Tiny gutter on gable end overflowing

[Newbie81]

Hey there,

I’m a newbie to doing up a period property and first job is to get the house dry and tight.

Got a roofer coming to look at this but wondered if anyone had any suggestions.

We’ve got a very small section of guttering on a gable end that is overflowing from volume of water it’s dealing with, it’s also being fed from a valley return.

See pic.

Any ideas on possible solutions. Interested if anyone else has had this issue and fixed it.

Been looking at gutter aprons etc but concerned the area is so small there may not be a decent fix.

Thought maybe a deeper gutter L shaped round the corner.

Thanks
K

 

[Flyfisher]

Have you had a good look at what's happening during heavy rainfall, apart from just noticing the overflow?

Could the gutter/downpipe be slightly blocked? Can the single downpipe cope with heavy rainfall? Does heavy rain run past the gutter?

There are online calculators that will estimate the flow rate of rainwater in litres/second. That's a good starting point to establish if the actual guttering and downpipe can cope with the expected flow rate. If they can, then you'll need to check that the roof-gutter arrangement is able to funnel all that water into the gutter without spilling over.

 

[Newbie81]

Hey thanks for the reply.

Not seen it in heavy rain yet, the online calculator is a great tip I’ll check it out.

We don’t move in for a few weeks and it’s always dry when I’m there so far. No shortage of rain though that’s for sure

 

[a twig]

Potentially two issues:

Most likely is blockage, could be at the top or at the bottom. We’ve had downpipes with nowhere to go at the base, they fill up and then the water forces its way out at joints or overflows at the top, creating splash patterns like what you’ve seen there.

Second is velocity, if water coming down that valley at a rate of knots it may be hitting the gutter and shooting over the edge. In that case (slightly counterintuitively) installing gutter brushes may help catch and slowdown the water. Alternatively installing a larger hopper to catch the water and provide a buffer to the flow rate may do the job

As @Flyfisher says, observation during a rainstorm will help provide answers

 

[Newbie81]

I’ll get up there in the next down pour and have a look at the base, I had that recently with my boiler overflow.

Hopper also a good shout! Just looks like such a small area to feed all that rain into.

 

[Flyfisher]

I agree it looks like a small area to feed all the rain run-off from that roof area but in terms of carrying the water away, the limiting factor is going to be the drainpipe, not the length of guttering that the water falls into. If the drainpipe cannot drain the water fast enough then even a larger/deeper gutter or even a hopper will eventually overflow when there is sustained heavy rainfall.

I also agree with @a_twig about the velocity of water rushing down that valley. It could well be that the gutter and downpipe arrangement is perfectly adequate as far as capacity is concerned but the velocity of the water hitting the gutter is such that it partly overshoots the gutter altogether.

I suspect the solution will turn out to be fairly simple but it's almost certainly going to need a close-up inspection of what's really happening during heavy rain.