roof construction confusion

[bigwainy]

Hello

I am currently planning a small extension and am confused by the roof construction stated by my architect.

the roof is a fairly low pitch (18 deg) and will be covered with slates

the construction spec is

slates on
battons on
counter battons on
2 layers of 1f type felt fully bonded on
18mm ext. ply

Its the 2 layers of fully sealed 1f felt I aint sure about, the internet aint really educating me too much as how this should be constructed.

can anyone help.

ta
bigwainy

 

[Bostitcher]

heres a site that may answer some of your questions:
www(dot)jenkinsslate(dot)com

 

[Bostitcher]

Or you could try http://www.marblemaster.com/slate/roof_slate/Roof_Slate_installation.html

 

[Matthew]

You don't say what sort of slates you are using, but I would be worried about any slates with just an 18 degree pitch. I would guess this is why you have got the extra layer of felt.

 

[bosshogg]

Simply ask your architect to clarify