parging a site block wall 1

[samdamon]

Gents-

I am designing a site retaining wall of 8" block that in plan describes a shallow arc about 30' long. Retained height is 4 ft or so, and the block is designed as a vertical cantilever, reinforced with vertical bars with all cells generally grouted solid. The block will project above the retained earth about 3 feet. Am specifying a vertical expansion joint in the block at 15'. Would like to finish the exposed faces of the block on both sides with a solid cementitious finish but am unsure what to specify.

An old PCA manual I have suggests a two coat stucco system for concrete masonry, without mesh. My impression from looking at a few older existing block walls is that mortar joints will eventually reflect through stucco via hairline cracks. The cracks catch dirt and water and the wall eventually starts looking somewhat ugly. I would normally just be happy if the wall works properly and doesn't move, but this particular client is going to be sensitive to appearances.

Is there a good way to minimize cracks in the stucco on both sides? There will be a vertical exp joint in the stucco to match the one in the block. I would think including the mesh could help limit reflected cracks, but perhaps this is not a good idea in a site wall exposed to weather on both sides. Have no experience either way. Am assuming that stucco on the "high" side of the wall will only extend a few inches below top-of-grade el.

Any comments or experience welcome, thanks.

 

[JAE]

A company called STO and one called Thoroseal each have products that are stucco-like - check them out and perhaps call their technical reps to cover the joint reflecting issue.

http://www.stocorp.com

http://www.thoroproducts.com/product_detail.asp?product_id=T501

 

[Ron]

I agree with JAE. There are numerous products on the market to do what you want.

You are essentially looking for a PB-class Exterior Finish System. You obviously don't need the insulation that comes with an EIFS; however, most EIFS companies (STO, R-Wall, DryVit, etc.) have a direct applied system, and in your case you want the "flexible" one (PB), since you have a concern about the reflection of mortar joint cracks throught the finish.

Absent that, a good quality elastomeric coating would suffice.