Rain running into vents

[Mark-UK]

I am in urgent need for some advice.

The way my shed roof has been constructed I have vents above the insulation (warm roof I think it's called). The main issue was working within the council height restrictions where I live, so I had to place the vents in the plastic (fascia? soffit?) that runs around the top of the wall that joins the roof.

Trouble is, the water runoff is running right over the open vents and I'm worried that rainwater is getting in. It probably is getting in and it's going to ruin the roof and cost me a load of money.

I have an idea to extend the roof a few inches so the water runs off further away as I show in the pic below.

Trouble is it's a fibreglass roof so I was wondering if there's a way I can do this?

Ideally, I want to by an extended trim or something and fix it to the roof without messing around with fibreglass because I can't do it and the person who did isn't around any more.

I know I'll have to extend the guttering away from the wall as well to catch the runoff (I think I can manage this).

I'm not very experienced at this at all so I was really hoping someone might be able to help me out here with some advice on what I need to buy.

Thank you.

 

[JohnD]

what about the end walls (in your pic, the one facing us, and the end facing away)?

Do you have access to them?

 

[Mark-UK]

Hi John

No, it's all sealed up. My only access to the vent is head-on. I was considering one of these (perhaps hacksawed to size):

https://www.screwfix.com/p/map-vent-fixed-louvre-vent-with-flyscreen-white-229-x-152mm/4695d

 

[JohnD]

A cowl vent is much more weatherproof

https://www.screwfix.com/c/heating-plumbing/air-vents/cat840496?producttype=cowl_vent

 

[Mark-UK]

Yes, I was looking at them earlier, and they'd be ideal. Only thing is, they're too big. Even if I remove the fascia covering to reveal the vents themselves, I've only got about a 90-100mm area I can affix things to.

EDIT: I'm going to take another look and measure up because they would be perfect.

EDIT: I could push it to 120mm but then that means removing the drip tray which guides the rainfall into the guttering.