Let make a few comments about the detail. The flashing, drip edge and weeps are essential parts of the detail. The following figure shows the recommended detail.
Finally, there is the use of mortar or caulk at the sills. It creates one more barrier to moisture and deicer intrusion at grade. In general, this is a good idea for architectural veneer. You also mentioned using a post-installed water repellent. Many highway departments have used CMA formulations for years. These deicers do not have chlorides and reportedly are less harmful to concrete and masonry and not harmful to plants. An alternative deicer that is available uses calcium magnesium acetate (CMA). While chloride-based deicers are rated as the most effective, they are also the most damaging to concrete and masonry and adjacent greenery. Deicers come in different formulations, usually containing a chloride. Deicers should be avoided or used sparingly. If possible, snow and ice removal could be followed by sanding rather than deicing. Precautions can be proposed to mitigate the possible problems. However, the reality is they are used and the masonry will be negatively impacted, both the mortar and the units. Preferably, no masonry wall should be exposed to deicers. Additional guidance comes from NCMA TEK 5-1B, Concrete Masonry Veneer Details which recommendations Type N mortar more for flexibility. Again, resistance to deicing salts is not mentioned. Type N is a suggested alternative. However, ASTM does not address mortar selection for the condition of using deicers. ASTM suggests Type S for masonry at or below grade. Designers usually take mortar type recommendations from ASTM C 270, Standard Specification for Mortar for Unit Masonry. Table X.1.1 Guide for the Selection of Masonry Mortars. #Masonry stack bond in seismic category code#
Is there a right answer?Ī: Thank you for the question! There is no “right” answer because there is no code item that specifically addresses the use of deicers adjacent to a wall. We can offer and opinion and some information that you the team can use in making a decision. The only point I won was to use a post – applied clear water-repellent. I thought T ype S mortar was more appropriate for the veneer and sill.
The mason want s to use T ype N mortar for the veneer and sill and caulk the mortar at the sill. There will be a sidewalk alongside the wall and the architect said the owners will be using salt deicers during the winter. The w indow openings will have CMU sill s. The veneer will extend about 2 feet from grade above the wall will have EIFS installed over the CMU backup. The masonry wall s are to have a cavity wall of 4 -inch architectural CMU veneer with a CMU backup. I just left a meeting with a mason and an architect where we had a discussion on mortar types.
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