I'd put this thread to the back of my mind to catch up on (for my eyes, the images of white plastic construction need a larger screen). The buildings are an impressive scale and - unusually for 0 - depth.
I haven't contemplated buildings of this bulk (even in 4mm) and badly sagging roofs aren't all that common so the thought of replicating the effect isn't something that had occurred to me. I can see how it will work, and it looks reasonably* secure, technically.
Having seen the back of some quite large and durable 0 gauge buildings (Yeovil MRG's Gasworks), I did wonder about the reinforcements - what thickness are you using for the main walls? 60 thou'? I think that's what most of the Gasworks buildings use but the larger ones are about 2mm and they aren't braced nearly that heavily and are about 30 years old now (I think they used Chloroform - Bob Oaksford was a vet so could lay hands on the stuff which had some similar properties to Limonene, but was obviously, a bit... well, the clubrooms were well ventilated).
Adam
* I mean that it really should work, but plastic sheet does what it does, and I can never be sure anything I do will work 100% of the time.
Morning Adam,
You've identified one of my pet layout hates! Boards rammed with railway and only an inch or so at the edge given over to things on the other side of the railway fence. This, as you say, is prevalent in 7mm but understandably so as the real estate needed for a layout is larger. There are exceptions though like Love Lane which IMO strike an excellent balance.
The downside to this approach, if not done carefully, is that you end up with walls and buildings pressed right up against the backscene and this results in very 2d elements: sawn off gable ends, buildings with no roofs, buildings with incredibly steep roofs and improbable placement of trees to hide the lack of depth.
On Pencarrow my aim is to set the trains in a surrounding and the boards being almost 1m deep does help with this. But I've also given over some of the length at the station end to the grain store and an access track. I could have had longer sidings and more track instead. It's a balance thing and I've purposely turned the dial down a bit from trains and towards scenics.
It probably helps that my main interest always has been scenics and buildings and I couldn't imagine being happy with a layout that was all track. Others have no interest beyond the railway fence and want to maximise operation and layout siding capacity. Each to their own.
So yes, it was a very conscious decision to model buildings as more than just scenic flats. At the very least I like to have the roof ridge (where it runs parallel to the layout front) on board and, to give a sense of depth, some of the rear roof too.
Only modelling the front half of a building does give a problem with the gable end being sawn through though. On a previous group layout (Treneglos in 00) we had 500mm deep boards and this resulted in the goods shed (which I built) having a rear corner cut off. For all the 12 years we exhibited that layout, that one feature alone really narked me.
On the current buildings I'm making for Pencarrow I don't have enough depth on the board to model the entire building footprint. The roof ridge line is however well forward of the backscene and the large lean-to roof at the left end will hide the chopped through gable end. I do have an idea for the right end, but that will be far less visible anyway.
With regard to your other questions....
I have tried using 60thou for building carcasses but no longer do as it's a sod to cut (both the main elements and window openings) and, although it's thicker, you don't get a markedly stronger structure. Heavier yes but not massively more rigid. So I now use either 30 or 40thou and gain the rigidity and flatness, like on a steel H column, through adding perpendicular ribs.
I think an analogy would be to look at old churches. The small ones started off with very thick walls but, as size and height increased, they moved away from sheer wall mass and towards bracing through the use of butresses and additional naves etc.
I imagine using Chloroform to join plasticard could be entertaining and somewhat problematic in a club environment! I do use Limonene but only where I either need the extra time (laminations or positioning detail) or I need a less viscous solvent (adding thin plasticard roof tiles). It's fairly useless for the main joints as the initial grab is poor and very slow.
My solvent of choice is the bottles of Butanol from Hobby Holidays. I used to use Slaters Mekpak but they must have changed the formula a few years back. I didn't find the resultant formulation as good and hated the revised smell. Others swear by the Tamiya jars and the squeezy bottle with the long metal tube.
I agree that sagging roofs are generally an exception and, if overdone, can look very wrong. I have, however, been lucky(?) enough to have found a number of prototypes for Pencarrow that did have sagging and irregular roofs. The method I posted above (which is effectively making an upsidedown boat hull) makes this easily achievable. The current buildings have no sag as none is visible in current photos.