h a l f b a k e r yExpensive, difficult, slightly dangerous, not particularly effective... I'm on a roll.
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Houses suffer from unsightly cracking and eventual structural damage due to uneven seasonal expansion and contraction of the soil, and slow settling where loads are greatest or the soil is wet or less compacted.
I propose a system of small electrically powered automatic jacks, one per load-bearing
underfloor column, or similarly distributed over continuous footings. Each would detect its height relative to, for instance, a reference stake driven deeply into the ground, and adjust itself up or down as appropriate, thus keeping the whole building level.
Detection of height could involve a permanently installed laser level, and light sensors associated with each jack.
Advantages: Door and window frames would stay true, preventing jamming and leaking. Cracks would be reduced, saving on repair costs. Thermal performance, etc. will be maintained. Ultimately, the house will be in better condition for longer.
Limitations: I don't see this working well for concrete slab constructions. It would be best for timber-framed houses.
Straighten Up!
Straighten_20Up!#1103588871
Prior art [spidermother, Dec 18 2008]
House on lifts
Houses_20on_20lifts#1132272967
More prior art. This is to raise the house above floods. [spidermother, Dec 18 2008]
[link]
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+ In theory, concrete superslabs are supposed to be on beams deep enough to not be so much effected by soil expansion / contraction due to moisture. |
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If you have ever read a Geotechnical report, they're a hoot, though. (I saw a section that talked about how a digging dog could cause foundation damage by reducing the amount of earth next to the foundation, thus increasing the possible soil expansion / contraction zone). |
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I thought maybe this would be levelling like Hurricane Katrina levelled houses. One could prophylactially level your house to keep the hurricane from having the satisfaction, and also do it when the weather was nice enough outside for a house levelling party. |
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Zimmy those stats probably reffered to the depth of soil needed to insure that the foundation stays below the frost line, at least in northern climates. The expansion in the soil would be water turning to ice and can wreak havoc on a foundaiton if a dog digs next to the house. The code here calls for the foundation to be a minimum of four feet below the surface. |
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What happens if there's a software glitch? |
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//software glitch// The motors would be of low power, and the jacks of limited scope, so they couldn't wreak great havoc. They could also be controlled by a very simple feedback circuit, such as a couple of relays linked to photocells, rather than software. |
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A useful feature might be a warning if a jack bottoms out or otherwise fails and needs to be adjusted or replaced. |
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I jacked up a part of my house by about 12mm recently, to correct subsidence where a fair part of the roof's weight was concentrated on one pylon (1950s pre-truss house) using a 4000kg hydraulic jack; I imagine a simple threaded rod spreader turned by a worm-drive motor could easily exert similar forces. |
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A back-of-envelope calculation came out at about $5,000-$10,000 per house. |
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The etymology of jack is interesting. Jack refers to an unspecified person, i.e. any Tom, Dick, or Harry, and thus to a device to hold something up when you don't have such a person to hand. |
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Be interesting to see how it coped with earthquakes ! Could lead to a whole new field... |
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//Could lead to a whole new field//
You mean the one at the end of the garden? |
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There exist active inertial damping systems to cope with earthquakes, as well as springs and shock absorbers to isolate buildings from vibrations large and small; those are outside the scope of this idea, which is intended to deal with much slower movements, but I don't see them as mutually exclusive. My idea may make earthquakes more destructive, since the relatively narrow jacks could topple over; on the other hand, it may allow a small amount of lateral give, increasing tolerance to (mild) earthquakes. |
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A refinement would be buttress-like angled supports around the perimeter to correct for lateral movement; again, the way these interact with earthquakes would be interesting. |
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It's a shame this couldn't be retrofitted to houses with stone foundations, but...well, it probably can't. Bun for forward thinking, though. |
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I'm fairly sure my house could level itself if I left the gas on and a candle burning |
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