Sealant Inspection and Maintenance
Start with a thorough inspection. Occasionally there are circumstances when immediate action is necessary, such as when joints have been breached and are allowing water and/or air leakage. In these circumstances, contractors should be up to date on the best way to perform maintenance on these important building elements.
Documentation and ChecklistsBefore beginning any repairs, inspect the entire structure for problems and document what you find. Often a sealant failure can be attributed to an issue that could be several feet away or even on another portion of the wall.
Start by creating a simple checklist. On each wall or surface examined, note the site’s general condition. If there is a problem, try to assess if it is a structural or waterproofing concern. Does the joint of the wall panel or fenestration appear to be sound and in-line? Is the condition of the substrate and the joint sealant bead sound and free from breaks? If a condition is found, take note of water leakage, efflorescence, cracking, and any evidence of previous maintenance or repairs. Also, notate the location and approximate linear footage of the issue.
Why Joint Sealants May Need Maintenance
There are three basic ways sealants fail:
1. Sealant Adhesive Bond Loss – When the sealant has separated cleanly from the surface of the substrate, a gap may appear. This condition indicates the adhesive bond has been lost.
Pay close attention to the substrate. Sealant adhesive bond loss is commonly the result of improper substrate surface prep, substrate contamination, or poor application procedures. Sealant performance is very dependent on substrate preparation.
Bond loss is not always attributed to poor workmanship. Sealants do not necessarily bond to all materials equally well. Sealant-substrate incompatibility may result in sealant adhesive bond loss.
2. Sealant Cohesive Tearing – If you see a split or tear occur within the body of the sealant bead, the failure is due to excessive or restrictive movement. This split is often parallel to the length of the joint, extending through a portion of the bead, or in severe cases along the entire bead.
Sealant cohesive tearing can result from improperly installed sealant. But more commonly the failure is caused because the joint movement is greater than the movement capability of the sealant. Excessive movement can be the result of poor joint design, improper sealant selection, or joint widths that did not meet the design specifications.
3. Substrate Failure - when the substrate ruptures or degrades at or near the sealant bond line, it’s an indication that the adhesive and cohesive strength of the sealant was greater than the cohesive strength of the substrate. Normally the sealant remains adhered to the substrate unless the substrate separates from itself.
This failure is often misidentified as sealant adhesive bond loss, so take the time to closely examine the bond line. You’ll know it’s substrate failure if the substrate is embedded in the sealant surface. Prolonged water exposure and/or freeze/thaw cycles can often be the cause of this condition.
Choosing the Best Approach for Joint Sealant Restoration
When working with building owners be cautious about proposing the extent of a joint restoration project. Carefully document your site examination, and review why the joints need restoration.
It may be wise not to begin restoration efforts until other building defects are corrected. Often joint problems are not related to their installation or sealant properties. There could be structural issues causing unplanned movement. There could be moisture penetration issues from plugged weeps, faulty flashing, or façade damage. And there could be other issues like leaking windows, or excessive condensation. These issues must be resolved before joint sealant restoration begins.
When the majority of the joint seals are in good condition and there appears to be no structural issues, consider spot repairs. It’s an economical approach especially when you can accurately assess the type of joint sealant failure. The spot repair approach addresses the areas of failure only.
But when the general condition of the sealant is nearing the end of its service life, or your examination finds a large number of joints needing repair, you should suggest a total restoration.
Before you begin, it’s important to review some important decision factors to estimate the scope of work and order adequate sealant. Conditions may have changed since initial construction, suggesting that the sealants originally used on the structure may not be the right ones now.
A custom color, matched to the existing color of the substrate or the existing joint sealant, may create more desirable aesthetics. Often the building substrates and/or the existing joint sealant’s color has shifted from its original appearance due to normal weathering and various other factors.
Avoiding façade staining
On some older structures, you might see staining, streaking, and dirt pick-up problems on the façade that are in contact with some sealants. Occasionally the plasticizer chemical within the sealant migrates from the bead and is absorbed by surrounding materials. This chemical reaction normally doesn’t affect bond strength but does make a joint look poor. If you discover this situation, ask the manufacturer to try a lab test to determine a sealant’s propensity to stain any given façade material. The lab test isn’t always a true indicator, but it might help avoid the problem after restoration.
Test for substrate-sealant compatibility
Weathered materials react differently with sealants than they did when first installed in new construction. Test materials that will come into contact with the sealant, being sure there are other no adverse reactions nor loss of performance properties. You may need to opt for a primer or special surface prep to ensure proper adhesion.
Measure the joint widthUse a gauge to verify the joint width. There could have been movement that may have changed the original design. Or during restoration, workers may have widened the joint during surface prep. Be sure to select a sealant that can accommodate the expected range of movement following the restoration.
Select the right sealant technologyDepending on the age of the structure, there are many new products to choose from. There may also be more than one sealant choice for any particular application that can be more economical or longer lasting. Check in with your White Cap experts for help in selecting the right sealant technologies, such as urethanes, silicones, kraytons, butyls, acrylics, and pre-compressed, impregnated foams.
And when possible, try to apply the same chemical type of sealant to the restored area. As a general guideline, silicone sealants should be used to repair or replace silicone sealants. Urethanes should be replaced with urethanes. But certain conditions might call for other options. For example, a pre-compressed self-expanding, flexible, polyurethane joint sealant might be a good choice when you’re sealing against wind-driven rain, sound, and dust. Another consideration might be a dual-sealed joint.
Your White Cap Account Manager can help you through the selection process, and provide the right sealants, supplies, tools, and safety equipment to complete the restoration project effectively and safely.