preserving timber joists

[mongrell]

giday all am putting a veranda on the side of the house ,it will be half roofed half open to the weather .tying to do it on the cheap with some f7 joists. now only being ash or some mixed species i know without treating it its gonna rot fairly smartly . so what would i be best doing ,paint them ,creasote them ,oil them ?or will the moisture just come in through the decknails anyway ?or something else ?

[mic-d]

Use rubber joist strap and perhaps even prime the joists first too.

Cheers
Michael

[strangerep]

am putting a veranda on the side of the house ,it will be half roofed half open to the weather .tying to do it on the cheap with some f7 joists. now only being ash or some mixed species i know without treating it its gonna rot fairly smartly . so what would i be best doing ,paint them ,creasote them ,oil them ?or will the moisture just come in through the decknails anyway ?or something else ?

I'm a little confused when you said cheap F7 and "ash or mixed". Normally
even the cheapest utility grade hardwood is up around F17 - or did you
mean F7 treated pine? (The latter is probably preferable over class3/4
hardwoods for durability, if you treat the cut ends and timber-meets-timber
spots with preservative.)

I'd creasote the tops, ends, and timber-meets-timber places, wait ages for
them to dry, then put on an oil-based primer and paint the entire joists with
several coats. The creasote will bleed through the primer, but that doesn't
matter too much if it's unseen. The benefit of using creasote along the
tops is that it sinks down into the timber, so if any water creeps through
along the decknails, the potential rot still has to deal with the creasote.

Some may think this is overkill, but the principle of giving maximum
attention to the most at-risk places that you'll never see again (i.e: can
never easily give attention to later) seems a wise precaution.

Oh, and of course use joist protectors as well, like mic-d said.

- strangerep.

[UteMad]

Steer clear of painting the joist tops with an acrylic or oil based paint as it only traps the moisture that gets in throught the nail holes....Use a deck oil ...deck stain ....or cresote type absorbant that with soak in and repel water due to the oil and water don't mix theory.... Cover the joist tops with a rubber joist protector or alcor... More important is to keep good subfloor ventialation which means don't store all your junk under the deck so the air can't flow through

cheers utemad