The glasswork on the original door is really nice (in my opinion), if you were going to make a new door would you try and salvage it somehow? It would be a shame to throw it out since you can't get glass like that anymore without spending
serious amounts of cash.
You could repair the door, but patching in and doing a decent job of it is very difficult, perhaps more difficult than actually making a new door. I've seen plenty of doors that have been "repaired" and after a year or so all the patching and filling begins to show after the patch timber moves with the humidity irrespective to the original timber and the joints pop and crack open, making the door look a shambles. There's perhaps one person I know that could actually do a good job of repairing a door and making it last, everyone else's work including mine would just be a ticking time bomb until it's back to where it was before it was repaired, which usually isn't long.
Now, Steve Maskery rightfully mentioned that you can't use PVA or anything waterbased with Accoya, which I kind of forgot when I mentioned that Accoya would be a good choice that there's quite a few little niggles #-o. For gluing Accoya you need to use a foaming polyurethane glue such as Soudal 45P, Lumberjack PU, Wurth PU, Reca slow set PU, etc... It's a really rapidly setting glue and not particularly suited to a beginner really as it might go off before you can actually get the door together, you might have a chance with a really slow setting version. Another consideration with Accoya is fitments and fixings, It eats iron for breakfast, literally and figuratively. The timber contains a high concentration of acetic acid (which is completely harmless to humans) which corrodes regular steel fixings in a matter of days which isn't an understatement, I put in some temporary passivated steel screws into some hinges on an Accoya door and replaced them in 3 days and the passivation on the screws had disappeared and the screw thread in the timber was orange with rust. 316 Marine grade stainless steel must be used otherwise you'll be replacing hardware often, and 316 is not cheap. Another thing to consider with Accoya which hasn't been mentioned I think is how soft and brittle it is, it's an excellent timber to work with machines but hand working it is a nightmare unless you have absolutely razor-sharp tools with lower than usual angles as the end grain tends to chip out rather than cut shavings, the same goes for the long grain as it's very difficult to hand plane from experience. Accoya seems to respond best to rotary cutting such as spindle moulders, planers and circular saws and leaves a lovely finish when cut this way. It dents very easily on the early grain and it also sands away far quicker on the early grain which can create a bit of a wavy finish to the paint surface. As has been already mentioned, the timber isn't the greatest quality at the moment and there seems to be a lot of tension in the boards from over-cooking. Just today, I was ripping some 8" x 2 1/2" down the middle to make door stiles and the two pieces bowed at least a half an inch each after the tension was released, after being straightened and planed 4-square they were mortices and rebated, the rebate took away material which resulted in the timber bowing once again, fortunately this matters not so much with a 3-rail door such as yours but for a 2-rail pattern 10 style door this isn't a great attribute. So it's best to buy the material in the sizes you need such as 4" x 2 1/2" stiles and top rail with 8" x 2 1/2" mid and bottom rails, rather than buying bigger planks and getting smaller sizes from it, the smaller pieces which have already been cut to a certain size won't bow as much because you won't be releasing as much tension as ripping a large plank down the middle. Other than those niggles, it's a great material as you never have to go back to a job because "My doors swollen up can you please plane it for me" or "All the T+G boards have shrunk and I can see my neighbour staring at me through the gaps" :lol:
If you do make a new door from Accoya, the construction admittedly doesn't
need to be as bulletproof as any other timber since it doesn't move massive amounts which would stress the joints in a normal door. I through mortice and tenon all my work since that's what is set up and it takes no time at all because everything is set up for the job, does it make for a better and more stable door in regular softwood and hardwoods? It certainly does. In Accoya, I'm not so sure if it's that critical comparatively, the construction needs to be strong as the timber itself is weak but I don't think you need to go as over the top like a traditional door with through wedged M+T joints, I think good amount of well-sized dominos and good PU glue would hold very well since the wood is basically like a sponge and absorbs glue like no other and the modern glues hold very well.
I would recommend George Ellis' "Modern Practical Joinery" as a bit of reference material, it may be over 100 years old but it's a gud'un!
