Freestanding pergola is built in the same way as a pergola that is connected to a house with some additional support. Freestanding pergolas are completely self-supporting with the entire load transferring to the post and then to the concrete footings. However the main problem with freestanding pergolas are not that they carrying extra weight, but in fact the weight wants to move sideways in the wind. The main loads of all freestanding pergolas are the weight of the timber and structure and the wind load. Wind load will depend on where the pergola is built and the area or volume of the pergola.
Steps of Building a Freestanding Pergola
Step one: Pergola location and set out
Select the location of your freestanding pergolas maximum winter sun and block summer sun. Then mark out the site with builder’s string and timber pegs. Make sure that the pergola is square by measuring the diagonals. Dig 300mm x 300mm by 600mm deep and concrete in galvanized post supports or stirrups. Take care to get them exactly right or use the quick and accurate method using props.
Install the four side bearers of your freestanding pergolas and bolt into place with galvanized or stainless steel bolts. At the end of step two you should have all posts in place and bearers bolted into position. It is important to clamp or nail on a temporary brace timber on one side and one end of the freestanding pergolas. If you do not and you get wind you may end up with a pile of firewood.
Step three: Install corner bracing on all pergola posts
This is where a freestanding pergola will differ from an attached pergola because there is nothing to stop the swaying motion of the wind you must create it. Using pergola span table select the appropriate size of corner bracing for the size of freestanding pergolas and the wind rating of your area. If you do not know the wind rating, contact your local council or building authority for advice on area wind rating. I built the pergola in the photos in a very high wind area and it does have corner bracing on it. The photo was take just before the corner bracing was added, before this the whole structure was braced.From this point on you will need to select a flat roof pergola or a gable roof pergola. Special care must be taken so all timbers are locked together with the correct fixings.
Flat Roof freestanding Pergolas – Run your rafters as per your pergola span tables ether on top of the bearers or inside the bearers. If you want to run your rafters inside you will need to use joist hangers or galvanized bulge head screws through the bearers into the rafters.Gable Roof freestanding Pergolas – Install your center board on temporary supports and work out the cut out and sizing of your rafters and mark and cut one. Then check your one rafter against the pergola sit it on the bearer and the top on the center board. If correct mark and cut all of your rafters using this as a template.
Whether you are building a flat roof or gable roof freestanding pergolas install your battens and nail them off. Then using galvanized bulge head screws screw them all down to the rafters.To finish check all fixing are tight and that the pergola cannot sway. If you try to shake your freestanding pergolas it should not move. Then paint and install your desired roofing and roof flashing.
Once you’ve decided to build your own freestanding pergola instead of using a contractor, and have chosen a design and drawn a basic plan, it’s time to start building. If you’re using a simple design and have two people working, you can probably finish your pergola in one weekend.