Building a Large Composite Decking and Planter

Hi,

My name is Jake and I am a maker/Inventor and I have recently undertaken my biggest project yet; a 4x6.6m deck built using composite decking from Envirobuild.

This Instructable is part 1 of 2 of a larger garden project that will be completed over the next few months. I also have plans for a kitchen, garden, BBQ area to allow for garden cooking next year.

While building the decking I learnt a lot about planning, structure and a few tips that I will share in this Instructable.

I have been incredibly fortunate to be able to partnered with Envirobuild on this deck and planter build. Having worked with the company I can honestly say it was a super simple, informative and an easy process from the beginning to even after delivery. You can visit the website and see the vast amount options they have available by visiting the below link. More on Envirobuild in the "Supplies" section.

Composite Decking, Cladding, Fencing & Flooring | EnviroBuild

Supplies

The list below covers all of the materials used for the build

The base structure

6x2 Treated Softwood @4.8m 15 (Joists)

6x2 Treated Softwood @2.4m 6 (Joists)

4x2 Treated Softwood @4.2m 6 (Beams)

4x2 Treated Softwood @2.4m 2 (Beams)

Postcrete 30 Bags

Post base for concrete 11 Units

Black weed membrane 40 Meters

Joist tie 30 Units

Added extra's

Steel 90degree angle brackets 8 Units

Plastic mesh

Flat steel plates

The composite decking

Explorer Decking Walnut 58 Units

Hyperion Decking 6mm Hidden Fasteners - 100 Box (inc. screws) 7 Units

Hidden Starter Fasteners 3 Units

The decking I decided to go for was the Walnut Explorer 4m boards to use for the decking its self, the picture frame boarder, the facia of the deck and the surround for the garden planter. After I initially contacted the team at Envirobuild, the team were super excited to support the project and directed me to their website to take a look at the extensive range of products, use the decking calculator to figure out exactly how many boards I need for the build and offered extras such as coloured screws and the substructure they offer.

I ordered their sample box which came with a small piece of each colour of decking they offer with an information booklet on the boards. After using the online calculator I decided I needed 58 boards in total. This meant 51 for the main deck, picture frame and fascia and that left 7 boards for the planter.

Once I had calculated this and chose a board type and colour, I sent the information through to the team. The next day I had a call from the sales team to confirm the numbers and to ask if I needed anything else, such as the coloured screws or fascia boards. After confirming my order, an invoice was sent out for me to make payment for the boards. I made the payment during the evening via bank transfer (they have multiple payment options) so the next morning, I received confirmation that payment had been received and a date for delivery.

The delivery information was great, it gave details on how the delivery will be made and what to do if you find any issues with the delivery. I had a great delivery driver who let us know how far away he was from our delivery, made the delivery when he said he was and even took the cardboard back with him.

Step 1: Levelling the Ground, Digging and Concreting the Post/beam Mounts in Place

When it comes to the garden. I was lucky that the garden was basically a blank canvas but at the same time its a new build which means the garden was in no way flat or level in the slightest. The garden drops by around 200mm over 4mtrs.

Levelling the ground under the deck wasn't needed as the foundation for the deck is 11 concrete pads with post/beam brackets concreted into each pad. Ensuring the brackets were level with each other and in line with each other was the most important part at this stage.

I started by measuring and marking out the location for the holes I needed to did using marking paint. To do this I created the outline of the deck with a string line, using the 3,4,5 rule to ensure the corners were 90degrees. I then measured 16" in from each line and used where the lines crossed to put the corner posts, then measured 2.4m from the patio (half way from start to end of the deck) and marked the whole location there, 16" from the outside string line.

Once I had all of the post locations I used one of the small 15"x15" concrete top forms to mark a square with the marked X in the middle, giving me a size to dig. Then, came the digging! 11, 600mm deep holes, dug by hand!

With all the holes dug it was time to set the first beam bracket. I knew the first post bracket was the most crucial as this would basically set the height of them all. I started at the bottom left as I knew this bracket needed to be level with the patio. I dropped a form over the top of the hole and levelled it with patio. This mean moving some soil and building it up on one side a little but was fairly easy to do.

This is where a magnitude of string lines come in. I ran a line so that the top of the bracket touched the string line and the base was level with the patio and top of the form. Measured out 14" so I knew where the edge of the bracket should sit and ran another string line in the other direction. I used stakes and string line levels to ensure they were level as well as the 3,4,5 rule to ensure it was square.

Once the string lines were set for the first bracket, I filled the bottom of the hole with a couple of inches of stone and started filling the hole to 1/3rd with water, I then dropped in a whole bag of Postcrete. It took around 2.5 bags per hole to get the level right, but once the Postcrete was at the right level I buried the bottom of the post and used a small spirit level along with the string lines to ensure it was square, level and in the right location.

Be aware, it starts setting FAST so make sure you have at a least somewhat good process before you add the Postcrete to the water.

Once I had the first one done it was a case of repeating these basic steps 10 more times. String lines are great however ensure the string lines are not touching each other when they cross as this could cause issues down the line, literally.

Once all of the brackets had been set and the Postcrete was dry I used one of the beams to ensure they were all level and straight. I am pleased to say they were all level and correct first time. This is an important step as if one isn't level, fixing it now will be soo much easier than later when half of the deck is built.

Step 2: Laying the Weed Control and Building the Base Structure

When the support pads and beam brackets are set and hard I then took the time to remove any high spots in the soil and got to work laying the black weed membrane. This step is key if you want to prevent weeds growing through your decking. I made sure to start the membrane around 12" bigger than the area of decking and overlapped each run of membrane by 12" at least. I used small plastic garden pegs to secure it into the ground and ensured I had covered the entire area. When cutting to allow for the beam brackets to come through I cut the smallest gap possible to ensure as much membrane coverage as possible.

The beams are made up of two 4x2 pressure treated timber boards fixed together with screws from both sides. The deck was designed in a way where these did not need to be cut to length. Once all of the beams were ready these were secured into the brackets using lag bolts from both sides. I also ensured that the beams were sitting at the correct distance away from what would be the finished edge of the decking, this is taking into account the thickness of the fascia boards. This was important as we wanted the fascia boards to be in line with the edge of the current slabs. At this stage I raised the decking slightly on the left side to allow for drainage towards the fence on the right. This is key to stop water sitting on the top of the deck.

Once everything was set and in place, I laid out 10 2x6 joists and roughly spacing them 16" on centre, making sure the ends were somewhat level and the first joist on the left was on the end of the beams and square.

Once I had the first joist in the correct place, I secured it to the beam with two galvanised 75mm nails each side of each joist directly into the beam. I then continued to do the same for each of the other joists ensuring the 16" on centre and making sure the ends were level with the first joist. I checked for square every 3rd joist to ensure I was on the right track. I did this by pulling a tape and checking corner to corner. After each joist was toenailed into the beams I added the end boards and cut blocking to go between the joists. Adding blocking adds a lot of rigidity and strength.

After the main part of the deck was complete I repeated the same steps for the smaller section at the front. When securing the joists I overlapped the joists by about 400mm, nailing each joist together both sides. I then went around and added small 90degree joist bracket/hangers to each joist for added strength.

As we decided to add a picture frame border around the decking therefore I went around and added a more blocking to the outside of the deck to give something for the end of the main deck boards as well as the picture frame border to rest on and be secured too.

At this stage I did add black joist tape to the top of the deck joists however I found that the tape did not stick well so I didn't bother buying more to do the small part of the deck.

Step 3: Starting the Decking, Adding the Picture Frame

Adding a picture frame border was a fairly simple process. I began with the bottom left corner and started by cutting the first of six 45degree angles needed for the whole deck, placed the piece onto the corner ensuring it was square to the corner, provided sufficient room for the main boards to rest on the joist and provided the overhang we were looking for. I then drew a line down the back of the board and used the hidden starter fasteners, fixed to that line to hold the piece in place.

I then marked the halfway point down the joists and cut that frame board to that mark. As the deck was longer than one board I wanted the join to be in the centre.

Once one piece was installed it was a simple case of repeating all the way around the deck, ensuring the angle was correct for each cut, the length was correct and that each corner was square.

Step 4: Adding the Main Deck Boards

Just like the picture frame border, the main decking boards were super simple to install. The main things to ensure are, that your cut length is correct (if you need to cut the boards) and where to start. As I have a border I needed to cut the boards down and as I have a decking shape that is not a simple square/rectangle I also needed to start with the smaller section of the decking. I wanted to ensure that the transition between the small section and the main section was a full board and not a strange cut. By doing this it means the thin pieces will fall at either end of the deck.

I started by laying a full piece at the transition from main deck to the small section, measured from that board to the end of that section to calculate the number of boards I needed to cut. I checked the distance at a number of different points across that section to confirm each board would be the same length and started cutting. Once I had all the boards cut I got to laying this section.

The boards are secured to each joist with a hidden fastener. The fasteners are not only hidden, because they sit between the boards, they also provide the 6mm gap between the boards AND fasten the boards to the joists. The TX screws are black and the heads are are around 5mm so they fit between the gaps and disappear into the fastener, and they even supply a TX bit with each box of screws. It is a super awesome system as it means no visible screws, all the gaps are consistent and it so easy to install.

Once I had completed the small section it was a case of repeating the process the whole way down the deck.

One tip is to try and get into a rhythm, and be careful stepping over the joists! I tripped a couple or 15 times!

Step 5: Fascia Boards and Overhang Support.

Adding the facia board and overhang supports was super simple. The fascia boards are face screwed into the rim joists at the top of the board to hide the screws.

The supports are steel 90degree angle brackets that are fixed to the rim joists behind the fascia board and screwed into the overhanging picture frame border from underneath.

As before it is a case of cutting the boards with a mitred end for the corner and having the butt joint in the centre of the deck.

Step 6: The Matching Planter

The planter at the side of the deck is 2x8ft and 2.5ft high. This has been built to enable the kids to learn to grow they're own food.

Very simple construction using pressure treated 3x2 timber for the main frame with pallet wood and decking offcuts as the main base, laid out with a 1" gap between each board.

I used black weed membrane to line the bottom of the planter and pierced a few draining holes along the bottom. The membrane is breathable however the holes will help when there is a lot of rainfall.

The next step was the main look of the planter. I used the same boards that were used for the deck to line the exterior of the planter and also added a matching picture frame border. I used a black 90degree plastic angle for the corners, this is not structural, it is there as part of the overall look of planter. We loved the look of the black corners that we decided to add them to the main deck also.

We also added a mesh at the bottom to stop the cat and unwanted animals from making a home underneath.

After that it was a simple process of filling the planter with soil, adding the blue slate and getting the kids planting their chosen fruit/food.

We may also have the only 7 year old girl that would choose to grow sprouts!