Sealant Replacement

Chips Off the Old Block

and other ruminations about masonry by

Larry D. Jenks

Sealant Replacement 

Missing, damaged, or deteriorated sealants in masonry work, and between masonry and adjoining materials, such as windows, door frames, and expansion joints, are fairly easy to see, and are a likely a source of moisture penetration. The sealant joints in these areas should be inspected carefully to discover areas where the sealant is missing, or was installed but has deteriorated, torn or lost elasticity (figure 1).

Figure 1: Cracked and missing sealant

Deteriorated sealants should be carefully cut out and the opening cleaned of all existing sealant material. You should use the least invasive method of cleaning the substrates as is effective in removing sealant remnants (bristle brush; wire brush;  powered wire brush; chemical solvents; grinder with metal brush; etc.). The clean joint should then be properly primed and filled with a backer rod (bond breaker tape if the joint is too small to accommodate a backer rod) and a full bead of high-quality, elastomeric sealant compatible with adjacent materials. The sealant bead should be carefully tooled to achieve a professional looking result.

To give you some idea of how long you can expect your sealants to last, here is a summary of performance for caulks and sealants by Bobby Corrigan, RMC Pest Management Consulting, Richmond, Indiana…

Life expectancy of Common Caulks and Sealants

If you aren’t sure what type of sealant you have at various locations throughout your building, the first place to look for an answer is the specifications prepared by the architect for the project. This won’t narrow down the actual brand of sealant, as that determination is usually made by the contractor from among several choices offered by the architect. But the type of sealant should be evident. If the specifications are not available, I would recommend contacting a sealant manufacturer, who should be able to help you identify various types of sealants (Dow; Prosoco; Pecora; W.R. Meadows, to name a few).

As the steward for your building, it would be prudent to remain mindful that there are many forces at work on your building’s sealant and mortar joints, that could eventually lead to failure. These include: 

1. shrinkage/restraint

• drying shrinkage 
• temperature changes
• carbonation 
• restraint 

2. differential movement 3. excessive deflection 4. structural overload 5. differential settlement6. and even living pests 

So, in my opinion, it would be best not to wait 20 years to make your first examination of sealants, including those that may not be easy to get to.