Install Ceramic or Porcelain Floor Tile Backer Board

A. Finished-Project Specification

Quantity: one complete backer-board substrate covering the defined inspection area, with every panel embedded in mortar, fastened to the specified field and edge spacing, every seam taped and treated with mortar, every movement joint preserved, and one completed inspection record confirming plane, support, gaps, fasteners, seams, and cleanliness.

B. Component Schedule

Component	Quantity	Material	Finished Size	Preparation
Field panels	As required by room area and specified panel size	Cementitious or approved tile-backer board, thickness per tile assembly specification	Cut to fit dry-laid layout with offset joints and no four-corner intersections	Dry-laid, marked, and numbered before cutting
Perimeter panels	As required by room perimeter	Same backer-board product as field panels	Cut to maintain the specified perimeter gap	Measured and marked against wall and fixed-object references
Seam reinforcement	One continuous strip per seam	Alkali-resistant mesh tape	Cut to seam length	Applied over mortar-filled seams before final mortar coat

C. Material Takeoff

• Backer board: quantity sufficient to cover the inspection area plus the waste allowance specified for the product, at the thickness required by the tile assembly.
• Embedding mortar: quantity calculated from the coverage rate of the specified trowel notch size across the full inspection area.
• Fasteners: listed backer-board screws or nails in the quantity required by the field and edge spacing schedule for the total panel count.
• Seam tape: alkali-resistant mesh tape sufficient for the total linear seam length.
• Movement-joint material: as specified for each perimeter and structural movement location.

D. Fastener and Hardware Schedule

Joint	Fastener	Spacing	Installation Notes
Field	Listed backer-board screw or nail per product specification	Per manufacturer field-spacing schedule	Driven flush without crushing the board face; not overdriven through the panel
Edge and seam	Listed backer-board screw or nail per product specification	Per manufacturer edge-spacing schedule	Positioned at the specified distance from the panel edge to avoid crumbling

E. Acceptance Standards

Check	Standard
Layout	Every backer-board joint offset from the subfloor joint beneath it by the specified distance, with no four-corner intersection
Embedding	Full mortar contact confirmed beneath every panel; no unsupported or hollow area
Fastening	Every panel fastened to the specified field and edge spacing with fasteners flush and not crushing the board
Seams	Every seam taped with alkali-resistant mesh and treated with mortar
Movement joints	Every designated movement joint free of rigid backer-board material, mortar, or mesh tape
Plane	No rocking, proud fastener, or unsupported edge detected during inspection
Cure	Specified cure time observed before tile layout begins
Documentation	Board, mortar, fastener, layout, and cure information recorded on the project record

F. Review and Subfloor Verification

1. Review tile assembly, subfloor, joist deflection, backer-board type, thickness, mortar, fasteners, seam treatment, and movement joints. Confirm every product and spacing value against the approved tile assembly specification before beginning layout.
2. Confirm the floor structure and subfloor satisfy the approved tile requirements. Verify the Chapter 1 substrate findings and the completed Chapter 3 and Chapter 4 corrections apply to the inspection area.
3. Verify the subfloor is clean, flat, dry, and securely fastened. Reject any area that does not meet these conditions before proceeding to layout.

G. Dry Layout

1. Dry-lay backer-board panels. Place full and cut panels across the inspection area without mortar or fasteners to confirm fit.
2. Offset backer-board joints from subfloor joints as required. Measure and confirm the specified offset distance at every panel joint.
3. Avoid four-corner intersections. Adjust the dry layout wherever four panel corners would otherwise meet at one point.
4. Maintain panel and perimeter gaps. Confirm the specified gap between panels and at every wall and fixed-object perimeter.
5. Mark panels and fastener fields. Number each panel in position and mark the field and edge fastener locations before removing panels for cutting.

H. Cutting and Dust Control

1. Cut boards using score-and-snap, shears, or wet-cutting methods approved for the product. Use the method specified for the backer-board product and the assigned dust-control plan.
2. Control silica and cement dust. Use local extraction for wet cutting or contain dry-cutting dust at the source; wear the specified respiratory protection.
3. Vacuum the substrate. HEPA-vacuum all cutting dust and debris from the subfloor before mixing any mortar.

I. Mortar Mixing and Embedding

1. Mix the specified mortar. Use the exact water ratio, mixing time, and slake period required by the mortar product.
2. Spread mortar with the required trowel. Comb the mortar with the notch size specified for the backer-board product across an area sized to the mortar's open time.
3. Embed the first panel while the mortar is workable. Set the numbered panel into its marked position before the mortar skins over.
4. Walk or press the panel into full support without using mortar to level the floor. Confirm full contact beneath the panel by checking a representative edge or corner.

J. Fastening

1. Fasten with listed backer-board screws or nails. Drive fasteners at the marked field and edge locations while the mortar remains workable beneath the panel.
2. Follow the required field and edge spacing. Confirm actual fastener spacing against the manufacturer's schedule as each panel is completed.
3. Keep fasteners flush without crushing the board. Stop driving each fastener at the point of flush seating and back out any fastener that has crushed the board face.
4. Install remaining panels. Repeat the mortar-spreading, embedding, and fastening sequence for every panel in the dry-laid layout.

K. Seam Treatment, Movement Joints, and Cure

1. Treat seams using the specified alkali-resistant mesh tape and mortar. Apply mortar into each seam, embed the mesh tape, and apply a final mortar coat over the tape.
2. Do not rigidly fill required movement joints. Keep every designated movement joint free of mortar and mesh tape.
3. Allow cure as specified. Protect the completed substrate through the mortar manufacturer's cure time before tile layout begins.

L. Inspection and Correction

1. Inspect panel plane, support, gaps, fasteners, seams, movement joints, and surface cleanliness. Walk the completed substrate and check a representative sample of panels for rocking or hollow areas.
2. Correct rocking, proud fasteners, unsupported edges, and improper joints. Reset or replace any panel, fastener, or seam that fails inspection.
3. Document board, mortar, fasteners, layout, and cure. Record product names, lot numbers where available, layout confirmation, fastener spacing verification, and cure completion on the project record.