What quality for roof battens?

[Medan]

We are re-roofing part of the roof, and I'm reading about the quality of the battens. But I'm not getting any wiser from the wood guides.

We have Monier concrete tiles, 27-degree roof slope, and live in snow zone 2. The house was built around the '90s. Battens 45x70.

I'm thinking of using the same, or should I go for 45x95?
What quality? G4-2 or better (G4-1 or G4-0 as I understand it?)
Do you also need to consider C-grade, like C14-35?

Reusing existing undamaged battens: Is it risky considering the age even if they look fine?

 

[Rickard.]

45x70 will be good, G or C classification are slightly different things but it's not particularly important for your roof. Simply put, gx-x is a sorting and Cxx is the strength classification. As far as I know, C14 is the best (only?) that lumberyards usually have in stock for just 45x70, and it's sufficient for roofing.

Reuse is good if you're up for it and feel confident in making the assessment, but it places slightly higher demands on the dismantling and reinstallation. I don't see age as a problem, but for example, dry boards tend to crack more easily than new ones that are just dry-ish.

 

[Medan]

45x70 will be fine, G or C classification are slightly different things but it's not particularly important for your roof, but simply put gx-x is a sorting and Cxx is the strength.
C14 is, as far as I know, the best (only?) that lumber yards usually have in stock for 45x70 and it's suitable for roofs.

Reuse is good if you're willing and confident in making the judgment, but it requires a bit more during disassembly and reassembly, I don't see age as a problem, but for example, dry boards may crack more easily than new ones that are just dry-ish.

Thanks for the reply!
When I've googled, I've found 45x70 with a slightly higher C-rating, but there was no info on G-classification. From what I understood from wood guides, it's risky with material with knot holes and cracking when it comes to battens.
You write that the classification doesn't really matter for my roof, it is classified as a "light" roof despite the tiles weighing a ton, right?

 

[Rickard.]

With 45x70, there is much less of a problem with cracks/knots than with thin battens. Structural timber (C-classified) is sorted by strength, which is the important part, so you don't need to worry about the rest.

No, I don't think it classifies as a lightweight roof, but in any case, snow is still the heavy part. With tiles, there are so many of them that it holds up anyway. A metal roof can have half as many battens on the roof, and then you might need to increase the dimension and/or C-class.

 

[Testarn]

45x70 is very strong as a load-bearing batten, so you don't need to think about C-classification but take what is available and cheapest. I don't know what is "normal" nowadays, but when I worked as a craftsman in the Stone Age (read: the 80s and 90s), 25x38 was used as a load-bearing batten for tiles, and I've never heard that it was a problem. There, it was a little more careful to keep track of larger knots, and it sometimes happened when walking around on the roof before the tiles were in place that a batten broke, and you had to saw off a piece and nail a new one.

 

[Medan]

45x70 is very strong as roof battens so you don't need to think about classification, just take what is available and cheapest.
I don't know what is "normal" nowadays, but when I worked as a craftsman in the stone age (read: 80s and 90s), 25x38 was used as roof battens for tiles and I've never heard of any problems with that. Back then, it was a bit more important to keep an eye on larger knots, and sometimes when you walked around on the roof before the tiles were in place, a batten would break and you had to saw off a piece and nail a new one.

Great, thanks for the answer!