# Forum Home Renovation Roofing  Capillary action on corrugated roof

## sailezzy

Im after some advice to fix a roofing issue caused by capillary action.  We have an existing brick garage with a skillion roof clad with corrugated iron.  The pitch is less than 5°, more like 3°, which I suspect is causing most of the trouble.   When it rains the water runs back under the roofing sheets into the eves. Ideally the fix would be to replace the roof but Im looking for a little less expensive fix.   I was thinking of snipping the end of the roofing sheets in every valley of the corrugated back 25mm and bend these down vertical to prevent water running back. Does anyone have any advice that may help?

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## chipps

Perhaps consider the long term moisture damage to your eaves, are they OK, or need attention also?

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## GeoffW1

> Im after some advice to fix a roofing issue caused by capillary action. We have an existing brick garage with a skillion roof clad with corrugated iron. The pitch is less than 5°, more like 3°, which I suspect is causing most of the trouble. When it rains the water runs back under the roofing sheets into the eves. Ideally the fix would be to replace the roof but Im looking for a little less expensive fix.  I was thinking of snipping the end of the roofing sheets in every valley of the corrugated back 25mm and bend these down vertical to prevent water running back. Does anyone have any advice that may help?

  Hi, 
This is at the very end of the roof sheeting, not where the sheets overlap, right? 
According to Blue Orb info it is standard practice to turn down the valleys at the very end of the sheets by using a pair of multigrips or a shifting spanner, gripping about 20mm in from the end, then turning down as far as possible. Snipping the sheets is not needed or recommended. 
I think that might fix the drips. See  http://www.steelselect.com/download_...file.php?id=47 
Cheers

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## rrobor

How about painting the roof. Dad bought second hand corrugated sheets which were from a large WW2 warehouse in UK. The sheet wasnt galvo and the metal was paper thin. What they had though was layers of paper glued on with bitumen. The shed he built from it lasted into the 90. So some bitumen paint and the daily mail, when thats dry, paint to colour of choice.

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## Tools

> Hi, 
> This is at the very end of the roof sheeting, not where the sheets overlap, right? 
> According to Blue Orb info it is standard practice to turn down the valleys at the very end of the sheets by using a pair of multigrips or a shifting spanner, gripping about 20mm in from the end, then turning down as far as possible. Snipping the sheets is not needed or recommended. 
> I think that might fix the drips. See  http://www.steelselect.com/download_...file.php?id=47 
> Cheers

  I think you will  find that is for the top end, not the bottom. 
Tools

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## bklooger

mate two things you can try
1/ install a flashing dropping over the back of the spouting and running under the roof sheet it will make the water run off into the spouting 
2/ drill a hole in the bottom of the corrugation over the spouting and hit it out with a prick punch. it will make the water drip off straight down  
both of these suggestions may fix your problem however without looking at the job its hard to tell what else might be needed 
cheers 
brad

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## GeoffW1

> I think you will find that is for the top end, not the bottom. 
> Tools

  No. Turn UP at the top end, turn down at the bottom. 
Cheers

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## Pulse

If custom orb is at 3 degrees it will probably always have these problems, turning down might help a bit, as will flashing into the gutter. I've also seen people run a small bead of silicone under the end of the sheet, 0.5cm from the end as a drip edge. 
Cheers
Pulse

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## finger

My roof pitch is roughly the same. 5 degrees tops. When it rained it use to run down the fascia. Plumber turned down all the valleys and no more water running down the fascia, although he did turn them down too far and it tore the sheets. A couple of spots are starting to show signs of surface rust. I figure by the time it gets bad I'll be getting the roof re-sheeted anyway.

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## sailezzy

Thanks so much for the replies. I've turned down the ends of the valleys to create a drip edge and tested with the hose and all seems to be working ok so far. Unfortunately it did rip the sheet but I'm not too worried, I'll coat it with some cold gal which should protect it. BTW, Chipps, the eave linings are only new as is the facia and this is how I noticed the problem.  Previously there was no facia or eave linings and the brick walls of the garage were always wet when it rained but I thought this was from the rain hitting the walls or run off from the roof.  It’s a coast house that were only at on the weekends and haven’t had it that long either so didn’t have much opportunity to investigate what was going on.
<O :Tongue: </O :Tongue: Thanks again, Michael.

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## Tools

> No. Turn UP at the top end, turn down at the bottom. 
> Cheers

  This is done for deck,not corrugated.
Tools

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## Pulse

> This is done for deck,not corrugated.
> Tools

  lysaght in their 2008/9 manual on page 44 suggest for under 25 degree slopes then turn up the ends 
Cheers
Pulse

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## GeoffW1

> This is done for deck,not corrugated.
> Tools

  Better tell Lysaghts then ;-] 
From the Blue Orb Corrugated installation sheet: 
"Ends of sheets 
It is usual to allow roof sheets to overhang into gutters by about 50mm. The valleys of sheets should be turned-down at lower ends, and turned-up at upper ends" 
I would certainly agree that on steep pitches you could get away without that, or use infill strips under the ends to protect the eaves, but turning down is not confined to decking profiles for any reason. 
Cheers

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## Tools

Ok, I pull my head in. In 25 years I have never seen the bottom of the sheets turned down on corry. Always the top, but never the bottom. 
Tools

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## Tools

> lysaght in their 2008/9 manual on page 44 suggest for under 25 degree slopes then turn up the ends 
> Cheers
> Pulse

  The top end should be turned up no matter what the pitch. I was not contesting that. 
Tools

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## Pulse

sorry tools, misunderstood. 
As i recall they want you to turn down the bottom end if close to the 5 degree minimum, I've found it tends to tear the sheet though.. 
Pulse

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## jaytee

This is slightly removed from gal sheets, but my laserlight sheets drip or cause the spouting to drip, as I cant turn them down - any ideas on how to stop them dripping back? It is on a 3deg slope, am thinking of putting new rafters under to raise the fall
jt :Doh:

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