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https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Carpentry Questions >> Tanalised timber https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1087657497 Message started by Glocko on Jun 19^th, 2004, 4:04pm

Title: Tanalised timber
Post by Glocko on Jun 19^th, 2004, 4:04pm

What is the life expectancy of tanalised timber used to build a garden workshop?
I know you can prolong the life by treating it with wood care stuff but what about 4x3 posts concreted in, how long before the underground part starts to rot?

Title: Re: Tanalised timber
Post by Dewy on Jun 19^th, 2004, 4:23pm

It's usually expected to last up to 25 years.
I've always used treated timber and given the post ends 2 or 3 coats where they will be in contact with the soil & left them soaking in an old oven tin full of the preservative overnight to soak up more & increase life expectancy.

Timber rots when in contact with the ground and also rots in concrete because the moisture can't drain away.
The latest idea is to dig the hole deeper then put gravel at the bottom of the hole, put the post in and add a bit more gravel so the end of the post can drain then fill to just above soil level with concrete and slope the concrete so rain runs away instead of into the post.

Title: Re: Tanalised timber
Post by Kesh on Jun 20^th, 2004, 1:20am

As an extra precaution, you could always paint the section to be buried with bitumastic paint afterwards.

Title: Re: Tanalised timber
Post by woodsmith on Jun 20^th, 2004, 9:00am

You would be better off not burrying the wood in the ground but build some brick piers and rest the structure on them. It will need some restraining straps, but this is the way to go if you want it to last any length of time.