# Forum Home Renovation Roofing  Joining Tiled and Corrugated Roofs

## laan

Hi, 
I'm building a verandah using corrugated Zincalume and Polycarb sheeting as roof. For various reasons, mainly to get enough height under the verandah, I've removed the house eaves and attached the verandah rafters on top of the house wall top plate. The house is single brick veneer with cement tiles for roofing.   
The original plan for how to make the tiles/sheet joint water proof was to simple stick the sheets up under the tiles (but below the battems), make sure they are bend upwards as much as possible. I've got about 60cm to spare for tucking the sheets in under the tiled roof. This is shown as the purple arc in the picture.  
Now, there's just one little detail that I forgot to consider! What to do where the house rafters are in the way of sticking the sheeting in all the 60cm under the tiles? Where the sheets are blocked by the house rafters they'd only go in about 14 cm from the edge of the last tile (the bluish line in the image). 
Another solution would be to try to bend the sheets to sit on top of the rafters, but that would require bending the sheets almost 20 degrees in a pretty short distance (house roof pitch is about 25, verandah about 5). Can you bend zincalume/suntuf polycarb that much? 
I hope I have explained the situation and my problem well enough. Any advice would be greatly appreciated as it seems to be a rainy week coming up in Canberra!

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## SilentButDeadly

Zincalume flashing that extends up under the tiles to the first batten with a 90 degree turn up...then runs out over the sheeting at least 100 mm. Turn up the valleys of the sheeting. 
Forget the polycarbonate unless you fancy living in a greenhouse...

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## r3nov8or

What SBD said. Especially turn up the valleys of the corrie. 
If you do use some polycarb, a good blob of silicone at the top of the valley does the same job as turning up the valley on steel sheets. 
use a white or reflective (more expensive) polycarb if you do use it. Not clear, not dark.

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## laan

Thanks. You mean something like this? (red is the flashing)   
Where can I buy this sort of flashing? Would the part of the flashing that sits on the corrugated sheets also need to be corrugated?  
As for the greenhouse, I'm planning on using the Suntuf Solarsmart Diffused Ice sheets, which according to the manual should only let through 20% of the heat and 50% of the light... I'll be interleaving 4 sheets of zincalume with 3 sheets of suntuf. You still reckon that will be too hot for Canberra weather?

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## SilentButDeadly

> Thanks. You mean something like this? (red is the flashing)   
> Where can I buy this sort of flashing? Would the part of the flashing that sits on the corrugated sheets also need to be corrugated?  
> As for the greenhouse, I'm planning on using the Suntuf Solarsmart Diffused Ice sheets, which according to the manual should only let through 20% of the heat and 50% of the light... I'll be interleaving 4 sheets of zincalume with 3 sheets of suntuf. You still reckon that will be too hot for Canberra weather?

  Yes. That flashing. Any roofing supplier like Steeline will be able to manufacture the flashing based on your measurements (including the angle of the bend). It won't need to be corrugated. 
We had those same sheets on a south facing verandah. They are now stacked in the shed waiting for another use. Verandah roof is now full tin, much cooler and there's been little reduction in light.

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## dmac

> Where can I buy this sort of flashing?

  Someone like WR Engineering can fold this up for you.

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## laan

> We had those same sheets on a south facing verandah. They are now stacked in the shed waiting for another use. Verandah roof is now full tin, much cooler and there's been little reduction in light.

  Ok, I've already bought the sheets, but the 7 of them will cover a bit more that the required roof width, so I'll take your advice and make the zincalume cover the polycarb as much as possible.

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## laan

Ok, after actually putting up the rafters and the roofing sheets, the situation looks more like this:  
(the scale is 10 times too big, those 2791mm should be 279mm). 
I.e, the tile sticks out about 27cm past the inner edge of the roofing sheets.  
Would the suggested red flashing in the attached picture do the job? I'm not too happy with it though since the tiles will rest on the zincalume (and potentially scratch it), and on the polycarb (and potentially bend it). 
Had I been smarter or more experienced, I would probably have put the last verandah rafter further out, or better yet, held off putting in the last row of screws until I actually had the flashing I need. If the red flashing needs to stick further out, past tile tiles and past the row of screws, I guess I'll need to unscrew the screws. The problem with that is that the battens are pretty thin hardwood (35x42mm) and I've predrilled holes for all roofing screws to avoid it splitting. I'm worried that if I simply put new holes and screws in the last batten in order stick the flashing under the screw heads, the batten might split... It seems pretty tricky to put the screws back in the same holes when the flashing is on top of the sheets, hiding the existing holes...  Hope what I'm trying to explain makes some kind of sense...  
I guess I COULD carefully measure out where the holes are and predrill holes in the flashing. Anyway, ignoring polycarb bending etc (caused by tiles resting on the sheets rather than on metal flashing), do you thing the red flashing in the attached picture is enough?

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## SilentButDeadly

No it's not enough. Needs to stick well out past the tiles. You can use anti noise tape between poly and flashing to minimise damage to poly. When fitting flashing remove poly screws and replace once flashing in place to hold down both poly and flashing...

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## r3nov8or

If you are worried about the batten splitting, you could add another one clear of the tiles/towards the end of the extended flashing. Might seem to be a bit of pain to thread it between the sheets and rafters, but possible.

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## laan

> No it's not enough. Needs to stick well out past the tiles. You can use anti noise tape between poly and flashing to minimise damage to poly. When fitting flashing remove poly screws and replace once flashing in place to hold down both poly and flashing...

  Ok, thanks, that settles it then... I'll have to remove the last row of screws. If I don't put them back in the current holes, I guess I better put silicone in the old holes through the sheets to avoid leakage? I'd prefer to be able to put them back in the same holes though, partly to avoid messing with silicone and partly to avoid risking batten splitting. Got any clever tricks of the trade for how to do that when the flashing is covering the old holes and I can't see where they are? My best idea so far is to stretch a strip of plastic dampcourse or similar over the string of holes, make a puncture at each hole location, put the flashing in place over the sheets, and finally the plastic dampcourse with marked hole locations back on top of the flashing... Any better ideas? Hmmm, I wont be doing this mistake again.    
I'm not too worried about the flashing damaging the poly, but the cement tiles resting on the poly would be more of an issue I think.

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## laan

> If you are worried about the batten splitting, you could add another one clear of the tiles/towards the end of the extended flashing. Might seem to be a bit of pain to thread it between the sheets and rafters, but possible.

  That'd work... I'd probably have to remove the old screws in the current top batten anyway though and cover the holes with silicone or something, because having the flashing rest on top of the screw heads seems dodgy (they stick up 5-8mm). Even if I manage to put the old screws back in the current batten through the flashing, adding some screws near the edge of the flashing (past the tiles) might be a good idea to make sure it doesn't start flapping in strong winds.

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## r3nov8or

When you order your flashing, make sure you get it creased as per the left of this picture. This will give the flat some strength, and when you screw it to your new batten it will have good pressure on your sheet ridges, i.e. no flapping.

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## laan

> When you order your flashing, make sure you get it creased as per the left of this picture. This will give the flat some strength, and when you screw it to your new batten it will have good pressure on your sheet ridges, i.e. no flapping.

  Cheers, will do.

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