Wood trusses are prefabricated frameworks made of lumber and connected by metal plates that support roofs, floors, and other structures. They are widely used in residential, commercial, and agricultural construction. While trusses can be designed in almost any shape or size, restricted only by manufacturing capabilities and shipping limitations, they are specifically engineered for each application. Building codes prohibit truss members to be cut, notched, drilled, or otherwise altered in any way without the approval of a registered design professional, as it could affect the structural integrity of the truss.
When you need flexibility to adjust the length of a truss on-site to fit specific dimensions of a building, trimmable end trusses could be used. They can help to avoid costly repairs when construction errors occur, such as out-of-square foundations or dimensions have changed, and truss specifications have not been updated prior fabrication. They allow the truss to be trimmed on the job site for an exact fit without needing to re-engineer the entire truss system. This is especially useful for running mechanicals like plumbing and electrical wiring through the open web design of the truss. Trusses with trimmable ends are also great for angled walls or if you need to make nice curve shapes by the end of the trusses.
The MiTek website has an extensive library of trimmable end details available as downloadable PDFs at Trimmable End Details - MiTek Residential Construction Industry:
- MII-TRIM_FIT-1 – MiTek wood web 3×2 or 4×2 trimmable end detail (8-1/4” to 21” trim fit I-block plated in plane of the truss – 12” maximum trim)
- MII-TRIM_FIT-1_BLOCKING – MiTek wood web 3×2 or 4×2 trimmable end detail with blocking for wall load (8-1/4” to 21” trim fit I-block plated in plane of the truss – 12” maximum trim)
- MII-TRIM_FIT-1_FIRE – MiTek wood web 3×2 or 4×2 trimmable end detail with fire cut (8-1/4” to 21” trim fit I-block plated in plane of the truss – 12” maximum trim)
- MII-TRIM_FIT-1_RIBBON – MiTek wood web 3×2 or 4×2 trimmable end detail with ribbon block notch (8-1/4” to 21” trim fit I-block plated in plane of the truss – 12” maximum trim)
- MII-TRIM-P-1 – MiTek Posi web 3×2 or 4×2 trimmable end detail (8-1/4” to 13” pre-fabricated wood “I-joist” plated in plane of the truss – 24” maximum trim)
- MII-TRIM-P-2 – MiTek Posi web 3×2 or 4×2 trimmable end detail (8-1/4” to 13” pre-fabricated wood “I-joist” plated in plane of the truss – 12” maximum trim)
- MII-TRIM-P-3 – MiTek Posi web 3×2 or 4×2 trimmable end detail (2×12 vertical block – 12” maximum trim)
- MII-TRIM-PSL-1 – MiTek wood web 3×2 or 4×2 trimmable end detail (8-1/4” to 21” deep PSL plated in plane of the truss – 24” maximum trim)
- MII-TRIM-PSL-2 – MiTek wood web 3×2 or 4×2 trimmable end detail (8-1/4” to 21” deep PSL plated in plane of the truss – 12” maximum trim)
- MII-TRIM-W-1 – MiTek wood web 3×2 or 4×2 trimmable end detail (9” to 21” pre-fabricated wood “I-joist” plated in plane of the truss – 24” maximum trim)
- MII-TRIM-W-1_BLOCKING – MiTek wood web 3×2 or 4×2 trimmable end detail with blocking for wall load (9” to 21” pre-fabricated wood “I-joist” plated in plane of the truss – 24” maximum trim)
- MII-TRIM-W-1_RIBBON – MiTek wood web 3×2 or 4×2 trimmable end detail with ribbon block notch (9” to 21” pre-fabricated wood “I-joist” plated in plane of the truss – 24” maximum trim)
- MII-TRIM-W-1-FIRE – MiTek wood web 3×2 or 4×2 trimmable end detail with fire cut (9” to 21” pre-fabricated wood “I-joist” plated in plane of the truss – 24” maximum trim)
- MII-TRIM-W-2 – MiTek wood web 3×2 or 4×2 trimmable end detail (9” to 21” pre-fabricated wood “I-joist” plated in plane of the truss – 12” maximum trim)
- MII-TRIM-W-2_BLOCKING – MiTek wood web 3×2 or 4×2 trimmable end detail with blocking for wall load (9” to 21” pre-fabricated wood “I-joist” plated in plane of the truss – 12” maximum trim)
- MII-TRIM-W-2_FIRE – MiTek wood web 3×2 or 4×2 trimmable end detail with fire cut (9” to 21” pre-fabricated wood “I-joist” plated in plane of the truss – 12” maximum trim)
- MII-TRIM-W-2_RIBBON – MiTek wood web 3×2 or 4×2 trimmable end detail with ribbon block notch (9” to 21” pre-fabricated wood “I-joist” plated in plane of the truss – 12” maximum trim)
- MII-TRIM-W-3 – MiTek wood web 3×2 or 4×2 trimmable end detail (2×12 vertical block – 12” maximum trim)
- MII-TRIM-W-4 – MiTek wood web 3×2 or 4×2 trimmable end detail (2×10 vertical block – 10” maximum trim)
- MII-TRIM-W-5 – MiTek wood web 3×2 or 4×2 trimmable end detail (2×6 vertical block – 6” maximum trim)
- MII-TRIM-W-6 – MiTek wood web 3×2 or 4×2 trimmable end detail (2×8 vertical block – 8” maximum trim)
For additional information, or if you have questions, please contact the MiTek Engineering department.