French drain, roof water combined

[Barryscotland]

Anybody no if it’s ok with building control to have your gutters connected into 6” land drainage pipe that is at the bottom of the french drain surrounding our house? Also would I need an inspection chamber at every change of direction?

[Roundtuit]

Where does the land drainage pipe go to?  If you need a French drain around your house to get surface water away, I'm not sure it sounds like a good idea to dump all of your roof water into it too...

[saveasteading]

2 hours ago, Barryscotland said:

gutters connected into 6” land drainage pipe that is at the bottom of the french drain

I like French drains as they spread the water further,  and have more ground surface area to dissipate into, which tends to work better and is also good environmentally.

 

What is the existing drain for/doing ?

Where were the gutters going to connect before this idea?

If the french drain failed and water rose to the surface, where would it go next?

[Iceverge]

2 hours ago, Barryscotland said:

Anybody no if it’s ok with building control to have your gutters connected into 6” land drainage pipe that is at the bottom of the french drain surrounding our house? Also would I need an inspection chamber at every change of direction?

 

I wouldn't do this. Use a separate drain to take your gutter water to a soakaway. Otherwise you could be flooding your foundations rather than keeping them dry.  

[Barryscotland]

9 hours ago, Roundtuit said:

Where does the land drainage pipe go to?  If you need a French drain around your house to get surface water away, I'm not sure it sounds like a good idea to dump all of your roof water into it too...

Stream at the bottom of the garden.

8 hours ago, saveasteading said:

 

 

What is the existing drain for/doing ?

Where were the gutters going to connect before this idea?

If the french drain failed and water rose to the surface, where would it go next?

Its not existing, we are thinking of putting the gutter drainage as on the drawings but  using 6" slotted or land drainange instead of the 4" on the drawings and then back filling with gravel to create a frenchdrain to help get any water away from the house. French drain only around the house, the other 250m to the stream which is all downhill would just be normal 6" pipe. There would be a silt trap both sides of house. 

[joe90]

My builder did exactly this, I was a bit surprised but he used it often in our clay type soil. I also talked the BI out of needing a soakaway as it would just sit full of water and all the rain went to the ditch before the house was built anyway 🤷‍♂️.

[Barryscotland]

1 hour ago, joe90 said:

My builder did exactly this, I was a bit surprised but he used it often in our clay type soil. I also talked the BI out of needing a soakaway as it would just sit full of water and all the rain went to the ditch before the house was built anyway 🤷‍♂️.

So building inspectors will be ok about it.  what about inspection chambers/rodding eyes did you need one at every change of direction? The drawing we have for the surface water shows I think 5 inspection chambers which seems excessive.

[joe90]

1 hour ago, Barryscotland said:

So building inspectors will be ok about it. 

No two BI,s are the same or read the rules the same, you will need to negotiate with them, access at every change if direction is normsal, again discuss with your BI to see what he wants.

[ToughButterCup]

1 hour ago, joe90 said:

No two BI,s are the same or read the rules the same...

 

And sometimes one BI says one thing (about a potentially expensive decision) one day, and the same BCO unsays it another as in

 

"You need to coat that cladding with NonCom fire retardant" and a month later

"Naaaaah, it'll be reet wiout it mert " .

 

The NonCom fire retardant is sitting in the site container waiting for me to get round to coating the cladding: TBH, if the scaff had still been up, the job would have been done long ago .....

 

Cant take a joke? .... etc

Edited April 21, 2022 by ToughButterCup

[Radian]

I had the same dilemma as I'd already run a perf pipe about 30m to drain off the top of my back extension's foundations after water started building up under the block and beam floor. When it eventually came to dealing with rainwater off the roof it was tempting to drop it into the perf pipe because there were no nearby downpipes on the house - but it didn't feel right to be adding to a problem that I'd cured. More trenching it was then 🙄

[saveasteading]

You can't , or shouldn't, connect directly to a stream without permission. This is water that currently soaks into the ground, but would instead be flushed  immediately into the stream, then down to wherever floods might occur. It all adds up.

So you might need permission.

Even if you don't, this is usually down to planners non-understanding or caring. They allow a lot of drainage that could be much better.

Going to soakaways is better if you can, and if they work in your ground. Big IFs.

 

It is a planning issue, not building control, in the first instance.

[joe90]

3 hours ago, saveasteading said:

It is a planning issue, not building control, in the first instance.

We had no drainage conditions from our planners! Just the BI asking when building?

[ProDave]

The BC thing is so variable.  Here in the Highlands, BC wanted to inspect and test the foul drainage several times, but did not look once at any aspect of the rainwater drainage.

[joe90]

19 minutes ago, ProDave said:

The BC thing is so variable.

Yup, our BC knew my builder by reputation, did not test anything and just trusted him (me).

[saveasteading]

With floods being such a serious risk in some areas, it is incredible to me that planners allow new housing to tip rainwater into the river systems.

Even when controlled, they allow about 5 litres/second/hectare out. That is a lot of water.

In my opinion:

the planners don't understand it plus it is not their responsibility

developers accept the constraint as it allows development where other means wont work.

Environment Agency have very little clout

Government: don't understand and want to please the developers.

[Jenki]

8 hours ago, ProDave said:

The BC thing is so variable.  Here in the Highlands, BC wanted to inspect and test the foul drainage several times, but did not look once at any aspect of the rainwater drainage.

Was this pressure tested? Bungs and manometer?  or a more informal flow test? -  As I've just ordered 200M of 4" pipe, and the inspection chambers etc,  I was wondering what their stance will be.  Building in and around Bolton for the last 20 years, I've never 'had' to pressure test my drainage- poor really

[Barryscotland]

13 hours ago, saveasteading said:

You can't , or shouldn't, connect directly to a stream without permission. This is water that currently soaks into the ground, but would instead be flushed  immediately into the stream, then down to wherever floods might occur. It all adds up.

So you might need permission.

Even if you don't, this is usually down to planners non-understanding or caring. They allow a lot of drainage that could be much better.

Going to soakaways is better if you can, and if they work in your ground. Big IFs.

 

It is a planning issue, not building control, in the first instance.

 

 

We have permission to discharge into the stream, that where the water has always ended up as its clay all over our site so soakaways are not an option. They have asked for a filtration strip before the stream tho.

 

[SuperJohnG]

I have gutters tying into my land drain around the perimeter of the foundations, suggested by my groundworkers. Works well. 

 

Rodding points only required at changes of direction, I have inspection chambers where I am tying a number of lines together or they go under the slab so I can rod them. 

[saveasteading]

7 hours ago, Barryscotland said:

We have permission to discharge into the stream, that where the water has always ended up as its clay all over our site so soakaways are not an option. They have asked for a filtration strip before the stream tho.

OK so the question really is whether you can use the existing french drain or need additional drainage/filtering for the quantity.

 

How much land do you have? Fancy a pond which might resolve everything and be 'a good thing'

Edited April 22, 2022 by saveasteading

[Tosh]

We used solid 4'' slotted pipe around sides of the building with high water table, connected it to storm water downpipes and switched to 4'' solid from those all the way to the pond. Rodding eyes along each elevation to allow jet washing slotted pipe as a precaution. That worked for us as building/site layout allowed that solution. No issues from BC.

[saveasteading]

2 hours ago, Tosh said:

switched to 4'' solid from those all the way to the pond.

If searching for ways to reduce the flow to the pond, then perforated pipes all the way increases soakaway area. Or just a bit of perforated and the water will escape into the gravel, and only heavy rain reach he pond.

[Tosh]

Yes I could see in some cases that would be a good idea however for us we actually wanted to get as much as we could to the pond to keep it 'topped-up' for the ducks 🦆