Why not tell the CO to be truly authentic you will be applying the 1650 building regulation

Which is frequently the case in stonework in vernacular buildings, at best there would be a metal 'lug' mortared into the masonry at intervals to support the "glazing". And as John has already said, there are places where the original metal fixing bars were in place to which the leaded lights were fixed (similarly in wooden frames also).

Actually, John, could that not be done now to give backing support to the lead-camed 3g? (The 'lugs'.)

Good find. Could be the answer to your prayers, John, especially as the examples shown are in your part of the country.

Wonder how their cost would look spread over 80+ windows though, 'cos I bet they ain't cheap!

(Whilst the openers aren't exactly what I'd expect to see, a tad incongruous, they aren't that far off what you'll find in many old buildings with metal casements. I've fitted similar, but of slimmer section with an overall profile on the openers of just over an inch, but that was all single-glazed. If you want the d/g or 3g then you've got to sacrifice something in exchange for the benefits I guess.)

Its interesting to see your comments about the opening windows, and it made me look at them with new eyes. While I do think they stand out, on reflection if they had been powder coated in a silver or cream instead of jet black and if they were at the end of the series of mullions rather than in the middle, perhaps they wouldn't stand out quite so much!

That cottage isn't a million miles away from where I live either so perhaps worth a road trip to have a toot. :)

I looked into MVHR for my house with lots of chimneys and came to the conclusion that it was folly. Since the efficiency is more important than the chimneys I am removing them except for 1 room sealed stove and one room sealed range cooker. For a start there is no need for the MVHR if air tightness is not good (although some people say they prefer the air quality it gives) and for seconds it could compete with the fire and cause smoke to be drawn into the house (or worse, invisible fumes).

Whats the best recommendation for the triple glaze sandwich bearing in mind we need to stop as much heat going out but allowing as much heat in as possible. Due to the thermal mass of the house we need as much solar gain as possible. Although bear in mind we have 82 windows to replace so it must be cost effective.

Joiner

Thanks for that but I cannot get it to work on my Mac so have asked for a Mac version

Just spoken to my glass supplier and he's as amazed as I am. He confirmed the price as being reasonable. Your unit size (based on the dims you gave me) put it just over the 0.25 sq/m minimum charge, thankfully.

As to the toughening? He's no idea without talking to the manufacturer, but guessed it might have to do with the smaller unit's not having the "flexibility" to cope with the stresses of any movement that might occur, the middle pane being the one most likely to be affected. When I described your situation (fairly exposed location, old building) he dismissed the possibility of heat build-up, especially with the Optitherm, ended up plumping for the risk of stress breakage.

I can see where he's coming from on that, given that the units will be bedded directly onto the stonework. If you think about it, the 3g WILL actually make the unit more rigid than either a 2g or, especially, a single pane, because as you'll see from those drawings I sent you the glazing (including the mortar) covers the whole of that flat mullion face.

[IMG]http://i40.tinypic.com/2po60cg.jpg[/IMG]

The lead is Code 6. And the run of sealant around the edge of the lead came isn't shown.

Anyone else got any suggestions? The drawing gives you the actual situation.

The only other alternative I considered instead of the foam, John, was to use something like Exotex RAG/45 (rafter gasket) around the periphery... http://www.exitex.com/Capex/ItemInfo.aspx?PartRef=1.09.245.

Are the windows wide enough to get through even if they did open??

Joiner

Just like to say thanks publicly for such excellent drawings I hope I dont set a precedent otherwise you might be inundated.