Holiday (membrane)
A holiday is a gap or void in a waterproofing membrane where the coating missed a spot. Holidays allow water ingress through an otherwise intact membrane.
Ask Chalkline about this →A holiday is a localised gap, pinhole, or void in a waterproofing membrane where the applied coating has missed a spot or been applied too thinly to form a continuous film. The term comes from the paint trade (“missed a spot, went on holiday”) and applies equally to waterproofing membranes. A holiday allows water to penetrate an otherwise intact membrane at the point of the gap.
In internal wet areas, holidays are detected by flood testing: if the water level drops, a holiday exists. On external trafficable decks and roofs, holiday detection is more commonly done with an electric holiday detector (spark tester), which identifies breaks in the membrane by electrical continuity.
Holidays are caused by inadequate application rate, surface contamination, air bubbles trapped during application, or applying membrane over a recess or indentation in the substrate that wasn’t filled. They are distinguished from lap failures (which occur at joints) and penetration failures (which occur around pipes and wastes).
Also known as: pinhole, void, membrane holiday.
Category: Defects / Waterproofing.
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Last updated: 2026-05-10. Verified: 2026-05-10. Quarterly review for currency.