makie

No, that would be done before they come in.

It should be built up with steps to allow it to shed properly and make sure water doesn't creep back. Like this The felt should be ran down the valley and then the felt on the pitches should be lapped on top or into the valley. They have also used non-copper nails in it, plus lead valleys should never be nailed on the flat or further down than the top 3rd of it to allow for expansion.

Can be done but voids any warranty.

Breathable felt can leak with heavy rain over a prolonged period. The valley is most likely letting water in, doesn't look like it's been felted properly. Is it lead? if it is it's been installed incorrectly. Also the lead gulley, is it one piece? please tell me it has some elevated areas or expansion joints welded in?

Genuinely couldn't tell you, all of this was installed for us by the builder with the architect overseeing it. We just had to batten on top of them.

https://www.permavent.co.uk/products/easy-slate/ https://uk.onduline.com/en/professionals/tools/news/product/low-pitch-roofing-solution-thats-right-light-and-watertight It can be done. I've installed Rosemarys on a extremely low pitch with the bitumen sheets in the second link. 12 years and no leaks.

Can you take a picture of the felt? Just so we can clearly see what we are looking at.

Yep, cupa went up 10% a couple weeks ago

Valleys should be done in code 5. Front and back aprons on chimneys should be code 5 while side flashing can be 4.

It's not a good idea. Either get the correct tile, do the full roof or put a join in.

Get Marley JB reds, just expect to pay more for them

You would use them to repair any slates removed to fix the valley, if you didn't fully strip the area

You may be able to swing the slates, depending on if they are double nailed etc. Would remove the need to strip big sections. https://www.youtube.com/watch?v=or37dqQ1owM This video will show you what I mean. To ensure all slates are nailed yes. Depending on the area or need for a quick repair you could use a lead tingle and some glue to hold it down.

Code 5 is the best for valleys but you can use code 4, just don't expect it to last as long. For the affected areas if you really can't find anyone to repair or redo you could cut a line and slip a new bit of lead in. If you do I recommend 8 inches lap on the slit upwards and 8 inches past the last hole etc.

It is lead, the split in picture 3 is because it is longer than 1.5 (probably not even code 4 based on the holes from run off water)

You should have a run of membrane under the the valley and then membrane should lap the grp/lead etc

There is, breathable membrane should never be used under lead as it sweats badly. Lead manufacturers recommend building paper.

Long lengths no. My comment was in reference to a Watergate slated in (see picture), not long soakers. It would be near impossible to do what your roofer is proposing and I doubt it would work. No matter what happens that lead can't be used for soakers. Soakers should be code 3 with those slates.

There is nothing technically wrong with it, that's how it's done most of the time in Scotland. Saying that soakers and stepped flashing looks much better.

It's a repair. it's in the name. And no glue is not a bodge. If the slate has a fixing already then it can be used. Unless you want to tell architects working on historic Scotland buildings they are wrong.

Ask any qualified roofer. I am one. It's a simple job. Two ways. Either the same method here and install a slate hook or simply take one nail from each of the above slates also to allow them to turn. Then double nail the repaired slate and glue the two above back into position.

Might just be the angle but it looks like you need a bit of lead under each window, cover looks short.

Repairing a double nailed slate is easy if you know what you're doing. It's a 2 minute job.

Who specified flat tiles? I always recommend a profile on an older house when a customer asks for flat I let them know that there could be some areas that have slight bumps, firewalls, walls etc

You are always better to replace the fascia as it would reduce the distance the tile drops into the gutter. Also replace the fascia if you don't put cents in the soffit as it will rot.