Deteriorated Existing Brick Wall (Replace with CMU?) 5

[TroyD]

I could use some advice on a small remodel project I'm working on. Typical main street brick building circa 1900 in small town Minnesota. Single story, 24' wide. 12' clear height. 2x12 roof joists and 2x12 ceiling joists pocketed into the brick wall. Limestone foundation to frost depth. Contractor encountered some deteriorated/weathered brick along the foundation at one corner of the building, likely due to poor roof drainage and poor site grading back by the alley. Contractor is proposing to remove a portion (approx. 10 LF) of the existing brick side wall and replace with CMU block, or possibly 2x6 stud wall. I assume the CMU would require a sort of leveling pad to sit on. Would need to tie into the exist brick with ties or angles equally spaced up the length of the wall for lateral stability. CMU is typically reinforced with dowels in grouted cores lapped with foundation rebar, but that doesn't work here. No change in roof loading. What are acceptable methods for replacing existing brick like this? I'm meeting the contractor and mason on site tomorrow to discuss further. I have attached a sketch.

Any advice is appreciated.

 

[JAE]

Some thoughts:

1. If you replace the 10 ft. wall portion with the CMU, you must figure out a way to tie the top of the CMU into the roof diaphragm I would think.
2. This is assuming that the new replacement wall extends all the way up.
3. The stud wall is an option but would want to ensure that no moisture gets up into the wood from below...perhaps some type of vapor barrier under the bottom sill plate.
4. Would also want to ensure a good water resistant joint between the CMU and the brick - or the wood stud wall and the brick. Tough to seal with old, soft weathered brick.
5. The concrete leveling pad is a good idea for either type of new wall system.
6. If you do any repointing, be sure not to use "modern" hard mortar (Type M or S) with old soft brick. Should use a custom mortar based on sampled/tested/analyzed existing mortar or, at the least, use a soft Type O mortar.



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[hokie66]

I would lean toward replacing only the deteriorated clay brick area with new clay bricks. But if you are going to replace this section of wall full height, you could use grouted concrete block.

 

[dhengr]

TroyD:
I agree with JAE’s listing of important considerations for this rework, and will add the following. His item #6 is particularly important on the existing brick work, and you should also try to generally match the existing brick if you are just replacing some brick.
7. The limestone found. wall is, as likely as not, going to start falling apart when you start unloading and dismantling the brick wall above. So, you will likely have to do some work on it too. The poured conc. leveling beam on top of the found. wall is a good idea and should have some rebar in it.
8. Obviously, the existing roof has to be supported while you are removing the brick wall, and then, properly tied into the new wall, whatever wall material you use.
9. Correct the grade and drainage problems, so you actually start to solve/correct the old problem, not just build a new wall and leave the real problem as is.

 

[TroyD]

JAE, hokie, and dhengr:

Thanks for the great input! Here is a site photo showing the condition of the brick and the extent of proposed removal. The vertical crack visible on the outside could be a result of settlement caused by the roof runoff and drainage issues. Those issues will be corrected. The current plan is to replace brick full height with 10" or 12" CMU.

-Troy

 

[dhengr]

TroyD:
That vert. crack seems to be a fairly straight line and there does not seem to be much relative vert. movement btwn. the two sides of the crack. I would want to investigate that further and try to gain a better understanding of its cause or origin. Otherwise, the condition of the two wall surfaces does not look appreciably different. So, which is in the worst condition and really needs replacement? What is the material on the right, in the first photo, which looks like a stepped conc. found? Is that just some sort of parging to cover up the old brick near grade? It does appear that immediately above that material some different brick may have been used for an earlier repair. Mixing conc. blk. and clay brick, side-by-side at a vert. joint, is a tricky proposition because they expand and contract quite differently. In the second photo, the two brick wythes under the 8” conc. blk. does not make for a particularly strong/stable return wall.

 

[TroyD]

dhengr:
That is a parging repair on the exterior. The end wall is being demolished, and a 12 ft building addition is also proposed. I proposed that a CMU pilaster be added at the existing corner, replacing that mixture of brick/CMU return wall shown.

Here are a couple more pics. (Sorry for the large file sizes). The deterioration of mortar up the roof level is significant (likely due to water intrusion). Second photo shows some weathered bottom course brick that the GC is concerned about.

 

[hokie66]

I don't think there is much to save, based on your photos. Since there is new construction to come, knock it all down and start over. You've got crappy brick walls, 2x12 joists spanning too far. Not much worth saving. If you design and construct a whole new building, you can incorporate lateral stability, which you don't have now.