The Walipini Project (aka greenhouse shenanigans)

Oh there's a tonne of ways! I was going to simply direct glaze but now more inclined to add a rebate and glaze into that.
There's no real requirement for the bird's mouth outside of having a nicer finish.

I have just realised that the rebate places the glass 5mm or so lower into the wood though, so my template might be off!

 

There's no rush tbh. It feels like there is but I have no need to be done by a certain date. Rebate will be done with a router run up the edge but will give the glazing a bit more thought.
Direct glazing goes on top of the rafter; glazing tape sticks it down and butyl tape goes on top of the glass which is then hidden by a batten.
The structure is around 100 years old so I'll not be using glazing bars, it just doesn't feel right.

 

I suppose one advantage of the birds mouth it provides a strong fixing point for guttering, assuming you have an overhang.

 

This birds mouth in this case is on the other, internal, side of the top plate so the external appearance is the same as just making a simple butt joint. The external type (crowsfoot) is over the top for what I need.
The only benefit I can see is that it would provide a bit of wood to settle against the top plate although I don't think it adds anything structurally.

So this is possible


But this is more likely

 

For the gutters I'm hoping there's enough of the top plate to screw into! If not then I'll figure something else out

 

I thought a birds mouth cut was more like this:


That second photo looks like a cowboy job:



It's relying on nails to stop the roof spreading! They should be using truss clips and a wider plate. Also not sure why the plate is on the wrong wall, gosh it's a bodge up.

 

Ok bad pic; it's of an ancient building restoration and unfinished so probably explains the lack of fixings. Same principle though.
After a bucket of research, there's a misunderstanding in the birds mouth cut. The one you've shown is (apparently) the crowsfoot cut although commonly called the birds mouth.
No idea why and makes little difference to me!
It's the tidiness of this approach (rafter seat) that is drawing me.

 

I'm thinking about ties, I don't think my aluminium greenhouse has them, there are braces at the eaves joins I suppose to stop the roof spreading. With a wooden structure you might need some, maybe like a raised truss to still give you headroom. They would be useful for tieing plant supports in the future.

 

I'm just recreating the original design with fewer rafters. No cross ties or trusses and it lasted donkeys years
The top plate is having masonry screws into the wall and the majority of forces will be downward into the wall. I'm planning on adding a middle support for the ridge but can stick in some ties I should think.
Given the rebate question I might swap the end to a seat and plumb cut. It will be tidier looking and give enough depth for a rebate. In honesty I'll probably fiddle with some options then pick one.
Any ideas on end stops for the base of the glass? I could add an angled cut (matching the roof angle) to a trim piece and run it across the rafter ends so the glass butts up to it. That would block off any gaps in the eave area too.

Back is knackered today so I'm going to dig out the router and check that and just ponder the rest

 

I've found the router buried in the garage and given it a clean up. Managed to get the bit out after a slight encouragement and did a test run. I need a sharper bit! I think I have a new one somewhere...

In principle the it should work. I'm going to look at ways to create a makeshift router table as it will take a while without one. If I can't then c'est la vie and I'll just have to take the time.