Think I’ve messed up the batten spacing

[lozcozard]

I’ve nailed all my batons down for a door canopy. I’ve been wondering what stops slates wobbling once they are nailed in almost half way down. It looks like the top of the slate is supposed to rest on the next baton up. I don’t know how I missed that when planning it. Mine won’t as the batons are spaced too far.

All the calculators online and the person at the roofing merchant said the headlap could be between a range of values. Whereas if the top of the slate is to rest on a baton then there is no range of headlap it’s just fixed, I can’t choose a 100mm or 200mm headlap. The baton spacing would be fixed at slightly less than the top of the tile to holes. No website says that, it’s all calculations. One website says of the batons “Their spacing is determined by the size of the tiles and the height and pitch of the roof to be covered” - but if the top of the tile rests on a baton then it’s not! There’s only one spacing the batons could ever have.

So I’m a bit confused. Do the slate tops need to rest on the next baton up? And if so I’d need to pull them all out and start again. Am thinking it may be easier put more batons in between rather than pull them out and have holes in the mebrane everywhere.

 

[lozcozard]

Never mind I have reduced the spacing and so top of all tiles will now sit on batten above. I feel so much better for it, and it only took an hour.

I do have the old nail holes in the membrane... wondering if its a big issue because the slates should be keeping dry, if its not, then I haven't a good job on the slate!

 

[datarebal]

There is a range , small range but there is.
The merchant is a seller , not a slater

 

[lozcozard]

There is a range , small range but there is.
The merchant is a seller , not a slater

Yes I gathered that when they couldn't answer other questions. One of them thought the slates go sideways (he was new!)

If you want to rest the top of the slate on the same batten you nail the next slate in, then the range is only like 1-2cm or so. With 38mm battens. You cant have a higher headlap as the holes will overlap the slate below. You can go less but only if you add more battens to rest the top of the slates on.

OR you start creating your own holes, but I dont see the reason to.

 

[Vinty]

The formula for batten spacings is length of slate minus headlap divided by 2.
Synthetic fibre cement slates are normally preholed to give a headlap of 100mm or 4 inches.

 

[lozcozard]

Ok but you need to know the headlap to work it out. No one could tell me. So I just placed the slates on battens on the floor and measured it. But key information I missed was the top of the slate needs to rest in the batten above.

 

[datarebal]

For anyone to give you head lap you needed to provided roof pitch , exposure .
Your op indicated you were trying to work out how many slates required .

A simple how many per M2 and gauge at ** pitch .

 

[lozcozard]

For anyone to give you head lap you needed to provided roof pitch , exposure .
Your op indicated you were trying to work out how many slates required .

A simple how many per M2 and gauge at ** pitch .

I’ve come to the conclusion when I read this, which is the advice on many sites, it must be referring to slates without holes and you put your own holes in because for pre-holed slates this recommendation is simply not true as there can be only one headlap due the holes already being there IF you rest the top of the slate on the battens above.

perhaps the advice is also for tiles which hang onto battens and not slates?

 

[datarebal]

It's not strictly correct a slate holed for say 90mm can cover less and more .
And still be sat on the batten .
Sorry if you don't work with slate on a daily basis you probably wouldn't grasp it.
Bits of batten laid on the ground would not help you understand it.
Glad you're ok with yours now , but advise you steer clear of random slate in diminishing courses .