The contractor wants to use a split face unit for the single wythe load-bearing walls of a small building with two ADA restrooms and a small storage room for a private park. The building will be ventilated only. My concern is moisture intrusion into the interior spaces. The walls are not insulated.
Will a waterproofing coating at the exterior and the use of a waterproofing additive to the mortar keep water out of the wall system?
Is there an additive that can be added during the mixing and forming of the wall units?
Some think that a single-wythe CMU wall cannot be effectively built to repel moisture. It can. I am attaching a NCMA TEK that can be very helpful. Water repellant is typically put into architectural CMU as a standard procedure especially if the units are colored. You MUST add the repellant to the mortar also. When this is done and you add a compatible flashing at the base of the wall. you should have the wall you are trying to get. If you want to stain or paint the wall I would suggest an elastomeric coating as it will bridge any small voids. You should contact Lisa Pelham (813-255-4737) @ Oldcastle or Daryl Gorenflo (407-280-1487) @ A-1 Block. Either are more than willing to help you, TIf I can also help I'm in Gainesville. Call me. Be safe.
Jerry Painter, FASTM,CGC, SMC
It is our understanding that the current best practices for Central Florida residential subcontractors is to install inspection holes at filled cell locations, and not perform consolidation of grout. Is this allowed by the code?
Also, what is the standard method of determining if all of the cells were completely filled with grout?
MAF Response (Jerry Painter):
The inspection holes are to make sure the base of the CMU cell is clear and that the masonry grout reaches the bottom. The requirement for consolidation and re-consolidation is not forgiven any where in the structural masonry code, TMS 402/602.
Sounding is one way to determine solidity. I feel a lot more comfortable with thermal photography if you can achieve the temperature differential and access to the wall. The MAF has a Structural Masonry Workshop we do 4 times a year. Last year we did 2 in Broward County for their Building Officials, Plans Analysts and others. Maybe we need to do a better job in Central Florida of reaching Code officials.
MAF Response (Don Beers):
I just wanted to concur with Jerry on the requirement for consolidation and reconsolidation in both commercial and residential construction built in accordance with the Florida Building Code.
The code requires a minimum 3"x3" cleanout for all wall over 5'-4" in height but, as Jerry pointed out, this requirement has nothing to do with consolidation of the grout once it is in place. The problem with residential construction is there is usually no inspection on the job during grout placement so the inspector uses the cleanout as a means of determining that the cell was completely filled with grout. Unfortunately, just because the cell is filled at the bottom does not mean that the cell is filled all the way up with no void areas. Careful sounding of all grouted areas of the wall is a standard method of determining whether void areas are present in the cell, however, again as Jerry pointed out, thermal imaging is a more accurate and preferable method.
I would also recommend a review of the delivery tickets for slump and times to determine if a potential problem is obvious. The grout should have been fluid (8" to 11" slump) and placed within 90 minutes of batching. This might help inform you as to the method used to determine whether all cells are completely filled.
Jerry Painter, FASTM
Don Beers, PE, GC