# Stone foundation repair in Philadelphia



## cb_philadelphia (May 14, 2016)

I live in a Philadelphia row house in center city (built ca 1860). Have noticed in last year or so an increasing moisture problem in the basement. The foundation also seems to have some structural issues because there are signs of movement on the front wall (horizontal crack in brick facade, uneven floor joists) and side wall that are not attached to a neighboring house (cracks appearing inside the house at seams where walls meet ceiling/floors).

After lots of reading and watching endless youtube videos on basement waterproofing I think that there are a few steps I need to take to secure the foundation and eliminate water issues before I attempt to refinish the basement or do any floor leveling and refinishing on above ground floors.

* 1) Eliminate any sources of moisture entering the structure above grade.* For example, ensure all windows are properly caulked, roof has no minor leaks, etc.

* 2) Ensure proper drainage on exterior.* The front downspout flows directly into a drain pipe that connects underground to the sewer line in the street. The drain at the rear corner of the house ties directly into the main waste pipe that runs inside the basement. The rear downspout flows directly into this drain. I have to fix a bunch of cracks in concrete in back patio that are allowing excess water from hard rains to drain into the ground around the house instead of into the drain pipe. I also need to ensure that none of those underground pipes have cracks in them (they are quite old).

Assuming I take care of 1 and 2 properly, I think there is work to do to fix the foundation -- *looking for your help / advice on what's required*

Foundation is showing signs of deterioration and moisture issues:

 Flaking and sloughing off of outer layers of parging that have been applied over the years (2 parge layers, see below)
 Lots of sand and other materials accumulating on perimeter of basement floor
 Efflorescence and general dampness in many areas
 Horizontal and vertical cracks in inner layer of parging

There appear to be two layers of parging over the original fieldstone or rubble stone foundation:

a) inner most layer is 1-2" thick in places (see photos) and appears lighter whitish-gray. Looks as though it was installed over the original stone foundation instead of re-pointing areas where mortar may have deteriorated from the original foundation. I can see cracks that have been "self healed" in this layer of parging when i peel back the outer layer in places. I notice lime 'blebs' in this inner layer, which fizz up when vinegar is applied. I will say that this layer is still quite hard and requires some serious effort to remove where it is quite thick (see some chisel marks in the second photo below)

b) outer most layer is only 1/4" thick and is a darker gray in color. I believe it was applied by the previous homeowners about 10 years ago. It appears not to be lime-based. I don't notice any lime 'blebs' in the materials nor does it fizz when I put the material in vinegar. Seems like a crappy slap job meant for aesthetic but likely did more damage than good by an inexperienced contractor

(search youtube for "Is it Lime or Cement Mortar" for the tests I used)

I am thinking that the following is the best course of action, but would love to get others' opinions:

* Divide foundation wall into a set of 4' sections labeled A, B, C, A, B, C ... and so on. Then start in the A sections, remove two outer layers of parging, scrape out loose mortar in stone foundation, and then repoint with NHL 3.5 based mortar. Move around the foundation doing all of the A sections. Then move to the B sections, complete those, then move to the C sections and complete those. *

My thoughts behind removing both layers of parging instead of just the outer layer: I'm guessing the underlying stone foundation is in bad need of repointing because the original mortar has deteriorated to the point where stones may be shifting ever so slightly and that is what is causing the bulging foundation walls and movement in the upper walls of the house. * Would you come to the same conclusion?*

Once the foundation is repointed and returned to a state where the materials are fully breathable, I should be able to waterproof the basement using a pressure removal system (e.g., a french drain and sump pump) before finishing it. Or would you advise against it?

So to recap, my main questions are:

1) What's your assessment of the composition of the foundation?
2) Would you do anything differently to restore and repair the foundation?
3) Would you proceed with finishing the basement once the foundation is repaired and a pressure relief system installed?

Thanks for reading and look forward to hearing any comments you might have.

CB


** Photo descriptions **
1 - View down side wall where building abuts neighboring house, notice bulge in foundation
2 - Investigating foundation wall, notice three layers
3 - Another view of the three layers of the foundation
4 - Efflorescence on rear wall of foundation, notice the line where it stops which is approximately where grade is on the exterior
5 - Flaking off materials on the front wall of the foundation
6 - Shot down the front wall - you can see a bulge in the lower portion which is the foundation. Notice the ledge where grade is and the foundation stops. The parging continues up onto the wall above grade, too


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## cb_philadelphia (May 14, 2016)

Additional photos:

1 - more efflorescence and deterioration of parging on front wall
2 - deterioration on side wall opposite from where I did the investigation digging in previous photos
3 - piece of inner layer of parging in vinegar
4 - piece of outer layer of parging in vinegar


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