BR
The Building Reference
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The Building Reference

Glossary

Plain-English definitions of terms you'll encounter on contractor bids, product packaging, and building permit applications.

B
Bonded Membrane
A waterproofing layer that adheres directly to the substrate behind the tile. Unlike older "unbonded" systems that relied on a floating mortar bed, bonded membranes — like Schluter KERDI or liquid-applied products like RedGard — bond to the backer board and move with it, reducing the risk of cracking at transitions.
F
Flood Test
A water test performed on a shower pan after waterproofing installation but before tile is set. The drain is plugged and the pan is filled with water for 24 hours to verify the waterproofing membrane holds with no leaks. Required by code in many jurisdictions and standard practice among quality tile installers.
U
Unmodified Thinset
A tile adhesive mortar that contains no latex or polymer additives. Required by Schluter Systems when bonding KERDI membrane — latex-modified thinset can retain moisture and cause debonding over time, particularly in steam shower applications. Using the wrong thinset with a Schluter system voids the warranty.