Builder left gap under new window sill

[sleepless_amateur]

Apologies if this is the wrong forum.

Recently one of my concrete window sills started to crumble and needed replaced - not a job for me, so I got a builder to do it. It looks like he's done a decent job except he's left a gap of about 5mm under the sill as seen. I quizzed him about whether I needed to plug it up with mortar but he said no, the gap is there to allow any water that penetrates to get out, and that the sill is wrapped in a waterproof membrane which you can see.

I can't shake the feeling that this doesn't look right to me though, considering that none of my other sills have a gap under them. Has he done me a favour or cut a corner for some reason?

 

[Ian H]

I think he’s having you on.

You would have weep holes over a window to let any water out, not a gap under the cill.

 

[Notch7]

He forgot to put in a line of silicone and cabt be a rsed to come back.

The only place water can penetrate is from the window above it - and windows on stone cills should have face drainage.
Above the window will be weep holes to discharge water from above.

So where does he think water will come from

 

[sleepless_amateur]

What should I do, should I fill the gap with mortar? Here's another pic from a different angle.

 

[bobasd]

no, use silicone or similar as advised above.
maybe its me but i can't see a drip groove under the sill? unless that "line" in pic one is somehow a drip groove?

 

[sleepless_amateur]

There is a drip groove although it's quite shallow compared to the old one.

 

[bobasd]

run some water down the sill and watch what happens at the drip groove - if the water bye-passes the groove and feeds back into the brickwork then the drip groove needs a little deepening with - a small grinder is best and safest.

 

[sleepless_amateur]

This pic shows the groove a bit better.

 

[Leofric]

Well the builder appears to have put the cill on a dpc tray which is good.