[biotinker]

> Colonial New England barely exists outside of active preservation attempts.

As someone who grew up there, this isn't really true. It's more that buildings have been upgraded/replaced over time by choice, resulting in a sparse patchwork of old buildings rather than large old cities. Places like the Wayside Inn[0] predate the country by a century, and have been "preserved" only because they have more-or-less continuously operating as an in since 1686.

The New England climate isn't all that different than the original England. I think the cultural and legal climate around old buildings is more impactful here. I would be curious to know about the comparative longevity of 17th-century wooden buildings in Europe.

[0] https://en.wikipedia.org/wiki/The_Wayside_Inn_%28Sudbury%29

[gerdesj]

Some years back an aunt and uncle owned a cottage in Devon (near Exeter) with 1649 carved into the wall by the front door.

Cottages like that had a simple timber frame and cob walls, which is only a slight improvement on wattle and daub! Cob is mud and straw and a few binding agents and traditionally: horse piss to act as an accelerant to aid setting or something. Floors are joist and boards. The roof is thatched, often with a "cat slide" and foundations are laughable.

The thatch needs replacing something like every 25-50 years. Cob needs patching, especially if the roof leaks (not replaced on schedule) and it starts rotting. However all this stuff happens gradually and it can be repaired gradually too in most cases, as and when you like and within budget.

A concrete structure ... let's say Charles Cross multi-storey car park in Plymouth ... well hello concrete cancer! OK this is a bit different to the cottage but let's see how the "modern" world has progressed with a building material that was used by the old Romans and likely before.

A concrete beam on its own is "quite" good as a supporting material. Conc is superb in compression and quite good in tension. In a horizontal beam when you put a load on it, the top will be compressed and the bottom will be in tension. Think about a wide thin rectangle and imagine pushing down on it. Imagine it bending into a U shape - the top side will be compressed and the bottom will be stretched (tension). That's a fairly simplified model!

Now, cast your concrete beam around a long steel bar and put nuts and washers on both ends and tighten them so that the entire beam is in tension. There are other methods to do this but this is easier to envision.

Now you have locked in a lot of energy into the system. The upside of "pre-stressed" concrete is that a given beam ("member") cross section can carry a lot more weight than a non pre-stressed member. The down side is that deliberate demolition is really hard and non deliberate demolition is possible.

So, that concrete cancer thing. Conc cancer is caused when salty sea air and moisture (rather likely in Plymouth) permeates conc made from Portland cement. Its more complicated than that but the sea salts are key. The conc gradually degrades in a rather strange way - map cracking and a gel develops in the cracks (I think, I studied this stuff quite a while back). The usual conc matrix ends up with weak lines running through it.

Anyway - you have energy locked up in members and those members are failing. Boom!

There is a lot to be said for old school materials and practices.

[physicsguy]

These almshouses are near where my father lives, and are fairly unremarkable: https://historicengland.org.uk/listing/the-list/list-entry/1...

[WalterBright]

> cast your concrete beam around a long steel bar and put nuts and washers on both ends and tighten them so that the entire beam is in tension.

I think you meant "compression".