I'm Alfie Jaques, a City & Guilds-qualified carpenter based in Bournemouth (BH2), and I build decks and pergolas across Poole, Christchurch and about 10 miles around. Every quote I give is written and itemised after a free visit to the garden.
"How much will it cost?" is the first question on nearly every deck. There's no honest single number, so this guide doesn't give one. It goes through what moves the price up or down on a real garden, so that when quotes come in you can see why they differ and which questions to ask.
Does the choice of boards change the price most?
It's a big part of it, but it's rarely the only thing.
Timber is usually the lower upfront build. Composite costs more to start with and asks less of you afterwards: a brush and a wash, where timber needs treating from time to time. Which way to go depends on the garden and on you. As I put it when people ask, "it depends what look you're going for". My composite vs timber guide compares the two for shade, salt air and upkeep.
Near the sea, the fixings matter too. Marine-grade A4 stainless is the grade made to stand up to salt air: see which decking screws last near the sea.
Why does height add so much to the price?
Because a raised deck needs more frame, more footings, often a balustrade and steps, and sometimes permission.
A low deck on a flat lawn needs a frame and footings. Lift it up and every post is longer and carries more, steps need building, and once the drop is more than 600mm the government's guidance on falls calls for guarding round the edge.
Height also changes the paperwork. The Planning Portal says decking over 30cm high needs planning permission, and that Building Regulations should be assumed to apply to any deck that does. My guide to raised decking on a sloping garden goes through each line.
How does the ground change the quote?
Sand, clay, slopes and tree roots each need a different footing, and footings are a big share of the hidden work.
Ground across Bournemouth and Poole varies from free-draining sand to clay that moves with the seasons, often within a short distance. The British Geological Survey notes sand and clay sitting side by side in the local Boscombe Sand and Branksome Sand formations. A protected tree nearby can mean digging differently round its roots, and BCP Council's permission is needed before any work on a tree with a Tree Preservation Order.
That's why I look at the ground before pricing it. A quote written without seeing the garden can't know any of this. See decking on clay soil in Poole for one example of how it changes the build.
What if there's an old deck to take out first?
Taking it up and getting rid of it is real work, and it should be on the quote as its own line.
An old deck has to be lifted, broken down and taken away. There's a legal side to that for you as the householder. BCP Council's advice before letting anyone take waste away is to:
- ask where it will be taken and ask to see their waste carrier's licence, and not use them if they don't have one
- check they're on the Environment Agency's public register of waste carriers
- keep a record of their paperwork, the dates, their name, phone number and registration number
The council says you could be prosecuted and fined if waste is fly-tipped and you haven't taken those steps. A quote that includes removal should say how it's being disposed of.
Old decks also hide things. If the joists turn out to be rotten once the boards are up, what happens next should already be written down. Ask any installer how anything found underneath will be priced before you agree to the job.
Why is one quote so much higher than a handyman's price?
Usually because of what goes into the frame, the footings and the fixings, which you can't see once the boards are on.
A frame can be laid out and screwed together with brackets, or it can have its joints cut so the timber slots together. I cut the joints. As I put it: "I don't just lay them on top. I actually cut out the joints." Add UC4 treated timber in the ground, stainless fixings near the coast, and footings matched to the ground, and the price goes up for reasons that are hard to spot on the finished deck.
That doesn't mean the dearest quote is right. If what you want is a simple square on flat ground, a kit might be all you need, and I'll tell you to go do that. You won't get a fully custom fit to your garden out of the packet, and for some gardens that doesn't matter.
The fairest way to compare is line by line. My buyer's guide to hiring a decking installer lists what a written quote should include.