Rod wrote:

Terry Pinnell wrote:
Andy Burns wrote:

Terry Pinnell wrote:

http://i154.photobucket.com/albums....341.jpg
http://i154.photobucket.com/albums....cks.jpg
Something has broken your URLs

Strange, thanks for letting me know Andy. They seemed OK when I
checked before posting, but something must have screwed up. Here they
are again. I can click these in my message composition window and they
both open OK:

http://i154.photobucket.com/albums/s...314-083341.jpg
http://i154.photobucket.com/albums/s...-BadBricks.jpg

Could it be that the drainage channel (visible in the picture) is
preventing flow from the paved area?

Not suggesting you actually do this, but if you lifted the grilles and
drilled holes sideways towards the paved area, would that allow water
from underneath to drain away? Are the drainage channels bedded onto
some mortar which makes them an impenetrable barrier? Of course, this
would only be likely if you have something like clay below everything.

We certainly have some areas that dry out much more readily than others.
But nothing quite as permanent as you describe.

Rod, John, Kevin:

Thanks all. I'm not really sure exactly what the arrangement is near
the drain, but I'm guessing it looks like this in cross section:

http://i154.photobucket.com/albums/s...icksDrain2.jpg

That suggestion of Rod's makes sense, especially as there *is* a lot
of clay here. I don't see that it could do any harm anyway to drill
holes in the drain walls, and hopefully it will allow any excess water
to flow into it.

A key question is whether the membrane is waterproof or not (the
latter I understand being called a 'permeable membrane'). The quote
wasn't explicit on that. But if it was impermeable, wouldn't that mean
that *all* the bricks over the sloping drive would be showing the same
'dampness marks'? Not just this tiny proportion near the drain? On the
other hand, how can a permeable membrane protect against weeds?

The drain simply drops down at its RH end and runs under the garage to
some soakaway point somewhere in the back garden.

The possibility that Rod and Kevin have suggested, that the drain is
somehow blocking proper drainage at the bottom of the drive, seems to
be a logical one to me. I wonder if drilling a dozen 10 mm holes on
that side will solve it? Assuming I *can* get the drill in at that
angle, and that there's no significant obstruction, like cement.

--
Terry, East Grinstead, UK