Some bricks permanently wet?

[terrypin]

Hmm - starting this post again as it seems to have vanished while I went away to get some background info. This time I'll copy/paste as I compose it!

This is my first post and I'm a 'customer' not a paver or DIY-er, so my question may turn out to have an embarrassingly simple answer.

A year ago I had my drive block-paved. I understand they are 'Marshalls' on hardcore plus 'membrane' plus sand. They replaced mainly the original concrete slabs, and a small stretch of lawn. Here's a photo:

http://i154.photobucket.com/albums....341.jpg

Overall I'm pleased with the job. But after a long enough dry spell early this year I noticed that a score or so of the bricks seemed to have dark patches, as if they were permanently damp. Most of these were near the garage entrance, just in front of the drain, as shown here:

http://i154.photobucket.com/albums....cks.jpg

Note that the marks remained identical, not varying at all. (That photo was taken about 2 months ago, yet that area looked exactly the same yesterday morning.) So I have been assuming that the bricks were flawed.

To cut to the quick, it's taken me until yesterday afternoon to get the paver to replace them with new bricks. ("Next week, I promise..." etc, since April!) He rushed it and missed 3 that needed replacing, but as he left me some spares I replaced those myself afterwards.

However - and sorry for taking so long to reach my point - I now see that the sand in this area is very wet. Despite having had a few days without rain. So could it be that that's the main cause, not any significant flaw with these particular bricks? Are there perhaps always some porous areas in these bricks that allow moisture to seep through, and darken the top surface in specific patches like this?

If so, presumably this means rainwater is not draining away sufficiently at this small area? So how should I fix that please? Frankly, I don't want the hassle of getting the paver back yet again, so want to do it myself. Can I just remove a few bricks and puncture the membrane in a couple of spots? Would I need to first remove the wet sand and replace it with dry, or would it eventually dry out anyway? I doubt my skill at getting it level again if I do so!

Any advice would be much appreciated please.

[Tony McC]

It probably is the fact that the laying course isn't draining as readily as would be desired. There's nowt wrong with those blocks.

I don't know what was used as "hardcore", but it's likely that it's not permitting the laying course to drain. A simple fix would have been to create an 'escape channel' from the laying course into that linear channel, but as I'm not familiar with the job layout, I can;t say exactly what would have been best.

Assuming that it *is* the laying course that's retaining water, all that is likely to happen over the next few years is a small amount of settlement and gradual loosening of the blocks in that area, which can be fixed with minor remedial work.

[terrypin]

Thanks Tony, appreciate the fast reply. Here's another photo showing the plastic drain separating the sloping main drive area from the flat bit in front of the garage.

http://i154.photobucket.com/albums/s247/terrypin999/BricksDrain.jpg

What I'm not clear about is how the water is supposed to get into that drain channel? Is the membrane at the bottom (next to the clay/soil), with the 'high quality hard core' on top? If so, is the membrane supposed to overlap slightly into the U-shaped drain, or what?

Does the suggestion I mentioned, of lifting a few bricks in the wet area and poking a screwdriver down to make some drainage holes make sense please?

--
Terry, East Grinstead, UK

[Tony McC]

It takes a special construction to drain a laying course. Sometimes, it can simply be a matter of having 6-10mm holes in the side of the channel, backed by a filter membrane, or it may be easier to install a true fin drain or horizontal drainage composite (waffle board). Each site is different, so a different solution may be required.

Some typical constructions are shown on this page but because I'm not familiar with the site, I can't say which, if any, would be most appropriate. You need to discuss this with your contractor.

Poking holes with a screwdriver is unlikely to have any long-term impact.

[lutonlagerlout]

terry, you have a nice looking drive there,you are worrying over nothing mate,take the dog for a walk,go for a drink and watch the footy
but dont lose sleep over this :;):
LLL

[Tony McC]

LLL - did you notice the different standard of cutting-in either side of the linear channel? Looks as though it was done by two different contractors!