Ask three companies what composite decking costs and you will get three very different numbers, because most quotes bundle boards, subframe, groundworks and labour into one figure. The board price is usually the smallest part of the job. Here is how the cost actually breaks down in the North West, so you can read a quote properly rather than just comparing the total at the bottom.
Composite boards on their own typically run from around £35 to £60 per square metre for entry level hollow or co-extruded boards, £60 to £90 for mid range solid capped boards, and £90 to £130 plus for premium ranges with heavy embossing, longer warranties and matching fascia. Cheap boards are not automatically bad, but hollow profiles feel more drummy underfoot and are less forgiving over a subframe that has any flex in it.
Fitted, most straightforward jobs in and around Bolton land somewhere between £150 and £260 per square metre including the subframe, fixings, fascia boards and labour. Below about £130 per square metre, something is usually being left out, most often the groundworks or a properly specified frame. Above £280, you are normally paying for raised structures, steps, balustrade or difficult access rather than fancier boards.
Size matters, but not the way people expect. A 12 square metre deck rarely costs half of a 24 square metre deck, because setup, waste, delivery and the fiddly perimeter work stay much the same. Small decks almost always have a higher cost per square metre, and any company quoting a flat rate regardless of size is either padding the small jobs or losing money on them.
Shape and level are the bigger drivers. A simple rectangle sitting close to ground level on a prepared base is the cheapest thing we build. Add a raised platform over sloping ground, steps down to a lawn, mitred corners, picture framing or an inset for a hot tub, and the labour hours climb quickly. Many Bolton gardens slope away from the house, which often means a raised frame with posts and a skirt rather than a simple ground level deck, and that can add £40 to £80 per square metre.
Access is the quiet cost. Terraced streets around Halliwell, Farnworth or Great Lever often mean everything goes through the house or down a shared alley by hand. Barrowing spoil out and boards in adds real hours compared with a property where a van can back onto the driveway.
Composite boards last decades. A timber frame that has not been treated, spaced or supported properly will not, and when it fails you are paying to lift and refit boards that were perfectly fine. Most composite manufacturers specify joist centres of around 300 to 400mm, closer still if you are laying boards diagonally, and going wider is one of the most common ways a quote gets cheaper.
Treated C16 or C24 timber is the usual choice and does the job well when it is kept off the ground and ventilated. Aluminium subframes cost noticeably more, often adding £30 to £60 per square metre, but they will not rot, twist or move, which makes them worth considering for a raised deck or anywhere drainage is poor. Given how wet a Greater Manchester winter is, a frame that sits in standing water is the fastest route to a bouncy deck.
Ask any company what joist centres they are working to and what the frame is bearing onto. The answer tells you more about the quote than the brand of board does.
Groundworks are the most commonly missed line. Clearing an old timber deck, digging out turf, laying a membrane and putting in concrete pads or a compacted base can add £25 to £70 per square metre depending on what is already there. Removing an existing deck and getting the waste off site is usually a few hundred pounds on its own.
Balustrade is the other one. Composite or glass balustrade is priced per linear metre, commonly £120 to £300, and if your deck sits more than 600mm above the ground you will need it for safety regardless of appearance. Steps, integrated lighting, under deck storage and matching skirt boards all sit outside the per square metre figure too, which is exactly why like for like comparisons are so hard unless every quote itemises them.
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