Best Construction Boards AI pick
Chosen by an AI model from its trained knowledge, with its reasoning.
AI pick (line): James Hardie HardieBacker Cement Board
A fiber-cement backer board for tile on floors, walls and wet areas that cuts more cleanly and weighs less than glass-mesh cement board.
Not for: Anyone who wants a single board that is also a waterproof membrane, or anyone building curbless showers who needs a foam board system.
AI picks by need
For traditional glass-mesh cement board
USG Durock Cement Board (line)
A long-established glass-mesh-faced cement board for tile backing in wet areas and on floors.
Not for: Anyone who wants lighter, easier-cutting board or a built-in waterproof surface.
For lightweight waterproof foam board for showers
Schluter Kerdi-Board (line)
A lightweight foam-core board that is itself waterproof, so it can replace backer board plus membrane when used inside Schluter's system.
Not for: Floors under heavy point loads, or anyone not planning to use the matching seam and fastener system.
For gypsum-core tile backer for walls
Georgia-Pacific DensShield Tile Backer (line)
A glass-mat gypsum tile backer with a moisture-resistant face, lighter and easier to cut than cement board for wall tile.
Not for: Floor tile installations or setups where the board will be soaked continuously.
What the AI looks for in Construction Boards
- Thickness by location
- Use 1/4 in board for floors over a sound subfloor and 1/2 in board for walls and shower surrounds. The 1/4 in board on floors adds bond, not stiffness. Walls need the thicker board to span the studs.
- Waterproofing
- Cement and fiber-cement boards are water-resistant, not waterproof. Inside showers, add a liquid or sheet membrane unless the board system itself is rated waterproof. Water passes through cement board and rots the framing behind it.
- Fasteners and seams
- Use corrosion-resistant backer-board screws at the manufacturer's spacing, and tape seams with alkali-resistant mesh embedded in thinset. Drywall screws corrode, and paper tape fails under thinset.
- Floor installation
- On floors, set the board in a bed of thinset over the subfloor before screwing it down, and offset seams from the subfloor joints. Without the mortar bed, voids under the board crack the tile.
- Applicable standard
- Cement backer units are covered by ASTM C1325 and ANSI A118.9. Boards that meet these standards are rated for tile substrate use.
Brands that matter
- James Hardie: HardieBacker fiber-cement board, with no glass mesh.
- USG: Durock glass-mesh cement board.
- National Gypsum: PermaBase cement board.
- Georgia-Pacific: DensShield glass-mat gypsum tile backer.
- Schluter: Kerdi-Board waterproof foam building panels.
- Wedi: Waterproof foam-core building panels and shower systems.
What to avoid
- Green-board drywall as a shower tile backer
- Skipping the thinset bed under floor backer board
- Drywall screws or paper tape on cement board
Questions
Is cement board waterproof?
No. It does not break down when wet, but water passes through it. Shower walls need a waterproof membrane on top or behind it.