Waterproof garden bar roof

[Kingbroady]

Hi.

I'd like to waterproof my 6x4 feet

garden bar, as much as possible, starting with the roof. I'm thinking 11mm OSB3, with 2 to 3mm shrinkage expansion accounted for. Then applying EPDM adhesive and EPDM membrane, followed by drip edge trims. Is this the right approach, please?

I've elevated it slightly to allow for air movement within to avoid condensation and mold.

The current roof is feather edged timber. I'm thinking of using some timber I have around the perimeter and vertically in line with the existing batons to allow better insulation and a more level base on which to lay the OSB. Again, am I on the right lines here, please?

Any thoughts appreciated. Thank you in advance.

 

[Kingbroady]

View attachment 417378

 

[jj4091]

Would you not be better with just EDPM on the roof or fibreglass, it's not very big or going to be taking any weight is it?

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[Kingbroady]

Just with it being uneven, I thought a flat base would allow the EPDM to adhere better. No additional weight to be added. I'd not considered fibreglass. I'll take a look.

Thank you.