Zincalume roof, battens and valley

[leeton]

G'day all,
I am replacing my old cement tiled roof with zincalume, and using 40mm zinc battens, the question I have when it comes to the valleys, should I put in timber valley boards, or can I use the zinc battens to support the valley.
The problem with the timber is it is not 40mm and I would need to pack it up or similiar, but using the zinc the height is spot on, of course. Am I on the right track here?
Thanks in advance.

[journeyman Mick]

The valley boards need to be lower than the roof battens, otherwise there's nowhere for the actual valley to sit. Depending on the pitch of your roof, the length of the valley and the rainfall intensity in your area you may need the entire 40mm difference available to you to get a gutter that will carry enough to avoid overflow and leak issues.
I'd be looking at sheathing the entire valley area in 15mm ply and sitting the valley gutter on it. This will give you a valley gutter 25mm high. Any thinner and the ply won't be able to carry the weight of a full valley.

Mick

[leeton]

Thanks Mick for the response, the roof is 30 degrees, valley lenth approx 4m, location Melbourne East.
Now I don't intend on doing all this myself, just estimating costs and planning etc, so I know whay I am talking about for ordering and speaking to chippy, another question you may not be able to answer but I will ask anyhow, batten spacing, is it around 900, on timber trusses, N2 weather category.

[journeyman Mick]

No idea what the N2 category is, but 900 spacing for batttens is fine.

Mick

[barney118]

Leeton,

I have just finished a 180m2 reroof and I was hell bent on using topspan 40's because of the straightness and lengths of the steel. But the downside is installing insulation blanket and I changed my plan and used wood battens. WHY??

to get the isulation stretched firm before sheeting, its quite easy using foil clips into wood, I believe you have to use magnets for the topspans and they are exy.

I found the cost of the wood battens was not much different to the steel and when you install to the rafters make sure you OFFSET the screws to rafters. Hence the roof screws will end up centre of battens, so the the battens tie down are on the edges (alternate on rafters) to allow a straight run for the roofing.

[sports fan]

i use 100 x 25 oregon for valley boards

[billbeee]

Mick,
We have gone that little bit extra and pay more for a 2mm or more thick valley gutter with no boards at all. A bit dearer but deeper, which is what it is all about eh!

Cheers
Bill.

[journeyman Mick]

Mick,
We have gone that little bit extra and pay more for a 2mm or more thick valley gutter with no boards at all. A bit dearer but deeper, which is what it is all about eh!

Cheers
Bill.

Good thinking, would mentally file it away for future reference, but not planning on doing any more building unless it's for myself.

Mick