Rotten Decking Boards: Repair or Rebuild?
Boards feel soft underfoot, splinter, or show dark staining and cracking.
The visible boards are rarely the whole story. Before quoting board replacement we always lift a section and check the joists, because rotting boards usually mean water has been sitting in the frame as well.
Causes we typically find
No ventilation beneath
A deck boxed in solidly on all sides cannot dry, so the frame stays damp year-round.
Frame in contact with soil
Joists or bearers laid straight onto ground rot within a few seasons.
Water in screw holes
Unprotected joist tops hold water at every fixing point — the classic early-failure route.
Untreated cut ends
Boards and joists cut on site without re-treating expose untreated timber at the most vulnerable points.
Check it yourself
- 1
Walk the deck and note any softness or movement.
- 2
Lift one board near the house wall and one at the outer edge, and probe the joists.
- 3
Check whether the frame sits on pads or straight on soil.
- 4
Look for standing water beneath after rain.
Fix options
Board replacement only
The frame probes sound
Affected boards swapped, joist tops taped, and fixings upgraded. Good value where the substructure is genuinely fine.
Partial frame repair
Isolated joists have gone
Sistered or replaced joists, improved pads, and boards refitted.
Rebuild the deck
The frame is widely soft
Correct ground preparation, treated frame on pads, joist tape, ventilation and a drainage fall — the failure does not recur.
Rebuild in composite on a new frame
You want to stop maintaining it
Boards that don't rot on a substructure built to the board manufacturer's spacing.
Prevention
- Keep the frame off soil, always
- Use joist tape over every joist top
- Maintain airflow beneath the deck — never box in every side
- Keep the deck below the house damp-proof course
Frequently asked
Can I replace boards without touching the frame?
Only if the frame is sound. New boards on a rotten frame is money wasted.
How long should a deck last?
Twenty years is achievable on a properly built, ventilated frame. Five years is what a frame laid on soil delivers.
Is softwood decking a false economy?
Not at all when it's built correctly and oiled. Most early failures we see are frame failures, not board failures.
Do you re-use the old frame?
Only where it probes sound and meets spacing requirements for the new boards.