Waterproofing OSB for outdoor use

adocholiday · 18-08-2020 07:20PM #1

Just wondering what the best sealant might be for OSB for outdoor use? I got some sheets of it from a neighbour for free and I'm building a new chicken coop with it. I know it's not ideal but it's saving me a few bob. I was thinking I'll seal it, then either paint it or clad it to give it extra protection. It will have a roof too.

Is there something like tanking for tiles but for OSB? Or some sort of roll on membrane?

CJhaughey · 18-08-2020 09:13PM

I think you would be better off cladding it, no matter what you do to it regarding coatings I don't believe it will hold up as well as say plastic or metal cladding.
The surface texture will hold water.

adocholiday · 19-08-2020 08:11AM

Yes I was planning on cladding it anyway, but just wondering what sealant I could use under it or if it would even be worth it.

Pkiernan · 19-08-2020 08:14AM

Marine/yacht varnish would last a couple of years.
But its about E60 a gallon.

Lumen · 19-08-2020 08:20AM

You could try a few coats of regular outdoor varnish, e.g.

https://www.screwfix.ie/p/ronseal-exterior-varnish-satin-clear-750ml/533fg

You should treat the inside too (with paint or varnish) to avoid red mite infestation.

listermint · 19-08-2020 10:47AM

tbh, its a roof and it has strong angles on it, water will just wash off.

As its free, its cheap. Id just Paint it with a gloss or varnish it with any varnish 3 coats. It will last years.

cheif kaiser · 19-08-2020 11:11AM

Bitumen Paint.

I use his one https://www.amazon.co.uk/Everbuild-Black-Jack-Bitumen-Paints/dp/B00M2UT3FY/ref=asc_df_B00M2UT3FY/?tag=googshopuk-21&linkCode=df0&hvadid=427962779498&hvpos=&hvnetw=g&hvrand=8401422448805430219&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1007850&hvtargid=pla-907232478850&psc=1&tag=&ref=&adgrpid=108041153508&hvpone=&hvptwo=&hvadid=427962779498&hvpos=&hvnetw=g&hvrand=8401422448805430219&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1007850&hvtargid=pla-907232478850

Can get it in most decent hardware shops. It's basically the same as tar so waterproofs brilliantly. Have also used it on OSB and worked great.

fiacha · 19-08-2020 11:53AM

I've been using Weathershield masonry paint on outdoor wood projects for the last 3 years. I had a can spare so just wanted to use it up. I've been very impressed with it so far. Have used it on stakes, planters, trellis etc. Sheds water quickly and is easy to wash down.

I made some wall mounts for dog bowls out of WBP and they are holding up great. They are used as bird baths so get scrubbed and hosed off regularly. No damage to the original coats of paint so far. No sign of the plywood delaminating either.

If you are going to clad over it anyway, it might be an economical way to seal the sheets as you can often pick up good quality masonry paint on clearance.

fiacha · 19-08-2020 11:58AM

This is a quality product. I used the trowel-mastic and bitumen paint to repair an old cement-asbestos roof. Bulk of the patches are over 6 years old and still sound. I think I've only put one extra coat of the paint on in that time and it wasn't really needed..I just wanted to finish off the can

cheif kaiser wrote: »

Bitumen Paint.

I use his one https://www.amazon.co.uk/Everbuild-Black-Jack-Bitumen-Paints/dp/B00M2UT3FY/ref=asc_df_B00M2UT3FY/?tag=googshopuk-21&linkCode=df0&hvadid=427962779498&hvpos=&hvnetw=g&hvrand=8401422448805430219&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1007850&hvtargid=pla-907232478850&psc=1&tag=&ref=&adgrpid=108041153508&hvpone=&hvptwo=&hvadid=427962779498&hvpos=&hvnetw=g&hvrand=8401422448805430219&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1007850&hvtargid=pla-907232478850

Can get it in most decent hardware shops. It's basically the same as tar so waterproofs brilliantly. Have also used it on OSB and worked great.

adocholiday · 19-08-2020 12:04PM

Thanks all some good options there. I'll be sure to treat it too as suggested!

Waterproofing OSB for outdoor use

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