Floor joist 6 x 2 (min) laid at 300mm centres will give you a very solid deck tanalised timbers will need less maintenance. Note the hollow timber filled ground post.

Your caravan deck should be level use a straight edge and a level to check raising or lowering corner posts as required. Measuring the diagonals will ensure your deck is square.

Note the top of the post is covered with a timber which is fixed flat between the joists, This section of wood supports the ground post and the balustrade post once the decking is in place.

For added strength the ground posts should be bolted through the sides ensuring the heads of the bolts finish flush with the timber.

Once the base is in place and all fixings done you can lay your deck note the deck finishes 10mm short of the edge this will allow for expansion when the side fascias go in to place (see next picture). 

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7mm fascia boards are used around the edges simply pinned in to place around the sides. Fascia corners can be used to hide corner cuts and fascias joints can be used on runs in excess of 6m.

Balustrade posts are screwed down in to the flat timber as shown in picture 3 if posts line up it adds a neat look to the finished job.

Expansion-when installing balustrade post look down in to the hollow post section to ensure a 10mm gap is left clear on the top and bottom rail.

Lights if using globe or lantern lights have your electrician run electric cables through before you screw the posts down.

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Hold the metal bracket in place then mark the four corner holes before drilling your pilot holes then using 10 x 2 screws fix the metal post in to place. Tip when using gates the ground posts will need to line up with gate posts

Plastic gates are available pre made they come complete with hinges etc.

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Your new deck will need the odd wash, but on the hole you should spend plenty of time on it enjoying your view. Once installed a good quality deck installed on 6 x 2 tanalised timber should give you ten years and more maintenance free caravan space.

WHY DIY ? YOU CAN DO IT RIGHT.