Below grade silll repair ?

[rjn2649]

The walls in my 1940's garage through the years have become, below grade because people thought if they raised the dirt around the garage it wouldn't flood. Can't make this **** up.
Current code is really limiting what I can do as far as fixing the issue properly so I have to live with a garage that gets wet at times.
I have replaced two sills with 4x4 treated. this is working where I can change the grade for better drainage.
The problem is my neighbours side. My sill is about 5" under grade, dirt is pilled against a wooden wall.
My plan is to rebuild the wall with a 6 x 6 concrete block for the first layer then a pressure treated 2x4 sill.
My question is mortar material. the blocks will have dirt against them that get wet and hold the water. I will be putting the blocks down on an existing slab. We can't change the slab, would if we could.
is there a special king of mortar that would be belter for below grade? I can pressure wash and clean the edge of the slab as needed.
Special paint/coating on the concrete blocks and mortar? How long for the morter to dry before putting the wall load back on?

Am I overthinking? (PROBABLY) The walls ands sills have probably been below grade since the 70's.

 

[BillK]

Is it wood or something else ? How far below grade ? Pictures ?

 

[Shiftless]

How did the dirt on the outside of the wall come to be above the level of the wooden sill? Have you lived there a long time and just never noticed that serious situation or ??

Regrade first. Then fix the sill. You’ll probably have to support the building from the inside section by section and cut out rotted sills and also sections of the affected wall studs.

 

[Superbowl]

Most any mortar is water proof, but after it cures you may want to seal it.

To fix your problem however, I would trench around the garage and fill with gravel after installing a membrane like roofing ice guard to the bottom of the walls. Hopefully you can trench or pipe to grade so the water naturally flows away. If a gravity drain is not possible, there are two options.

1. Dig up a larger area of yard and fill with gravel (cover with landscaping fabric and dirt to plant grass) making a French drain to hold rain water until it seeps into the dirt under the gravel.

2. Install a sump pump. Such sump pumps are best put inside the garage to keep debris out and protect from freezing so you will have to chisle a hole in the slab and go through or under the wall foundation so water from the outside gravel can reach the pump.

 

[rjn2649]

So, on two walls re-grading IS possible and has been done, by me. I do have an outside sump pump pit for flooding situations (maybe 3 times a year) I know inside is better, but the flooding is not a winter issue and pulling the sump pump in and out, while a pita, isn't the worst thing. The dirt packed up on the sides of the walls have been there 20+ years. I haven't been here that long. I did dig an area as a retention space that flows into my pit. Not ideal but it's the best I can do with the situation I think.
The side I can't really re-grade on is the neighbour. The garage wall is right on the property line, no longer allowed. the place next to us is a rental. The owner don't care, and the current tenants are polite, but lets just say, they are obviously renters.
The have 3 dogs, not really aggressive, but any work on their side has to fit in with their schedule. Anything I do on that side, I'll have to maintain, so how long it will be owned by the person renting it out? I have no control.
And yes, I have supported the walls from the inside when changing out the sill plate and will do the same when I lay the blocks.
I'll look at adding membrane to the side, good idea.

Also this project got started over 5 years ago! But life and a hoarding issue got in the way, Now that I can SEE the floor again...

 

[rjn2649]

And to add there are NO gutters, when the roof gets done, hopefully next spring, gutters will be added.

 

[Shiftless]

And to add there are NO gutters, when the roof gets done, hopefully next spring, gutters will be added.

I bet your lack of gutters, downspouts and tubing connected to the downspouts to take rainwater AWAY from the foundation is a big contributor to your rotted mud sills.
Try to get that done too.

 

[mm08822]

Grading away from the wall is needed. If grading possibility is limited, then you need to drain the soil by running run sleaved perf pipe sub-surface to carry the water away assuming you have a drop in elevation that you can daylight to.

Gutters will eliminate the splashing of roof water as it hits the ground next to the foundation/sill plate/siding. Each the down spout water should be carried away.

As for mortar, there are different Portland cement-based mortar mix types: N, O, M, S. The cement ratio is what's different. Type-S is common for load bearing uses and for below grade.
2 Parts Portland
1 Part hydrated lime
9 Parts sand

You should drill holes in the slab to accept re-bar dowels to help lock the wall to the slab. Fill the block cores with mortar. Also either add sill plate strapping into the mortar of J-bolts.