Deck Construction Inspection

Terrace foundations must be adequate for soil conditions. Posts must be durable timber (class 4 for ground contact per EN 335) or protected with proper hardware.

1. Verify foundations are adequate for soil bearing capacity

2. Check foundation depth — below frost line or on stable subsoil

3. Verify posts are durability class 4 timber or better for ground contact

4. Check post-to-foundation connections — galvanised steel post shoes recommended

5. Verify posts are plumb

6. Check post dimensions are adequate for the span and height

7. Inspect for excessive notching or cutting

- Foundations too shallow — movement with frost heave

- Posts in direct ground contact without protection

- Untreated timber in ground contact

- Undersized foundations

- Posts not plumb

- Excessive notching

Wall connection must be structurally adequate with proper waterproofing. Coach bolts or through-bolts into masonry with appropriate fixings. Lead flashing above connection.

1. Check fixings — coach bolts or chemical anchors into masonry (not plastic plugs)

2. Verify fixing spacing and pattern per structural requirements

3. Look for lead flashing or equivalent above the wall connection

4. Check that render or cladding was removed at the connection point

5. Verify a drainage gap exists between timber and masonry

6. Inspect for any trapped moisture at the junction

- Inadequate fixings into masonry

- No flashing above connection — water entry to wall

- Timber in direct contact with masonry (moisture transfer)

- Missing DPC (damp-proof course) at connection

- Fixings into render only

- No drainage gap

Subframe must be properly sized for span and loading. Joists spaced per structural design. All timber must be durability class 3 minimum or pressure-treated.

1. Check joist spacing per structural design (typically 400-600mm centres)

2. Verify joist connections — galvanised joist hangers or equivalent

3. Check fastener type — stainless steel or hot-dip galvanised nails

4. Verify timber is treated or naturally durable (minimum class 3)

5. Check bearing on beams — minimum 40mm

6. Look for nogging/blocking at mid-span for long joists

7. Verify fall/slope for drainage (minimum 1:80)

- Wrong fastener type in joist hangers

- Missing joist hangers

- Untreated timber

- Joists undersized

- Missing blocking

- No fall for drainage

Balustrades required when fall height exceeds 600mm. Minimum 1100mm height for residential buildings. Maximum 100mm gaps between balusters.

1. Measure balustrade height — minimum 1100mm from deck surface

2. Check gaps between balusters — maximum 100mm (a 100mm sphere should not pass through)

3. Check bottom gap — maximum 100mm

4. Push firmly against railing — should be rigid with no excessive movement

5. Check post fixing method — bolted or bracketed to structure

6. Verify no climbable horizontal elements

7. Check all fixings are stainless steel or galvanised

- Balustrade too low

- Gaps exceeding 100mm

- Posts inadequately fixed

- Bottom gap too large

- Wobbly railing

- Climbable horizontal elements

Decking must be securely fixed with appropriate stainless steel or galvanised screws. Gaps between boards for drainage. Boards should be straight without excessive bowing.

1. Walk the surface — check for loose, bouncy, or raised boards

2. Check gaps between boards — 5-8mm for drainage

3. Verify screw heads are flush and in alignment

4. Check board ends are supported and have gaps

5. Look for splits, warping, or damage

6. Verify all screws are stainless steel or galvanised

7. Check boards for correct orientation to minimize cupping

- Insufficient gaps for drainage

- Proud screw heads

- Unsupported board ends

- Standard steel screws corroding

- Board cupping

- Warped or bowed boards