wood preservative - shed timbers

1 Feb 2011
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United Kingdom
I am building a shed from re-claimed timber. I have 4”x2” and 8”x2” I intend to use for the floor and 3”x2” I intend to use for the pitched roof. The shed will be 12ft by 8ft.

The timber is from my house roof – removed to build a loft conversion. The wood is around 45 yrs old and seems good quality; no rot, some splitting but all straight and strong.

Obviously, its not pre-treated wood so what would be the best way to provide long term rot prevention? I intend to build the floor frame off the ground, on piers. Would a paint-on wood preservative or a coat of bitumen be a good idea? would appreciate suggestions.

Many thanks
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First thing is to ensure any timber is not sitting on the ground, raise it up and put in a damp proof layer and ensuring air flow should keep the timbers fine.
You can treat with any number of brush on products to help prevent the nasties making a meal of your shed . A google brings up loads of products e.g.
I'd steer clear of painting the timbers with bitumen, it'll only hold in any damp that does get in and can cause it to rot quicker.
Cuprinol Green is very good for this. The timber will tend to get damp anyway. You are using piers so put DPM under the timbers in contact with them. Timber that will be wet or in contact with the ground needs to be dipped or have multiple wet-on-wet coats

it is quicker and easier to treat timbers all over before fixing, but remember to re-treat cut or drilled surfaces.

If you are in the UK I think you will find it easier to buy Cuprinol than Copper-Green.

Wickes own-brand appears from the ingredients list to be the same as Cuprinol. It works out cheaper in big cans. Use skin, hair and eye protection as it is of course poisonous. Throw away or wash clothes and gloves afterwards.
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no, the green one

or has it been discontinued after all these years?
the green one used to contain copper salts and the clear one used to contain zinc salts.

The green one was "stronger" for outdoor use but the clear had the advantage you could stain and varnish the timber if you wanted to.
What i should have said was larsen told me the green was discontinued and the clear has replaced it.

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