If I don't ask this I will inevitably get it wrong...

[Crofter]

Just about to order the guttering, and wanted to check: I know I need two bends to take it from the outlet to the downpipe, to account for the width of the soffet. But I see there are 92.5 and 112.5 bends, so do I need one of each, or two of one, and if so, which one??

[RichS]

2 x 45

[Crofter]

4 minutes ago, RichS said:

2 x 45

 

Not an option, unfortunately!

[RichS]

2 minutes ago, Crofter said:

 

Not an option, unfortunately!

Ha ha, Touche

[ProDave]

Then 2 the same, 112.5

 

Either will do, it just puts the "return" piece at a different angle.

 

In my case because the soffits are so close to the wall with little overhang, I had to choose the make of joint carefully so it could be shortened.

 

You wait until you try and get a sloping down pipe around a corner and find nobody makes the "correct" angle to do that without some "straining"

 

With  tin roof I would use the high capacity gutter as the run off will be quite fast.  I got all mine from BP plastics on line.

[Crofter]

12 minutes ago, ProDave said:

Then 2 the same, 112.5

 

Either will do, it just puts the "return" piece at a different angle.

 

In my case because the soffits are so close to the wall with little overhang, I had to choose the make of joint carefully so it could be shortened.

 

You wait until you try and get a sloping down pipe around a corner and find nobody makes the "correct" angle to do that without some "straining"

 

With  tin roof I would use the high capacity gutter as the run off will be quite fast.  I got all mine from BP plastics on line.

 

Is that these chaps? http://www.plasticdrainage.co.uk

How were they on delivery?

[ProDave]

2 minutes ago, Crofter said:

 

Is that these chaps? http://www.plasticdrainage.co.uk

How were they on delivery?

That's them.

 

I placed quite a big order a whole load of drainage, inspection chambers, gutter and downpipes.  Delivery was quick. I ordered underground drain pipe in 6M lengths as that was cheaper. they phoned me to say there was an issue with delivering 6M lengths and would I accept twice as many 3M lengths instead (which would normally cost more) so I said yes.

[Jeremy Harris]

I'm in the process of replacing all our house guttering with the deeper high flow stuff, as the standard half round stuff overflows in heavy rain.  Last week the gutters were overflowing along their entire length, on both sides of the house, and I'm pretty sure it's down to the 45 deg pitch and the smooth surface of the slates and solar panels.  Interestingly, when they overflow they do so very evenly and always on the gutter edge nearest the fascia.  The odd thing is that the protection strip thing projects out just beyond that edge of the gutter, so the overflow water is coming under that and then over the gutter edge.

 

Hopefully when I get the deep guttering up the problem will go away.

Edited September 17, 2017 by JSHarris

[Crofter]

I'd be a little worried that larger guttering could look big and bulky on my wee building.

Can I mitigate the risk of overflow by having a steeper fall and/or a downpipe at each end?

[Jeremy Harris]

I'm not sure.  The guttering at the front of our house has two downpipes (because it's divided by the projecting gable) and that at the back only has a single downpipe.  Both overflow in heavy rain.

 

However, the garage (roof is around 6.5m x 4.5m), whitch has a shallower 35 deg pitch gabled roof, with the same slates, is fine, the gutters never seem to overflow in heavy rain on that, so it may well be that the roof pitch plays as big a part in the rate at which rain flows off as the roof material.

Edited September 17, 2017 by JSHarris

[MikeSharp01]

8 minutes ago, JSHarris said:

However, the garage (roof is around 6.5m x 4.5m), whitch has a shallower 35 deg pitch gabled roof, with the same slates, is fine, the gutters never seem to overflow in heavy rain on that, so it may well be that the roof pitch plays as big a part in the rate at which rain flows off as the roof material.

Sounds a bit odd doesn't it. Thinking about it, and I could be way out here given surface tension might play a part at very low angles, in a steady state the rate at which the water arrIves at the gutter must be the same as the rate it is falling on the roof. The only difference is the velocity it is travelling at. Given this it may well hit the outer edge of the gutter and some of it run upwards and over the edge. If this is case deeper gutters might not help. The other overflow possibility is that the downpipes are unable to cope. If this is the case then the system will still overflow in a high flow steady state (long down pour) only it will buffer it for longer. Is my thinking way out cos like the vapour permiability this morning I am now worried about our gutters which are internal but the down pipe cross section is bigger than the gutter cross section.

[Jeremy Harris]

I have a feeling it's a dynamic thing, as the periods of over flow are only very short, barely more than a minute or so, and only in extremely heavy rain.  It was raining so hard when it did it last week that I was disinclined from standing outside to try and make some more  detailed observations.................

[MikeSharp01]

+1 on not observing in the pouring rain

[Crofter]

OK so returning to the original question, I need the two bends to be the same, and doesn't really matter what angle I go for. Inclined (see what I did there) to go for the 112.5 for a slightly steeper fall.

Next question- with the small quantity I need, if I go to Screwies/Toolstation I potentially have to mix and match to get the quantities I need (e.g. I need seven lengths of guttering, and TS sell it in six packs). Recipe for trouble, or is everything standard sizes?

[ProDave]

Don't screwy's sell individual lengths as well? I have a feeling they do in the shop but only sell the packs mail order? I guess it's a long drive to get to a shop?  What to the BM's on the island have?

 

The downpipe seems a standard size I definitely mixed makes, using the bends in TP as they could more easily be shortened than the ones I got from BP plastics

 

[CC45]

I fitted deep flow gutters and despite some big roof areas & 45deg roof (design had 2 downpipes per section but I only put one in) - no probs with overflowing under v v heavy rain.  Wont be using normal gutters in future.

[TerryE]

15 hours ago, JSHarris said:

Last week the gutters were overflowing along their entire length, on both sides of the house, and I'm pretty sure it's down to the 45 deg pitch and the smooth surface of the slates

 

We have similar problems, but this only occurs in extremely heavy rain and like you, the overflow is pretty uniform along the gutter length.  Our current thinking is to live with this as it isn't really anything other than a cosmetic issue. The walls get pretty soaked anyway with this level of rain.

[joe90]

On a slightly different note, I used polypipe "pretend" cast iron guttering, made from plastic with a rough surface that looks like cast iron, different brackets etc, looks the dogs doodads, people have commented " gosh you used cast iron guttering". Won't be using the shiny stuff ever again ?.

 

P.S. We have had no overflowing on a 35' roof with slates.