I've worked on plenty of hastily built houses from the 70s that are still standing half a century later and in relatively good condition. They may run up slight

I've worked on plenty of hastily built houses from the 70s that are still standing half a century later and in relatively good condition. They may run up slightly higher maintenance bills, but I'd be surprised if they don't last to see 100 years. Houses today are undoubtedly better constructed. The quality of materials in the old days compensated well for the stress from poor environmental and thermal design, but you can probably get the same longevity by designing the house to not have that stress in the first place.