Retiling with natural slate - are these issues?

[hollisca]

Hi, I'm in the process of getting an old roof redone in natural slate and am curious as to your opinion on its progress.

It's not complete yet, with ridge tiling being the most obvious, but also the porch area. However, I feel the look isn't as uniform as I'd have expected, with several areas seemingly uneven.
I've read other threads here and is this an example of a poor 'thickness grading' job done by the roofers?

Some on the right hand side of the roof near the top appear to have gaps in excess of 3mm consistently too, and slate cocking at angles is especially noticable at the left hand side border with the neighbouring roof (there is an existing led border here likely impacting it). Is this called 'kicking'?

The velux were existing and the tiles around them seem decently uniform and compact, would you agree?

What advice could you give me about how to communicate best with the roofing contractor to address these concerns? Are they just nitpicks or do you think the work is being rushed?

Thanks

 

[DAZB]

Looks like a combination of poor slate mixing and really substandard workmanship. No idea what is going on at the left party wall edge but how they can think that is finished is beyond me. The spacings are wrong in several areas, slates should have been graded and laid with the thickest to the lower courses, and a few of the slates actually look to have a slight twist ?! I think you need to voice your concerns to the roofer as no doubt you will be paying a pretty penny for it all and you should not be getting that in return.

Edit
Sorry just had another closer look and they have lost the bonding by over an inch to the top left area above the velux and not sure if you asked for smaller slates than your neighbours but that is what they have done as the courses no longer run through.... they should have had no need to install the leadwork between the houses as this could now cause them an issue too if water gets in.

 

[hollisca]

Thanks for your reply DAZB.

The left party wall had those pieces of led (the bonding if I understand) added when the neighbours redid their roof years ago to my knowledge. Nothing new's been added in the current job, and it is something I will query - particularly if I'll be told it's what's causing the issues there. My roof extends higher than the neighbours into an immediate rear flatroof extension, whereas theirs falls slanted from that point. Are you saying the bonding should carry on to the top regardless? It may have mortar filling it there.

I didn't ask for smaller slates, but these are close to what I had originally, which were the original size (vs what the neighbour got).

Regarding the poor mixing, is that something that can reasonably be remedied by swapping out some key offenders, or is that just a game of whack-a-mole; it shouldn't have happened in the first place seems clear.

The spacing issues in the top left and right would need to be addressed by simply re-doing them, would you imagine?