OSB3 Roof Joins Seal?

[Littledave]

Hi all apologies for my 1st post asking question, I have been lurking around for a while, and seeing some great workshop builds.

I have re roofed my workshop with OSB3 and have left 3mm gap In between sheets. I plan to felt over the top and then maybe some onduline over the top at a later stage.

My question is do I seal the joins with tape of maybe mastic or bitumen based sealant.

 

[Jameshow]

I'd use felt adhesive and squeeze a bit in the gap..

In this warm weather it will be a easy but hot job!

 

[Stigmorgan]

I'd use felt adhesive and squeeze a bit in the gap..

In this warm weather it will be a easy but hot job!

And make sure you cover everything inside with plastic because in this heat the bitumen will run and drip everywhere, AMHIK.

 

[HOJ]

You don't say what thickness you have used, but generally for sheathing purpose you leave the 3mm gap for expansion, so I wouldn't be inclined to "fill" but you could tape it, for roofing work we would use 18mm T&G OSB.

 

[Littledave]

It’s only a shed / workshop so I used 11mm OSB3.

I was thinking of using the lap sealant/adhesive, or roofing mastic as it semi cures so the OSB can still move.

 

[HOJ]

The point I was making was the fact it will expand, so if you "fill" it with anything, even if it is flexible, it wont allow for compression of the joints, but now you say its a shed so it's not big enough to worry about.

 

[Dave Moore]

Hi,
Normally you use tongue and groove osb and glue together with 5 minute polyurethane glue. Rubber would be a better choice as it’s guaranteed 30yrs.
Regards,
Dave

 

[TheTiddles]

It’s only a shed / workshop so I used 11mm OSB3.

I was thinking of using the lap sealant/adhesive, or roofing mastic as it semi cures so the OSB can still move.

I don’t know if this is true anymore, but last time I was buying OSB only the 18mm was rated as waterproof