Metal Building Lean-too flashing

[sinnett]

I bought a few acres in Maine because it had a 30 x 50 metal building in the box (well, unboxed and layed out) with the pad poured ready to erect. Since I'm not the original owner and didn't spec it, I want to add a lean-too on the 50' side wall. For you seasoned metal build guys I have a couple questions; My gut tells me to buy the transition flashing bent to my pitch and install it as I side the build (flashed at the upper girt 12' above grade. Side wall is 16". But that means having to cut 17 panels (full sheet 16' panels) at the upper girt height. My problem is how to do that efficiently and correct? Or if I should.
The other option is to complete the build as original and flash over the exterior of the vertical PBR panels. There isn't many choices for obtaining this die pressed profile as transition to lean-too flashing. I'm having a hard time really finding anything that seems workable. Any thoughts or guidance is well appreciated.

 

[PCustoms]

Flash then panel.

I've cut panels to length with a skillsaw and a diablo metal blade, you can do 3-4 in a pass. Makes a mess and edge will likely rust.

Nibbler may be a better tool, but I've never done about panels and I figure the edge is still exposed to rust so haven't bothered.

 

[dcs13]

Look at page 13 on the Mueller Steel catalog. That may be what you need. Ive used them when adding a "lean to" to existing structures. https://www.muellerinc.com/document...4-e422-1428-59e6-041372aa6c48?t=1595362970865

 

[readhead]

What type of building? Red iron, cold formed or tube steel? Attach leanto frame and then side or side and then attach frame? Eather way the sheets should be cut and flashing installed under upper sheet. I make lots of money fixing buildings when lazy people try to flash over the siding.

 

[jack stand]

A few good "practice" items.
Any panels that you have to cut, cut the edge that will see the least water ie; uphill, top or in/under an accessory like channel or flashing.
Your leanto will probably be receiving all the snow from the upper roof (eventually). This can come all at once and impose tremendous forces on your connection to the main building. Do not be casual with this connection and use lots of lumber and Simpson or GRK structural fasteners , this thinking of course applies to the lean to rafter sizing.
I've lost a similar lean to after 20 some years to a freak back to back snowstorm. The failure (after 20 years) was the attachment of the ledger to the posts.

I would build my supporting ledger on this wall, and side up to it terminating into j channel with the trimmed end in it.
When you get to the point of roofing the lean to you'll want to order the metal to extend 2-3" beyond the last framing (on the lower side) be it rafter tails or a fascia board and up to within an inch of the plane of the wall on the upper side. You'll probably need to add some extra wall girts and possibly an extra roof purlin for fastening the flashing and the lower end of the wall panels.
I'm a big fan of the foam closures, both under and over for all roofing. It's inexpensive and a ***** to add later after you've discovered just how much snow can blow in or how many bugs and wasps will make their way into your building.
I'll add a picture of the simple wall flashing at your transition that would be helpful to have onsite so you'll be able to add whatever backup (location) necessary for screwing the metal to.

 

[billconner]

I know little about this kind of building but why not just build a taller lean and just continue roof line of main building. The extra material for a taller lean seems like a whole lot less work and potential problems. Probably have to reinforce wall supporting half of lean since it was probably not designed for that load, but have to do that anyway.

 

[Joemctag]

I know little about this kind of building but why not just build a taller lean and just continue roof line of main building. The extra material for a taller lean seems like a whole lot less work and potential problems. Probably have to reinforce wall supporting half of lean since it was probably not designed for that load, but have to do that anyway.

Old thread, but lots of us are gonna do lean-to s.
First, a lot of us might want it to “look right” and maybe our ideas on that are because of all the local buildings we see. Some people don’t care about these things, but some of us really need to try to get it to “look right”. And when it does, we feel good every time we look at it. Really! Second, you probably want your lean-to roof to provide shelter from sun and driven rain more than being as high as possible.
Me, I actually want to be able to touch the lower edge of the roof. I want “shelter”.
Did I help explain?