How to make this cut

[MitreKnown]

So what's the weatherproofing detail around door edges & where they meet?

I'm also curious about cavity closure and dpc ...

Both leaves of the garage wall have DPC layers (plastic DPC roll) below the level of the frame. There is a plastic cavity closer that I am going to have to use packers with my frame screws to compensate for. I think I could have omitted the cavity closers as the frame is going to bridge the cavity so could have sealed it, but the wall is full of bead insulation now so not going to touch that. I am going to use Rustins green wood preserver on the bottom cut ends of the frame and sit them on slate 'shims' cut from roofing slate. There is quite an eave overhang too so I hope that will help. I plan to white primer (Bedec Aqua Advanced) the whole frame before fitting too.

The doors themselves are going to be sealed round the edges using weather strip (this or this). That would go on the face of the stops.

The 2528mm dimension is inside the cavity closers (which are around 3mm thick)

 

[MitreKnown]

im meaning the linings rather than the frame that supports the brickwork.

I think my terminology is probably off and this is a lining. The brickwork is all self supporting. The inner leaf has steel beams (UC 203x133x25kg) and the outer leaf has a concrete lintel (R15 I think). I am going to have some fun screwing the top of the frame/lining at the top as I can't screw it into the concrete lintel. I plan to use Baypole screws to screw it to the steel beam (400mm or 600mm c/c) and perhaps hang some timbers down the cavity from above.

 

[MitreKnown]

are these doors 120mm thick? seems a bit chunky monkey. your basically making a door frame with a 120mm rebate.

Yes, 120mm thick. They include a 95mm thick layer of insulation inside so as to keep them nice and warm (overall U-value ~0.4 I think). I could make them thinner or warmer by using PIR insulation, but they are to include windows as well so probably not worth it and I have the lesser insulation already.

I don't think the doors will be opened very often, so best to keep warm (there is a pedestrian door).

 

[rogxwhit]

I am going to use Rustins green wood preserver

Stand the lower ends of your uprights in a bucket of the stuff for an hour or two.

 

[MitreKnown]

I'm going to be battling against the cold a bit, but may treat and paint in the house if I can keep them hidden from the wife