On Tue, 10 Jun 2008 22:39:48 +0100, George \(dicegeorge\) wrote:

My first thought was to use the old slates on the posh side, and new
ones on the hidden bits of roof.

This is what we had done. New replacements for the ones that didn't
survive being lifted went on the back. About 80% reuse of old slates.

But if the old slates are from different bits of the roof, some from
north facing, some from south facing, won't they be weathered different,
and thus the posh side would have a splotchy chequerboard look.

Not as splotchy as a mix of new and old. If you are not going to get 50%
reuse of old slates it suggests that they are in pretty poor nick and it
maybe better to buy new(*) for the entire roof.

They will be weathered differently but being the same slate in the same
location they will be pretty similar and very quickly become anyway. Far
more so than new/old.

(*) "New" as in fresh out of the welsh mountains or "new" as in reclaimed.
Reclaimed can be a bit iffy though, depending on how old and where they
came from. 50years old and from an heavy industrial area they might not
be in very good condition (acid attack), conversely 100 years old but
from a rural area away from industry they could be fine.

--
Cheers
Dave.