Drainage - damp and gravel drive

[hellboy777]

Hi everyone,

First post....

I hoping to install a gravel driveway & patio at my victorian terrace.

The current paving has been laid too high, with the dpc approx 75mm above ground level. I would like to lay gravel (core / grid for driveway) but I'm concerned that the water would sit against the wall where there has been previous damp issues?

The footings are quite shallow and i'm not sure how deep down I would have to dig to lay a french drain (if thats whats recommended).

The drive currently drains onto the road (laid pre 2008 I think) and has a decent gradient away from the house.

Could anyone advise what you would typically do in this situation, to prevent rainwater sitting against the wall of the house??

Apologies for my lack of knowledge, keen to learn.

Thanks in advance.

Hellboy

[seanandruby]

have a look here.

[hellboy777]

http://i1376.photobucket.com/albums/ah1 ... gofcgw.jpg

http://i1376.photobucket.com/albums....38a.jpg

http://i1376.photobucket.com/albums....ppb.jpg

http://i1376.photobucket.com/albums....axa.jpg

had a good read of the info, answers a few questions. I've added some photos to shed a bit more light on my problem. I've gone from choosing decking to paving to gravel to paving! The house had a previous issue with damp and little front to back ventilation, so I've had installed air bricks in the only areas possible. My estimation, at worst, are the double height air bricks sit just below the DPC level for the building.

However, part of the issue is that the DPC height and footing depth of the 2 areas of building appear to differ, is this a known thing?

The kitchen (outrigger building) is rendered, and Im struggling to find the DPC. The 2 brick courses below the bell-cast have been rendered also, I'm figuring this is bad? The original drain sits a brick course below the current paving level.

If I were to dig down to respect the original DPC and not cover the air bricks, then there is a chance I will only be 1 course of brick above the start of the outbuilding footings, is this acceptable? My understanding is so long you don't UNDERMINE the footings then it should be ok?

I have labeled an area where I have had to repair the brick work. The drain in this area was damaged and leaking water from the waste pipe for god knows how long (before we purchased the house).

So....the question is...How do I lay new patio whilst respecting the DPC's, air bricks and without under mining any footings???? The patio extends to the rear of the property (total area 21m2).

Thanks to all in advance.

[seanandruby]

Where those airbbricks are under the door are you putting a step? You can extend the cent through the step with some drain pipe. The rest of it try and get as much depth as you can below dpc, maybe install a linear drain against the wall to take any surface water.

[hellboy777]

Hi Sean,

Not sure what i'm going to do regards steps, but i'll look into the pipe extensions for the air bricks.

Having done some excavation in the side-return, I've discovered that what I believe is the original bitumen DPC, it was covered by the patio flags that had been previously laid.

The kitchen DPC sits only 3 courses above the top of the spreader course of bricks for the foundations. The foundations on the main building are at least 3 courses lower than this.

I'm going to struggle to get 150mm below the DPC without getting too close to the foundations. Depending on sub base depth, I would at least have to lay the sub base on top of the first spreader course.

I thought I read on this site that a sub base isn't essential for patios, but all over the forums a type 1 sub base 75mm minimum seems to be advised?? Confused

If anyone can give some advice, i would be very very grateful.

[seanandruby]

You need to keep the paving as low as you can below dpc
Level. If sub soil is sound then a sub base isn't necessary but we always try for at least 75ml mot.

[hellboy777]

Cheers pal.

How would I know if the sub soil would be deemed 'sound'? I've got 265mm between DPC and top of the footings, any idea how I can get a patio down and still leave 150mm to DPC?

Would prefer yorkstone, likely sawn, but open to ideas.

Cheers mate

[Tony McC]

Keep away from the spreader courses. Forego the sub-base, if necessary, for the half-metre or so closest to the spreader courses. The flags can be laid on extra-thick mortar bedding, if required.

[hellboy777]

Hi Tony,

Thanks again for your time. So;

The side return is 1820mm wide and the spreader course extends 200mm from the wall.

I leave a 500mm strip bordering the walls, where the current sub-base will remain whilst I compact the 75mm MOT on the remaining area.

To lay the flags; dig down approx 100mm into the the remaining sub-grade and lay extra mortar mix then screed the whole patio with a 6/1 mix. Then lay the flags!

The bottom spreader course sits on clay and its 330mm from the top of this brick to DPC. There is a hardcore type base under the existing patio.

I'd like to take up the design service once we have identified the flags we intend to use. What is you're turnaround time mate, I'm on a tight schedule!

Thanks,

Gav

[Tony McC]

Probably get a design done in 24-36 hours at the moment....depending on size and type of flags, obviously.

[hellboy777]

Great, thanks. Will be in touch once we found the supplier. For info mate, tried Kerridge Stone and they don't do paving but they pointed me in the direction of Earls Stone which is in the same area.

[Tony McC]

Doreen Earl! Is she still going? Scary woman!!!