Expert: Bruce E. Johnson - 10/26/2009

Question
In the Lake Chapala area of Mexico, a common problem in nearly all buildings is the spalling of both exterior and interior concrete walls. It appears that ground water is wicking up into the walls. What can be done during new construction to prevent this? How can this be repaired so that it isn't a continuous repair problem? It does not freeze here.

Answer
Hi Rick, the best way to prevent moisture penetration is to stop it at its source which is the exterior of the building.  By using waterproofing coatings on th walls below ground level and by installing vapor barriers underneath the concrete slabs you can stop this ground water penetration.  A good footing drain around the foundation will also help keep the water from building up around the building and forcing itself through the wall masonry or concrete.  As far as wicking of moisture goes, a good penetrating sealant or elastomeric paint applied properly will keep the water from getting inside the wall from above grade..There are also ways to add waterproofing to concrete during the mixing process using additives and air entrainment. You might check with your concrete supplier to see what is available in your area.  I hope this information helps, feel free to write again regarding this or other matters, sincerely bruce e johnson..bejohnsonconsulting.com