Sweet Wilma’s Retreat is a multi-level lake residence engineered around long-span parallel chord trusses and an octagonal tower volume. The structural system prioritizes open interior space, unobstructed deck views and clear load transfer across multiple roof planes.
The residence includes:
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Main and upper great rooms
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Master suite on main floor
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Three bedrooms above
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Post-free games room designed to accommodate a 6 ft x 12 ft snooker table
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Octagonal tower housing a sunroom at main level and spa above
Eastern white pine serves as the primary structural timber species.
Long-Span Parallel Chord Trusses
The defining structural feature is the use of long-span parallel chord trusses. This configuration allows wide interior spans without intermediate posts.
Structural behavior of parallel chord trusses includes:
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Uniform load distribution along top and bottom chords
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Efficient force transfer through vertical and diagonal web members
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Reduced mid-span deflection compared to simple beams
Engineering advantages:
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Larger open volumes in great rooms
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Improved flexibility in floor planning
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Controlled ceiling alignment under sustained load
Member sizing accounts for:
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Regional snow load
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Dead load from roof deck and insulation
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Wind uplift
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Long-term creep deformation
Connection detailing at web intersections ensures adequate shear resistance and axial load transfer.
Post-Free Games Room: Clear Span Performance
The games room is engineered without interior posts to accommodate a 6 ft x 12 ft snooker table. Clear-span requirements impose strict deflection and vibration limits.
Structural considerations include:
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Reinforced beam sizing across full room width
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Deflection control to prevent floor slope
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Vibration mitigation under dynamic load
Floor framing beneath the games room is designed for concentrated live load typical of recreation spaces.
Continuous load paths from roof through upper framing into foundation maintain stability without interior support columns.
Octagonal Tower: Radial Structural Geometry
The octagonal tower houses a sunroom on the main level and a spa above. Radial geometry introduces multi-directional load transfer.
Engineering implications:
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Radial rafters transferring load to perimeter posts
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Concentrated reactions at each corner segment
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Snow drift accumulation at roof transitions
Upper spa loads introduce additional dead weight. Floor framing in the tower is reinforced to resist water and equipment load.
Because spa environments generate elevated humidity, moisture management and vapor control detailing are critical to preserve timber integrity.
Dual Great Rooms and Vertical Load Stacking
Main and upper great rooms require consistent load alignment between levels. Vertical stacking of posts and bearing walls ensures:
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Direct axial compression transfer
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Reduced eccentric loading
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Controlled floor deflection
Balcony or open overlook areas contribute to diaphragm stiffness and improve lateral stability.
Master suite on main floor and three bedrooms above introduce distributed live load that must align with primary structural grid.
Deck Systems and Lake Exposure
Wide lake views are accessed from both main and second floor decks. Elevated decks must resist:
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Occupant live load
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Wind uplift
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Lateral shear forces
Engineering features include:
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Uplift-rated post anchorage
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Corrosion-resistant connectors
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Reinforced beam-to-post joints
Upper-level deck structures require lateral bracing to prevent sway under wind exposure.
Proper flashing at deck-to-wall interfaces prevents moisture intrusion into structural assemblies.
Exterior Half-Timber Detailing
Half-timber details at entry and lakeside elevations provide architectural expression while integrating with the structural frame.
Engineering integration includes:
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Anchored decorative timbers aligned with structural axes
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Moisture isolation between timber and cladding
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Reinforced gable framing for wind load resistance
Exterior timber elements are sealed to protect against UV exposure and seasonal humidity variation.
Timber Species and Finish
Eastern white pine is selected for primary structural members. Pine offers:
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Adequate compressive and bending strength
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Favorable workability
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Predictable dimensional behavior when properly dried
Interior timbers are finished with Sansin UV Clear. Transparent finishes allow inspection of surface condition while providing UV protection.
Moisture control during installation minimizes shrinkage stress and joint movement.
Environmental Load and Durability
Lakefront conditions impose:
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Snow load accumulation
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Wind uplift across open water
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Freeze-thaw cycling
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Elevated seasonal humidity
Structural countermeasures include:
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Continuous load paths from roof diaphragm to foundation
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Uplift-rated hold-down anchors
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Ventilated roof assemblies
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Reinforced tower framing
Creep deformation in long-span trusses is incorporated into serviceability analysis to maintain ceiling alignment and glazing performance.
Foundation systems include frost protection and drainage control to prevent differential settlement.
Structural Summary
Sweet Wilma’s Retreat demonstrates advanced long-span timber engineering with:
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Parallel chord trusses creating expansive interior volumes
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Post-free games room engineered for recreation load
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Octagonal tower with radial load distribution
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Dual-level deck integration for wide lake views
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Eastern white pine structural frame with protective finish
This project illustrates how disciplined timber engineering supports complex geometry, multi-level occupancy and clear-span performance while maintaining structural reliability in a lakefront environment.
