Fibre Cement Slates - shed

[EdTurtle]

Hi,

I have a mono-pitch brick built shed that I am about to roof. I have 4x2 rafters at 450 centres, 2x1 battens (not fitted yet) and a pitch of 15deg. The shed is 7foot wide, so the roof will be 7 foot, plus about 4 inches, and the depth of the rafters/roof is 4 foot (including two inch overhangs) (I think that's all the relevant info but if you need any more let me know)

I have watched/read countless slating videos and there a few questions i have - please bare in mind this is a small garden store, not a house, i would like it water tight, but there are no soffits and the front of the store will have gaps so plenty of airflow.

1) Would i be ok to use galvanised nails rather than copper (if not why)?
2) I have three holes on the slates - I have seen that the top two are nailed, and the bottom is for a disc rivet, but would it be acceptable to nail all three?
3) I have seen that with cement slates you use three slates at the bottom, is this so you can use the disc rivets, and if so, and i can nail rather than use rivets, is this necessary?
4) What do you do at the top, as i wont have a ridge the top two nails will be visible, is this a problem?
5) Is some sort of membrane under the slates essential for a shed?


Thanks very much

 

[palaceray]

You could use the galvenised nails if you want to , but ally nails are better and very cheap to buy.
You can not nail through the bottom hole as you would be nailing through the two courses below and the roof would leak everywhere.
The copper rivet sits on one course of slate and the 2 in the course above sit over the edges of the rivet and the next course hooks over the rivet and holds down the bottom of that slate.
You do need the under eave and eave at the bottom to work properly.
At the top of the roof you should have a mono ridge or copping to cover the top nail holes.
Normally you would not need a membrane on a shed but due to the shallow pitch I would advise you to use one as a secondary layer against water creeping in.

 

[catlad]

You could turn the tiles sideways at the top considering its only a shed.

 

[EdTurtle]

Ok, thanks for your help

 

[datarebal]

The pitch is low, use a membrane, rivets hold the bottom secure and down they are not an actual fixing, no you cant nail through the rivet hole there's no batten under there anyway.
you can use galv if you want, its your shed you can get slight bleed but at that pitch it wont be obvious,
nail size is important 30 x 2.65 mm
use rivets or your slates will curl up 100%
the top, if you can see the fixings then it cant be weather proof.

 

[EdTurtle]

Thanks again, I've found the marley fixing guide online, and watched some videos, think ive got my head round it now! I was just making sure i understood everything before i started. Have found some copper nails and rivets online, but i cant find any small pieces of membrane.... can i use plastic sheeting, or does it have to be breathable?

Thanks

 

[chappers]

ordinarily I wouldn't bother with a membrane on a shed, but as has been said you do have a low pitch, alternatively up the slate size to 600x 300 and increase the lap( the amount one slate covers the top of the one two courses below) to 110mm and then fibre cements are good down to 15 degrees.

 

[datarebal]

as above but make your own fixing holes to suit... NOT rivet hole

 

[chappers]

yep good point fixing holes will now be in wrong place

 

[EdTurtle]

Thanks, I have the 600x300 slates, and i was going to use a 300mm overlap, which means all the holes are covered by a tile on top (not sure of correct terminology). With a 110 mm lap, does that mean i see 110mm of tile, or 490mm?

as above but make your own fixing holes to suit... NOT rivet hole

Not sure what this means?!

 

[chappers]

no you should see 245mm of each slate, this is the gauge (also your batten spacing) you lay slates double lapped, i.e each slate not only laps over the course below but also over the slate two courses below, in this case the lap should be 110mm, i.e. each slate should lap 110mm over the slate two course below and 250mm over the course below. you also need a double course at the eaves to start off with.
The slate will be holed for 100mm lap or 250mm gauge so you will have to re-hole them for your new gauge approximately 10mm lower.
Each slate should be nailed approximately through the centre of the batten and the top should just catch the batten above leaving most of the batten exposed to nail the next course above.

 

[datarebal]

300 lap can not work and Chappers it totally correct.. They are in fact a double lap system

 

[EdTurtle]

Thanks, that is in fact how i have done it - just didn't fully understand the different terminology and which lengths were called what! On an unrelated note I was very supervised how difficult they were to drill, especially as they were easy to cut!

Thanks for all your help

 

[catlad]

Its been a while since I used those, but if I remember right you can nail straight through them.

 

[datarebal]

Drilling is better on cement fibre imho. pair of slate snips with hole punch is ok too...... on a shed