Weep Screeds and Moisture in the Plaster
When structures were originally plastered, the material was applied from the bottom of the freeze block at the top of the wall to the bottom of the foundation. Kind of like the picture you see here. Although the picture above is of a slab floor, plaster with a weep screed set to unfinished grade and an exposed aggregate concrete deck poured right to the edge of the plaster. At that time, foundations were generally sub-floor or piered flooring.
In the 1960’s concrete slab foundations became popular. Plastering all the way to the flat concrete floor allowed no way for the moisture to migrate out of the wall and created nightmares. Weep screeds became the Plastering Industry’s response to moisture migrating inside homes and ruining new carpets.
This picture is one of the reasons for building inspectors. Finish concrete is to be installed a minimum of 2″ from the bottom of the weep. What you see is a joint where the plaster is buried behind the concrete. That is how we know the plaster was applied first. The concrete was poured second.
The reason that the paint is delaminating from the finish coat and there is mold growing in the joint between the two is that the weep is collecting moisture from the wall, and there is no place for that water to go. The cracking at the base of the wall moving up is also a function of water pressure creating stress on the panel beyond it’s ability to resist.
If you have questions about this condition or other situations, call or email:
Bell Construction Consulting
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