[Timber Blog] How to lay decking….

Decking from Forestrall TimberWith this weekend’s weather showing us that summer is not yet just a distant memory, there’s still time to think about laying decking in your garden.  Why not create something now so that as soon as spring / summer 2013 hits, you’re ready to invite the masses for the first barbecue of the season, with a garden worthy of entertaining…

I’m reliably informed that although you’ll need some basic DIY skills but there’s nothing in laying decking that’s particularly difficult. Depending upon its size, you could do a deck in a weekend.

As with all DIY jobs, planning is essential.  Fail to plan, plan to fail! Initially, make a rough sketch of your design. In addition to this, you could also lay out battens to mark the edge of your planned deck to see how it will look in the area you have in mind.  You don’t want to suddenly realise that your planned decking area actually takes over your entire garden!

When you’ve decided on the extent of your decking area, draw a scale plan of the area. Mark on outside house walls, waste water soakaways, air bricks, manhole covers, door openings and any trees or other obstacles.  Make sure the top level of a deck (if it’s attached to your house wall) is at least 150mm below the damp proof course (DPC). That way you’ll be complying with Building Regulations.  Allow for access hatches or cut-outs in the deck around drain inspection covers. Make sure you don’t block any air bricks.

From your plan, calculate the area of your deck in square metres. Then I would suggest using one of the many online decking calculators to find out how many linear meters to purchase.  Below is an example table, based on 144mm softwood decking.

M/M

1

2

3

4

5

6

7

8

9

10

1

7

14

21

28

35

42

49

56

63

70

2

14

28

42

56

70

84

98

112

126

140

3

21

42

63

84

105

126

147

168

189

210

4

28

56

84

112

140

168

196

224

252

280

5

35

70

105

140

175

210

245

280

315

350

6

42

84

126

168

210

252

294

336

378

420

7

49

98

147

196

245

294

343

392

441

490

8

56

112

168

224

280

336

392

448

504

560

9

63

126

189

254

315

378

441

504

567

630

10

70

140

210

280

350

420

490

560

630

700

Work out how many posts and rails you need. If you’re unsure ask us your supplier as they’re likely to be glad to help (even take your deck plan with you to the timber yard).  Forestrall Timber and Fencing Merchants are always happy to help answer these type of questions.

QDeck have fabulous online planning tools that can help you with planning and installing your decking. http://www.jump-to.co.uk/pdfs/all/design-a-deck-planning.pdf

Before you get too carried away with your decking boards and the excitement of changing the image of your garden, the prep work has to be done!  Not the planning, you’ve now done that, it’s the physical work next! Use pegs and string to set out the deck perimeter. Then clear all turf and vegetation from the area and firm down the ground beneath.  Depending on the condition of the area you’ve chosen, this could be an easy task or a massive excavation project!

Lay a deck fabric over the earth to prevent weeds growing up through the deck. You can peg the fabric or weigh it down with concrete or paving slabs.  This really is important, or you’ll end up with unwanted greenery growing through your decking.

The framework for a deck should be laid onto concrete foundations rather than directly onto the soil. You can lay down concrete for this but it’s easier to use concrete paving slabs.  When laying slabs, arrange them in a grid pattern with each slab positioned about 1400mm from the next. These will support the timber joists that hold the boards.  If you are building your deck alongside your property, then use a spirit level to make sure the deck gently slopes away from the house. For every metre of deck there should be a 10mm drop.  Finally, lay squares of bitumen DPC membrane over the paving slabs before putting down the deck timbers.

Now the framework – Create the outer frame of the deck with joists (150mm high x 50mm wide). This rests on top of the slabs.  The joists are fixed together with 100mm rustproof screws and external wood glue. Use one screw on the top edge of the joist and two screws on the sides.

If you’re attaching the deck to your house, screw the first joist to the wall but put plenty of stainless steel washers between the joist and the wall to leave a gap of at least 10mm. Use a spirit level to make sure the outer frame is flat and sloping slightly away from the house.

Next fill the outer framework with the long joists, spaced at 400mm intervals and screwed to the frame. These joists should be fitted at right angles to the finished deck boards, just like an internal floor.  Fix short lengths of deck boards – or ‘noggins’ – at right angles between the joists to strengthen the framework.  Treat any new cuts in the wood with a timber preservative.

When all the joists are in place, the finished framework should be completely rigid. Now you can lay the deck boards, starting next to the house (if you are building this next to your property).

Lay about six boards at a time, leaving spaces between boards of 5mm (approximately the width of a fixing screw). This is essential for ventilation and allows for expansion in wet weather.  Use purpose-made stainless steel or galvanised screws so your decking isn’t spoilt by rust stains.  Pre-drill your screw holes to reduce the risk of splitting the wood.  Fix the ends of each board first, then screw the centre of the board to every joist in between.

If the deck is wider than the length of deck board being used, you’ll need to stagger the boards. Remember to join boards over a joist. Cut to size where necessary.

Hopefully, you will then complete your fabulous new area of decking!

Generally, deck boards are pressure-treated with a long-lasting preservative treatment but the colour will fade after a few months.  You can either leave your deck to age naturally or treat it with exterior penetrating oil that soaks into the wood rather than sitting on the surface. These come in various timber shades and can be brushed, sprayed or rollered onto the boards.

We’d love to read your DIY blogs or comments so please do let us know how you’re getting on?  Find us on Facebook, and leave us a message or Tweet us!

Q Deck HArdwood Decking

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One Response to [Timber Blog] How to lay decking….

  1. This was a great guide for rookies, also wanted to mention a big thank you for writing out the table above. I’m sure that will help hundreds of people that visit this blog!!

    -Adam Ahmed

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