The simple gabled roof is the most common form of roof employed in residential housing. Utilihab supports this form with a few approaches based on the unit room spans and the desire to employ vaulted ceilings or a flat horizontal ceiling.
For modest sized structures, the simplest gabled roof method employs 50mm series 1x2 or 1x3 rafters spaced at 1m that attach to two sides of the upper Primary horizontal frame members. The standard Primary framing usually attaches the top horizontal frame members to the sides of the posts. But for this type of roof system the post is shortened by the Primary frame thickness to allow two sidebeams of the upper frame to ride over the top of the vertical post where they are attached by tension plugs in the top of the posts, thus allowing them to serve as integral wall beams on which the rafter rest. The alternate upper frame beams then attach to the sides of these extended beams, serving as tie beams. The rafters then meet at the roof ridge where they attach to a ridge tie beam optionally supported at the roof ends by either a king post or queen posts along the end rafters.
The nature of Utilihab’s T-slot framing affords some interesting feature integration options with this simple roof structure. For instance, the ridge beam need not be a single beam but can, rather, be a combination structure such as a frame to support a continuous ridge skylight with integral ridge vent -a very clever way to illuminate a vaulted ceiling. The under-slot of the roof ridge can also be used to attach fans and lighting fixtures.
The roof frame will support conventional roofing with the mounting of an underlayment of joined plywood panel attached by T-nuts to the upper surface slot of the rafters. However, Utilihab favors the use of more modular roofing made of alloy or fiber-cement which can be similarly mechanically attached to the top surface slots. Foam tape or polymer wear strips can be added to the rafter tops. Alloy SIP paneling with integral insulation can be attached from beneath using angles mounted to the inner sides of the rafters or angle clips which lock into the flanges of the inner side profiles and are locked in place as the roof panels are tightened.
Ends of gabled roofs must employ a special series of cladding panels designed to accommodate their particular roof pitch. This will follow the usual exterior wall panel construction but must be matched specifically to the roof design -one of the limitations in the modularity of gabled roofs. These ends will typically employ vents and may have specialized window fittings, particularly where a vaulted interior ceiling is used.
Interior finishing of the vaulted ceiling is performed using the same insulation and interior panels as employed with interior walls with a panel grid created using Secondary framing spacers along the underside of the rafters, though extra-long panel sizes may be used for more a more continuous parallel appearance. Generally, wall panels with a more secure bolted clamped attachment must be used. A novel ceiling system for vaulted roofs can employ the same approach used for tension roof coverings based on membrane and fabric materials. Fabric or woven reed panels or a continuous ceiling ‘sheet’ can be fashioned with polymer wear strips adhesive bonded to their back side. These can then plug right into the underside rafter slots.
Vaulted roof designs will commonly employ a special ceiling feature called a ‘pelmet’. This consists of a shelf or box channel structure in some finished materials that attaches continuous along the upper inside perimeter of rooms to provide concealment of the point where the roof meets the upper frame members and where there may often be vents. These will often feature their own lighting elements or be used to conceal hardware for curtains. These are described in more detail in the Pelmets sub-section of the Ceiling specification.
For larger gabled roof spans and roofs with large cantilevered eaves, complete roof trusses are employed. These employ the usual braced king post, queen post, Howe truss, ‘w’ or ‘fan’ forms and are constructed as complete units which attach on top of extended side wall beams riding over the vertical posts. Each truss is a single modular unit linked side-to-side by spacer/purlins rather than a continuous ridge beam. They attach directly to the wall beam with a through-bolt through their lower chord and T-nut in the wall beam upper profile slot. Support for any sort of vaulted ceiling with such depends on the truss geometry -usually fan or scissor trusses- and any sloped space they can create with their sloped lower truss frame members. As some truss forms can be elaborate, Utilihab trusses may often employ less expensive tie rods for tension members rather than profiles braces, which are readily supported with the T-slot profiles. Roof truss designs can vary greatly with span, roof pitch, and architectural style. Tim simplify their use, the Utilihab platform provides a series of truss ‘kits’ in standard sizes for common forms.
Truss based gabled roofs are then finished as per the vaulted ceiling or standard Utilihab suspended ceiling using the usual selection of ceiling panels.
[Engineering study needed to develop specific kit truss specification]