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horsecrazy
Joined: 16 Jan 2005
Posts: 1
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 Posted: Sun Jan 16, 2005 5:36 pm Post subject: A idea with a flaw! will u help? |
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My dad has an idea that would need a hexagon shaped roof but if you place a pole in the middle for support then the purpose for the bottom floor is ruined  Do you know of any efficient, legal, and safe way of building this roof without a pole in the middle  |
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Architorture
millennium club
Joined: 31 Jul 2004
Posts: 1376
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| Posted: Sun Jan 16, 2005 5:46 pm Post subject: |
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| why do you need a pole in the middle? |
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Kevin
Site Admin
Joined: 13 Apr 2004
Posts: 1095
Location: Eugene, Oregon
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| Posted: Sun Jan 16, 2005 6:15 pm Post subject: |
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| You could roof a hexagon without a central pole several ways - with big rafters meeting in the center, held in at the outside with a compression ring, or with trusses, just for starters and building with wood. |
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SDR
millennium club
Joined: 02 Oct 2004
Posts: 1697
Location: San Francisco
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| Posted: Sun Jan 16, 2005 6:43 pm Post subject: |
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If three "scissors trusses" intersected at 60-degree angles, would you specify a star-shaped strap at the (top and) bottom of the intersection? Wait - I guess if just one of those trusses spans the hexagon, a continuous compression ring might be optional? How would you detail this roof (with or without structural members exposed)?
SDR |
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julie fox o'vil
Joined: 05 Apr 2005
Posts: 4
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| Posted: Tue Apr 05, 2005 7:24 pm Post subject: |
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Do you need the ceiling to be open? (ie, sans trusses?)
And I'm a moron as far as real engineering goes, so kids don't try this at home, but suppose you had a self-supporting pre-formed concrete roof (most likely sectional), if you curved it upward slightly (like a tent -- admittedly with a pole), would they brace one another? |
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LeCorbusier
Joined: 15 Apr 2004
Posts: 139
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| Posted: Wed Apr 06, 2005 11:20 am Post subject: |
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Moronic and excessive indeed. Concrete dome, oh please.
For residential work, Rafters with collar beams is the answer. |
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saturnalia
Joined: 23 Mar 2005
Posts: 4
Location: Ireland
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| Posted: Thu Apr 07, 2005 1:01 pm Post subject: |
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Ive built in the past a wood beam hexagonal roof with six beams meeting in the middle braced against a short centre piece.The weight of the beams against each other supported the roof.There is no need for a centre pole.
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Thank God!I thought you had a disease.You're a child. |
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SDR
millennium club
Joined: 02 Oct 2004
Posts: 1697
Location: San Francisco
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| Posted: Thu Apr 07, 2005 1:12 pm Post subject: |
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And what prevented the walls from spreading away from the center of the space, allowing the apex of the roof to descend, under the force of gravity?
SDR
_________________
"I'm the commander . . . see, I do not need to explain why I say things. That's the interesting thing about being the president. Maybe somebody needs to explain to me why they say something, but I don't feel like I owe anybody an explanation." GWB |
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lisatec
Joined: 02 Apr 2005
Posts: 3
Location: Viginia
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| Posted: Mon Apr 11, 2005 10:08 am Post subject: Hex roof |
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I'm assuming you are worried that taking away the central post will cause the roof to fall in the middle and push out the walls beneath it as the hyponteneuse of the hip rafters continues downward.
As with any double pitched roof, the solution to this is a bottom chord or ceiling joist that acts as a tie between the ends of the rafters where they sit on the top of the walls.
Since the load is horizontal and away from the center of the bottom chord, even a cable can be used to prevent the bottom end of the rafters
from moving away from each other and pushing out the top of the walls.
Couldn't you connect the hex rafter configuration in the same manner? Cables are less intrusive but if the ceiling finish is flat, you can use ceiling joists above the flat (wall board) finish. If you can't get lumber in the lengths required, use two pieces mechanically connected.
lisatec |
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