[Greenbuilding] metal roof question

[Reuben Deumling]

All very excellent suggestions. Thank you, Rob.

The only reason for the modest upstand as you call it is that this wooden
siding has a rabbet at the bottom which doesn't really easily permit much
in the way of a tall upstand to be slipped up under there without upsetting
the siding plane and creating all sorts of additional problems. If one had
more than the duck-billed locking pliers, one could probably form a rabbet
into the siding which would properly adjust to the profile of the siding
boards.


On Tue, Aug 26, 2014 at 6:30 PM, RT <ArchiLogic at yahoo.ca> wrote:

> On Tue, 26 Aug 2014 20:03:09 -0400, Reuben Deumling <9watts at gmail.com>
> wrote:
>
>  wondering whether for a 20" roof (housewall to soffit)use a single strip
>> of metal running horizontally, with a 3/4" lip at the top to slip under the
>> course of wood siding,and a ~2" lip at the bottom, like that soffit metal
>> has?
>>
>
> I'd say that the above would be the logical approach so long as the
> horizontal length of the roof isn't too great but even if it is, it
> wouldn't be difficult to resolve.
>
> Much of it could be resolved by increasing the height of the upstand at
> the top edge  from the proposed 3/4" which is too short to begin with IMO.
>
> Increasing the height to say 6 inches would help to make the panel more
> rigid and less likely to buckle during the process of getting it from the
> ground up to the roof.
> One could of course, simply clamp the panel to some sticks of wood to
> prevent buckling but I'd venture that the upstand should be at least 4 to 6
> inches to provide protection against leaks (ie wind-driven rain).
>
> I'm not sure what the "2 inch lip at the bottom means but if I were
> detailing the bottom edge, I'd provide at least a one inch overhang at the
> fascia and incorporate a drip edge.  I'd design it so that a drip-edge
> flashing is installed first and then have the bottom edge of the roof panel
> fold-lock over the drip-edge flashing using it like a cleat to anchor the
> roof panel without the need for exposed fasteners.
>
> And if the auxiliary roof is designed as a hip roof, I'd also incorporate
> fold-lock seams where the panels meet at the hips (with hold-down cleats
> installed on the first panel) eliminating the need for a separate ridge cap.
>
> All of the above can be formed into the panels on site using no much more
> than a couple pairs of duck-billed locking pliers and some appropriate
> lengths of steel bar to use as straight edges to form the bends.
>
> === * ===
> Rob Tom
> Kanata, Ontario, Canada
> < A r c h i L o g i c  at  Y a h o o  dot  CA >
> (manually winnow the chaff from my edress if you hit REPLY)
>
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