Old detached garage – stucco and slab below grade
First a big thank you for this site and the abundance of information here. I have learned an incredible amount reading here over the last 6 months.
We recently moved to a new home near Oakland, California. The property has a detached garage in the rear corner that I intend to use as a workshop (mostly woodworking). The house was built in 1914 and I imagine the garage is also quite old. The structure has stucco over the original redwood siding and is built on a 5 inch thick slab that is currently ~18inches below grade on 3 sides. One side is a planter bed that has been actively watered for many years and as you can imagine there was significant damage to both the wood members inside and the stucco outside. I have since replaced the sills and reframed as necessary. I also have bids from plaster subs to tear out the bottom few feet of stucco, tie in nwe building paper, and restucco with a weep screed installed (structure currently has stucco down directly to the slab foundation as was typical).
What I am not clear on is how to proceed with the grading on the outside of the structure. I am in a unique scenario as the garage is right on the lot line, and as such my ability to modify the grade is limited.
I recognize that the “correct” solution might be complicated and that there is no easy fix for this. I am trying to toe the line between keeping it in scope/budget, but also something that has a shot at lasting. We bought this house with the intention of being here for a long time.
I have documented the current topography and my current thought for a solution here (I also attached a PDF for those who have trouble accessing):
https://pdfhost.io/v/tq5X4QOHo_Garage_Projectpdf.pdf
I also have a bunch of photos showing the situation here:
https://photos.app.goo.gl/G2CuwL5WntVD2rpy7
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Replies
A few new thoughts:
1) I just realized that if I put a retaining wall along the back of the garage I will need a drain on the backside of the wall, facing my neighbors house, wont I? I was thinking I could just have a french drain along my foundation, but after some more reading it seems clear i need drainage on the side of the wall doing the retaining.
2) With the above in mind would it be a bad idea to not have a retaining wall at all and just fill the trench with gravel wrapped in geo fabric?
3) My next thought was to use elastomeric paint on the section of stucco that will be below grade to help with waterproofing a bit. I can also have a couple vents into the wall cavity on the inside of the garage to promote airflow.
I didn't look at the links, but from what I gather you have a garage that has walls below grade that aren't designed to be below grade, correct?
You have two options:
1. Change the grade. Lot line will complicate this, but it's done all the time in zero lot line building in the city.
2. Change the wall. Support the structure, cut out the bottom wood portion and replace it with concrete. That'll need something to keep it dry, dimple mat?
3. Wait, 3 options? This one is wacky, and might not work, but let's think outside the box...If the wall is still sound enough to keep, it might be possible to just dig a few inches wide down to the footer, place a drain, then put in something like the corrugated metal used for shoring. That would provide an air gap and drainage.