How to Build a Simple Raised Deck: Complete Guide

Transform Your Garden with Decking

A well-built deck extends your living space outdoors. It's a significant project but achievable with good planning and basic carpentry skills. Here's how to build a raised deck that lasts.

Planning and Regulations

Check if you need permission:

• Decks over 300mm high may need Building Regulations approval
• Decks exceeding certain sizes may need planning permission
• Check with local authority before starting

Design considerations:

• Size and shape to suit space and use
• Height - stepped down from door threshold ideally
• Access - steps if raised significantly
• Direction of boards (usually away from house)
• Location of posts and support structure

Materials

Softwood (pressure-treated):

• Most common and economical choice
• Must be properly treated for ground contact
• Requires maintenance - staining/oiling

Hardwood:

• More durable, attractive
• Expensive
• Heavy to work with

Composite:

• Low maintenance
• Long-lasting
• More expensive initially
• Different fixing methods

Framework:

• Posts: 100x100mm minimum
• Bearers: 150x50mm or similar
• Joists: 150x50mm at 400-500mm centres
• All must be pressure-treated

Tools Needed

• Circular saw or mitre saw
• Drill/driver
• Impact driver (makes screwing much easier)
• Spirit level
• String line
• Tape measure
• Spade and post hole digger
• Socket set or spanners

Building the Frame

Step 1: Set out and mark

1. Mark deck outline with string
2. Check for square using 3-4-5 method
3. Mark post positions (max 1200mm apart)

Step 2: Install posts

• Dig holes 450-600mm deep
• Set posts in concrete or post supports
• Level and brace while concrete sets
• Or use bolt-down post brackets on concrete pad

Step 3: Attach ledger board (if fixing to house)

• Coach screws into masonry
• Must be level
• Leave gap for drainage behind
• Flash above to prevent water ingress

Step 4: Install bearers

• Level across all posts
• Bolt securely to posts
• Check for level in all directions

Step 5: Install joists

• Run perpendicular to boards
• Space at 400-500mm centres
• Joist hangers on ledger, skew nailed on bearers
• Ensure tops are level - boards sit on top

Laying the Boards

Preparation:

• Pre-drill screw holes (prevents splitting)
• Leave 5-8mm gap between boards for drainage and expansion
• Spacers make consistent gaps easier

Fixing:

• Two screws per joist, countersunk
• Stainless steel screws for longevity
• Start from house end, work outwards
• Stagger board joints

Cutting boards:

• Overhang edges by 20-30mm
• Cut ends square or at angles for neatness
• String line ensures straight cuts across multiple boards

Finishing Touches

Fascia boards:

• Cover exposed joists and beam ends
• Gives clean finished appearance

Handrails (if needed):

• Required if deck is over certain height
• Must meet building regulations for spacing and strength

Steps:

• Rise/run to meet regulations (typically 150-200mm rise)
• Consistent step dimensions
• Non-slip surface

Common Mistakes

• Frame not level - check constantly during build
• Insufficient posts - causes bounce
• No drainage gap - traps moisture, causes rot
• Using untreated timber - fails quickly
• Screws too close to board edges - splits

Maintenance

To protect your investment:

• Clean annually with deck cleaner
• Apply deck oil or stain as needed
• Check for loose screws and boards
• Keep gaps clear of debris
• Address any rot promptly

The Bottom Line

Decking is a substantial project but very achievable. Take time on the frame - if it's level and solid, the boards go on easily. Use quality screws and fixings, and don't skip the gaps between boards. A well-built deck adds value and enjoyment for years.

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