Box Gutters... good or bad idea?

[John Smith Esq.]

Hello,

I want to put a pitched roof over a flat roofed extension. The truss roof has been designed and there would need to be a box gutter at the bottom of two roof slopes - the proposed one and existing. Do these things work well and last or will my new pitched roof end up with an achilles heal worse than the existing flat roof?

I want to make the change to improve the look of the house and because I don't trust the flat roof work done a couple of years ago, or want to keep messing about getting it recovered. The builder I use will be able to put this new pitched roof on for same price as getting a competent roofer to redo the flat roof properly, but with massive aesthetic improvement.

The house is a bungalow so I would be able to access the box gutter easily for cleaning it out.

Thanks

 

[Ivor Windybottom]

It's a big potential problem, especially if it's not visible. Our local church roof is similar, and it's a major issue. The problem is that WHEN (not IF!) it clogs then when it rains heavily it will fill up with water. Then the water fill find its way under the bottom courses of tiles above it, and ends up leaking over a large area quite a distance from the trough. There should be a continuation of the trough under the tiles but it's often not enough, perhaps a couple of courses, and the water finds its way over it. Or through the nail holes where the roofer didn't understand the concept.

If at all possible, design so that the pitches meet at a valley, i.e. a trough that slopes down the pitch. Then it will get cleared by the rain itself.

All in all, I'd say your current intended design is indeed worse than a flat roof.

 

[noseall]

Hello,

I want to put a pitched roof over a flat roofed extension. The truss roof has been designed and there would need to be a box gutter at the bottom of two roof slopes - the proposed one and existing. Do these things work well and last or will my new pitched roof end up with an achilles heal worse than the existing flat roof?

I want to make the change to improve the look of the house and because I don't trust the flat roof work done a couple of years ago, or want to keep messing about getting it recovered. The builder I use will be able to put this new pitched roof on for same price as getting a competent roofer to redo the flat roof properly, but with massive aesthetic improvement.

The house is a bungalow so I would be able to access the box gutter easily for cleaning it out.

Thanks

Surely you mean a valley not a box gutter? Conservatory type box gutters (compost factories) are the work of the devil and should be avoided at all costs.

 

[Scally-Ho]

IMO all valley gutters are problematic unless properly monitored and fully maintained.

 

[noseall]

IMO all valley gutters are problematic unless properly monitored and fully maintained.

Not necessarily, as long as they are built well i.e. with correct lap up the roof, correct tile support/stop fillet, correct falls, correct widths (for roof rainwater volumes) and mindful of getting the water out of the valley as efficiently as possible.

Box gutters however are always sheite no matter how they are built.

 

[catlad]

Shouldn't be a problem if the roofer/builder has experience in the pitfalls of the design, and builds accordingly.

 

[John Smith Esq.]

Thanks all.

So this would be a valley gutter. Doesn't it boil down to the same thing with what is basically a tray at the bottom of the valley to collect and channel the water away?

I'm assuming the valley gutter would sit above the lower part of the rafters of the two roof slopes so tiles have to be stripped off to accommodate?

Is lead best for the lining?

This gutter would be around 3m in length with an existing roof valley leading into it, plus a new one, along with three different roof slopes in effect.

Would you choose to do this for the benefits of the pitched roof, or stick with a flat roof and tolerate the downsides of that?

Thanks again!

 

[John Smith Esq.]

Just to be clear, the gutter would be where the yellow line is. This is currently where the flat roof of the extension meets the slope of the adjoining pitched roof.

So what I'm getting from this thread so far is that rather than have a mostly flat type of box gutter at the bottom of the valley, above where the current flat roof is, create a sloped valley gutter instead, cutting the tiles on both slopes accordingly to create a shallow sloped version of the valleys elsewhere on the house? Presumably if the gutter gets wider towards its end, and with appropriate overlaps of lead along the 3m length, also running up and under the tiles/roof felt, water will always flow well and wash away any ****e? Plus, if open rather than closed, I can always use a step ladder and hose it down a couple of times a year...

 

[noseall]

So this would be a valley gutter. Doesn't it boil down to the same thing with what is basically a tray at the bottom of the valley to collect and channel the water away?

No. Box gutters are distinct.

I'm assuming the valley gutter would sit above the lower part of the rafters of the two roof slopes so tiles have to be stripped off to accommodate?

Yes. The bottom meter of roof will need to be removed. The valley is then constructed with short spans of timber sloping down towards the outlet. If you decide to furnish the valley with lead, then the construction needs to be stepped. The plywood tray needs to extend up the slope of both roofs and finish with an angle fillet tile support.

Is lead best for the lining?

If you can find someone to design and construct it. We usually furnish ours with torch-on mineral felt layers.

This gutter would be around 3m in length with an existing roof valley leading into it, plus a new one, along with three different roof slopes in effect.

Would you choose to do this for the benefits of the pitched roof, or stick with a flat roof and tolerate the downsides of that?

Either would not bother me. I'd lean towards pitched for aesthetics.

 

[Dereekoo]

I'd lean towards pitched

 

[Ivor Windybottom]

Just to be clear, the gutter would be where the yellow line is. This is currently where the flat roof of the extension meets the slope of the adjoining pitched roof.

So what I'm getting from this thread so far is that rather than have a mostly flat type of box gutter at the bottom of the valley, above where the current flat roof is, create a sloped valley gutter instead, cutting the tiles on both slopes accordingly to create a shallow sloped version of the valleys elsewhere on the house? Presumably if the gutter gets wider towards its end, and with appropriate overlaps of lead along the 3m length, also running up and under the tiles/roof felt, water will always flow well and wash away any ****e? Plus, if open rather than closed, I can always use a step ladder and hose it down a couple of times a year...

I'd prefer a flat roof to that.

Will you be up on your ladder every six months when you're 93?
These are valleys...

This is absolutely no problem, as a leaf or dead bird landing anywhere on that lot will get flushed away by the rain.

I don't know what the name is for what you're proposing. I'd suggest "potential disaster". Anything falling into it will sit there, indefinitely.

I've seen it done though, but it always looks weird, and is definitely risky.

 

[Ivor Windybottom]

The only way you could do it without would be to extend a ridge out from the top of the existing roof, then have a hipped extra bit where the flat-roofed building protrudes. This would be a bigger job though.

 

[Dereekoo]

Will you be up on your ladder every six months when you're 93?

Statistically he'll be dead and if he got to that age he probably would not care a monkies or understand whats happening about him

 

[HERTS P&D]

Statistically he'll be dead and if he got to that age he probably would not care a monkies or understand whats happening about him

So John has come on here for advive and within 4 days he's been killed off!



Andy

 

[blup]

So John has come on here for advive and within 4 days he's been killed off!



Andy

He’ll be gutt(er)ed