This wooden balau pergola was built at Plantations in August 2016. We had custom-made galvanised steel base plates made up in order to secure the uprights to the existing paving. Because the uprights had to be installed on the edge of the paving we couldn’t dig and bury the post so we installed them into these base plates which were then fixed to the paving using sleeve anchors.
When designing a base plate for this application it is important to make the tube that will carry the upright post long enough in order to give it lateral support to stop the structure “racking”. Also the actual base must be big enough to be sturdy, but small enough so as to still be neat and not get in the way. We used a 90 x 90mm balau upright. The back row of uprights were fixed to the outside of the wall surrounding the entertainment area.
On the top we installed 30 x 102 as purlins which were spaced at 600 centres. I’ve found that spacing a 30 x 102 at 600mm centres works best from a structural point of view and a cost point of view. Obviously the closer the purlins are spaced the more expensive the pergola will be and one must be careful not to space them too far apart as it affects the stability of the structure and the visual appearance.
On top of that we installed 30 x 40 balau battens running perpendicular to the purlins at 120mm centres resulting in a gap between battens of 90mm being 3 times that of the batten itself. This works well in order to give enough broken shade without creating a completely closed effect on top. It also helps on the pocket by using 30 x 40 as opposed to 30 x 60mm.
Because of the existing chimney on one side of the area we had to cut purlins beams and battens in order to finish it neatly around this chimney whilst still making sure that all ends were fixed. If the ends are left unsecured they tend to twist over time.
These balau pergolas can be left un-oiled or oiled. If left un-oiled then they will eventually turn a silvery grey colour. If oiled they will remain slightly darker. It is not advisable to coat them with any other product other than an oil as it will eventually peel and flake and maintenance then becomes difficult and expensive. They can be pressure washed to remove dirt and grime that settles over time.
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