Cheapest place to buy plywood (Midlands) and opinions?

Putting up a garage roof and I’m looking to use something along the lines of 18mm plywood.

The roof will be felted but I am looking to use external or Marine ply. There seems to be quite a price difference however. I am looking at 8 x 6 sheets 18mm thick. Has anyone used anywhere near Birmingham that has been pretty cheap. Harlow seem the best at the moment.

Also will I notice a difference with marine or external and will going up to something like 24mm give me much greater security?

Thanks

My Dad always used these guys when we lived in Brum:
Great Barr Sawmills
1139 – 1141 Aldridge Road
Great Barr
Birmingham
B44 8PD
Telephone: 0121 360 7373

Just off J7 of the M6.

8×6 is an odd size, do you mean 8×4?  You don’t want marine ply, exterior grade is the stuff to go for. Or use OSB3, which should be much cheaper. I doubt the thickness will make much difference to security. That’s more down to the rest of the structure and the number of screws. Can’t help with a supplier, I get mine from a local wood recycling place at £5 per sheet and it comes ready painted in grey gloss paint

Marine and external are bonded using the same glue to stop them delaminating when they get wet. Both types made using this type of glue might be marked as WBP

The difference between the grades is that genuine marine ply uses higher grade timber.

It’s extremely common to find all WBP plywood referred to as “marine” even if it isn’t.

It’s become a shorthand for weather resistant, a bit like Hoover is shorthand for all types of vaccum cleaners.

For a garage roof 18mm External grade WBP will be fine. If you want to make it more secure, use  metal mesh fixed on the inside rather than thicker ply.

Oh, and it’s 8′ x 4′ sheets or 2440mm x 1220mm in new money.

Also availabe in metric sizes to better suit the spacing of your roof timbers if that’s more approriate.

I did mean 8×4 sorry it was a typo. I was told by a timber merchant that marine would be overkill for my needs. Could anyone expand any more on the OSB3. If there is a big price difference it may be worth going for.

What sort of prices are you being quoted?  I needed some marine ply fairly quickly and ended up just getting it from the local wickes.  £70odd a sheet was a bit more steep than I expected.

I need to buy plenty more in the new year for my shed / summer house project so this time would rather be a bit better informed on prices

You could try this place in Aston:

built.com – timber & boards

I use Harlows, mainly because I live quite near them so can collect easily.  They’ve always been helpful so ask them what you need for your project.

Some good information about OSB to be had here: https://mdfosb.com/assets/uploads/downloads/4344_SMARTPLY_OSB4_2018_v5_WEB.pdf

Cheap: WBP exterior softwood ply, lower number of thick plys up to about 4mm each.

More expensive: WBP hardwood or birch ply. more resistant to water ingress,  and stronger.  Thinner plies and more of them. You are also paying for a better finish which is irrelevant for a roof.

Suspect the cheap stuff or OSB would be sufficient. P.S I used insulated aluminium panels for my roof,  cheap,  warm in winter,  cool in summer,  white inside to keep it bright. Outside is all ally trim, the only timber is the joists 🙂