How commercial caulking is done

It depends on the product. Standard polyurethane joint sealant typically gives seven to ten years in exterior service. High-performance silicone commonly reaches fifteen to twenty. Exposure matters: south and west elevations and joints in full sun fail first. Rather than replacing on a calendar, most owners survey the envelope every few years and act when adhesion testing shows joints letting go.

Published per-foot rates run roughly $4 to $12 for exterior wall joint replacement, $7 to $18 for expansion joints, and $10 to $16 for window perimeters at elevated access. Total cost depends far more on access than on footage: rigging a swing stage or renting a boom for a tall elevation can exceed the sealant line. A real number requires a joint survey.

Not on exterior joints that matter. New sealant can only be as sound as what it bonds to, and old sealant that is failing takes the new layer with it. Proper replacement means cutting the old material out to the substrate on both joint faces and cleaning the surfaces. Anyone quoting a caulk-over on a building envelope is quoting a short-term cosmetic fix.

Silicone handles more movement, resists sunlight far better, and lasts longer, which is why it dominates high-movement and glazing perimeter joints. Polyurethane is paintable, less prone to staining porous stone, and cheaper. Choice comes down to expected joint movement, substrate, whether the joint gets painted, and whether staining is a risk. A survey should name the product and the reason.

Usually one of four things: the old sealant was not fully removed, the substrate was not cleaned or primed, no backer rod was used so the sealant bonded on three sides and could not stretch, or a product with too little movement capability was chosen for the joint. All four look identical on day one, which is why adhesion mock-ups and pull testing exist.

Sometimes. Sealant failure is a common cause of water intrusion, but water enters at one point and travels, so the visible stain is often far from the breach. Flashing failures, cracked masonry, roof edge details, and failed glazing gaskets all produce the same interior symptom. Spray testing before the work identifies whether joints are actually the path.

Mild, dry weather. Most sealants have a minimum application temperature around 40 degrees, and joints must be dry and free of frost. There is a second reason to avoid extremes: a joint is at its widest when the building is coldest and narrowest when it is hottest, so sealant installed at moderate temperature sits mid-range and is not stretched to its limit in either season.

A single elevation on a low-rise building is often days. A full envelope on a mid-rise runs weeks, driven mostly by how fast access can be moved rather than by sealant application. Weather delays are normal since joints cannot be sealed wet or below the product's minimum temperature. Ask for a schedule that separates access days from production days.