What size OSB

[rick1632]

Building a custom shed
3x2 CLS studwork walls, with OSB sheeting on outside, membrane cover then probably 15mm shiplap.

Should I go 9mm or 11mm OSB?

Ditto for the roof (flat) which will be covered in standard roofing felt.

Also - aside from the bottom studs, the rest of the CLS won't be treated timber. How should I store it before I use it? Indoors, or outside under a tarp?

 

[foxhole]

I would use 11mm on inside , membrane on outside under cladding.

 

[^woody^]

You'll want at least 18mm for the roof and that's with 400mm joist spacing, thicker board with greater spacing.

Battens for the cladding?

4x1 sole and top plate?

Store the CLS inside until you come to use it, as its already dry and will twist and shake if stored outside.

 

[Notch7]

Cover your OSB with membrane, then 50 x 25 battens and then cladding - makes a much more watertight, dry structure and shipload will last much longer.

 

[rick1632]

I haven't got the space for battens on the outside between the OSB and the cladding as well as on the inside- the entire depth I have to work with is 1340mm - the membrane is Dupont Tyvek Housewrap which is breathable - can the shiplap not go directy onto that? I could put the OSB on the inside of the studwork instead, but then I lose a fair bit of space - not a problem in a larger, squarer structure, but in this long narrow shed it's about 10% of the space lost.

I was going to go 3x2 cls on a 2 foot separation, OSB - 11mm seems preferred, Tyvek Housewrap, then shiplap nailed through both the membrane and the OSB into the studwork frame. I based it on this video

The roof is only 1550mm deep (200mm overlap) - the span is about 1300 - centre of front/rear top plates. I was planning on spacing the rafters every 2 feet across the 3200 width - You think I should add more? Was going to use the 38x63 CLS again for this. Yes/No?

Sole plate and top plate are both 38x63 - sole plate is treated. I've got the anchor bolts in place and was going to add a bead of silicone between the concrete and the sole plate when installing.

 

[rick1632]

Looking at my plans, I've got just over 100mm of room at the front to play with out of which has to come the shiplap any battens and roof overhang, so if I use 15mm shiplap and 25mm battens, then I'm left with a 60mm overhang.

 

[rick1632]

Another option is to skip the OSB and just apply the shiplap direct to the frame - and to strengthen the frame install some cross pieces between the studs?