How to screed here for laying flags or blocks?

[Pipps]

I have a partially shaded back yard of circa 45m² area which I previously excavated 18" before laying a Type 1 MOT sub-base and then laying 20mm of granite dust originally intended for laying artificial grass.

The lower black horizontal gravel boards are approximately double the visible depth and were haunched into thick concrete, following the excellent guidance on this website, before the sub-base was laid.

Those gravel boards are not perfectly horizontal but were laid to run parallel with the lower edges of the existing fencing, which was fitted unevenly by undoubtedly the worst cowboy contractors in Wales.

I would now prefer to lay flagstone paving slabs rather than artificial grass and so would like to add another 10-20mm of the appropriate grit sand and screed it to a level finish with a 1:60 gradient.

This yard is clearly an unusual shape and will be paved edge-to-edge despite being unlikely to receive any footfall whatsoever over the next 10-20 years, but I nonetheless want to do this job properly.

Weeds are a problem due to airborne debris from adjacent gardens, which caused me to abandon the artificial grass idea in favour of flagstones or block paving, which should be more weed-resistant.

Due to the overwhelming difficulty of getting an even semi-competent local contractor to provide a quote, let alone be trusted to do an remotely passable job, I will be doing all work myself.

1. Would either 600mm flags, 400mm flags, or block paving be the most sensible way to go here all things considered, in terms of cost, technical difficulty and level of work involved?

2. If laying flagstones, once circa 10-20mm grit sand is laid, will screed rails still be necessary and appropriate, even though I will have no way of walking around the edges?

3. Would there be any other options for levelling the sand using traditional screeding methods before I then lay material starting at the back with no perimeter access?

Thank you

[Tony McC]

1 - Block paving is probably the easiest, and then 400 flags. The bigger the flag, the more awkward they are to lay.

2 - If the flags are consistent thickness concrete, then you could screed the bed. Set up edge rails, 100mm or so from the fences, then centre rails to sub-divide the area on spans of no more than around 3m. Start at the furthest point from the access and work backwards.

3 - the only other option is to do it bit-by-bit. There's nowt wriong in doing it that way, and it suits some DIYers, but you still need to set your screed rails for the whole area to ensure it all 'works' and then you'll need to protect them from accodental movement while you're working.

[Pipps]

You had me with your first two words...

I am going to do this with block paving!

I will draw a plan and report back...