Thread: How to Strengthen a Pergola

The best way to brace a structure is like this is to triangulate it (incorporate as many triangles as possible into it).

To help out in your case you need to bolt a timber brace from the middle pole at the camera end of picture (truss base level )to the ridge beam at the next truss. This will elimiante a lot of movement between the base of the trusses and the ridgeline. The material should be similar in size to the truss material, or heavier. This permanently replaces the temperary prop showing in picture 1. The temporary prop will only work in compression to stop the trusses moving toward the house as it is too long and slender to be effective in compression and stop the trusses moving toward the camera, it would just flex. A decent brace from the pole to the second truss would be much shorter and stiffer than teh prop and work in compression and tension.

For further rigidity, obtain a roll (or two or three) of galvanised strapping and run four braces diagonally across the tops of the trusses (centre of near end truss to bottom of far end, and centre of far end to bottom of near end, plus the same on the opposite side of the truss) nailing straps to the top of each truss where it crosses over. The straps should be fixed at one end and moderately tensioned at the other end before fixing there and then at the intermediate trusses.

The intermediate trusses could also be triangulated with a pair of diagonals from the centre of the lower tie to the point where the upper tie meets the rafter. Hard to tell from the pics alone but the truss material might be thin but wide, making a structure with little stiffness.

I have lightened up your picture and see that the back and right side beams are supported by your house . You can stop the rocking by using hoop iron bracing in the form of a cross placed on each side of the roof. On each side nail the end of a length of hoop iron on the low end of the rafter at the back and nail the other end at the ridge at the front, pulling it as tight as you can before nailing it . On the same side of the roof, nail the end of a lenght of hoop iron on the ridge of the rafter at the back and the other end at the bottom of the front rafter . You have formed a cross. Repeat on the other side . Buy some hoop iron tensioners which will allow you to tighten up the hoop iron . Then nail the hoop iron where it crosses each rafter . Should do the trick.

PS. You could use roof bracing as well but the hoop iron will sit flat . You should do this before you nail down your purlins.

I see I have just repeated Malb's advice so there you go .

thanks guys appreciate the fedback, will see if I can make some sense of it all and see how I go, tyring to get used to some of the terms.

cheers

adam

The surrounding roof structures will act as a diffuser if you like, but then you guys are just havin a bit of fun with us hey! Because the structure you are building once completed will in my opinion withstand Armageddon especially since you have all those buildings around it. Don't stress! Sit back and have brew with the old man for new year. There's got to be beer in that esky!

Cheers,

Oddjob1