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We have a passion for clarity—transforming complex conditions into spaces of elemental beauty and enduring value.

We work with our clients and partners to solve problems, reveal insights, and create inviting architecture for every place and purpose.

WAECHTER ARCHITECTURE



Mass Timber Innovation: All-Wood





If contemporary discussion around mass timber has gravitated towards the possibility of “Tall-Wood” buildings, our body of work has aimed lower to the ground: the potential ubiquity and necessity of “All-Wood” infill buildings.

Throughout the United States, new mass timber projects currently default to hybrid construction methods that employ significant amounts of steel, concrete and finishes like gypsum. Due to market assumptions of cost, schedule, code compliance and local fabrication limits, only one All-Wood building has been built in the western United States: the Mississippi Avenue building by Waechter Architecture. 

This body of research aims to break down the percieved barriers to competitive construction of All-Wood buildings in our region by showcasing lessons learned from our Mississippi project and a range of possible approaches moving forward. 

In an All-Wood building, the structure is the finish. In an All-Wood building, the ceilings, supporting structure and the walls are all exposed mass timber, creating a continuous material experience. All surfaces can be wood, except perhaps the floor, which depending on programmatic need can be concrete, carpet or other finishes if desired.







Structural Approaches for All-Wood Buildings 


We group the various structural components of an All-Wood mass timber into three overtly broad categories: the exterior structure at the envelope of the building, the inner structure throughout the floor plate, and the horizontal structure that supports that floor plate. We find that broadly speaking there are three approaches per category, resulting in a diverse matrix of options that may be considered for particular scales, programs and sites.


Exterior Structure:
Tilt-Up


Exterior Structure:
Platform



Exterior Structure:
None (Cantilever)



Interior Structure:
Columns


Interior Structure:
Walls


Interior Structure:
Cores


Horizontal Structure:
Beams & Girders



Horizontal Structure:
Beamless (Point Load or 2-Way Deck)



Horizontal Structure:
Longspan CLT Beams







MEP Approaches for All-Wood Buildings


In any mass timber building, one of the most important design decisions and ultimate challenges is how to resolve Mechanical, Electrical and Plumbing requirements. In an All-Wood building in particular, there is no typical wall cavity to hide equipment. Instead, we are identifying a set of five approaches to organizing and sometimes hiding MEP systems altogether in a way that complements our All-Wood structural approaches. The hypothetical details below show the timber elements in one image, and the MEP elements next to it.





Vertical Structural Offset: Timber Elements


Vertical Structural Offset: MEP Elements


Horizontal Structural Offset: Timber Elements


Horizontal Structural Offset: MEP Elements


Structural Cavity: Timber Elements


Structural Cavity: MEP Elements


Integrated Floor: Timber Elements


Integrated Floor: MEP Elements


Raised Floor: Timber Elements


Integrated Floor: MEP Elements








All-Wood Details from Mississippi Ave 


Collecting the key structural moments from our All-Wood Mississippi building, the following details work as a series of triptychs. The first version of each detail expresses the visible assembly, the timber-only assembly second, and third, the major metal fastening patterns. Each one of these details works from a fire code perspective, and for the seismic zone of the Pacific Northwest.

Learn more about this All-Wood building.


Beam to Wall Connection: Visible assembly


Beam to Wall Connection : Timber assembly


Beam to Wall Connection : Fastener assembly


Stemwall Bracket Connection: Visible Assembly


Stemwall Bracket Connection: Timber Assembly


Stemwall Bracket Connection: Fastener Assembly


Stemwall Corner Bracket : Visible Assembly


Stemwall Corner Bracket : Timber Assembly


Stemwall Corner Bracket: Fastener Assembly


Ledger: Visible assembly


Ledger: Timber assembly


Ledger: Fastener assembly


Drag Plate Connection: Visible assembly


Drag Plate Connection : Timber assembly


Drag Plate Connection : Fastener assembly


Core Bulkhead Corner: Visible assembly


Core Bulkhead Corner : Timber assembly


Core Bulkhead Corner : Fastener assembly







This research is funded through a 2022 USDA Forest Service Wood Innovations Grant with additional support from the Softwood Lumber Board. Ongoing post occupancy evaluations are being conducted by the University of Oregon Institute for Health in the Built Environment.