On Aug 2, 7:46*pm, wrote:
RicodJour wrote:
What keeps a cable supported porch roof from acting like a huge sail...

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...

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