Shed roof flashing?

[lennyzx11]

What’s the simple way of flashing from a clapboard sided wall to over a corrugated metal roof covering?

This is an open leanto. Butting to a wall under a 1 foot overhang.

2x10 header on wall with siding removed.
2x6 rafters on 16” centers
2x4 purlins on flat with 2x6 at top and bottom.

I planned on using flashing to go behind the siding and then over the tin roofing but wondered about the corrugations. Whether to use a filler or a lot of silicone to prevent water blowing back under the flashing.

 

[KennyG]

Unless I misunderstand, you are going backward. The metal flashing is a standard pole barn trim piece. After the purlins are on and before the roofing is installed, install the flashing over the purlins and siding. Then install the roofing over the flashing. If it is a sealed building, use sealing strips over the flashing and under the roofing that is fabricated to fit the corrugations.

Take a look at page 15 of this detail sheet. https://www.bestmaterials.com/PDF_Files/metal-roof-fastening-details-postframe.pdf

 

[Diggin It]

What’s the simple way of flashing from a clapboard sided wall to over a corrugated metal roof covering?

I planned on using flashing to go behind the siding and then over the tin roofing but wondered about the corrugations. Whether to use a filler or a lot of silicone to prevent water blowing back under the flashing.

Need pictures.

 

[Diggin It]

Take a look at page 15 of this detail sheet.

I think he wants page 21. Or page 36 using Flashing ASW-1 for Residential.

 

[lennyzx11]

Here’s the pictures. I’ll go read through the links and pages now.
That’s why I wanted to ask before I place that top purlin or any corrugated tin roofing.
It is a tight 3:12 pitch BTW.

 

[Diggin It]

I would use the ASW1 or similar flashing and start at the red line I've added. I'd probably caulk the edge into that corner also.






.

 

[747driver]

I would take the existing eave trim board off first. Put your purlins flat side down. Then run your roofing all the way to the where it touches the existing siding and caulk that seam.. With the eave board off you will have room then to install flashing from the existing side wall to your new roof panel. Install the rudder/foam closure weatherstripping between the roof panels and flashing. Then put your existing eave trim board back on. This will keep your lean to connection tucked under the existing wall eave for better weather protection and a nice look.

 

[Diggin It]

^^ I would leave the existing trim board and put the metal flashing over it as noted. But I might be inclined to add another PVC 1x3 or 1x4 trim board over top of the metal flashing. They're fully weatherproof and don't even need to be painted.

 

[lennyzx11]

Great Suggestions and Thank you all! I’ll start hanging metal tomorrow.

 

[747driver]

I had thought about at first doing that. I just like the look of overhang eaves. Plus you wouldn't have to box in the ends to keep critters and weather out.

 

[lennyzx11]

Well, an early start today got most of the metal up but a surprise visit from the “inspector” who insisted on testing the “Ninja Warrior Obstacle Course” has delayed progress.


I did learn on the internet this trick for forming the flashing. This rates right there with putting a magnetic strip on the back of the tractor to hold pins!


I did get the flashing nailed up under the eaves as suggested.
What’s the right way to do the bottom edge that lays over the metal roofing? I think foam closure strips but also read of cutting on top of each rib and forming down with sealer. Sounds like a lot of work.

 

[Diggin It]

The foam closure strips are made for the prefabricated trim pieces illustrated in the PDF file above. Not sure how well they'd work with thin aluminum. I've used spray insulation foam cans in some cases. They make special low expansion formulas that fill voids but don't push too heavily.

 

[beenthere]

but also read of cutting on top of each rib and forming down with sealer.

Sounds like a lot of work as you said, but also compromising your roofing and then relying on the temporary sealer.

I think I'd leave the space open and let it help keep the space dried out..

You are fortunate to have a cute inspector checking your work....

 

[Snobdds]

This isn't a knock, but you eastenders build funny.

We never put purlins on a roof. We always deck roofs here, lay a waterproofing and then either metal or shingles.

Our snow and hail would destroy a non decked roof...

 

[Diggin It]

We moved to the real world so we didn't have to deal with the frozen white devil.

 

[Snobdds]

We moved to the real world so we didn't have to deal with the frozen white devil.

Would you please take the rest with you...

Another thing, I hear about a lot of condensation issues with non decked roofs. We never have issues with condensation on our buildings. Decking might be a poor thermal break, but it seem to be enough to prevent the indor rain phenomenon...

 

[atsah]

This isn't a knock, but you eastenders build funny.

Not all of us, I would not have added on to that building in that way myself but it's almost done.. I would have made the roof so that it was fairly seamless with the roof on the building.. I see an ice dam problem there, that's just me, different strokes..

 

[TimberHole]

If I understand your situation the flashing would go behind the wall sheathing and above the roof sheeting. Foam closure strips would be used between the flashing and the roof sheets. The foam closure comes in about 6’ lengths and is continuous over the highs in the deck. A screw thru the flashing and foam closure into the high of the deck will secure the foam for many years. You just need to make sure your screw goes thru the foam.