During the Masonry Workshop I attended, there was a mention of a website where you could get AutoCad details of for masonry. What was that website?
A good source of details is the National Concrete Masonry Association's (NCMA) website. Other websites that offer good information on masonry construction details is the International Masonry Association (IMI) and the Masonry Contractor's Association of America (MCAA). For Clay Masonry you want to visit the Brick Industry Association's (BIA) website.
On the NCMA's website the details and the NCMA TEK notes (another great source of info) are housed under the "Solution Center" button. All of these websites are great sources of masonry details and Info.
A school gymnasium was built with concrete masonry and direct applied stucco. It experienced leakage and so they put a stucco on lath over the direct applied stucco. They are now experiencing more leakage and are wondering what they can do.
There are two completely separate issues created by the stucco over lath added to the structure. The first and most important issue is the nature of the fasteners used to attach the stucco on lath to the structure. The fasteners should have been stainless attached through the existing stucco into the masonry substrate. Since the structure is leaking again it can be assumed that the drainage plane between the two coatings is holding water. If the fasteners were not SS then there could be problems with corrosion.
The second issue is the leakage which, if the new stucco on lath has been properly fastened to the masonry substrate, is a matter of completely sealing all cracks and control joints and giving the stucco a few new coats of acrylic paint.
Does the backer rod have to be larger or smaller than the joint that is being created?
Backer rods are important to prevent 3-point bonding at the crack in the back of a joint. Also, they control the amount of caulking that a joint requires.
For expansion joints the backer rod should be just large enough to fit snugly into the control joint (which should be 3/8" for CMU walls). There should be about 1/2" of depth from the backer rod to the surface of the masonry wall. The backer rod should be snug enough to stay in place during caulking of the joint.
Jerry Painter, FASTM
Don Beers, PE, GC