In Plain English
Quick Answer
A flexible sealant squeezed into gaps between materials to block air, water, and drafts.
Definition
Definition
Caulk is a flexible sealant compound applied to fill gaps, cracks, and joints between building materials to prevent air, water, and pest infiltration. It is available in silicone, latex, polyurethane, and butyl rubber formulations, each suited to different substrates and exposure conditions. Proper caulking at penetrations, perimeters, and transitions is essential for weatherproofing and energy efficiency.
Context
Why It Matters in Bidding
Caulking is a small unit-cost item that appears across nearly every trade, so it is easy to under-scope and easy to leave gapped between subcontractors, creating finger-pointing and warranty risk at building joints. Estimators must define who caulks what in scope sheets, since the right sealant chemistry at penetrations and transitions determines weatherproofing performance the owner will judge.
Example
Example
A GC's estimator writes a scope note assigning exterior wall-penetration sealant to the caulking sub and interior trim caulk to the painter, closing a common gap that otherwise surfaces as a punch-list dispute.
See Also
Related Terms
FAQ
Questions Contractors Ask
Who is responsible for caulking on a construction project?
Responsibility splits among trades depending on location: painters handle interior trim joints, glaziers seal around windows, and a dedicated caulking or waterproofing sub may handle exterior control and expansion joints. Estimators should assign each condition explicitly in scope sheets so no joint is double-bid or, worse, omitted by everyone.
Does sealant type affect the estimate?
Yes. Silicone, polyurethane, latex, and butyl differ in price, movement capability, paintability, and substrate compatibility. High-movement structural or exterior joints require premium sealants and surface prep that cost more than interior latex. Pricing a generic tube where the spec calls for a specific ASTM-rated sealant understates both material and labor.
Why is caulking a common source of change orders or punch-list items?
Because it sits at the boundary between trades, sealant joints are frequently assumed to be in someone else's scope and end up unpriced. Missing or wrong-chemistry caulk then shows up as leaks or failed punch items. Clear scope division and a defined joint count during takeoff prevent these costly gaps.
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