Case study: A composite deck in Bolton, built from the drainage up.
Jamie called us in for a composite deck that would hold a true level from the patio doors out over a falling garden. Three days: drainage in, seven posts down, a 6x2 treated frame, and a board surface finished with ash trim and balustrades.
Project at a glance Verified Wolsten build
- Property type
- Family garden -- Bolton
- Service
- Composite Decking
- Time on site
- 3 days
- Structure
- 7 x 4"x4" posts, 400mm deep
- Sub-frame
- 6"x2" treated timber, top-face treated
- Drainage
- Under-deck drainage + weed membrane
- Finish
- Ash corner trim + balustrades
- Customer
- Jamie
Why Jamie called us.
Jamie Mackie wanted a composite deck off the patio doors -- a low-maintenance surface the family could walk straight out onto, at the same level as the house. The complication was the garden itself: the ground fell away and held water, so a deck laid on the existing levels would have been neither flat nor dry for long.
The answer was to build the level rather than chase it: drainage and posts first, then a frame engineered to hold the patio-door datum all the way out. Quoted for 3 days.
What we did.
Everything that matters on this deck happened before a single board was cut.
The build sequence:
- Removed earth to find a true level for the garden
- Installed drainage under the deck footprint, covered with weed membrane
- Set seven 4" x 4" treated, additionally weather-guarded posts 400mm into the ground -- holding the level from the patio doors, where the first section of sub-frame was installed
- Built the full sub-frame in 6" x 2" treated timber
- Applied a further coat of timber treatment to the top face of the sub-frame for additional weatherproofing
- Fitted the composite boards using 3mm spacers -- one on every joist -- for super sturdiness and identical gapping
- Cut every composite board with a fine-toothed circular saw blade for clean, chip-free edges
- Finished with a lovely ash corner trim throughout, plus balustrades
Three days from falling, waterlogged ground to a dead-level, free-draining composite deck the family can step straight out onto.
The whole project, in four shots.
Real photos from the actual Bolton job.
The garden as found -- no usable level, no drainage to speak of.
Seven 4x4 treated, weather-guarded posts set 400mm into the ground.
Full 6x2 treated frame, level held from the patio doors out.
Composite boards, ash corner trim throughout, balustrades on.What Jamie said.
I have been looking into decking for months. I was leaning towards timber decking, however I decided to go with composite after Liam visited and showed me samples, and explained for a slightly higher upfront cost, I could have something that was virtually maintenance free and had a huge warranty. 5 Star service and work
Jamie's decision is the exact trade-off we walk through at every survey -- timber's lower upfront cost against composite's near-zero maintenance. Liam brought samples of both so he could see and feel the difference before choosing.
Every detail of the Bolton build.
The full set of photos taken throughout the project.
For the discerning homeowner.
What we actually built into this deck.
Seven 4x4 posts, 400mm into the ground
The garden falls away from the house, so the deck level is set at the patio doors and carried out on seven 4" x 4" treated and additionally weather-guarded posts, each set 400mm deep. That's what makes a raised deck feel like solid ground instead of a stage -- no bounce, no sway, no movement at the edges.
Drainage first -- under the deck, not around it
Before any structure went in, we removed earth to find a true level and installed drainage beneath the deck footprint, covered with weed membrane. A deck shades the ground under it; if water sits there, the structure lives in a swamp. This one drains -- and nothing grows up through the void.
A 6x2 treated sub-frame -- with treatment on the top face
The full sub-frame is 6" x 2" treated structural timber. We then applied an additional coat of timber treatment to the top face of every joist -- the surface that sits in contact with the boards, where water lingers longest and factory treatment alone wears first. It's a ten-minute job that adds years.
3mm spacers on every joist
Board gapping wasn't eyeballed: 3mm spacers, one fitted on every joist, so each composite board is supported and gapped identically across the whole deck. Consistent gaps mean consistent drainage, consistent expansion room, and a surface that feels super sturdy underfoot.
Fine-toothed blade, ash corner trim
Composite boards chip if you cut them like timber. Every cut on this deck was made with a fine-toothed circular saw blade -- clean edges, no fraying caps. The finish: a lovely ash corner trim throughout, wrapping every exposed edge, with matching balustrades to complete it.
Three founders, plus extended crew when the job calls for it.
Liam, Ryan and Paul on every job. Where the work needs more hands, we bring in trusted regulars.
Liam
Surveyed and quoted. Supervised the build on site.
Ryan
Ground works, drainage and the post settings.
Paul
The 6x2 frame, every board cut, and the ash trim finish.
Bolton
Bolton is home turf -- our base is in Westhoughton, minutes away. We supply and install composite and timber decking right across Bolton and the wider North West.
Questions homeowners ask about decking builds like this.
How long does a composite decking install take?
This Bolton deck took 3 days, including the ground works, drainage and the post-and-frame build. Most standard ground-level decks run 3-5 days; raised decks on posts sit at the upper end. Use our decking price calculator for an instant indicative price.
Why do some decks need posts?
When the garden falls away from the house, the deck level has to be held -- here with seven 4x4 treated posts set 400mm into the ground. Posts done properly are the difference between a deck that feels like solid ground and one that bounces.
Do you need drainage under decking?
If the ground holds water, yes -- and it's far easier to do before the deck exists than after. On this job we installed drainage under the footprint and covered it with weed membrane, so the void under the boards stays dry and clear.
Do I need planning permission for decking?
Usually not. Decking under 30cm off the ground covering less than half the garden generally falls under permitted development. Raised decks can be the exception -- we check and flag it at the free survey.
What maintenance does composite decking need?
A wash-down once or twice a year. No sanding, staining or sealing -- that's the point of composite. The treated sub-frame underneath is built to outlast the boards.
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