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Recently I have been considering the economics and feasability of building a house versus buying a used one. In my design I settled on a hexagon as the logical shape for the frame, which I am considering for masonry construction. This would be a big house, each side being at least 30 feet wide (footprint 2340 sq ft). The advantages of a hexagon are obvious: simple roof shape, no valleys, space efficient, heat efficient (this would be in New England and subject to cold winters), good wind resistance.

What I can't understand is why there seems to be no-one building hexagonal houses? The only notable building I could find at all was the Supreme Court.

Possible explanations would be that the shape is expensive for small houses due to the 6 corners, but for a large house like mine the room shapes work out fine, in fact they are better than a box house. Maybe its just tradition? People don't like it because it looks like church? Builders have some objection to 60-degree angles?

What is the reason there are no hexagonal houses?

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Consider an Octagon house instead. There's at least a reasonable number of extant examples from which to cadge design details: en.wikipedia.org/wiki/List_of_octagon_houses –  Wayfaring Stranger Jan 28 at 15:50
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I'm not sure I follow how those 'obvious' advantages are different than via a square house. But yes, the reason people don't build them is that 90 degree corners are cheaper to build. –  DA01 Jan 28 at 17:47
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(That said, if you're looking to build inexpensively, and like the idea of round-ish dwellings, perhaps consider a yurt.) –  DA01 Jan 28 at 17:49
    
The first two masons you approach to request a quote for an octagon block foundation will laugh and who ever you hire will want to kill you. Try building a model of this house with Lincoln logs to understand the problem. –  Dopeybob435 Jan 28 at 18:15
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Hexagon, not octagon Dopey. –  Tyler Durden Jan 28 at 19:33

3 Answers 3

up vote 5 down vote accepted

Building parts, building tools, building techniques, and building skills are all based on square walls. With building parts, you have things like bricks with 4 sides, wood sheathing with straight edges, not to mention studs, drywall, and most other building materials with factory edges. With tools, framing squares, levels, speed squares, and corner tools for drywall mud and paint, are all based on 90 degree angles.

However, the big reason to me are building techniques and skills. With 90 degree cuts, a top/bottom plate for framing the wall doesn't matter if it's upside down. You don't have to worry about which side of the framing the measurements are based on because it should be the same measurement. When checking that walls are aligned, builders use 3-4-5 triangles and measure the diagonals of a rectangle to ensure that they are square.

Finally, many homes are built on lots that often have parallel sides and homes are often built to maximize the utilization of these lots.

When building things that aren't square, there's also an increased risk for waste due to mistakes. Construct the framing with the 60 degree angle reversed and you'll likely have to throw out some of the framing. And for the exterior siding/finish, you'll end up with lots of cuts for bricks or custom corner pieces for siding. With the added materials and labor, this significantly increases the expense of building a home.

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Plus fitting furniture can be a pain. There was a geodesic dome and steep A-frame craze around here. The first always has spherical domes of wasted space behind everything, the second has large prisms of wasted space behind everything. The one octagon house here has issues with corners (think A-frame laid on its side for the rooms). The most econimical is to build it square to reduce surface area and make sure the corners are fully insulated with no dead space in the join (the usual sin found for why you have cold corners). –  Fiasco Labs Jan 28 at 16:08
    
Good catch @FiascoLabs. There's also things like kitchen cabinets that are a serious pain when walls are just slightly out of square. Almost everything placed inside the home is designed for square walls. –  BMitch Jan 28 at 16:11
    
Exactly, you end up with only three usable walls in an octagon, the used space has to be well away from the entry and the corners. Built-in cabinetry done in an attempt to use the wasted space in the corners has odd angles and encloses a kite shaped space that stuff can get lost in. The area is very interesting to live in if you like the "lateral thinking" lifestyle. But rarely do the people who originally built it stay in it. –  Fiasco Labs Jan 28 at 16:15
    
The house down the street from me is a triple octagon structure. The original owner was an architect, so figure. It was a total nightmare to frame and roof. the cost per square foot was probably 50 to 60% more than conventional 90 degree corners. –  shirlock homes Jan 28 at 21:04
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No mistakes needed - hexagon, octagon, geodesic dome - you can expect to put a LOT of scrap from rectangular building materials in the dumpster. You get a lot of cute little triangles that you have no use for... So there's a lot of waste. –  Ecnerwal Jan 28 at 21:57

I live in an area with at least 3 or 4 N-gon (not necessarily octagon) houses. I've been inside one and, as a house geek, asked the owners plenty of questions.

Here's what I picked up:

  • They love the house
  • It is FAR larger than it looks from the outside. Like most houses in the neighborhood, this is in the 2000-2800 ft² range.
  • Cabinetry wasn't a problem. The kitchen runs a large part of the diameter of the house, so isn't along the outer walls except for one side. (Side note: The kitchen is quite nice and the design works really well).
  • Many were built, probably from the same contractor. We are in a low-population area, so if we have a contractor with such experience, you probably do, too.
  • Because of the pseudo-curve of the roof, the view is particularly amazing in this house because the windows facing the valley view both out and up without interruption.

Downsides:

  • Just last Saturday, I commented about how Re-roofing must be pretty interesting. Many of the shingles are bent over the diagonals joining each triangle. They hired a roofing company which did the work just fine, but it's better in the rear than the front where they started. So if you have a spherical roof built, be sure they start shingling in the back of the house.
  • Looks small for the internal volume.
  • Replacing the view windows I mentioned was done by the owner and required rope hanging form the top of the roof because there's no safe surface on which to to stand.

We live in an area which gets quite cold in the winter, but I have no information on their HVAC cost. I'd say it's MUCH more important to build your house using closed-cell spray-in foam insulation than it is to make the house any particular shape if the target is saving utility costs.

Here's a map of one of the houses: https://www.google.com/maps/preview/@42.8755102,-112.4149699,51m/data=!3m1!1e3

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I agree with others... the amount of custom work required is going to obliterate your budget. Custom-cut flooring, custom-cut drywall, custom wood framing, custom kitchen. Everything will be a hand-done one-off. I wouldn't be surprised if the final cost were double what you'd pay for a square house of comparable footage, and take a lot longer to build.

If you're concerned about heat efficiency (and you should be, in New England), spend a fraction of that money on extra insulation and a high-efficiency furnace instead.

Edit

I don't mean to sound pessimistic about a hexagonal house. Sounds like a very cool idea, and if you're passionate about building an unusual house I'm sure you will find a builder willing to work with you. If a contractor laughs you off, tell them they just lost a big job.

Just don't have any disillusions about making a "more efficient" house. A hexagonal house is definitely going to cost more money and it will not pay for itself in energy savings. But that doesn't mean you shouldn't do it. Stainless steel appliances and granite counters don't pay for themselves either; people install them because they like them.

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Agreed. All the green building I've been involved with focused on deeper exterior walls (2x6 minimum), lots of weather sealing, newer more-efficient windows and doors, and high efficiency appliances. When the home gets this tight, you have to introduce a heat recovery ventilation (HRV) for fresh air. –  BMitch Jan 28 at 19:08

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