Moggaman Posted February 3, 2022 Share Posted February 3, 2022 Hi. U would like some advice please. I have a canopy section on the front of my house. It overhangs but about 1.2m. See photo. It is not supported at the moment because in all likelihood it doesn’t need it. It is a 7m long 7x2 rafter supported at wall plate level and further up by steel beams. So I am looking at putting in a column for the look and to prevent any possible sagging in that area over time . I am looking at bringing up a 4x4 galvanised box iron(3mm thinkness) and across that a 4x2 box iron birds mouthed into the rafter, mortared into the wall on on side and bolted to the Column on the other. The span will be around 3.7m. I am wondering will a box irons section 3mm wall thinkness sag over 3.7m ? And are the wall thickness of both ok. Like I said , the roof is build, these will slot in under it.. thanks Link to comment Share on other sites More sharing options...
SuperPav Posted February 3, 2022 Share Posted February 3, 2022 Feel free to consult a SE as I am not one, but I don't think that needs any support whatsoever. The weight on the rafter across its length means any sagging will be in the middle of the roof, so if anything it will be pulling the end of your overhang UPWARDS with that ratio of cantilever... If you want a column for aesthetics, just whack one on there but I don't think you need any structural support or beam/lintel across the ends (might just want to put a fascia board/timber on to finish the ends off). Link to comment Share on other sites More sharing options...
Mr Punter Posted February 3, 2022 Share Posted February 3, 2022 Agree with @SuperPav. Unless you have cut a very deep birdsmouth around the wall plate the 1200mm overhang should be OK. Link to comment Share on other sites More sharing options...
Moggaman Posted February 3, 2022 Author Share Posted February 3, 2022 1 hour ago, Mr Punter said: Agree with @SuperPav. Unless you have cut a very deep birdsmouth around the wall plate the 1200mm overhang should be OK. Looks like not too far Into a 7x2 rafter. It’s a 4x3 wall plate Link to comment Share on other sites More sharing options...
Mr Punter Posted February 3, 2022 Share Posted February 3, 2022 Looking at this again, you may need a SE to design as you need to factor in snow loads etc. Should not cost much. Link to comment Share on other sites More sharing options...
JohnMo Posted February 3, 2022 Share Posted February 3, 2022 I would strongly suspect 4x2 3mm wall steel (not iron) over 3m will sag quite a bit with it laying flat. 6 or 8mm wall would be better, the calculations would have to be done for wind and and snow loading etc. But it needs to be designed. Link to comment Share on other sites More sharing options...
Russell griffiths Posted February 3, 2022 Share Posted February 3, 2022 (edited) bit bigger span span than yours, but something like this. I would use a couple of 225x45 glued and screwed, sitting on top of 90x90 no brackets needed get a tab welded on top of post and hidden fixing into timber. Edited February 3, 2022 by Russell griffiths Link to comment Share on other sites More sharing options...
markc Posted February 3, 2022 Share Posted February 3, 2022 (edited) If you want a post for aesthetic purposes put one in without the other box sections. as mentioned previously 100x50 laid flat will deflect under its own weight so pointless. even with a big snow load I can’t see any problem with what you already have so post should be fine on it’s own. Edited February 3, 2022 by markc Link to comment Share on other sites More sharing options...
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