Jan 5, 2022Liked by Brian Potter

I think it would also be interesting to consider the opposite extreme. I visited the North Carolina Outer Banks a few years ago, and noted how transitory the islands and sandbars are compared to the houses and strip malls built on top of them. We usually think of the location a building is built on as a layer that is even more permanent than any of the building layers, but for a place like these barrier islands that naturally move on a timescale of decades or even years, but are still desirable places for people to live in or visit, it would be interesting to think about what construction methods are best for a building with just the right lifespan to be moved or replaced as the island has shifted.

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Jan 6, 2022Liked by Brian Potter

Very thought provoking, thank you. A few thoughts:

- Gutters are a significant source of problems if not cleaned an maintained; instead why not use a design with overhangs and a properly graded and hard-landscaped building perimeter?

- A much cheaper alternative to masonry cladding would be something like fibre cement siding (e.g. HardiePlank); it's resistant to fire, insects, damp, and rot, and requires almost no maintenance. Granted, it's not nearly as attractive as masonry, so the preservation value would be lower, but it's much easier to install and replace as new technologies appear.

- Perhaps I missed it, but you didn't spend much time discussing the other elements of exterior walls. It would be worthwhile to consider techniques and materials for all of the layers:

- exterior cladding

- mounting system for cladding

- water / insect barrier

- structural components, usually with insulation

- vapour barrier

- service space

- interior cladding

To make modification easier as technologies and usage change, a "service space" for electrical, plumbing, and other services inside the structural layer (e.g standard softwood studs placed inside the vapour barrier) makes changes much easier and protects the service runs from moisture and temperature changes.

- While I agree that wood burning fireplaces are a good idea for longevity (notwithstanding the climate issues), I would worry about the chimney construction, cap durability, and roof transition design. Debris accumulates around chimneys and can lead to roof failure.

- On that note, a roof height and design that makes access easy would encourage regular maintenance.

Thanks again, very interesting!

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Jan 5, 2022Liked by Brian Potter
Jan 5, 2022Liked by Brian Potter

I would caution against choosing the area around London. It is a mild climate now, but climate change has the potential to disrupt the North Atlantic Current (https://en.wikipedia.org/wiki/North_Atlantic_Current) and plunge the British Isles into a northern Canada type climate.

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Jan 5, 2022Liked by Brian Potter

"Unreinforced concrete" in your foundation can mean a lot of things. Modern concrete has very different formulation from ancient concrete, and it matters; for example, modern concrete deteriorates if chloride ions get into it. So if you're going to use concrete, you have to make sure you get the chemistry right, and that probably means you're not going to be using anything you can just order from a random supplier. You need "advanced concrete" in the sense of having real control over the properties.

For that matter, not all reinforcement is corrodable metal. You could put a bunch of fiberglass or something in your foundation concrete, although admittedly future repairs might fail to maintain that.

Why a crawlspace and not a full usable basement? Even when you don't need to get below a frost line (and I do think you'd be a lot better of building somewhere where it doesnt' freeze at all), a basement is nice to have. You're already going to be excavating like crazy anyway.

It seems strange to try to fireproof steel framing with concrete or brick masonry (with bolts through it!) rather than the more traditional gypsum plaster. Plaster is easier to apply, definitely easier to repair, probably less technology-intensive, and actually cools the structure as it calcines in a fire. And you can easily buy gypsum with very well characterized fire resistance in both plaster and panel form today. You could of course then bury the plaster in interior masonry walls if you wanted a thicker layer around it. You could even use firebrick.

I think your brick exterior walls are gonna fall apart. It seems backwards to rule out any and all organic polymers, but then to be willing to rely on having somebody regularly maintaining the wall. Somewhere in your 1000 years, there's almost certainly to be a 100 year period of nearly total neglect. You don't seem to be treating cost as important, so maybe interlocking masonry that would hold together even if it didn't have mortar? Would stone or something be better than brick?

You could stick a superficial insulation layer on the outside of the wall where it belongs. It will fail, and need to be replaced, but you can probably design the wall to be more or less OK with or without the insulation in place. The insulation won't be pretty, but if future people demand pretty, then they can rip the insulation off and use the base wall. You'll meet energy efficiency standards now, and reduce wear and tear for a while, and it may be easier to survive if the power goes out.

If you build the house in an urban area and expect the area to stay urban, where are you going to be getting the wood for those fireplaces? Fireplaces only work as a "collapse of civilization" alternative if you have a large dedicated woodlot. And chimneys have their own problems. Oh, and new fireplaces are ILLEGAL to build in the urban area where I live, and I imagine in others too, and for very good reasons. Can you come up with passive design elements that will keep the building more or less habitable even with no heat at all?

I'm also unsure about urban locations in general; they tend to get redeveloped.

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Jan 5, 2022·edited Jan 5, 2022Liked by Brian Potter

I am very skeptical of the exterior wall/insulation choices. Modern living temperatures are substantially higher than those in medieval buildings, leading to increased energy loss and higher water saturation.

Wherever you have a warm, moist living interior and an exterior at freezing temperatures, water will tend to migrate into the exterior. If the walls are porous and the dew layer falls inside your brickwork, that's a very bad situation where freeze and thaw cycles over days and seasons will damage the masonry. Maybe not be substantial in a place like London, where freezing cycles are relatively rare, but a fundamental drawback in many places of the inhabited Northern hemisphere.

The energy consumption of the building cannot be ignored, and past trends, in a Europe or US densely covered in trees, cannot be extrapolated into the future. It's good that we have fireplaces as a fallback, but the building should also have extremely high thermal insulation, close to passive house standards, made of very hardy materials like AAC. If the future will be energy rich, it won't matter, but we don't see that yet.

Maybe try something like the free online tool Ubakus to figure out a better exterior wall choice from both the humidity and energy waste aspects.

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Jan 5, 2022·edited Jan 5, 2022Liked by Brian Potter

We should consider the value of the building as a piece of architecture. Design with a great architect and it is very likely that the intrinsic value of the building helps it to make the 1000 years. Imagine Le Corbusier built your house, your house would be preserved indefinitely even if the repairs were costly and materials would need replacement

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Very interesting thought experiment.

I was surprised you added a fire place.

Given the public sentiment against air pollution and climate change these will likely be banned in the next decades.

Building codes in many countries and regions already prohibit the construction of these.

On top of this, fire place are often a cause of housefires, so this would not help with the longevity.

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slate dislikes hail.

any structure you build large and durable enough is likely to be used as a fortress in times of war.

The only long-lasting constructions are those with continuous use- castles and hostels, sometimes resteraunts and spas. The only reason other buildings have survived is as cultural icons or practically uninhabitable structures.

For these reasons, i will be going with a different approach- short sections of enormous quansit hut arches angled for a sloped roof to allow ventilation and updrafts to reduce moisture, overlaid by concrete, to form several hundred feet wide and 5-8 thousand square feet floorplans, all built into hillsides underground but above flood plains and with clear drainage to the front.

The front of the structure will slightly protrude from the hillside and be sloped, consisting mainly of glass with a stone foundation facing at the bottom where an outwardly sloping base will incorporate drainage along with utility functions. Internally the structure will incorporate several large, thick, fiberglass reinforced (which is not susceptible to corrosion) spacing walls with cutouts for doorways and utility spaces, all of which will be brought together by composite lumber. That way it will not be subject to extended bombardment in an attempt to exterminate the inhabitants and the building if burned out can be rebuilt and repurposed.

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1000 - 2000$ per sq ft, that's just crazy! Our 91 m2 rowhouse would cost between 980 thousand to 1.96 million at those prices.

I'm trying to figure out how much 18th - 19th century European houses with decent amount of ornaments would cost today to build.

(Estonia's old town type of buildings) Back then buildings used to be beautiful, unfortunately not these days.

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I appreciate that you mentioned climate -- but not in the way I had hoped! Construction and demolition are environmentally impactful activities and I wonder whether lifecycle emissions from longer lived and more efficient buildings could be a nontrivial source of GHG reductions.

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Thanks for the thought experiment. I really like the choices of stainless steel structure and a Slate roof. That's going to go a long way to getting you to 1,000 years. I'd take the roof a good 2' past the walls in every direction, Gutters fail fast so just don't use them. I'd even consider stainless for the roof structure itself. You could lay slate on top of metal sheets and only put wood on the inside surface of the roof holding up the insulation. That combination may take your slate (and now all metal) roof well past 150 years. The roof really is the most attacked part of a home so spare no expense on making it as durable as possible. No need to hole out your beams as external and internal walls should provide lots of room for utility placement. Granite cladding on the beams is great. Stainless makes your walls non-structural which really allows you much more flexibility than typical wall construction. Of course you aren't really using that flexibility and defaulting to a simple but higher maintenance brick than what fits your thought experiment. I'd think a full granite block base up about 2' high and a foot wide. Big blocks (1'x2'x1') and no mortar with weeping spots. It would have to hang over the foundation a bit to keep water away. On top of that base you take up 2 walls with a giant air cavity. Here you can use less long lasting materials but to keep with the theme I'd still argue granite cladding with mortar on the outside. Inside how you like I guess, go with brick inside as it lasts much longer inside and can be covered with gypsum if preferred. You might consider aluminum windows as I suspect you'll get better functional use and longevity from them than even hardwood windows. Frame windows in granite. Like the fireplace heating but it would be a backup solution nowadays. Functionally heat pumps work great but you could thicken the walls even more and be near passive anyway. If you are building pilings down to bedrock (absolutely mandatory) you've got the equipment to put in a great vertical geothermal system which would be about the best way possible for heating. A big enough vertical system can be near passive heating I believe. Well thanks for the mental exercise!

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You know.... there are 200 year old Cob houses still standing and they cost perhaps 1/2000th of what this would cost. I think with maintenance one could get a Cob to last 1000 years.

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I would recommend looking into basalt rebar for concrete. Should alleviate any corrosion issues.

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Feb 13, 2022·edited Feb 13, 2022

> Surely this would be worth it, right?

I think a life cycle cost to create the same volume of living space for 1000 years, assuming today's technology with its construction and maintenance costs, would suggest whether it is worth it. Just looking at the initial capital cost, such as comparing $/sqft on day 0, is insufficient and misses the point of building a 1000 year life building; namely, to not have to rebuild every couple of decades.

Say the $/sqft is 10x greater for a 1000 year old building than a 30 year building: 1000$/sqft vs 100 $/sqft. Well, you have to demolish and rebuild the 30 year building 33x over 1000 years. Brian, maybe you could do a comparison on a leveled cost basis, something like $/sqft/year over the 1000 years. I imagine the results will be extremely sensitive to inflation rate, interest rate, and yearly maintenance cost assumptions. Without actually doing an NPV calc, the 1000 year building would be 3.3x cheaper at 1 $/sqft/year.

That said, $/sqft/year assumes all sqft are equal. NOT SO. Quality of life is so much improved by living in good solid structure that can last a few hundred years with higher quality matierals and fixtures that are worth it from the 1000 year perspective and the human experience perspective. The low cost building is usually a minimum viable living space, often just a few steps above a shed, that lacks the touches that make a building beautiful and nice to live in because those touches aren't worth it for a low cost building.

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Thank again Brian. I hope you continue this discussion by going deeper into the various tradeoffs associated with the potential wall and roof assembly systems. Although the Hutcheon-Building Science Corp. research on this is extensive, the longevity standard you've imposed forces us to look harder at certain material choices---particularly those that relate to modern insulation and waterproofing materials. I suppose that all of our plastics and polymers are doomed, but how long can we trust them?

I'm wrestling with redundant structural systems you've included in your design. If you pick a "safe" location, i.e. no seismic or flood risk, then the steel moment frame never pays for itself. A robust masonry wall combined with timber framing for the floors and roof decks creates a 1000+ year structural system---and more importantly, provides a working surface for sacrificial waterproofing and insulation materials. If fire resistant interior finishes are applied to the wood structure, then the risk profile is very good. Granted, we can't entirely trust some of our gypsum panel products to be installed or maintained with absolute perfection, but it's about probabilities.

For wall insulation I'm really going to put my head on the chopping block and advocate an EIFS system. For good measure, do it with rock wool instead of plastic insulation. It will offer a 40-50 year protective coating that fits into a maintenance regimen for future owners. It also allows for future technical improvements to the application.

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