French windows

The door between our living room and conservatory has pretty much come to the end of its life. Victorian, lightweight, single glazed and no security that would keep a flea out, so time to replace it with something different, before we do all the other jobs in that room. Said door is paired with a fixed panel (like a pair of doors where only one opens) and is glazed above. The opening in the brickwork is about 5' 6 ( as it's a Victorian house, my measurements have regressed to Imperial these days!)
I went to the local doors place and was quite taken with their base price for a pair of 5' doors, low panel at the bottom and open for glazing above - about 260. So I got the blokey to come and quote to do the whole job (install, glaze etc and the panel above): 1580!
Definitely plenty of scope to do this job myself then(!) Got the same doors online (190) and a new frame (80), which will be delivered at the weekend. Quotes for double glazed panels amount to around 100 all together. Can't see any real problems in the job (famous last words!).
So what are the questions?
1 Building regulations (i.e. a door into a s=conservatory is an external door blah blah) notwithstanding, is it a good idea to double glaze these doors? On the one hand all insulation is a good thing. On the other hand, the conservatory is south facing and gets pretty warm even on a cool day if it's sunny (Today it was 36 degrees when it was 14 outside). My guess is it's a swings and roundabouts thing but someone may have experience of this situation.
2 I have yet to decide whether to paint these doors or show the hardwood. The originals are painted but it always seems sacrilege to paint hardwood (if the grain etc looks good enough). If they are not painted, what's the recommended treatment? The pro said they would use a satin varnish with multiple coats before hanging - does anyone have any recommendations?
3 I realised I have never put double glazing in a timber door (or window) before. These are made to accept a d/g unit, but it occurred to me that there might be a good way to do it. Searching the web gives almost nothing except the pdf of the Wickes 'How To' sheet, which is pretty superficial. I was assuming spacers around the outside of the glass, then maybe some sealant on the faces where it meets the beading, but then d/g in uPVC frames uses gaskets. Then there's all manner o rubber strips, sticky security tape etc etc. So what's the best approach?
4 Locks etc: I'm thinking a sash lock, hinge bolts and rack bolts or flush bolts on the 'slave' door. The door pair are rebated, so I'll need a rebated lock. All the nicely finished rebated locks seem to be 3-lever, which is hardly 'secure' in modern terms, while the few 5- lever, BS-approved versions have industrial rebate kits that might look the business in a warehouse or something but look pretty dire in a nice french window. Has anyone solved this issue recently?
5 Seals: I've been thinking that it would be good to make sure the final product is properly draught proofed. In fitting a new door there is clearly an opportunity to route grooves to accept sealing strips but these would have to be pretty low profile and most that I have seen work to a gap of 3mm or so. I had been thinking of putting this in along the hinge edge of the door and along the rebate but it wouldn't feel fight to set the door up with an intentional gap to accommodate this. Has anyone encountered / solved this one?
Any sensible opinions gratefully received as ever! (I'm not sure there's a role for an angle grinder here)
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1st. rule is to check the rebate depth. If the glazing unit is 4+16+4mm and you use 3mm thick butyl glazing strip both sides that adds to 30mm and you still need space for beading.
The belt and braces way... 3mm butyl glazing strip all round the back of the rebate, mitre or butt the joins. Place plastic spacers (supplied by DG Co.) for unit to rest on. Fit unit and press firmly into position. 2nd. lot of butyl strip on unit face and covering the gaps between the unit and the glass. Bead of low modulus silicon sealant to bed the mitred and brass pinned beading. Trim off any surplus butyl. Finally, the skilled bit, run a bead of low modulus silicon, colour matched to frame finish, to seal between the glass and the edge of the beading.
regards
--
Tim Lamb

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Horizontal does sound easier - perhaps until it comes to fitting the door, which why the usual way is to fit the door then glaze it, saving the weight in the manoeuvres. Probably best to fit, then take off, glaze and re-fit.
I had a chat with the glass man: He recommended non-setting butyl putty as the sealant, since the space I have is 18mm, which isn't enough to take 2 x 3mm butyl tape on top of a 14mm (4 + 6 + 4) DG unit. He did mention (more than once) that it's messy stuff to work with and not to be taken lightly.
After a bit of a chat, he said that a lot of people use silicone and there's no reason not to, but didn't mention the neutral cure thing, which is a very good point. He also bunged me a handful of spacers, which will be useful. I've a feeling the glass will be ready before the door since I'm intending to treat it thoroughly then fit it before glazing. Still wondering what makes a good finish for hardwood though - maybe the Sikkens range, if I can get over to a supplier during the day soon.
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