10 feet wide fixed roof window - non-conventional drainage

[frontiersman]

I'm investigating the possibility of installing a 10-feet wide fixed (cannot be opened) roof window. Drainage might be a problem and I'm wondering if it would be possible to replace the standard top gutter by e.g. Wakaflex so that the roof above drains *over* the roof window instead of via the sides.

I understand side gutters will still be needed but has anybody here ever seen a roof window without a top gutter? (Or can anybody tell me why this would be a horrendous idea?)

Thanks!

 

[freddiemercurystwin]

All conventional rooflights have the rainwater running along the top so that it runs down each side. Rain can't drain over the rooflight because there is kind of a natural gutter that prevents this, thus water is forced down each side. I don't really see the problem tbh.

 

[frontiersman]

With a very wide window the amount of water that has to be "diverted" becomes significant as there still is about 12 feet of roof above the window.

I can imagine the (significant!) water flow could easily spill over the side gutters at the top corners.

As this will be a very much non-standard roof light I could replace (fill up) the normal top gutter by a "triangular beam" with flashing tape on top.

And yes, perhaps I'm making this more complex than it is.

 

[freddiemercurystwin]

I see your point, I would be concerned with all the crap off the roof running down the rooflight (though this does vary dependent on the roof covering) and lead would be far superior.