On Sat, 26 Sep 2020 19:58:42 +0100 (GMT+01:00), Jimk wrote:

As title - will it work?

The boards (4ft X 2ft) will get wet (but not immersed) I want to
make them last s few months at least...

If so I have never had need to use fibreglass resin etc - any gotchas?

OSB3 will last for years without any protection. Vertically mounted (boarded
up windows and doors for instance) do so; I've had OSB3 (it had had a couple
of years over a window) covering a water butt. It's horizontal (obviously),
rather humid underneath, doesn't drain and gets no sun for several months.
It's been there for 15 years and is still sound (18mm thick) although
sagging slightly - it does have several kg of washing basket on it
sometimes, so that might explain the sag.
--
Peter.
The gods will stay away
whilst religions hold sway

On 27/09/2020 10:34, Jimk wrote:
PeterC Wrote in message:
On Sat, 26 Sep 2020 19:58:42 +0100 (GMT+01:00), Jimk wrote:

As title - will it work?

The boards (4ft X 2ft) will get wet (but not immersed) I want to
make them last s few months at least...

If so I have never had need to use fibreglass resin etc - any gotchas?

OSB3 will last for years without any protection. Vertically mounted (boarded
up windows and doors for instance) do so; I've had OSB3 (it had had a couple
of years over a window) covering a water butt. It's horizontal (obviously),
rather humid underneath, doesn't drain and gets no sun for several months.
It's been there for 15 years and is still sound (18mm thick) although
sagging slightly - it does have several kg of washing basket on it
sometimes, so that might explain the sag.

"When used externally all faces and edges should be treated with
an appropriate preserver"


Have fun finding that too. Everything seems to be water-based and
OSB manufacturers no longer seem to pre-seal the cut edges of
OSB any longer

On 26/09/2020 19:58, Jimk wrote:
As title - will it work?

The boards (4ft X 2ft) will get wet (but not immersed) I want to
make them last s few months at least...

If so I have never had need to use fibreglass resin etc - any gotchas?

You mean resin on its own? Not together with cloth or strand glass matting?

I think I would be more inclined to use simple (single pack)
polyurethane varnish. How weatherproof does it need to be? Does it see
direct sunlight, or rain and gales straight off the Atlantic?

The enemy is cracking; does it get bent or see wide temperature ranges?
I'd generally think of ply as having better life than OSB, especially
proper marine (WBP) ply although that is much more expensive. But if you
are not too worried about appearance OSB is not too bad.

On Sun, 27 Sep 2020 10:34:28 +0100 (GMT+01:00), Jimk wrote:

PeterC Wrote in message:
On Sat, 26 Sep 2020 19:58:42 +0100 (GMT+01:00), Jimk wrote:

As title - will it work?

The boards (4ft X 2ft) will get wet (but not immersed) I want to
make them last s few months at least...

If so I have never had need to use fibreglass resin etc - any gotchas?

OSB3 will last for years without any protection. Vertically mounted (boarded
up windows and doors for instance) do so; I've had OSB3 (it had had a couple
of years over a window) covering a water butt. It's horizontal (obviously),
rather humid underneath, doesn't drain and gets no sun for several months.
It's been there for 15 years and is still sound (18mm thick) although
sagging slightly - it does have several kg of washing basket on it
sometimes, so that might explain the sag.

"When used externally all faces and edges should be treated with
an appropriate preserver"

I didn't even think of that and the longevity is excellent. Not sure what
I'd use, BFLN!
When I re-roofed the 'barn' (local name for brick-built shed, to
differentiate it from wooden sheds, so not anywhere near Yorkshire's
standards) I used 9mm OSB3 and put on a solvent-based preservative that's
water-repellent for about a year before putting on the roof. Has the
advantage of providing a 'ceiling' that is painted white to improve
lighting.
Too soon to tell how it'll last but, extrapolating somewhat, it'll outlast
me!
--
Peter.
The gods will stay away
whilst religions hold sway

As title - will it work?

The boards (4ft X 2ft) will get wet (but not immersed) I want to
make them last s few months at least...

If so I have never had need to use fibreglass resin etc - any gotchas?

--
Jimk


----Android NewsGroup Reader----
http://usenet.sinaapp.com/

PeterC Wrote in message:
On Sat, 26 Sep 2020 19:58:42 +0100 (GMT+01:00), Jimk wrote:

As title - will it work?

The boards (4ft X 2ft) will get wet (but not immersed) I want to
make them last s few months at least...

If so I have never had need to use fibreglass resin etc - any gotchas?

OSB3 will last for years without any protection. Vertically mounted (boarded
up windows and doors for instance) do so; I've had OSB3 (it had had a couple
of years over a window) covering a water butt. It's horizontal (obviously),
rather humid underneath, doesn't drain and gets no sun for several months.
It's been there for 15 years and is still sound (18mm thick) although
sagging slightly - it does have several kg of washing basket on it
sometimes, so that might explain the sag.

"When used externally all faces and edges should be treated with
an appropriate preserver"

--
Jimk


----Android NewsGroup Reader----
http://usenet.sinaapp.com/

Andrew Wrote in message:
On 27/09/2020 10:34, Jimk wrote:
PeterC Wrote in message:
On Sat, 26 Sep 2020 19:58:42 +0100 (GMT+01:00), Jimk wrote:

As title - will it work?

The boards (4ft X 2ft) will get wet (but not immersed) I want to
make them last s few months at least...

If so I have never had need to use fibreglass resin etc - any gotchas?

OSB3 will last for years without any protection. Vertically mounted (boarded
up windows and doors for instance) do so; I've had OSB3 (it had had a couple
of years over a window) covering a water butt. It's horizontal (obviously),
rather humid underneath, doesn't drain and gets no sun for several months.
It's been there for 15 years and is still sound (18mm thick) although
sagging slightly - it does have several kg of washing basket on it
sometimes, so that might explain the sag.

"When used externally all faces and edges should be treated with
an appropriate preserver"


Have fun finding that too. Everything seems to be water-based and
OSB manufacturers no longer seem to pre-seal the cut edges of
OSB any longer


Finding what?
--
Jimk


----Android NewsGroup Reader----
http://usenet.sinaapp.com/

newshound Wrote in message:
On 26/09/2020 19:58, Jimk wrote:
As title - will it work?

The boards (4ft X 2ft) will get wet (but not immersed) I want to
make them last s few months at least...

If so I have never had need to use fibreglass resin etc - any gotchas?

You mean resin on its own? Not together with cloth or strand glass matting?

I think I would be more inclined to use simple (single pack)
polyurethane varnish. How weatherproof does it need to be? Does it see
direct sunlight, or rain and gales straight off the Atlantic?

The enemy is cracking; does it get bent or see wide temperature ranges?
I'd generally think of ply as having better life than OSB, especially
proper marine (WBP) ply although that is much more expensive. But if you
are not too worried about appearance OSB is not too bad.




Concrete shuttering that my car will run on....

Appearance is unimportant.

Tried paints & bitumen, the edges start delaminating first...
--
Jimk


----Android NewsGroup Reader----
http://usenet.sinaapp.com/