How to Plan Your Decking Project for Spring 2026
Spring is the perfect time to build a deck. The ground is firming up after winter, the days are getting longer, and you've got the whole summer ahead to enjoy the results. Whether you're planning a simple patio deck or a multi-level outdoor space, getting the planning right before you buy a single board will save you time, money, and frustration on site.
This guide covers everything you need to know — from choosing the right timber to calculating how much you need, getting your frame right, and making sure your deck lasts for years.
Step 1 — Choose Your Decking Timber
The first decision is softwood or composite. Both have their place, and the right choice depends on your budget, how much maintenance you're willing to do, and the look you're after.
Softwood decking is the most popular choice for good reason. It's cost-effective, widely available, easy to work with, and — when properly treated and maintained — will last 15 years or more. Our softwood decking boards are pressure-treated with UC3 green tanalith treatment, which gives excellent protection against rot, fungal decay, and insect attack. The most common size is 32mm x 125mm, which gives a good solid feel underfoot and suits most domestic applications.
Composite decking is growing in popularity, particularly for homeowners who want a low-maintenance solution. Made from a blend of recycled wood fibre and plastic, composite boards don't need annual oiling or staining, won't splinter, and hold their colour well. The upfront cost is higher than softwood, but the ongoing maintenance cost is essentially zero. It's an excellent choice for busy families, rental properties, or anyone who simply doesn't want the annual maintenance job.
At Nick's Timber Store we stock both — view our full decking range here.
Step 2 — Work Out How Much Decking You Need
This is where most people either over-order or under-order. Here's a straightforward method:
Calculate your deck area — length x width in metres. So a 4m x 3m deck = 12 square metres.
Account for the board width — our standard 32mm x 125mm softwood decking has a finished face width of approximately 120mm (0.12m) once the groove is factored in. Divide your deck length by 0.12 to get the number of boards you need per row, then multiply by the number of rows.
Add 10% for waste — cuts, board ends, and any mistakes. Always round up to the nearest full pack or length.
A worked example: A 4m x 5m deck (20 square metres) using 32mm x 125mm boards in 4.8m lengths:
- Number of board runs across the 4m width: 4m ÷ 0.12m = 34 boards
- Each board is 4.8m long, covering the 5m length with one cut
- Total boards needed: 34 + 10% waste = 38 boards
If in doubt, call us on 01452 300159 and we'll calculate it for you — it takes about two minutes and we'd rather you get it right first time.
Step 3 — Plan Your Frame (The Most Important Part)
A deck is only as good as the frame underneath it. This is where corners get cut and where problems start — a poorly built subframe leads to a bouncy, uneven deck that deteriorates quickly.
Joists should be treated C16 or C24 carcassing timber — 47mm x 100mm is the standard size for most domestic decks, spaced at 400mm centres. For longer spans or heavier loads, move up to 47mm x 150mm. All joists should be UC3 or UC4 pressure-treated if they're going near or into the ground.
Bearers sit below the joists and transfer the load to the ground or posts. Use 47mm x 150mm or 75mm x 150mm treated timber depending on the span.
Posts for raised decks should be 100mm x 100mm UC4 brown treated posts — the UC4 rating is important if the post is going into the ground, as it gives significantly better rot resistance than UC3.
Joist spacing — for 32mm decking boards, space joists at no more than 400mm centres. For thinner boards or composite decking, check the manufacturer's guidance as some require closer spacing.
We stock everything you need for the frame — view our treated carcassing range and fence posts.
Step 4 — Think About Orientation and Drainage
Decking boards should always be laid with the ridged/grooved face up to aid grip and water runoff. Lay boards with a 5–8mm gap between them to allow for expansion and drainage — this is especially important with softwood, which will move slightly with changes in moisture and temperature.
Orient your boards so that rainwater drains away from the house. On a flat site, build in a slight fall — 1:100 (10mm per metre) is usually sufficient. This prevents water pooling on the surface, which is the main cause of premature wear and greening.
Step 5 — Fixings
Use stainless steel or hot-dipped galvanised screws for decking — ordinary zinc-plated screws will corrode and stain your boards within a year. The standard decking screw is 4.5mm x 65mm, two per board per joist.
Pre-drilling through hardwoods, and near the ends of softwood boards, prevents splitting. A dedicated decking bit makes this much faster.
We stock a full range of landscaping screws and fixings.
Step 6 — Treatment and Finishing
If you're using pre-treated softwood decking (which all our decking is), you don't need to treat it before laying. However, cut ends should always be treated with an end-grain preservative before they go down, as the sawing exposes untreated timber.
Once the deck is laid, leave it to weather for 4–6 weeks before applying an oil or decking stain. Applying finish too early — before the timber has dried and settled — can result in peeling. After that initial treatment, plan to re-oil or re-stain once a year, ideally in spring before the summer season and again in autumn.
A good quality decking oil will feed the timber, restore the colour, and maintain the water-repellent properties. We stock a range of decking treatments and finishes to suit all timber types and colour preferences.
Planning Checklist
Before you order, run through this list:
- Deck dimensions measured and area calculated
- Board type chosen (softwood or composite)
- Quantity calculated with 10% waste allowance
- Joist size and spacing confirmed for your span
- Post size confirmed if building a raised deck
- Fixings — stainless or hot-dipped galvanised screws ordered
- End-grain preservative for cut ends
- Decking oil or stain for after laying
Ready to Order?
We stock a comprehensive range of decking boards, subframe timber, fixings, and treatments — all available for delivery within 75 miles of Gloucester or collection from our depot in Gloucester same day.
View our full decking range or call us on 01452 300159 and one of our team will help you work out exactly what you need for your project.
Nick's Timber Store, Canada Wharf, Bristol Road, Gloucester GL1 5TE. Rated 4.9/5 on Trustpilot from over 96 reviews.
