How to build a raised deck?

Building a raised deck will take some time and is trickier than laying standard decking at ground level, but if you want to build decking on a slope or uneven ground it’s the best way to do it. If you do your research and follow instructions, you and a friend or family member can build a raised deck over a few days. Here’s a simplified guide of the steps you’ll need to take. Plan carefully It’s best to plan your raised deck by drawing it to scale on paper before you go and get supplies. This will help avoid wastage and making more cuts to timber than necessary. Prepare the area Prepare the area according to the instructions we give in the FAQ ‘How to lay decking’. However, because you’re building a raised deck, you’ll need to add posts: Place a post in the corner of the frame you created with the pegs and string. Measure and mark out 100mm from each side. Dig out this soil to a depth of 700mm (watch out for cables or pipes). You should have a 300 x 300mm hole. Repeat for the other 3 corners. Using a brick bolster, split a concrete block in two. Put a section of the block in each hole. Get a length of post longer than you need and place one in each hole. You can cut it down later. Create props on each post to hold them in place until you’re ready to add a cement mix. Check that they’re level. When you’re happy that they are, secure them in place with a concrete mix, making sure you create a slope in the concrete so that rainwater runs away from each post. When the concrete is set, remove the props. Create a string line around each corner post and find the centre point between each. Place a timber batten at each point, ensuring that they’re not spaced any more than 1500mm apart. Make the outer frame Working from the corner where the deck will be at its highest above ground level, measure and mark on the post where the highest part of the frame will be. Measure from the far side of one post to the opposite and cut sections of joist to size. Line up a piece of joist with the mark you made and temporarily secure it. Factor in a 2mm fall for every metre of decking so rainwater can run off. Secure the frame to the other corner post, ensuring it’s at the right level. Do this for every side of the outer frame. Using 100mm coach screws with washers hanging on the end, secure each end of the four sections of frame. Mark out where the centre of the support posts will be and secure all of these posts to the frame, except the centre post. Add your central support joists. These should run in the same direction as the deck boards will run. You’ll need to measure from the inside of the frame on one side to the inside of the frame on the opposite side. Attach the joist in the same way as you did for the other posts. Repeat so the centre post is in between two sections of frame and secure the posts with concrete. Trim down all the posts to the correct height using a saw. Add your weed-control fabric and weigh down with gravel across the entire area. Add your joists Measure 400mm from the centre of the outer frame and mark a line. This will be where the first joist is positioned. Repeat at 400mm intervals down the length of the frame – if the last one will be more than 400mm, add another joist to create enough support. Attach a joist hanger to each end of the joist. Place the joist in position so the centre lines up with the 400mm spacer mark. Secure using external grade screws once you’re happy that the joist is flush with the frame. Lay your decking boards Refer to our FAQ on how to lay decking to see how you should attach your decking boards. Remember: Always treat cut ends and pilot holes with decking preservative to keep your decking in good condition for as long as possible. Building a raised deck isn’t a straightforward task. If you’d rather leave it to the professionals, get a range of quotes to help you get the best price and a high quality finish.

Wooden Decking in Lisburn and surrounding area

Wooden Decking in Lisburn

Wooden decking is an increasingly prevalent option for creating outdoor seating areas in gardens. Due to the natural beauty of wood, they can be very elegant areas which can be used year round by installing additional heating and illumination. Wooden decking is frequently fitted in locations in front of patio or French doors where they can create a smooth transition between inside and outside spaces. Wooden decking can come in virtually any size or shape to complement any area. Curved designs or large areas connected by pathways can produce a striking effect. Wooden decking is reasonably simple to install and causes minimal disruption, especially when compared to other possibilities like patio or paving. It could even be installed over the top of an existing patio. It is crucial however to make sure that your wooden decking is structurally sound and capable of taking the load of any furniture or plants that you want to use on the decking. There is a choice of types of wood that can be used in wooden decking. Typically decking is made of hardwood, but there are softwoods available that fulfil the durability requirements. As hardwood decking will need maintenance, which generally consists of annual cleaning and staining for weather proofing, composite woods have become popular for use in wooden decking because they are more robust and require far less maintenance.

Avg. price low	Avg. price low £1,125
Avg. price	Avg. price £1,500
Avg. price high	Avg. price high £1,725

Avg. price low

Avg. price low
£1,125

Avg. price

Avg. price
£1,500

Avg. price high

Avg. price high
£1,725

How much decking you need will – of course – depend on how big you plan your deck to be. There is an equation to help you work out how many deck boards you need. It’s a little complicated until you’ve been shown how it works, but once you know how to do it it’s easy to work out how much decking you need for any project. The equation takes into account the recommended 10% wastage and includes the expansion gaps that are required, which is between 5-8mm along the length of the deck boards (EGL, or expansion gap length) and 3mm along the ends of the deck boards (EGW, or expansion gap width) for timber. It also assumes you’re laying your decking horizontally, as if you’re looking for a diagonal or chevron design you’ll need more deck boards. Let’s go through an example, assuming you have a 10m x 6m area that you want to cover with decking made from timber boards that are 2.4m long and 144mm wide. We’ll use the EGL of 5mm and EGW of 3mm.

Calculate the surface area for your decking Multiply the length (L) of your decking area by the width (W): L x W = Decking Surface Area (DSA) in m² 10 x 6 = 60m²
Work out the coverage of your deck boards Add your deck board width (DBW) to the expansion gap length (EGL), then add the deck board length (DBL) to the expansion gap width (EGW). Then multiply these numbers. (DBW + EGL) x (DBL + EGW) = Single Board Coverage (SBC) 0.144m + 0.005m = 0.149m 2.4m + 0.003m = 2.403m 0.149 x 2.403 = 0.358m²
Calculate the number of deck boards you need Multiply the SBC by 1.1 to allow for 10% wastage. Then, divide the DSA by the SBC. DSA / SCB x 1.1 = Total number of boards required 60m² / 0.358m² x 1.1 = 184.36 boards – so round up to 185 so you’re not left short.

If that all seems a bit complicated for you, let a professional do the maths – they will be able to give you an idea of how much decking you’ll need in no time.

Properly installed wooden decking will not need a lot of maintenance. Most manufacturers recommend regularly brushing leaves and dirt off the deck, and a yearly cleaning and staining procedure. This will keep the wood in the best condition. Fluids and treatments are readily available from all DIY shops and stores.

Yes, although you should make sure that the terrace or decking is able to support the weight of a hot tub. Usually, you will need to have a structural survey carried out on the area. Seek the advise of a hot tub retailer or installer about the logistics of installing one at your property.

Building a raised deck will take some time and is trickier than laying standard decking at ground level, but if you want to build decking on a slope or uneven ground it’s the best way to do it. If you do your research and follow instructions, you and a friend or family member can build a raised deck over a few days. Here’s a simplified guide of the steps you’ll need to take. Plan carefully It’s best to plan your raised deck by drawing it to scale on paper before you go and get supplies. This will help avoid wastage and making more cuts to timber than necessary. Prepare the area Prepare the area according to the instructions we give in the FAQ ‘How to lay decking’. However, because you’re building a raised deck, you’ll need to add posts:

Place a post in the corner of the frame you created with the pegs and string. Measure and mark out 100mm from each side.
Dig out this soil to a depth of 700mm (watch out for cables or pipes). You should have a 300 x 300mm hole. Repeat for the other 3 corners.
Using a brick bolster, split a concrete block in two. Put a section of the block in each hole.
Get a length of post longer than you need and place one in each hole. You can cut it down later.
Create props on each post to hold them in place until you’re ready to add a cement mix. Check that they’re level. When you’re happy that they are, secure them in place with a concrete mix, making sure you create a slope in the concrete so that rainwater runs away from each post. When the concrete is set, remove the props.
Create a string line around each corner post and find the centre point between each. Place a timber batten at each point, ensuring that they’re not spaced any more than 1500mm apart.

Make the outer frame

Working from the corner where the deck will be at its highest above ground level, measure and mark on the post where the highest part of the frame will be.
Measure from the far side of one post to the opposite and cut sections of joist to size. Line up a piece of joist with the mark you made and temporarily secure it. Factor in a 2mm fall for every metre of decking so rainwater can run off.
Secure the frame to the other corner post, ensuring it’s at the right level. Do this for every side of the outer frame.
Using 100mm coach screws with washers hanging on the end, secure each end of the four sections of frame.
Mark out where the centre of the support posts will be and secure all of these posts to the frame, except the centre post.
Add your central support joists. These should run in the same direction as the deck boards will run. You’ll need to measure from the inside of the frame on one side to the inside of the frame on the opposite side. Attach the joist in the same way as you did for the other posts. Repeat so the centre post is in between two sections of frame and secure the posts with concrete.
Trim down all the posts to the correct height using a saw.
Add your weed-control fabric and weigh down with gravel across the entire area.

Add your joists

Measure 400mm from the centre of the outer frame and mark a line. This will be where the first joist is positioned. Repeat at 400mm intervals down the length of the frame – if the last one will be more than 400mm, add another joist to create enough support.
Attach a joist hanger to each end of the joist.
Place the joist in position so the centre lines up with the 400mm spacer mark.
Secure using external grade screws once you’re happy that the joist is flush with the frame.

Lay your decking boards Refer to our FAQ on how to lay decking to see how you should attach your decking boards. Remember: Always treat cut ends and pilot holes with decking preservative to keep your decking in good condition for as long as possible. Building a raised deck isn’t a straightforward task. If you’d rather leave it to the professionals, get a range of quotes to help you get the best price and a high quality finish.

	Labour cost	£1,050
	Material cost	£375
	Waste removal	£75

Wooden Decking in Lisburn

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