What thickness of plywood for shed roof...?

[The Z'eer]

On Saturday I collected a couple of 18mm sheets of plywood. Since this is my first attempt at carpentry I was unaware of just how heavy and awkward it would be to manouver these sheets, though I soon found out.

Due to requiring extra tools for cutting the sheets to size, the roofing job for the shed hasn't been completed. However in the meantime I've given some thought to this and I'm now pondering if perhaps 18mm plywood is better suited for the intended floating floor. Maybe I should be using 12mm plywood instead for the roof?

Shed is 6ft x 4ft by 8ft tall.

Thanks

 

[eLuSiVeMiTe]

These are handy.
https://www.toolstation.com/shop/p6...RR1fL6yQNOs1-Tw4liZHXFNIB0oRAWI8aAsQBEALw_wcB

Or these.

And 18mm for the roof.

 

[The Z'eer]

These are handy.
https://www.toolstation.com/shop/p6...RR1fL6yQNOs1-Tw4liZHXFNIB0oRAWI8aAsQBEALw_wcB

Or these.

And 18mm for the roof.

Thanks there's a tool which would make things easier!

12mm will be to weak for the roof?

 

[gaz1]

there heavy but you have to know how to carry them on your own which ive done often same as getting then up a ladder to do dormers with them one on a rope one on the ladder is no fun i can tell you

use 18mm but if needs be go smaller but reference to use 18 is to stop thievs really but makes no difference if they want in there they will do

its 11mm not 12mm next size down

 

[bigegg]

It depends on the grade of ply, and the spacing of the supports, and the covering, and the expected longevity...

18mm phenolic on 16" centred 4x2 tantalised rafters and two layers of good felt sealed at edges will last 100 years

12mm chipboard on 3ft spaced 2x1 beams *might* last until Easter.

2x2 rafters on24"(600mm) spacers then 12mm shuttering ply coated with bitumen damp proofing, and decent felt, should last 20 years+


Edit:

The covering is more important than thickness of ply:

I use 15mm ion 3x2 rafters (450mm centres) cos I'm fat and the roof needs to hold my weight when I'm nailing on the felt.
But the felt /outer layer is *much* more important.


For the floor - it's basically the same.
18mm is better than 9mm, but fill it with gravel and put down a damp proof sheet ,sand, and paving flags is better still.

 

[Ton-up]

15/16 mm available too.

 

[eLuSiVeMiTe]

Thanks there's a tool which would make things easier!

12mm will be to weak for the roof?

i have the first link already. the second was a bit pricey but found some on the bay cheap so just nabbed one.

12mm warps easily 18mm is a lot more stable.

if i had to do a roof out of 12 id be looking at 400 centers and doubling up joists under all ply joints. ( no unsuported joints )

 

[roofman]

Bite my lip and hold my nerve...i must not get involved in roofing discussions on the interweb as there are too many roofers who know better

 

[eLuSiVeMiTe]

Bite my lip and hold my nerve...i must not get involved in roofing discussions on the interweb as there are too many roofers who know better

don't bite your tongue boss. Always happy to learn something new.

 

[bigegg]

don't bite your tongue boss. Always happy to learn something new.

Me too.
If I'm talking schapps I'd like to know.

 

[roofman]

ime only joking guys...always here for advice as are other forum,eers for me when i need it

 

[roofman]

Me too.
If I'm talking schapps I'd like to know.

 

[bigegg]

Nordlicht abcschaum ":
Scum of the northern lights?

 

[slim_boy_fat]

@The Z'eer Do you get a lot of snow? Unlikely, but you never know...... [think...load]

 

[The Z'eer]

It depends on the grade of ply, and the spacing of the supports, and the covering, and the expected longevity...

18mm phenolic on 16" centred 4x2 tantalised rafters and two layers of good felt sealed at edges will last 100 years

12mm chipboard on 3ft spaced 2x1 beams *might* last until Easter.

2x2 rafters on24"(600mm) spacers then 12mm shuttering ply coated with bitumen damp proofing, and decent felt, should last 20 years+


Edit:

The covering is more important than thickness of ply:

I use 15mm ion 3x2 rafters (450mm centres) cos I'm fat and the roof needs to hold my weight when I'm nailing on the felt.
But the felt /outer layer is *much* more important.


For the floor - it's basically the same.
18mm is better than 9mm, but fill it with gravel and put down a damp proof sheet ,sand, and paving flags is better still.

I've used tantalised 3 x 2 rafters placed at 24" centres.

I agree, the covering is very important. That's something that needs a little research too.

I'm opting for a floating floor so I might insulate the area a little better. A 1200 gauge DPM with insulation between the framework and plywood on top is the plan.

 

[The Z'eer]

@The Z'eer Do you get a lot of snow? Unlikely, but you never know...... [think...load]

That's a fair point, and a valid one too. Thankfully Essex sees very little of the cold white stuff

 

[roofman]

Nordlicht abcschaum ":
Scum of the northern lights?

back to front and delete the lights

 

[slim_boy_fat]

hankfully Essex sees very little of the cold white stuff

I'll send you some next time we get a blizzard. Which is actually less frequent than in past years. Thank God for 'global warming' ........

 

[eLuSiVeMiTe]

Arrived today. Impressed with its grip.
Held my weight suspended off the deck. Can't grumble for 16 squids.

 

[CornishPete]

Thickness of ply depends on the rafter spacing. The closer the rafters the thinner the ply in theory. Iv'e always used 18mm whatever the rafter spacing though. Typically i use 400mm rafter centres with 18mm osb on top. Plywood is more expensive and seeing as the covering keeps the weather out I can't see any reason to use ply instead? But if you've already got it then just use it!