Eli5: why do people say its cheaper to build up than out?


I’ve heard contractors say this over and over again. It’s cheaper to build up when adding sqft to a home than to build an addition out? Is this true and if so why?

In: 1

Building up reuses existing structure; foundations, walls, … . Building out has nothing to reuse. There are also paperwork costs, as the land around your house might have stuff in it that needs to be relocated and that means more cost for drawings and digging and stuff. Not to mention that you might need a variance from some zoning rule (which sometimes is needed to build up, so that’s not always a deciding factor).

If you’re in a city center, land is scarce and insanely expensive, especially the particular land that happens to be next to the land you already own. So you have to make the most of the land available by building a very tall building on it.

If you’re out in the country, it might be more economical to build a sprawling bungalow

If you build one multi-family unit for four spaces on land that could fit two single family units, then that’s four units sharing the fixed costs that otherwise two would share. That’s cheaper.

Architect here. Almost entirely excavation and concrete costs. Most houses structure is strong enough to carry the weight going up – so it’s the exact same building, but out requires foundation, up doesn’t

Out means more foundation, more roof. Out means more issues with zoning/setbacks and such so more legal/regulatory expense. Out also means needing more land and land is expensive in many places.