Browse Forums Outdoor Living 1 Oct 04, 2011 12:44 pm Hi we are building a pergola that is attached to the back of our house. Its going to be 8m x 4m with a flat roof. It will be about 3.35m high (at highest point - attached to house) and 3m (at lowest point - 5 degree fall away from house). Rafters about 1m apart, no battens as the roofing we are using (makrolon) doesnt require them. Posts to be direct in ground about 600mm deep. 4 posts - 2.66m apart (the otherside is attached to the house) So thats the background; now the questions what size posts will we have to use? will 135mmx135mm treated pine bow at that height? do we need additional bracing on the pergola given the low side is approx 3m high? can we use 4m long F17 seasoned hardwood 140mm x 45mm for the beams/rafters? thanks Re: Help with pergola timber sizes? 2Oct 05, 2011 1:25 am 90x90 cca posts will be fine, although I wouldn't be concreting these directly into the ground. I'd use a galvanised stirrup bolted to the bottom of the post and then set that into concrete. Beam size would be 190x45 mgp10 cca pine. Rafter size would 120x45 mgp10 cca pine this is for 900mm spacing. You will also need knee bracing on the post and beam to prevent lateral movement. These are the span tables I use for pergola construction, it also shows the construction details for a typical pergola. http://www.tabma.com.au/documents/TABMA ... Tables.pdf Hope that helps. Accessible Carpentry & Cabinets accessiblecarpentry@gmail.com accessiblecarpentry.com.au https://www.facebook.com/pages/Accessible-Carpentry-Cabinets/583314911709039 Re: Help with pergola timber sizes? 3Oct 13, 2011 4:14 pm Chippy, why do you think its not good to have the post concreted directly into the ground? Would putting the post on stirrups and concreting the stirrups to the ground be more secure? I would have thought concreting the post directly to the ground to be more secure? I've got that dilemma at the moment as I'm about to build my pergola as well. Thanks. Idiots are fun, that's why there is one in every village! - Dr. House - Help with pergola timber sizes? 4Oct 13, 2011 9:37 pm wonderland Chippy, why do you think its not good to have the post concreted directly into the ground? Would putting the post on stirrups and concreting the stirrups to the ground be more secure? I would have thought concreting the post directly to the ground to be more secure? I've got that dilemma at the moment as I'm about to build my pergola as well. Thanks. The reason you use a stirrup is that timber rots pretty quickly in the ground. There are treatments that can be applied to timber but at best all they will do is delay the inevitable to greater or lesser degrees. Cement the stirrup into the ground and bolt the post to the stirrup is the most sensible option I think. It might seem a bit more work cementing the stirrup then attaching the post, but not when you consider the time and effort you would expend in a short few years after concreting the post directly into the ground. Replacing that would entail digging out the concrete plug that the post has rotted away in so that you can then put the new post in to replace it. Structurally, the sturdiness of each method of securing the post is likely to be just the same Re: Help with pergola timber sizes? 5Oct 13, 2011 10:33 pm You have a very good point. Do you have any advice on how to go about getting the posts to be straight and in line with one another? Should I bolt the post onto the stirrups first and then try a d cement the stirrups in, or cement the stirups in first and then bolt the post into the stirrup? I find that trying to figure out the best way to do the posts is the hardest part of the whole project! Any advice would be greatly appreciated Idiots are fun, that's why there is one in every village! - Dr. House - Re: Help with pergola timber sizes? 6Oct 13, 2011 11:47 pm Is the pergola free standing or is it attached to the house? Accessible Carpentry & Cabinets accessiblecarpentry@gmail.com accessiblecarpentry.com.au https://www.facebook.com/pages/Accessible-Carpentry-Cabinets/583314911709039 Re: Help with pergola timber sizes? 7Oct 14, 2011 7:01 am One side of the pergola will be attached to the house Idiots are fun, that's why there is one in every village! - Dr. House - Re: Help with pergola timber sizes? 8Oct 14, 2011 8:23 am We were told that we should use 115x115 posts for 8.2m total span (but unsure will there be 3 or 4 posts). wonderland, how big is your pergola? My signature is distracting people from my wise posts ... Re: Help with pergola timber sizes? 9Oct 14, 2011 8:33 am hi Lex, My pergola will be 6.5m x 4m, therefore my rafters will be 4m continuous span. My post is 100x100 cypress pine and there will be 3 post to support my beam which is 3.25 single span. Our beam and rafter size will be 190x45 Idiots are fun, that's why there is one in every village! - Dr. House - OK it's been a little while! I've been busy getting time where I can to work on this. I started by grading a pad (borrowing a… 26 19869 I have a box of quality drill bits that seem to be new but their engraved sizes covered by rust ,,,,I tried to sand them to see their sizes but still I am finding… 0 1387 Is there a building permit? RU in Victoria? What is the value of the building contract? 1 6788 |