This image is an illustration detailing a cross-section of a building's structure, specifically focusing on an insulated floor truss assembly and its connection to an exterior wall, likely above a garage or unconditioned space.
Here's a detailed description of the components and their functions:
Overall Structure and Context:
The illustration shows a portion of a wall connected to a floor system. The terminology `Insulated floor-truss assembly` and `Exterior garage wall` suggests this is a floor separating a conditioned space (above) from an unconditioned or semi-conditioned space (below, like a garage).
Key Components and Features:
1. Insulated Floor-Truss Assembly:
* This is the primary horizontal structural element. It consists of `trusses`, which are engineered wood components made of top and bottom chords connected by web members (the diagonal pieces).
* The space within the trusses is filled with insulation, indicated by the text `Insulated floor-truss assembly`. This insulation helps in thermal separation between the levels.
* Metal plates (gang-nail plates) are visible at the joints of the truss members, used to connect the individual pieces.
2. Exterior Garage Wall:
* This is the vertical structural element below the floor assembly. It appears to be a framed wall, possibly with exterior sheathing and siding (partially visible on the far left).
* On the interior side of this wall, there's `Exterior garage wall` (the finished surface, likely drywall or similar).
3. Insulation and Air Sealing:
* Rigid foam: A layer of `Rigid foam` insulation is installed below the floor trusses, likely providing continuous thermal barrier and potentially acting as an air barrier. It's positioned between the trusses and the finished ceiling below.
* Continuous beads of sealant: These are applied in multiple locations where different building components meet, specifically where the floor assembly connects to the wall framing. This is crucial for creating an air barrier,
4. 2x4 Sleepers:
* These are horizontal wooden members, indicated as `2x4 sleepers`, installed below the rigid foam and attached to the underside of the floor trusses. Their purpose could be to:
* Provide a fastening surface for the ceiling material (e.g., drywall) below the rigid foam.
* Create an air space or accommodate wiring/plumbing if needed.
* Support the rigid foam insulation itself.
Structural Connections:
* The floor truss assembly rests on top of the exterior wall.
* There are structural connections visible, where the floor trusses meet the wall framing, often involving a rim joist or blocking (not explicitly labeled but implied by the connection points).
Purpose and Benefits:
This type of construction emphasizes:
* Thermal Performance: The insulation within the trusses and the rigid foam work together to provide good thermal resistance, minimizing heat transfer between the garage and the living space above.
* Air Sealing: The `continuous beads of sealant` highlight the importance of air sealing to prevent drafts and moisture intrusion, which are critical for energy efficiency and indoor air quality.
* Structural Integrity: The use of trusses for the floor provides a strong and stable platform.
In summary, this illustration provides a clear insight into the energy-efficient and structurally sound construction details for a floor separating a conditioned space from a garage or similar unconditioned area, focusing on insulation and air-sealing techniques
