace what is rotted with PT and that will suffice for a while. I also like this route because it is simple and quick and gets me back to working in instead of on my garage.

Another option would be to cut studs short and install a course of concrete block and new sill plates in a newly elevated position. This option allows me to get the sills up and off grade offering some more protection, and wouldn’t change the look of the outside of the garage at all. It is complicated solely by the complexity of securing the course of block properly and supporting lid bearing portions of the wall (which are currently also on rotted plates, so not a huge concern)

My third option, short of demolishing everything a repouring a new slab and installing a new building, is the lift the entire garage, lay a course of block, and reinstall new sills on top, adding the height of the blocks to the total garage height. This would normally cause issues with doors, but I foresee having to replace all of those now, so a reframe wouldn’t add much more difficulty in the exposed framing style of my garage.

Additionally, I would be ok with the outside appearance of a course of exposed block around the foundation, so I don’t think it would necessitate a change to the existing vinyl siding outside of the pieces over the existing door openings.

The complexity from the third option, in addition to those from option two and the ones mentioned above, is that my garage is full of projects and tools, which would likely need a new home during the work. Also, raising a building, even an 18’ by 30’ open framed one like mine, is no doubt a lot of effort and work.

So, I guess my question is, what would you do?


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[couch67]

I'd likely replace the rotted pieces and call it day. They have held up 60+ years so you should only have to do it once. Can you change the grading to get yourself a few inches of space between the ground and the wood? Also do you have gutters - they help with keeping water off the foundation.

 

[Fortress68]

I'd likely replace the rotted pieces and call it day. They have held up 60+ years so you should only have to do it once. Can you change the grading to get yourself a few inches of space between the ground and the wood? Also do you have gutters - they help with keeping water off the foundation.

I can likely change grade around most of the foundation, but the front is partially on grade with the driveway, so rain stacks up despite a sewer drain being five feet in front of the wall.

Interestingly enough however, even though occasionally water will come into the garage under the plates there, they show no signed of rot in the a spot.


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[Copymutt]

The spaces have since been joined together under a single refinished roof.

Third option would cause a roof mismatch if I’m understanding correctly. For that reason alone I’d rule it out.
Sometimes the easy way out is the best.

 

[Fortress68]

The spaces have since been joined together under a single refinished roof.

Third option would cause a roof mismatch if I’m understanding correctly. For that reason alone I’d rule it out.
Sometimes the easy way out is the best.

That’s a great point... I hadn’t thought about the added complexity there. Secretly, I would have loved to go with option number three, but I think that combined with the innate complexity of the operation rule it out.


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[rsanter]

For me....
Option one would be to shorten the studs just a little to replace with double pressure treated base plates. This would eliminate the issue of the different thickness pieces plus if you find any rot in the end of the studs.
This would also allow you to raise the garage later and set on a course of blocks

Option two...
If you want or need to raise the garage, if this would really benifit you then I say go for it and do that now.
Kind of the tear off the bandaid approach

 

[matt_i]

If you can source UC4B rated 4x4s for your treated timber replacement, it should easily outlast any of us here. (I'm envisioning your sill plate as the bottom plate of a stud wall.)

That's what I would do in your shoes.

Raising the walls and installing block is a longer-lasting solution but imo you'll be doing that for someone else.

 

[theoldwizard1]

I know I can simply cut out and replace what is rotted with PT and that will suffice for a while. I also like this route because it is simple and quick and gets me back to working in instead of on my garage.

That is what I did. You don't even have to completely lift the wall off the plate. Just use a sledge hammer and knock the new one in place while it knocks the other one out the other side.


I would be more concerned with termite damage on the studs.