Low Pitch Roof Preparation

[actionjackson]

This is a timber framed enclosed garage and the roof is overboard with T&G boards.

In preparation for metal sheets I have fitted a breather membrane directly to the boards and counter battened at 600 centres to provide good ventilation for likely condensation.

I feel I have missed a couple of steps and would appreciate some pointers.

This is only a 12deg pitched apex roof and I didn't use nail sealant tape under the counter battens. Is this going to cause me a problem in the long run as I have read weather can drive water unter the battens?

The battens are 25x50 and are fixed into the T&G and rafters with 90mm stainless screws. I went with screws rather than galv nails because I live in a exposed costal area with high winds. Im however concerned the horizontal battens needed a longer screw as there will only be 40mm into the roof (20mm T&G and 20mm rafter). What do the experts think about this?

My intention is to fix the sheets through both battens only and not penetrate the roof.

 

[catlad]

If you are worried about the sheets being blown off then why don't you fasten the sheets to the rafters with 6" tek screws

 

[actionjackson]

I'm now seeing a bigger issue as a result of my car port roof structure.

The counter battens and horizontal battens have been screwed down at the same place in the joists that run through the rafters because there are only 4 rafters across the 6m building which are on the structure posts.

It is not possible to get a 3rd fixing for the sheets in the same place but if I fix anywhere else in the batten it won't be supported by the counter batten. Do I need to fit an additional counter batten in this situation?

 

[Best Glaze]

I'm now seeing a bigger issue as a result of my car port roof structure.

The counter battens and horizontal battens have been screwed down at the same place in the joists that run through the rafters because there are only 4 rafters across the 6m building which are on the structure posts.

It is not possible to get a 3rd fixing for the sheets in the same place but if I fix anywhere else in the batten it won't be supported by the counter batten. Do I need to fit an additional counter batten in this situation?

I would, you want more than two runs of fixings.