www.ultimatehandyman.co.uk

I bought a shelving kit for my garage back in December and it came with MDF shelves.

Even though I used MDF sealer on them all, they began to shred. Plus they bowed under hardly any weight.

I just bought some OSB sheets yesterday to replace them all and planned on buying some Thompsons Water Sealer, but on the Screwfix Q&A, the Thompsons expert says this shouldn't be applied to OSB.

Is this bunkum? Or could anyone recommend an alternative?

MDF is not suited to exterior use and it is not very good at load bearing either, the OSB will do a better job. I do not know if the Thompsons has a chemical make up that will attack the resin binder used in the OSB manufacturing process? I would have thought that you do not need a waterproof finish you just need to guard against damp so a simple varnish type product to seal the OSB all around will do the job.

DWD

Do you have a damp issue in the garage?. I have some mdf shelves in my garage that are still as good as new after at least fifteen years. The only shelving I had problem with was the Axminster racking that came with 1/2 inch chipboard . That sagged over time but that was mainly due to the amount of weight my wife cramped on them. Personally if you have any left over paint I'd just use that simply for cheapness , doesn't really matter what colour it is , only some garage shelves after all. You could always use an oil of course . Shelving by it's very nature is going to get scuffed and scraped as stuff goes on and off so it's likely to need periodic redoing.

dewaltdisney wrote: ↑Sat May 07, 2022 7:31 am MDF is not suited to exterior use and it is not very good at load bearing either

Yes, it was utterly useless and only 9mm thick, so god knows what it would have been like in a few months time.

Grendel wrote: ↑Sat May 07, 2022 8:22 am Do you have a damp issue in the garage?.

Yes, there definitely is an issue that I will sort before Winter comes along.
I have loads of leftover paint and a few varnishes too, so I'll have a look on the tins.

If it's OSB3 you shouldn't really have to use any sealer.