De-lignification of beams

[Milo]

I have bought an old house and when working in the roof space I have found some of the Jara tile supports are "fluffy" apparently caused by de-lignification of the wood.

Having checked they do not seem to have lost a lot of strength.

Where can I find out more about this, as you may have gathered I am not from Australia.

Many thanks for any help.

[Wayne Davy]

I'm guessing but I think he means a laminated beam is coming apart. De-laminating maybe??

[q9]

http://dictionary.reference.com/search?q=lignification

So we can assume it means the opposite, ie the structure of the wood cells are breaking down.

[John Saxton]

Lignin which comprises between 22-30% of wood ,occurs in the form of very complex polymers of molecular weight,consistining of about 65% carbon, 6% hydrogen and 29% oxygen and is virtually impossible to dissolve without being broken down into simpler substances.
The Lignin in softwood is a little different to that of hardwoods, and represents a higher percentage of the wood.

A simple method of detecting Lignin is to smear the clean wood surface with a 2% solution phloroglucinol in alcohol,followed by a drop of concentrated hydrochloric acid.The presence of Lignin will cause the formation of a gright red colour.

All this info is available from the wood bible "Wood in Australia" by Keith R Bootle ...and Milo you can probably access this book in Perth from Rellim technical books in Hay St.

Cheers
A footnote in that I have seen 90 year old Jarrah move but not necessarily lose it's structural strength.

[Eastie]

Sounds similar to some forms of dry rot.
The Timber Promotion Council should be able to help if further info is needed.

[Darryn]

Originally posted by doorstop
good on you Johnno but DElignification? How could that happen? Especially in a roof space!!

I never knew it had a scientific term but it is not what you would call uncommon. Working the in the air con/electrical field in Perth I am up in roofs all the time and see it quite a bit. As Milo said it makes the jarrah or karri tile battens (who can tell easily when it is old) go soft and furry. If you brush the stuff away you will get to solid timber but it can make you wary on some roofs as the timbers can get a bit skinny. You tend to see it on clay tiled roofs that are probably 50 years or older (possibly some chemical reaction) but isn't terracotta supposed to be fairly inert.

My roof at home has it and I know from my neighbour that our house was built in 1957, as an interesting point the tile battens at ur house are actually T&G floor boards which have been ripped into strips!!
I'm not too stressed about the delignification or whatever as the hose is going to get bulldozed in a few years

Darryn

[Zsteve]

delignification - sounds abit strange.

Sure its not just old rough sawn timbers (as they tend to be in old houses) but with plenty of dust and or cob webs making them appear "fluffy"

[soundman]

It may surprise some people buy it aint real dry under a tile roof.

so a long spell of wett, a little fungus, a little bacteria and nothing would surpries me.

If you want a surprise stick your head up a man hole in a tile roof house during a howling storm and see how much mist is in the air.
Unless the roof has moisture barrier..


Iron roofs for ever!!!

[Milo]

Darryn,

Your description is correct, I have attached aphotograph. The damage seems to be directly below the clay tiles and as far as I can see if you scrape back the "fluffy" timber you get back to good wood with perhaps only 1-2 mm of loss

[John Saxton]

Query Milo, have you taken samples of the Fluffy Fibre and had it analysed to determine a bacteria or the reason for it becoming so?
Is it widespread throughout the roof space or is it localised in an area that may be subjected to varying temperatures/ weather cycles ...is it in a section of roof that faces the predominate weather movement?

I have seen Jarrah like this before that was milled close to the bark and gave the appearance of being fluffy even though green.
If you've ever seen off-cuts in a Jarrah mill there is a lot of fluffy stuffy that is part bark and part timber, but whether it deteriorates further as it dries I wouldn't know!
Just some thoughts.

Cheers