![]() ![]() I tried to add some drawings but had no luck sorry hope this is descriptive enough. Then 5 beams running left to right 1mtr appart, these 5 beams will be seperated by 1 mtr spreaders beams running front to back making a cris cross pattern when viewed from above. Name (Required) Email (Required) Phone (Required) Subject. If you have any questions or would like to order a hard copy of one of our guides, please leave us a message. The design uses all the same sized beams, 4 sides supported in each corner by 200x200 posts. LVL13 is commonly used as a rafter and can reach the extra spans required. Is this design acheivable considering the weight of the roof and the spans? The design I have come up with only uses beams with no rafters. The size of the structural beams I was wanting to use were either 300x50 or 300x75 in either pine or oregon. I really want to only use 4 posts if at all possible, and this may require me to look at alternatives other than timber. The biggest problem I can see with my wishfull design is going to be the 6m spans. The whole structure will cover a timer deck which is going to be built over a new concrete slab. The roof will be colourbond, and the underneath of the roof will be fully enclosed with fibro sheeting. AMPERE double main rafter, or beam, able be used to gift more support, and corner braces could also reduce the span, but do try to remove the away between posts if at see possible. I am wanting to build a freestanding pergola, 6m x 6m, with a skillion style roof with a slight slope from front to back supported on only 4 posts (the two front posts at a height of 2.8m and the two rear posts at 2.3m) which are going to be 200x200mm hardwood. PERGOLA SPAN TABLES - UPPER INGOT SPAN, ft. I guess what I really need to understand is, beyond the span table figures, what the realities of the current structure (span and bressummer) would be under that worst case max load.I am new to this forum and after reading throught literally hundreds of posts I am unable to find a match to the work I am wanting to carry out. Had considered changing the bressummer now, so that it is done, and then worry about the span later in the year. I can also extend it further to the right, and attach it to the neighbour's garage, if he will let me. So I expect a carefree summer, but winter is the concern.ĭon't want it coming down on my head when I'm eating my turkey.īecause it is fixed to the wall at one end, I had hoped that racking would not be a significant issue, but I can add some diagonals. I don't have any immediate concerns with the polycarbonate because, as Mr Chibs says, it will be hardly any extra weight. Yes my concern is sag under maximum (snow) load, using the 0.75kN/m2 span tables, and the same for the bressummer which is just a single 2圆. I am really loathed to run the extra line of posts at the midpoint of the rafters, but if I need to, then I will have to. I have also attached a couple of recent pics of the structure. I believe that it may be possible to save the situation, with the following changes.ġ) Rearrange the bressummer posts to set max span at 2 metresĢ) Replace bressummer with 75x225 C24 timber, still on 100x100 postsģ) Add a further line of posts at the midpoint of the rafters, with 75x224 C24 timbers, to reduce rafter span to max of 2.4 metres.īelow is a sketch I originally did, but the structure now goes further to the left and attaches to a wall that is 90 degrees to the rear of the house, plus the rafters are 4m to the centre of the house, but 4.8m to the left and right, where the rear wall is receded. ![]() I think that the bressummer is also underspecced. I would now like to finish it with a polycarbonate roof on but consulting some flat roof span tables, I can see that C24 2圆 can only support a 3m span (assuming 0.75kn/m2). Most of the structure has been stood for a year, just with a tarp over it (plus some loose poly underneath for rigidity). Rafter Span Tables - Use these tables to determine lengths, sizes, and spacing of rafters based on several factors such as species, load, grade, and spacing. 2x2 purlins 400mm centres above rafters If your code book says your snow load is 40 psf, then you. Second, use the snow load value for your region in determining which rafter table to use. First, remember that the rafter’s span is not its actual length, but its total horizontal projection (see Figure 6). rafters sitting on joist hangers at bressummer and wall plate When using the tables to size rafters, there are two points to keep in mind. bressummer supported on 100x100 posts at 3m spans and fixed to wall at one end C24 2圆 rafters with spans between 4m and 4.8m I have constructed an attached pergola roof with the following spec ![]()
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