A balustrade is a railing or barrier along the edge of a deck, conservatory, balcony, staircase or gallery that prevents people from falling off. It usually consists of a top and bottom rail with spindles, glass or other infill in between. A balustrade combines safety with aesthetics.
When is a balustrade required?
According to building regulations, a balustrade (or barrier) is required at:
- Height differences of more than 1 metre in new builds
- Height differences of more than 1.5 metres in existing buildings
- Staircases along the open side
The minimum height is:
| Situation | Minimum height |
|---|---|
| Deck/balcony (new build) | 100 cm |
| Deck/balcony (existing building) | 100 cm |
| Staircase (new build) | 100 cm |
| On a roof terrace | 100 cm |
For a deck or conservatory less than 1 metre above ground level, a balustrade is not required — but it may still be desirable for enclosure or ambience.
Balustrades for decks and conservatories
Building a deck
For a raised deck (for example on a slope or as a terrace), a balustrade is often needed:
- Timber spindle railing — Posts fixed to the deck, with horizontal or vertical spindles. The gap between spindles must be no more than 10 cm (child safety).
- Wire tension — Stainless steel cables horizontally between posts. Clean, modern appearance.
- Glass panels — Toughened or laminated glass between posts. Maximum views.
Building a conservatory
In a conservatory, the balustrade often serves as a parapet:
- Height usually 90-100 cm
- Lower section solid (timber panels) with upper section open (spindles or glass)
- Wide top rail can serve as an armrest or shelf
Materials
| Material | Advantage | Disadvantage |
|---|---|---|
| Timber | Warm, workable, suits garden buildings | Maintenance (painting/oiling) |
| Aluminium | Maintenance-free, slender | Less warm appearance |
| Stainless steel | Strong, modern, rust-proof | More expensive |
| Glass | Maximum views, modern | Fragile, more expensive |
| Wrought iron | Ornate, classic | Maintenance (rust), heavy |
Structural requirements
A balustrade must withstand a horizontal load of at least 0.5 kN/m (approximately 50 kg per running metre). This means:
- Posts firmly anchored to the substructure (not just screwed, but also bolted or with a welded base plate)
- For timber: posts at least 70×70 mm
- Spindle gap maximum 10 cm (child safety)
- No horizontal intermediate rails that children can climb on (vertical spindles preferred)
Common mistakes
- Posts attached with screws only — Under load, screws pull out of the wood. Use bolt connections or post brackets.
- Too large a spindle gap — Children can fit through. Maximum 10 cm.
- Timber directly on concrete or stone — Moisture wicks upward. Always use a post bracket or stainless steel spacer.
Related terms
- Deck board
- Post
- Glazing
- Trellis