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How to assemble deck railings

How to lay a deck

A deck is a great way to make the most of your outdoor space and can transform an old patio or an expanse of lawn into a stylish place to relax and entertain guests all year round. Not only are decks easy to build, but if you look after them correctly they will be long lasting and durable, leaving you with an attractive garden feature for years to come.

Once you’ve watched this video, you’ll know just how easy it is to lay your own deck. It gives advice on where to position your deck, how to build a sturdy and level frame, as well as how best to attach the deck boards and fascias.

Preparation & planning

Deciding where to build your deck is the first stage of the planning process. Is your priority maximum sunshine or do you want privacy? Be aware that heavily shaded areas will require more maintenance and you should avoid wet areas completely.

It’s a good idea to plan your deck to scale before starting as this will limit cutting and wastage and will help you to be accurate when ordering the materials you need.

If you are going to build your decking next to a house, make sure it’s 150mm below the damp proof course and that you don’t cover any air bricks.


Once the decking is complete, apply a decking stain to further protect the timber. These come in a variety of colours so be sure to look at the range.

If you choose a permanently shady spot, be prepared to clean and treat the wood annually to preserve the timber from damp and prevent algae growth. To keep the deck clean, remove any dirt or leaves with regular brushing.

Hints & tips

Always use structural treated timber and screws designed specifically for the job to ensure the deck is built to last. Also, don’t forget to treat all cut surfaces and holes with two coats of preservative.

When sawing, use the 90-degree guide marker on your saw or a set square to help you make accurate cuts. When drilling, we would advise that you measure and mark out all pilot holes to ensure your fixings are as accurate so possible.

Check regularly that the fall of the frame is 1:100 and running away from the house, this will aid water run off and will help to stop the deck from becoming slippery.

It is possible to build a deck on your own but it is much easier with a spare pair of hands, so ask a friend if they can help out.


Make sure you firmly secure the timber and take care when sawing, drilling and hammering in the nails. When drilling, it’s also best to wear safety glasses. Be sure to wear gloves when sawing, handling the deck posts or applying wood preserver. Also, always follow manufacturers instruction for drying and safety when using wood preserver.

Offcuts of treated timber should never be burnt, but need to be disposed of safely – your local recycling centre should be able to advise.


Notch out the deck posts 120mm x 20mm up from the bottom. Or, to make this part of the project much easier and faster, you can buy these pre-notched. If you need to extend your notch further than you can do this using a handsaw or circular saw.


Then, ask someone to hold the deck post in position whilst you mark the location of two evenly spaced pilot holes on the post.


Secure the post in your bench and drill the pilot holes.


To fix the deck posts to the bearer, hang washers on the end of a 130mm exterior coach bolts and then tighten the bolts with a socket.


Make sure they are evenly spaced with a maximum spacing of 1800mm between them.


If you need to notch a post into the decking to keep it flush, start by measuring and marking both the top of the deck and the fascia where the post will be.


Remove the fascia and, using a handsaw, saw off the section you have marked out.


Use a jigsaw to remove the top section.


Put the post into position and check that it is flush to the decking. Then, secure the post as before and reattach the fascia.

Assembling the rails


First, measure the gap between the posts so the tops and bottom rails can be cut to fit between them.


To make sure spindles are placed evenly, measure and cut a piece of spindle to 81mm and use this as a marker.


Measure 81mm from the end of the rail and mark a line. This line will be where the first spindle will be placed.


When you are marking the bottom railing, mark the centre of each spindle, as this is where the pilot holes will be drilled.


Turn the 81mm section on its side and continue to mark along the length of railing. You may need to adjust these measurements slightly to fit the length of your handrail. However, make sure all spacings are equal and do not exceed 82mm before fixing.


For the bottom rail, repeat the above with the addition of drilling a 3mm pilot hole through each mark.


Next, attach the spindles to the bottom rail using 76mm deck screws. You may need someone to hold them in place for you whilst you screw.


To attach the top rail to the spindle, use a 64mm galvanized finish nail but take care not to damage the wood whilst hammering. Alternatively you could use a nail punch to finish the nails.


Place the long side of the L brackets centrally into the fillet slot on the underside of the bottom rail. Check the L brackets do not stick out past the end of the rail before fixing the bracket to the bottom rail using the two 25mm screws that are supplied in the kit.


Mark on your deck post where you want the top railing to be, making sure it’s at least 900mm from the deck.


Centrally place the short side of the L bracket onto the mark and fix the bracket to each deck post using two 25mm screws.


Place the railing assembly on the fixed post L brackets and secure to the underside of the top rail using two 25mm screws.


Centrally locate the bottom rail on the deck post before fixing the bottom rail L bracket using two 25mm screws.


On each side of the top and bottom rails, measure 25mm from the end of the rail and mark.


Drill a countersunk 3mm pilot hole approximately 30 degrees through the rails and into the post.


Finally, skew two 50mm screws into each rail to secure to the post.


Your railings are now complete!

Tools required

Materials required


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