We started with our deck in a normal joist and beam system, but installed our main beam of 50 x 228 on the front in line with the joists rather than slotting it in underneath. This was simply because we didn’t have much space below the deck to slot it in. On the front edge it was fine to use a 50 x 228 beam, but midway across the deck we couldn’t use a 50 x 228 and had to secure each joist to the ground with a small post. It wasn’t a problem though because we were placing it directly on top of the slasto substrate. So there were no holes to be dug and filled with concrete.
We then attached two 76 x 76 pine posts, which can also be replaced with balau 90 x 90, to give us some posts to work from for our pergola. Our pergola was built using a 50 x 228 beam on the front, but this could have also have been replaced with a 38 x 152 as there is no real weight on top of the pergola. You do get some wind loading from beneath in pergolas with fixed roof sheeting, but not much weight from the top. We only used two posts as our main beam on the front was long enough to span across the 5.2m of the front of the deck. Adding extra posts in between clutters up the front of the deck.
We added 50 x 76 purlins and covered that with clear polycarbonate roof sheeting. This allowed the light to still get in but it will be protected from rain. This roof sheeting is however not that attractive from beneath so we clad the underside with thatching laths with no gap between them. I’ve tried building one of these before with a laths gap between laths, but it doesn’t work as you can then see the roof sheeting clearly. Because the laths are not a regular uniform thickness all the way along, you still do get some gaps, even if placing them side by side, which allows light through but takes away the view from beneath of the roof sheeting.
We added a step on the front, as the top of the deck was more than 200mm off the ground on the front so this made for easy access to the garden from the deck.
In the pics alongside you can see the roof sheeting on before we placed our thatching laths on. We’ve also previously used a translucent bronze roof sheeting which works very well to cut the glare from the sun. The polycarbonate roof sheeting is far better than fibre glass roof sheeting, albeit more expensive, as it doesn’t contain strands as the fibre glass sheeting does.
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