Strength of timber calculations?

[Daniël Bos]

Hi all, I was felling some nice oaks today (a dozen around 3'-4') with one or two of them with a nice brown colouring.

All of them were either dead or near dead but with reasonably straight stems, the heartwood still hard as a hard thing even on the very deadest tree I was wondering If I could use them for construction or not?

 

So, is there a way to measure the strength of a timber and relate that to a table of standard or minimum strength?

[agg221]

Timber strength calculations for hardwood are usually done by 'book values' based on species and visual grading. TRADA have a publication on this but a little google research will find you the grading specs.

 

The timber will almost certainly still be green (above 20% mc) which means there is no official grading scheme. This means that technically you just need to do dimensional calculations to meet building regulations. It would still be a good idea to visually grade though, just means you don't need to be in any sense official or certified when you do it.

 

The brown ones won't be advisable for this as it is usually a sign of beefsteak fungus infection and although the timber is hard it becomes brittle, but if you are interesting in selling I may be interested in one as I have a use for some brown oak.

 

Alec

[daltontrees]

Hi all, I was felling some nice oaks today (a dozen around 3'-4') with one or two of them with a nice brown colouring.

All of them were either dead or near dead but with reasonably straight stems, the heartwood still hard as a hard thing even on the very deadest tree I was wondering If I could use them for construction or not?

 

So, is there a way to measure the strength of a timber and relate that to a table of standard or minimum strength?

 

The only way I can think of that doesn't require testing a proportion of them to destruction is to use an increment borer and a Fractometer (Mk3).

[PeakOakFrames]

Hi. First post, been lurking a while though. Re visual grading there is a TRADA guide here http://www.forestry.gov.uk/pdf/GreenoakAppendicesRefsGlossary.pdf/$FILE/GreenoakAppendicesRefsGlossary.pdf pp24-25 is the quick guide to visual grading for green oak.

[PeakOakFrames]

Also I'd strongly advise against using brown oak in any load bearing members, not so much of an issue if it's minimal and in a non critical member of a frame.