Structurally Speaking: Posiframe™
Reducing Wasted Effort, Lowering Costs, Preserving Resources
Posiframe™ engineered structure designs go the distance to reduce waste of materials on the jobsite.
For example, walls that don’t carry roof loads (“non-bearing” – such as most gable ends) don’t need structural headers over windows or doors.
The methods presented below are simply some of our standards.
To reduce wood waste, increase structural efficiency, promote thermal efficiency and reduce gypsum wall- board cracking; studs, floor joists, floor/roof trusses and rafters are spaced 24″ on center, aligned directly over the top of each other; inline or stacked. Inline framing enhances the strength of a building, substantially reducing the overall amount of wood. Aligning framing members transfers loads more efficiently, so a double top plate isn’t needed; a single one does the job just fine. This further reduces thermal transference. It also makes a better frame for attaching the sheathing that spans these transitions.
High Thermal Efficiency
Using fewer studs can save a lot of wood and increase the energy performance of a building by making room for more insulation. 2×4′s set 24 inches apart (instead of 16 inches) saves a whopping 25% of the studs in exterior walls. We use Passivecore elements because of their high insulation value (min of 6.7 per in) together with DOW 1″ SIS sheathing. High R-value sprayed-in and injected foam insulation augments the air-seal and completes the wall cavity fills. The insulated sheathing truncates the heat loss and gain attributable to thermal bridging through structural members at the inside of the sheathing, while simultaneously making the envelope more “solid” than ever before.
When higher structural capacity members are required to maintain a 24″ O/C layout, 3×4 studs are used instead of 2×4′s or 2×6′s at a minimal cost, maintaining a minimum R24 in the exterior walls. For a more substantial upgrade to the envelope, a 6″ nominal exterior wall (using 2×6 framing members @ 24″ O/C) will render an insulative value in excess of R38.
Corners, Exterior Walls at Interior Partitions
Exterior corners and where interior partition walls meet exterior walls can do just as well structurally with fewer studs and more insulation. Exterior corners and intersections of interior partitions at exterior walls are framed to allow space for sprayed-in foam insulation, preventing any uninsulated spaces, making air-sealing complete and substantially reducing heat loss. This also reduces the overall amount of wood used in the construction of the building. Small nailed on braces are used instead of stud-nailers for the gypsum wallboard installation.
Doors and Windows
When aesthetics allow it, wherever possible we configure the framing and locate the door and window openings so that they line up on a 2-foot grid; again reducing waste and leaving more room for insulation.
In two-story structures, a structural rim joist (2x_ or LVL) is often used to eliminate the need for headers in first floor exterior walls allowing for full insulation. In single story homes and in second floor walls of two-story homes, single-ply headers are used in load bearing walls to allow for partial insulation. In non-load bearing exterior walls, headers are eliminated entirely to allow for full insulation.
MSR & Engineered Lumber
By using MSR (Machine Stress-Rated) lumber; dimension lumber that has been evaluated by mechanical stress-rating equipment, and metal web trusses, TJI floor joists, LVL’s and laminated structural lumber, KD studs, Sturd-I-Floor subflooring, Dow SIS Structural Insulated Sheathing, and 5/8″ OSB roof sheathing, we deliver a highly sound structure which reduces the impact on old growth forests, with less material warping, drying-shrinkage, gypsum wallboard nail-pops – and it allows more flexibility in design.
Fully Engineered, Fully Customizable
We’ll take care of the structural and mechanical engineering as part of our contract. Any plan; any creative bent that your building designer may have can be adapted to a Posiframe™ structure without affecting the aesthetics. We’ll work with any MEP engineer and architect to ensure the integrity of the design.
The value-engineered Posiframe™ is lean and green, forming the “infrastructure” for a primary air-sealing exterior membrane, increased wall insulation and overall R-value, allowing for a secondary air-sealing sprayed/injected poly-foam to completely eliminate air movement in the wall cavities, and delivering a fortified, high-integrity building envelope. Walls are simply warmer in winter and cooler in summer.
This is important because over 40 percent of our physical comfort is due to the radiant heat exchange between the surrounding interior surfaces and our bodies. The Posiframe™ infrastructure allows for a reduction of this radiant heat exchange, maintaining a more consistent level of comfort throughout the building.
Posiframe’s advanced structural engineering and framing techniques reduce the amount of lumber and labor needed to construct a home. These cost savings are invested in the additional energy-saving features such as higher quality insulation, mini-HRV’s for kitchen and bathroom exhausts (and the clothes-dryer), the various passive systems such solar air-heating (Trombe wall technology etc.), under- slab heat-exchanger, and air-circulation systems.
Lower Utility Bills
Proper air-sealing and using ultra-high R-value insulation together with a Posiframe structure as presented herein substantially reduces the amount of energy needed to comfortize the space inside the building’s envelope. The result is lower utility bills, building systems that are easier to service and maintain – and much less expensive to operate.