laurenco

Has anyone incorporated concealed gutters into pitched roofs?

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Our house design is similar to a house I saw once in Prestbury (see pic of the house I saw, and our design). Fully concealed gutters and aluminium cappings for the gables have been designed and the materials sourced. The only thing I'm struggling to find is a roofer who has experience doing this. My roofer (who is to lay the slates and fit the rooflights) said he'll have a go with bespoke alu lengths, but given any errors in the installation of concealed gutters will most likely put rainwater down the inside of our property, I'm keen to take an any advice from people who have gone down this route, before we mess up.

 

Has anyone else installed concealed gutters and/or aluminium cappings onto the gables in this way?

 

(please, no advice telling me not to go down this route - it's fundamental to the design, and ultimately, it's too late to change nowl!)

A15-A -Gable Roof Edge.jpg

Screenshot 2019-01-09 at 09.40.47.png

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Posted (edited)

@laurenco

I've done that detail on industrial units but not housing. The main issues are having a gutter lining that is seamless (IE similar construction to a flat roof in solvent welded plastic or rubber) and also it should be designed so that the front lip of the gutter is lower than the back by a decent margin so, if it gets blocked, the water overflow is outwards and it can't come back into the building by backing up under the roof finish.

Edited by Ian
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Posted (edited)

@laurenco Clarify for us - you are talking across the bottom of the roof, not drainage down the verge?

 

And do you want all the water from the roof to find its way into *this* gutter (which implies some sort of slot all the way along the bottom of the roof above your gutter-cover)?

 

If it is the former, I made a neighbour do something like this along a 20m roof when his gutter was going to overhang my garden - though it was not quite *fully* concealed. My dad designed a detail for them.

 

Essentially you sit the gutter on top of the wall, and flash underneath it and up the back and sufficiently down the face of the wall. And then you need a robust detail that will protect your wall and inside of the house, keep your gutter clear (anti-bird and insect grilles at the ends etc), and let the water get into it in a maximum water-flow event. It needs to be maintainable for when it *does* get blocked :-).

 

You also need the face and appearance of your wall to be robust to the runoff water that lands on the gutter-cover, and overflow if the slot has insufficient capacity or gets blocked.

 

I think my neighbour used lead flashing, but it could be one for glass fibre or EDPM.

 

Will try and get some piccies.

 

Ferdinand

Edited by Ferdinand
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I have done a hidden gutter with a zinc roof.  We built the substrate including falls and they did the waterproofing.

 

For your roof, maybe you could do the gutter and, say, 600mm up the slope in GRP, then tile over.  The ali copings are as much decorative as anything and a number of firms will supply these made to your spec.  I quite like the ones in your example being at the same angle as the pitch.  Any chance of you going to Prestbury to have a chat or stick a note through the door?

 

Not sure what you had in mind for downpipes?

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We have no experience but we are also doing this on our build. Although we have architects detail for it I keep revisiting the design mainly because of concern about condensation on the underside of the Ali section and although I can waterproof that I am not convinced this won't just move the condensation one layer in and venilating below the gutter is my thinking at the moment. 

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1 hour ago, Ferdinand said:

@laurenco Clarify for us - you are talking across the bottom of the roof, not drainage down the verge?

 

And do you want all the water from the roof to find its way into *this* gutter (which implies some sort of slot all the way along the bottom of the roof above your gutter-cover)?

 

If it is the former, I made a neighbour do something like this along a 20m roof when his gutter was going to overhang my garden - though it was not quite *fully* concealed. My dad designed a detail for them.

 

Essentially you sit the gutter on top of the wall, and flash underneath it and up the back and sufficiently down the face of the wall. And then you need a robust detail that will protect your wall and inside of the house, keep your gutter clear (anti-bird and insect grilles at the ends etc), and let the water get into it in a maximum water-flow event. It needs to be maintainable for when it *does* get blocked :-).

 

You also need the face and appearance of your wall to be robust to the runoff water that lands on the gutter-cover, and overflow if the slot has insufficient capacity or gets blocked.

 

I think my neighbour used lead flashing, but it could be one for glass fibre or EDPM.

 

Will try and get some piccies.

 

Ferdinand

some pictures would be great 👍

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1 hour ago, Mr Punter said:

Not sure what you had in mind for downpipes?

I'm thinking parapet downpipes (from out of the side of the house)

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28 minutes ago, MikeSharp01 said:

We have no experience but we are also doing this on our build. Although we have architects detail for it I keep revisiting the design mainly because of concern about condensation on the underside of the Ali section and although I can waterproof that I am not convinced this won't just move the condensation one layer in and venilating below the gutter is my thinking at the moment. 

 

I hadn't thought about condensation at all! What does your architect advise about this? Are you having a warm roof? And wouldn't flashing mitigate the condensation?

 

i'd love to see your architect's detailing if you're open to sharing it? Has he done working drawings yet?

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All of our soffits and fascias are covered in powder coated aluminium and I think it is fantastically sharp. Unfortunately I do not have a picture to hand of the finished work as they have just finished doing it, but I will take some at the weekend.

 

We have all the rainwater goods, the front door, garage doors and balustrades powder coated to be the same colour as our already ordered window frames. So one thing I would make sure is that if you go along this route you can get other metal items in a colour to match. We had considerable difficulty getting the garage door and front door made in non standard RAL colours.

 

Another thing to consider is how to conceal the fixings, our builders figured this out as they went along. One thing they did was to have a consistent join gap between pieces of aluminium and hide it by putting a piece of black rubber behind each join rather than trying to cover it. But certainly some thought is required as to where fixings will go.

 

I don't have any experience of concealed gutters in this fashion. The only thing I can think of is that you use a profile that is much higher on the inside than the outside so that if they overflow they overflow out the way as presumably the inside of the profile will have to be under the roof to catch the water. So a U shape with the inside higher than the outside.

 

You will need a way of attaching down pipes at right angles as the low point in the gutter will be on top of the wall. This might bee more difficult than actually designing the profile. You will also need the down pipes to be inside the house. They may be hard to hide and noisy. I think that you cannot combine them with the in house waste water until it has left the house.

 

As pointed out if they do overflow they will run down the walls, I would be less worried about this as it is a rare occurrence and even normal gutters will do this if blocked. Just keep them clean.

 

 

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52 minutes ago, laurenco said:

 

i'd love to see your architect's detailing if you're open to sharing it? Has he done working drawings yet?

Working drawings are down to me his remitt ends at BC drawings. I will post a section drawing when I get home from site - remind me if nothing here by tomorrow am. I don't think the architect was aware of the potential issue. I believe that Condensation can form between layers, assuming dew point is reached,  unless thermal contact is perfect so there is no air between them. As I understand it the external surface of the gutter is at air temperature while the surface below it is at envelope surface temperature and so dew point is possibly achievable I think.

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@laurenco  We were going to have concealed gutters but I bottled it in the end, I got these two drawings of separate solutions from, I recall not where, but they may be of some use.

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IMG_5533.JPG

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brilliant @RussdlThanks for this. I'm sorry you bottled it. Were you happy with what you went for in the end?

 

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@laurenco It's not built yet, but I would have liked to stick with the concealed gutters aesthetically (I think yours will look particularly sharp) however I was getting more and more concerned about the potential issues and the shear complexity of the detail that was emerging. Weak and feeble I know!

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6 minutes ago, laurenco said:

brilliant @RussdlThanks for this. I'm sorry you bottled it. Were you happy with what you went for in the end?

 

 

Looking at @Russdl‘s detail I would do one or two things differently.

 

I would not have OSB sitting underneath the gutter. At the least I would use waterproof ply, but ideally something even better that is entirely unaffected by water.

 

I would probably want a fall towards the outside wall in the sheet beneath the gutter for belt and braces.

 

I would ideally want to run the below tiles membrane straight down into the gutter for simplicity and continuous coverage. I am not sure how I would detail that.

 

Ferdinand

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Posted (edited)
4 hours ago, AliG said:

Those solutions are for outside walls with cladding panels, not sure if your walls are rendered panels or blockwork.

 

Anyway, Galenco as referenced by @Russdl has solutions for different construction methods.

 

https://galeco.pl/sites/all/pliki/do_pobrania_eng/katalog_bezokapowy_eng_24_08_2017.pdf

 

@AliG I love this, thank you. Will probably be very expensive, but lets see..

 

Edited by laurenco

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Just took some pictures of my gable end which is clad in aluminium although not with concealed gutters. We are waiting on a couple of small corner pieces.

 

IMG_6949.JPG

IMG_6946.JPG

IMG_6948.JPG

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what's the roof construction you are looking at? 

and what is your wall construction?

The detail changes for different roof types, you'll see a lot of the metal roof companies have standard details for concealed gutters, but it's hiding the downpipes that really makes the detail imo

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