Wood preservative for underside of shed floor.

  Old Deuteronomy 11:53 21 Jun 2018

I have bought a new shed, to use as a woodwork shop, due here in a few weeks. I already know what I will use to paint on the walls but, not certain if it is the right stuff for the underside of the floor, anyone got any thoughts?

I am going to use Cuprinol Garden Shades for the walls but, not sure if that is best for the floor where I won't be able to treat it again. The shed is costing a lot of money so, I want to use the right stuff, not the cheapest.

  Fruit Bat /\0/\ 12:41 21 Jun 2018

Have a shed that's well over 30 years old, floor is rock solid. Make sure its pressure treated before you buy.

Mine stands on three long 4 x 4 beams which in turn stand on bricks thus the floor is well above standing water and a good air flow underneath it.

Refelted the roof which didn't last long before leaking again so covered it with corrugated plastic sheet, have just replaced that after 20 years only because I walked on it (that's another story) and it had gone brittle.

  bumpkin 13:10 21 Jun 2018

In my experience anything water/acrylic based dosen't last very long despite their claims. I would use one that is spirit based and assuming the timber is sawn finish, keep soaking it in with as many coats as you like. Just as important as mentioned by FruitBat is good ventilation.

  Govan1x 14:45 21 Jun 2018

Just wondered if the bitumen you get for sticking down the Roof felt would be of any good.

I also used 4" x 4" wooden beams so that the shed was kept dry underneath.

Unfortunately my shed is falling apart now the floor is fine but the rest has seen better days. Must have had it for about 30 years so had good use from it.

Like Fruit Bat /\0/\ says the roof felt is the problem especially in high winds so his idea of covering the roof with corrugated plastic is a great idea unless you know of a better material to use.

I assume they use roofing felt because it is the cheapest way of doing it, But certainly not on the long run.

  hastelloy 15:35 21 Jun 2018

I've never done this and don't pretend to be an expert but the first thing that came to my mind was the underseal we used to use on cars. You can get it in a can to brush on or as a spray. I would think brushed on is better as you can get a good thick coat that way but don't expect to ever use the brush for anything else!

  Old Deuteronomy 16:13 21 Jun 2018

Thank-you all for your suggestions, plenty for me to consider over the next week or two.

  Al94 16:17 21 Jun 2018

Old engine oil will preserve it.

  wee eddie 17:02 21 Jun 2018

I don't think that you really need to worry so long as there is a good airflow underneath and it's not on top of a bog or burn

  LastChip 21:02 21 Jun 2018

You can beat creosote, but unfortunately, it's only available under licence now. However, there is a substitute called creocoat, which seems to be the same with the toxins taken out - blame the EU. It smells the same and seems to be the same in all but name and a slight modification in make up.

Putting the cross beams on bricks (or similar) is good advice.

  Forum Editor 22:30 22 Jun 2018

The best advice is to ventilate the underfloor space. There are suspended timber floors in buildings that have been there for 200 years and more, and never seen a drop of any kind of preservative. They are sound because they have been provided with cross-flow ventilation.

Stop worrying about applying any form of liquid, and start planning how to provide air flow under the floor.

In any case, if your shed is being properly constructed, all the timber will have been pressure treated with Tanalith E. It will not require any further preservative, unless it is exposed to the weather.

  Forum Editor 22:34 22 Jun 2018

As for the roof.....

use heavy duty torch-on underlay and grey or green mineral torch-on capsheet. It has to be hot applied with a Propane torch, and if you're not competent to do that, get it done by a professional. Properly applied, this material will give you 30 years of trouble-free life.

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