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PAVING & DECKING

Decking Slippery

Decking becomes slippery when algae, moss, dirt and moisture build up on the surface, especially in shaded areas.

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Make trip and fall hazards safe first

Loose slabs, rotten decking and slippery surfaces can cause serious injury. Stop using elevated or structurally soft decking until it has been assessed.

MOST LIKELY CAUSES

Start with movement, support and drainage

Algae and moss Organic growth creates a slick film.
Poor drainage Water remains on or beneath boards.
Shade and low airflow The surface dries slowly.
Worn or smooth finish The deck has little remaining texture.
◫ Symptom variations Match the movement, cracking or surface condition. ⌄
  • Slippery after rain
  • Green or black film
  • Problem worse in shaded sections
  • Boards stay wet for hours
  • Steps are particularly hazardous
✓ Quick checks Safe checks before lifting slabs or boards. ⌄
  1. Inspect for algae and moss.
  2. Check gaps between boards.
  3. Look for ponding or blocked drainage.
  4. Assess coating condition.
  5. Check handrails and step edges.
Important: Fix the support, drainage or structural cause before replacing surface materials.
1 Step 1 — Clean the surface thoroughly Make the smallest safe correction and retest. ⌄

Use a suitable deck cleaner and stiff brush.

2 Step 2 — Restore drainage and airflow Make the smallest safe correction and retest. ⌄

Clear gaps and reduce persistent moisture where possible.

3 Step 3 — Improve grip Make the smallest safe correction and retest. ⌄

Use an appropriate anti-slip coating or strips after the deck is sound and dry.

⌁ Why the problem happens How support, water and movement affect paving and decking. ⌄

Moist organic growth reduces friction and remains slippery even when the deck looks only slightly dirty.

⌘ Advanced checks Further diagnosis for persistent outdoor surface faults. ⌄
  1. Check board fall.
  2. Assess timber condition before coating.
  3. Review nearby planting and shade.
  4. Check sub-deck ventilation.
  5. Inspect previous coatings for peeling.
◇ Tools and information needed Useful items for accurate checks. ⌄
  • Stiff brush
  • Deck cleaner
  • Hose
  • Scraper
  • Protective gloves
▣ Parts or materials that may help Common paving and decking materials linked to this fault. ⌄
  • Anti-slip deck coating
  • Grip strips
  • Replacement boards
  • Drainage spacers
  • Suitable preservative
! When to call a professional Conditions that should end basic DIY diagnosis. ⌄
  • The deck is elevated or on stairs.
  • Timber is rotten.
  • The surface remains unsafe after cleaning.
  • A public or commercial access route is involved.
  • Structural repairs are needed.
? Frequently asked questions Common paving and decking questions. ⌄

Will pressure washing fix it?

It can help, but excessive pressure may damage timber and raise the grain.

Are anti-slip strips enough?

They help on sound decking, especially steps, but do not replace cleaning and drainage.

Why is only one area slippery?

Shade, poor airflow or local drainage may keep it wetter.