Rebuilding a Timber-Framed Brick Stair After Washout

Monsoon rains washed sand from a 6×6 timber stair with fabric-and-sand bed, sinking bricks. The rebuild must stop water intrusion and use a stable base.

Correct Base Build-Up

1. Compacted crushed aggregate (¾″ minus, no piece >1.5″) – 3–4″ thick, hand-tamped.
2. Geotextile (US Fabrics 115NW or equivalent) over aggregate; staple edges to timbers.
3. 1″ concrete sand setting bed, screeded level.
4. Bricks set tight (⅛″ joints), tapped level.
5. Bricks ¼″ above timber top to allow settling.
6. Sweep fine sand into joints; cover with plywood; plate-compact gently.
7. Re-sweep sand until joints full.

Critical Success Factors

• Timbers firmly anchored (no movement).
• Surface water diverted away from stairs (swale or regrade).
• Sand over geotextile, not under.
• Bricks cut to fit—no wide sand-filled gaps.

Reference: ICPI and US Fabrics.