Grading timber course

[nooie]

2 hours ago, Johnsond said:

postage to Dyce is ok, postage to Turriff is classed as the Highlands and is hit with the subsequent hike in costs. How did the greenheart go in the end ? I milled a few myself which came out lovely.  I saw the replacement timber Bobby had delivered to use up there, nice stuff it looked. 

I'm still at the planning stage! The paperwork has been a night mare. Finally got the building warrant through, but there are a lot of differences from "architects😡" drawings and the engineers drawings. Getting closer though. Ive milled a small amount so far, but hope to get proper stuck into it soon.

[GarethM]

Yeap, architects then engineers then the council building control, each wants a cut of the pie.

 

Daft question I'm guessing you're timber is for non structural things like cladding, as doesn't it have the be marked and tested for say floor joists?.

Edited May 30 by GarethM

[nooie]

7 hours ago, GarethM said:

Yeap, architects then engineers then the council building control, each wants a cut of the pie.

 

Daft question I'm guessing you're timber is for non structural things like cladding, as doesn't it have the be marked and tested for say floor joists?.

Hello Gareth, aye some of it is structural and the greenheart timber is the actual post and beam frame. The spruce will come from our own forest for stud work. We are going to use hemp Crete as insulation so the stud will be in the middle of that. Hempcrete isn’t strong like concrete, more like straw bales and lime. The experts say it should be called, hemp-lime. Super insulation and fireproof.

[GarethM]

11 minutes ago, nooie said:

Hello Gareth, aye some of it is structural and the greenheart timber is the actual post and beam frame. The spruce will come from our own forest for stud work. We are going to use hemp Crete as insulation so the stud will be in the middle of that. Hempcrete isn’t strong like concrete, more like straw bales and lime. The experts say it should be called, hemp-lime. Super insulation and fireproof.

Granted it should be breathable I guess which might be an advantage, depends on the insulation value I guess. Sometimes it's more efficient to use the evils of modern insulation than double the depth for natural stuff.

[ucoulddoit]

A few thoughts from a retired structural engineer with a fair bit of experience working on timber projects. 
 

Firstly, I’d say most visual grading is mostly done on large section timbers, not small stuff for studs, etc. Also, every milled piece of timber needs grading, it’s not possible to grade the timber in a log prior to milling. The grading process is relatively straightforward, looking at specific aspects of each milled piece of timber, such as timber species, knot sizes and positions, grain slope, growth ring spacing, etc. Soon becomes a matter of common sense really, to identify what’s good or bad. Can be self learnt using readily available publications, but not sure what is current as it’s 10 years or so since I did this.

 

A trained / qualified grader will stamp each piece of timber. But if it’s for your own use, you have the option of deciding whether the stamps are necessary. I’ve no experience of self grading timbers for a project needing building standards approval, but have heard of it being done. I guess it needs prior discussion with the council engineers to convince them you know enough about visual grading to be ‘trusted’ to do it. There is also the issue of what happens when a property is sold on, if a surveyor for instance queries the origin or spec of the materials used. Might make it harder to sell or reduce the value?

 

Re timber studs, your engineer’s spec almost certainly requires treated timber. Using a timber species with inherent natural rot resistance such as larch (heartwood) would be my starting point if looking into this. But maybe it’s possible to adequately treat other species on site? And no reason why the studs couldn’t be visually graded. Would be worthwhile checking with the design engineer if the sizes specified are based on strength, deflection, or the detailing necessary to incorporate insulation, air spaces, etc., i.e. the studs might be way ‘over engineered’ just to suit the detailing, in which case the strength grading would be less critical. But again, I’d research all theses issues and discuss all your detailed proposals with the council engineer before starting, so they are comfortable you can be ‘trusted’, rather than asking them how and what to do.

 

Andrew

[ucoulddoit]

Following on from my previous post, this thread re-kindled a long term interest in visual grading of timber, so I dug around a bit online to see what’s current.

 

The following link should go to the Wood Campus website which has a factsheet including relevant publications, etc. for visual grading.  Strength Grading (factsheet) - Wood Campus   I’d wondered if the Eurocodes might have superceeded the standards I’m familiar with from the past, but I see BS 4978 2007 is still listed. So I’ll look after my well used, dog eared paper copy. Not sure if there will be a free pdf on line as I only had a cursory look.

 

The factsheet includes a table showing the relationship between grade and strength. I think it’s worth noting that softwood visual grading using the British Standard will be either GS or SS. But in terms of strength, as an example, GS grade larch is stronger than GS grade spruce, i.e. timber species of the same grade are not interchangeable for strength.  The table relates the grades for different species to C16, C24, etc.

 

Re the original question on this thread, I found details of several courses for visual timber grading from a simple Google search. Typically circa £2k for a three day course and the qualification needs renewing annually, so a fair investment would be needed.

 

My previous post mentioned it’s fairly easy to separate the good timber from the bad using self taught visual grading. For my own projects, I had an ample supply of logs and just used what was obviously ‘good’. But I guess in reality, for a business, it’s necessary to also look at the middle ground, not just the extremes of good and bad, otherwise a lot of timber might be rejected that could pass a rigorous visual assessment. And I guess that would go towards justifying the investment in training.

 

Andrew