Soakaway size

[thomp1983]

Hi all,

I need to do something about where the Guttering is going to drain to on our new extension.

I've enough garden left to be able to site a soakaway 5m away from the extension but I've no idea what size it would need to be.

That's a picture of the roof I need to direct rainfall from.

The flat roof on the extension is approx. 13.5m wide by 4m deep,

The pitched section is approx. 6.75m high by 14.4m wide, that's measuring from the bottom tile to the ridge tile then all the way along the ridge tiles to give the width.

It all drains into the Guttering along the rear of the flat roof and then down by the rear door, currently a spare piece of Guttering directs rainfall into the garden.

Our ground is clay once you dig down about 700mm, the current rear garden is a bit damp but far from waterlogged with the rain that's been diverted there since about October so a soakaway should work ive just no idea about sizing it and how deep it should be.

Thanks
Chris

 

[jks7492]

Where did the roof drain to before you built the extension?

Soakaways generally do not work well in clay

 

[thomp1983]

House has soakaways front and rear for original drainage but given I've virtually doubled the roof size the existing will be unlikely to cope.

Both the flat roof part and the part with the velux windows in are all new extensions, the original house was just the part with the double window in.

 

[noseall]

Hi all,

I need to do something about where the Guttering is going to drain to on our new extension.

I've enough garden left to be able to site a soakaway 5m away from the extension but I've no idea what size it would need to be.

View attachment 259287

That's a picture of the roof I need to direct rainfall from.

The flat roof on the extension is approx. 13.5m wide by 4m deep,

The pitched section is approx. 6.75m high by 14.4m wide, that's measuring from the bottom tile to the ridge tile then all the way along the ridge tiles to give the width.

It all drains into the Guttering along the rear of the flat roof and then down by the rear door, currently a spare piece of Guttering directs rainfall into the garden.

Our ground is clay once you dig down about 700mm, the current rear garden is a bit damp but far from waterlogged with the rain that's been diverted there since about October so a soakaway should work ive just no idea about sizing it and how deep it should be.

Thanks
Chris

Tall ceilings you got going in that extension. A bit lazy of the builders to put the fence panels back without slotting the gravel boards in first though.

Soakaways are useless in clay.

 

[thomp1983]

Flat extension ceiling heights are about 245cm, double garage height is a bit more, upstairs ceiling heights aren't huge due to roof design.

All the houses around here use soakaways and none of them seem to have issues, I've never seen any in the 7 years I've been here.

Were also going to be having a circa 1500L water butt that will take water from the rear roof which will take some of the rainfall, I ideally want to avoid putting anything into the drains so I can get the standing charge removed from our waterbill aswell.

The front seems to be coping fine with the old soakaway but has less roof surface area, there will also be a second soakaway going in there to take water from our new tarmac driveway

 

[HERTS P&D]

TA bit lazy of the builders to put the fence panels back without slotting the gravel boards in first though.

I recon they have lifted out the gravel boards due to using it as an entrance by slipping out the fence panels and not tripping over the gravel boards every time they go in and out.

Andy

 

[AngleEyes]

If all of your roof rainfall goes to a soakaway, you can get a discount on your surface water charges.

 

[thomp1983]

I recon they have lifted out the gravel boards due to using it as an entrance by slipping out the fence panels and not tripping over the gravel boards every time they go in and out.

Andy

Indeed thats exactly why I've left them out

If all of your roof rainfall goes to a soakaway, you can get a discount on your surface water charges.

I know that's part of my reasoning mentioned earlier