Do all houses need a foundation? Like for example if a house is built in an area with hard ground, no earthquakes, and minimal rain does that mean a foundation isn’t needed?
Do all houses need a foundation?
Do all houses need a foundation? Like for example if a house is built in an area with hard ground, no earthquakes, and minimal rain does that mean a foundation isn’t needed?
Most new houses in socal since the 70s don't have a foundation, they're on slab construction. You engineer a concrete slab strong enough if the ground or house moves it all moves together.
This isn't as viable outside of the southwest because of water and frost issues. I think Florida might get away with it because they engineer it to just be floating on the water/soil
Even with a slab, footings still needed to hold the walls no? I'm a leaf, see lots of slab on grade but still, footings.
see pole barn.
I mean it all depens on your definition of a house, for example a mobile home.
>don't have a foundation, they're on slab construction. You engineer a concrete slab strong enough if the ground or house moves it all moves together.
Most of these houses have a thickened edge under bearing walls (a strip foundation) with a concrete slab for the ground floor. That's still a foundation; it's just all one monolithic assembly.
Ultimately, the foundation is just the part of the building which bears upon the earth and transfers its loads to the soil. It's kind of a conceptual thing. If you were in an area with hard, stable soil or stone like you're talking about, then it would be doable to simply build walls on top of the ground. As long as it's stable and durable, this is viable. There are already buildings located on large stone deposits where they simply bolt the house to the stone underneath; the loads are taken care of.
In this situation, the bottom of the walls would be the foundation of the building.
If the house is small and light enough it doesn't. Mobile homes don't have foundations, and small cabins/sheds are often just slid right onto a bed of gravel. Post construction is very popular too, but you might consider cemented 6x6 a "foundation" of sorts.
Local code is usually pretty smart about best practices relative to, well, local conditions. If your local code says you need a foundation wall, you probably should not do without one. In many cases you can still apply for a construction permit. but an engineer will have to sign off on exceptions, and it's going to be on your dime, so it might not be worth it just based on that.
As for the feasability, foundation walls help transfer the loads to a slab, but keep in mind that they exist mostly because the slab gets dug into the ground. The walls also serve the purpose of preventing water ingress. Plus, a slab directly on the ground can get very cold at the corners, in a way that is hard to insulate. This can damage your slab because of frost. By setting the slab lower, you can insulate the walls.
So it really, very much depends on climate. Hell, in some places they can just set ceramic tiles right on packed clay soils and call it a floor.
Thank you guys. I was just asking because I was reading a book on Arab architecture and it said that some old mudbrick homes were just basically just made on the ground barely in the ground (like a trench the width of your hand horizontally) when built in an area like a described in the op. I asked an older Arab about this and he said because they lived in a wetter area that back then they used to dig down a trench that would match the walls of the building to slighty above waist deep, fill most of the trench with rocks then break them down till they’re compressed and hard and mostly flat then they topped it off with concrete I think. How would this compare to more modern techniques especially in more comparable environments?
A trench the width of your hand filled with brick is still a foundation right? You can actually (somewhat) calculate this and your wall won't sink to the center of the earth if there is no foundation below it.
I think the sand where I live can safely support about 0.5 kg per square cm. So if your mud bricks are 10cm wide and weigh 2kg per liter you can build 2.5 meter high.
There are a lot of other things a "foundation" does by the way. And filling a trench with rocks and topping it off with concrete is fine and probably still used so what is a modern technique?
I’m sorry I meant as deep as the width of a hand
>And filling a trench with rocks and topping it off with concrete is fine and probably still used so what is a modern technique?
I was under the impression that modern techniques used basically all concrete for the foundation with rebar in between. Sometimes as a big slab instead of as a strip under only the walls like described before. No rocks
For the load bearing of the structure above, the most important thing is the area of the underside of the foundation (and how much the ground below can support)
You only really need rebar in the concrete if the ground below is not the same. And you need rebar in the cross-section if the foundation is wide but not high.
A pile of rocks has a natural slope, so it distributes the weight above it over a larger area which the soil might not be able to do.
A slab distributes the weight over a large area, but is also your floor at the same time, so that can be cheaper than other options.
There is no foundation type that works everywhere, my house was built with bricks directly on the sand, but less than a mile away you need 10 meter long concrete posts.
Pic related was built with long wooden posts to the first supporting layer (below the ground water so they wont rot) with a brick foundation on top of that.
https://en.wikipedia.org/wiki/Rubble_trench_foundation
>Do all houses need a foundation?
All houses have some kind of foundation, even if it's just posts in the ground
>Like for example if a house is built in an area with hard ground, no earthquakes, and minimal rain does that mean a foundation isn’t needed?
You need a foundation, but you can get away with some small pilings or a slab on grade foundation if you don't have frost heave to worry about
the shittiest foundation you can use for a house and expect it to last a reasonable amount of time is skids
You couldn't do this with new construction, but lots of older wooden houses in the South are just placed on piers that just sit on 6"-8" thick cement pads placed on grade...nothing is buried or cast in place and sheer gravity is the only thing holding it all in place.
Picrel is one example that sits next to a bayou in Loisiana where heavy (60"/year) rains and floods are common...been there most of a century without any dedicated footings or stem walls or anything bolted down...the soil is loam-y and saturates easily but is well compacted so any settling is minimal and even...the real danger it faces is what extreme hurricane force winds could do to knock it off the piers.
In mountains you can just set the house on the mountain rock
In Tennessee they just dig down the few feet to the bedrock and start stacking blocks
If you anchor to bedrock, that is your natural foundation. So yes, you need a foundation on which to bear weight, in such a way that said weight does not significantly shift
If the house is made out of the ground in the first place, do i still got to do the foundation? Cause that'd be bullshit.
It would also have to be temperate enough that the ground would never be below freezing. Because ground freezing & thawing causes shifting as it expands and contracts. Most areas require a house foundation that goes down below the frost line so that the structure remains stable regardless of temperature changes.
>Do all houses need a foundation?
nah
No. The purpose of the foundation is that it is settled and stable and won't sink, mudslide, or otherwise deform.
You could literally just put your house small footings and just jack up a footing of the house and re-level.
when I was a kid we jacked up my grandfather's house which my dad bought and we rented after. cut an access hole as there was no crawl space, used a 12ton hydrolic jack on some some stacked boards and then used screw jackstands to support it all. Worked great until the 5th set of renters kid burnt it down, god bless his merry souls. I think it was built in 1910 and this would have been in the late 80s. I remember being surprised at how uneven the ground under the house was. After it burned down we found the cistern which was the o.g. water source and quite scary since a gas station had been built next to the house and an industrial area was behind it.