londoneye Posted August 1, 2006 Share Posted August 1, 2006 apologies if this seems a really daft question, but to put into context we have two large beams (6.5 metres x 230 x 220) to be hoisted up to our barn roof.i have been trying to guesstimate the weight of each beam. I have looked on internet and am aware of course that different wood types have considerably different properties, including weight.our wood is douglas fir,and i have found a site which estimates that douglas fir weighs 530 kg per cubic metre. So far so good, the site then goes into quite ghastly detail about the differences in wet wood, kiln dried, air dried, every other way you can think of dried, and gives a mathematical formula which made me almost require a drink at 0700 to get my head around it. problem is that our wood has come direct from wood-yard, so therefore assume that no drying process per se will have been undertaken. Does this sound correct?Does anyone have an idea please of a ROUGH percentage increase which could be applied to give us an idea of weight of each beam when wet(ish). sorry to sound so vague, and i accept that people in the know may well say that what i am asking is not feasible, but thought it was worth a try? Link to comment Share on other sites More sharing options...
Albert the InfoGipsy Posted August 1, 2006 Share Posted August 1, 2006 Water weighs 1000 Kg (1 tonne, or ton, near enough the same) per cu m. I'd assume that your worst case scenario would be a lump of totally waterlogged wood, so using the density of water seems reasonable in allowing plenty of safety margin -- you seldom see wood so soggy it won't float!In fact, most soft wood bought from a woodyard is likely to be at least partly dried (seasoned) unless it's ben sawn from a freshly felled tree. They usually store the stuff in such a way that air can circulate (air dried). I'd guess (finger in the air) that your wet wood figure is about 50% more than the driest one. As you presumably are interested in lifting gear or wall strength I'd just use the heaviest figure you can find (675 Kg / cu m ?????). Link to comment Share on other sites More sharing options...
londoneye Posted August 1, 2006 Author Share Posted August 1, 2006 thank you very much for responding. i am sorry to be dense on this one, try to put it down to a female lack of knowledge on all things building if you can manage (!)when you say use the heaviest figure you can find - could you explain what the bracketted section means ? i can bear a little public humiliation to get the right answer !! Link to comment Share on other sites More sharing options...
Chris Head Posted August 1, 2006 Share Posted August 1, 2006 Each beam about 0,33m3, at 530kg perm3, about 175kg each, depending on moisture content could be higher or lower, I'd assume each one to be 250kg as a decent safety margin.Chris Link to comment Share on other sites More sharing options...
londoneye Posted August 1, 2006 Author Share Posted August 1, 2006 thanks both - much appreciated. Link to comment Share on other sites More sharing options...
Albert the InfoGipsy Posted August 1, 2006 Share Posted August 1, 2006 Sorry, that was just my guess at what the figure would be.By the way, a quick calculation based on that figure comes out to very roughly 200 kg per beam, so about the middle 0f Chris's range. As he's our resident timber specialist (OK, Chris, I know you're really an oak guy) I'd trust his estimate. Link to comment Share on other sites More sharing options...
Chris Head Posted August 1, 2006 Share Posted August 1, 2006 Sorry Albert I didn't mean to contradict you at all, it wasn't my intention. I'm not an expert at all. Experts are qualified, I'm not.Sleep well y'all.Chris Link to comment Share on other sites More sharing options...
Heath Posted August 1, 2006 Share Posted August 1, 2006 Oak works out at 875kg per cu.m. (dry-ish), chestnut, which is what most old beams are, is a lot less - at a guess, about half of the equivalent oak Link to comment Share on other sites More sharing options...
thunderhorse Posted August 2, 2006 Share Posted August 2, 2006 I Googled 'wood density', and got this site, first hit:hereDoes that help? [:)] Link to comment Share on other sites More sharing options...
Chris Head Posted August 2, 2006 Share Posted August 2, 2006 Bad info Heath, quantify 'dryish' Oak? Where do you get your info that sweet chestnut is approx 1/2 the weight of Oak in whatever state the Oak might be? Why are most old beams Chestnut? That's not my experience.Chris Link to comment Share on other sites More sharing options...
Heath Posted August 2, 2006 Share Posted August 2, 2006 [quote user="Chris Head"] Bad info Heath, quantify 'dryish' Oak? Where do you get your info that sweet chestnut is approx 1/2 the weight of Oak in whatever state the Oak might be? Why are most old beams Chestnut? That's not my experience.Chris[/quote]Er. sorry Chris, I'm not wishing to mislead anyone. I've always used the figure of 875kg per cube, dry and seasoned, but the stuff I get from my sawmill which is fresh from the tree (which has been kept wet) or has been standing out in the rain for some time is a fair bit heavier. Almost all the old beams I take out of old houses around here are chestnut (easy to cut, but very dusty), rarely oak, and they are still very heavy but, as I said, only a guess, possibly about 50% of the weight of oak.. Where do you get 530kg from? Link to comment Share on other sites More sharing options...
Albert the InfoGipsy Posted August 2, 2006 Share Posted August 2, 2006 [quote user="Chris Head"]Sorry Albert I didn't mean to contradict you at all, it wasn't my intention. I'm not an expert at all. Experts are qualified, I'm not.Sleep well y'all.Chris[/quote]Chris,I didn't see it as a contradiction, but I did mean that you know a lot more about timber than most people on this forum, including me. I was relieved to get somewhere near yur figure. Link to comment Share on other sites More sharing options...
Chris Head Posted August 3, 2006 Share Posted August 3, 2006 Just re-read my reply to you Heath and it doesn't read too well, apologies to you!The 530 kg figure came from passing a local builders yard a while back loaded with Douglas beams. The truck felt heavy and I weighed at their weighbridge and again on the way back, I worked out the weight from the cube of the timber I had and noted it down in my little black book. It was winter felled, plantation grown Duggy so not overly dense or wet, I would guess the moisture content to have been around 40%.Weight of timber will always be variable depending on it's density (the conditions it's been grown in), the time of year it's been felled, whether it's dried in the round or as planks....and many other anoraky variables.Cheers, Chris Link to comment Share on other sites More sharing options...
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