Advice on linear drainage channel near ext doors

[hander]

Hi,

Trying to spec a linear drainage channel at the rear of my house. It will be around 4m long and sit directly in front of the cill of four sliding folding doors.

The cill will be partly submerged in the ground - about 5-8mm

We have made the opening. It's into a cavity wall.

See here

The doors have a leadtime of 3 weeks or so, so we have time to put the drainage channel in. We're thinking it would be wise to put the channel in before the doors arrive as it will involve cutting through some paving slabs and it would be expensive to see a chip fly off and damage the glass in the doors.

We'd planned to:
(i) fill the cavity at the bottom of the wall with a cavity closer
(ii) run a dpm along the top of the outer course and lip it into the brickwork at either side at the existing height of the DPM (which is only one course higher - not conventional I realise but it wasn't done by us... )
(iiii) run a linear drain in front of the proposed site of the cill. (starting around 25mm from front of outer skin, where the cill ends)

Any thoughts on the above? Specifically:
(i) maybe a bit outside the reach of this forum but is a closer necessary or can the gap be filled with mortar?
(ii) should the dpm extend across the front brick and further to full cover the underside of the cill? And (how) does it tie in with the drainage channel?
Iiii) assuming I end up with gap between the fitted cill and the edge of the linear drain, what should this be filled with? (It won't be much but I'm thinking that we can't start the channel at exactly the proposed edge of the cill in case it has to come out any further for any reason).

I hope someone has got this far in reading ... I'm a bit desperate and my builder is not inspiring me with confidence on this particular part of the project.

Thanks in advance.

[hander]

In fact, halfway down this page (see illustration captioned 'Using linear channel option') is my situation but it doesn't give any details about the DPM.

Or I may be being dumb!

[hander]

No one ...?

[lutonlagerlout]

is the door disabled access?
generally speaking if its not then the top of your linear drain should be 150mm below the bottom of the cill,which is normally DPC
we do goalpoast doors sometimes for wheelchairs with high level acos ,and any small gaps must be filled ith strong mortar, the cill must be slightly higher than the aco for obvious reasons
LLL

[Dave_L]

A lot of new builds we get involved with have the tarmac brought right up to/ramped up to the bottom of the door thresholds to satisfy the DDA regs.......