Radical idea for Supporting Porch Roof


Actually, 34 years ago this technique was used to support the Upper Deck at Yankee Stadium after the columns & decorative frieze were removed:
http://www.flickr.com/photos/wallyg/152457252/sizes/l / Cable suspension!
That's right.
It just hit me that a home with a front porch, like:
http://www.flickr.com/photos/13083606@N02/2690725215 /
or: http://www.flickr.com/photos/62765927@N00/110279946/ (notice side profile of porch next door - this would be most feasible!)
Finally: http://www.flickr.com/photos/rnmary/2680235685/ (in this application, ideal porch roof profile is present but carries across garage. Cabling would obviously not be necessary at garage end.)
Could have unrestricted views from inside or on the porch with a roof supported partially via cable tiebacks reamed through the vertical studs inside the exterior house wall. Any railing or waist-high wall would remain on the porch for the restraint of children or pets, but there would be nothing contacting both rail or roof. These cables would run just under the roof slope of the porch roof, and be tied in a similar fashion at the front end of the overhang. They would share the load with existing rafters gusseted into those vertical exterior wall members.
My criteria include: -NO residential space above the porch roof(temporary occupancy allowed as evacuation route in fire). -MUST be able to support the weight of a standard occupied porch swing and/or at least 12" of snow. -Vertical studs to which cables are tied CANNOT have any rot/cracking/ other degradation, or home would be disqualified from having a pillarless porch roof. -Porch depths up to EIGHT feet are feasible.
No doubt it would take most people some time getting used to seeing a typical bungalow or two-story farmhouse with the porch roof just "hanging" there, but I think it would really open up the view a lot.
If they could do this 35 years ago at Yankee Stadium, resulting in cantilevers over 50' deep, then I'm sure the technique could be scaled town to residential applications.
Viable, anyone?
-ChrisCoaster
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On Sat 02 Aug 2008 10:13:24a, ChrisCoaster told us...

Viable, but hideous, unless it's applied to extremely modern architecture. Stadium architecture, regardless of age, does not a home make.
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Wayne Boatwright
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Beauty is in the eye of the beholder, but wind uplift forces are in the code books.
What keeps a cable supported porch roof from acting like a huge sail in high winds? How does it stay in place during an earthquake?
It'd be cheaper and easier to cantilever the 2nd floor joists to cover the porch.
R
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On Sat 02 Aug 2008 12:23:59p, RicodJour told us...

That might be something worth watching! :-)

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Wayne Boatwright
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Leonard Bachman's new Integrated Buildings book describes a house in Almere, near Amsterdam...
This radical design was a winning entry in a competition for demountable housing. Most designs for High-Tech residential projects work to identify transferable tecnnology from commercial building systems. This house takes the reverse approach. It is actually a residential laboratory for working out a construction scheme the architects were developing for a commercial project...
Working with store-bought pieces, the architects erected the house themselves in only three days. One of them, Jan Benthem, lived in it with his family during the five-year design award period.
Foundation: Four prefab concrete industrial floorslabs act as pads to support a steel space frame of 2m bays 2m above the ground with adjustable jacks. The space frame uses thin tube members flattened at the ends and is bolted together on 5 mm octagonal welded steel connectors.
Vertical members: Roof is supported on 3 sides by frameless glass walls and supporting glass fins. The glass is made structural by bearing carefully on the large thick panels and then bracing them with fins to prevent lateral deflection.
Horizontal spans: Roof span rests on inverted truss of steel angles and tension cables. Roof grid is vertically tied back to floor by 2 interior cables to resist uplift.
Roof: Loose laid EPDM membrane on 50 mm extruded polystyrene insulation over profiled steel metal deck...
The roof is supported by 3 tensioned stainless steel cables spanning from the deck side wall to the enclosed bays and 2 more cables spanning the other direction. This makes a 2 meter grid of cables under the metal roof deck matching the joints of glass and supporting fins. It both holds the roof up and holds it down. Pairs of steel angle run under the exposed metal deck on the same grid. Adjustable struts lift the middle of the roof from the 6 intersection points of the cables, forcing down against the cables and up against the steel angles.
The cable, struts and angles form a shallow and whispery 2-way tension truss, preventing deflection in the roof and perhaps introducing positive camber to insure rainwater drainage. Additionally, the center two strut points are tied back to the floor in the middle of the room by vertical steel cables to counter wind uplift forces. These 2 tieback cables pull directly down from the adjustable struts and are secured to the floor at points where it is directly supported by the space frame undercarriage.
Brief:
The competition emphasized a concern about the impact of permanent architecture. It asked if society would not be better served by having a portion of its buildings designed as deployable temporary structures to be erected, disassembled, warehoused as components, then erected again. This was postulated as a more intelligent response to changing needs and land use patterns than heavy investment in monumental buildings which constantly become obsolete and burdensome. Accordingly, the guidelines stipulated that entries must be removable in five years and leave no scars on the site. To assure the ease of construction and commissioning, the rules required that the houses could readily be assembled by the user...
Nick
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On Aug 2, 7:46pm, snipped-for-privacy@ece.villanova.edu wrote:

The Amsterdam house used cables suspended between fixed walls; the OP is asking about his idea for an roof suspended from one wall only. The OP also indicates low slope porch roofs and using 2x studs to support the cable - in other words using a 2x4 or 2x6 as a point loaded beam to support roof loads.
Counteracting the wind uplift load could be as simple as tying the roof down with a few cables, but why would someone want to use mobile home technology on a real house?
The other issues are much more difficult to deal with.
R
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Excellent option for new work. Prohibitive cost-wise for an existing house/porch.
-CC
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ChrisCoaster wrote:

Remember what happened to Howard Roark.
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