Superfluous downpipes?

[puntloos]

Noticed this on our design. 

 

Is it not possible to merge these into a single downpipe? Is it down to total volume of water expected 'worst case scenario'?

 

[Bonner]

Assuming the gutters will be joined at the corner, it’s all down to flow rates. Maximum rainfall per hour in your area vs. gutter/downpipe capacity. Meteorological data from various sites, capacity from the manufacturer. Unless the architect intended 2 pipes for symmetry?

[puntloos]

Thanks @Bonner - one thing my picture doesn't show (sorry) is that one pipe hits a roof not the floor. This picture is much better:

 

 

I want to remove #1 

 

Merging it into #2 feels like dropping a lot of water onto the small side roof. 

 

Having #2 handle most of the side water, but creating a pipe at #3 or even letting it drop through #4 might work better?

[Russell griffiths]

You are creating a disaster for yourself #1 is the only one that is actually going to work the others will overshoot the small roof, 

look at how our rainfall pattern is changing, heavy sudden downpours as opposed to old rain which was drizzle all day. 

That valley will have a monumental amount coming down it, you need to look at that area carefully. 

[puntloos]

1 minute ago, Russell griffiths said:

You are creating a disaster for yourself #1 is the only one that is actually going to work the others will overshoot the small roof, 

look at how our rainfall pattern is changing, heavy sudden downpours as opposed to old rain which was drizzle all day. 

That valley will have a monumental amount coming down it, you need to look at that area carefully. 

Yeah I think I see what you're saying. 

 

OK I guess we'll leave it unchanged. Perhaps we can have somewhat flatter (square) downpipes that hug the wall somewhat to minimise having to squeeze past.

 

 

[Mr Punter]

I think you could lose downpipe 2.  You may want a larger gutter at 3.

[puntloos]

2 minutes ago, Mr Punter said:

I think you could lose downpipe 2.  You may want a larger gutter at 3.

Agree, #2 seems somewhat superfluous but I was hoping to get rid of #1 instead.

 

[saveasteading]

Once water is in the downpipe there is spare capacity, so you could link 2 into 1 with 45 deg bends and keep the water off the small roof. But it might look clumsy.

Don't rely on water turning the corner in linked gutters unless they are larger than normal..and total trust in the builder.

Detail needed at bottom of valley. It is good that the architect has thought about it at all  but more thought needed.

Downpipes can be the same colour as the walls as camouflage,  or a feature colour to show pride in dealing with reality.

Old fashioned hoppers sometimes resolve tricky drainage. 

 

[Mr Punter]

Quite a lot of the square and rectangular downpipes are available flush to wall.  I don't think getting rid of #1 is a runner.

[Bonner]

2 hours ago, puntloos said:

Thanks @Bonner - one thing my picture doesn't show (sorry) is that one pipe hits a roof not the floor. This picture is much better:

 

 

I want to remove #1 

 

Merging it into #2 feels like dropping a lot of water onto the small side roof. 

 

Having #2 handle most of the side water, but creating a pipe at #3 or even letting it drop through #4 might work better?

 

Have to agree with others, #1 must be your primary route. Hope you find a slim downpipe 

[Kelvin]

2 hours ago, puntloos said:

Yeah I think I see what you're saying. 

 

OK I guess we'll leave it unchanged. Perhaps we can have somewhat flatter (square) downpipes that hug the wall somewhat to minimise having to squeeze past.

 

 

The farmhouse we rent has exactly what you propose and heavy rain launches off the roof as described 

[puntloos]

2 hours ago, Kelvin said:

The farmhouse we rent has exactly what you propose and heavy rain launches off the roof as described 

One devil's advocate question: is that actually a problem? 

[Kelvin]

Yep. The gutters were full of moss so I thought it was but still doing it after I cleaned them. Only happens with very heavy rain. The guttering is quite narrow though which doesn’t help. 

[puntloos]

5 minutes ago, Kelvin said:

Yep. The gutters were full of moss so I thought it was but still doing it after I cleaned them. Only happens with very heavy rain. The guttering is quite narrow though which doesn’t help. 

 

Yeah but I mean, why would someone deeply care if water 'falls off the roof' rather than neatly goes into gutters/drains/soakaway. I mean ok if it's a HUGE amount of water you might have quite a soggy surrounding of the house, but a reasonable-but-not-insane amount? Problem?

Edited November 22, 2022 by puntloos

[Kelvin]

It’s above the front door in our case. But it depends what’s beneath it I guess

Edited November 22, 2022 by Kelvin

[Radian]

I will always be using deep-flow guttering from now on after seeing how much better it copes with rainstorms than the standard half-round profile I have on the original parts of the house.

[SuperJohnG]

I only have deep flow I'm actually going with 1 downpipe now on 1 elevation - was 3. I have watched and tested it when it rains. It rains very heavy here and ALOT west of Scoland. 

[saveasteading]

1 hour ago, puntloos said:

why would someone deeply care if water 'falls off the roof'

1. A to d.  It might run down the wall and erode it, cause salts to emerge, reduce insulation, cause mould. Ditto to windows.

2. Likely to splash up the wall leading to b- d

3. Might erode the ground

4. Constantly wet ground more likely to settle differentially.

5. Unpleasant on visitors' heads 

6. Noisy.

 

All that being said, it is not unheard of, compensated by oversailing eaves and a gravel drain to catch it.

[puntloos]

3 hours ago, saveasteading said:

1. A to d.  It might run down the wall and erode it, cause salts to emerge, reduce insulation, cause mould. Ditto to windows.

2. Likely to splash up the wall leading to b- d

3. Might erode the ground

4. Constantly wet ground more likely to settle differentially.

5. Unpleasant on visitors' heads 

6. Noisy.

 

All that being said, it is not unheard of, compensated by oversailing eaves and a gravel drain to catch it.

Thank you, awesome info.

[Russell griffiths]

Water hitting the floor is dependent on your house design. 

I lived in tropical Queensland Australia for a few years, you don’t have gutters as they are pointless and just overflow, so you let it fly off the roof to be caught by a French drain all around, but the house is designed like that so the house is up on small stilts so the walls are 600mm above the floor, no rain can bounce up and hit the house. SORTED. 

 

 Your house @puntloos will be fixed to the floor with walls coming down to ground level, I’m presuming your having some pretty render, well not for long you won’t, if you allow the gutter to flow straight over the front you will get, green mouldy render and water bouncing above your damp course. 

 

Design the problem out with deep wide gutters before you come back in a couple of years time moaning that your walls are damp, and your render is green.