Norbert Krogstad, principal at Wiss Janney Elstner Associates Inc., in Chicago, was recently honored with the ASTM International Award of Merit. Here's a look back at his expert answers to five frequently asked masonry questions, the most read Q&As on the Masonry Construction website.
4. Q: I am a structural engineer in an architectural/engineering office. A contractor has asked permission to use automotive antifreeze in mortar during cold weather, claiming it is a common practice. Our response has been to deny permission because ASTM requires "clean" water. Do you have any information on this practice? What are the effects on the masonry or mortar?
3. Q: I recall that earlier versions of the Brick Industry Association's Technical Note 28B recommended that mortar should be Type S for brick veneer over steel stud back-up walls when wind loads exceed 25 psf, and that only portland cement-lime mortars should be used. I noticed that in the December 2005 version this language was modified. Now it states that Type N mortar is recommended with Type S as an alternate.
1. Q: Many buildings use steel wide flange beams as lintels in larger masonry openings that have a plate welded to the underside to carry the exterior wythe of brick. Since the steel plate is exposed on the outside and on the inside, this would appear to create thermal short. Is this a problem in cold weather?