Design FTAO shear walls
A wall with openings is designed as FTAO (Force Transfer Around Openings) using the APA T555 / Diekmann method. Walls without openings stay Traditional — the type is derived from the openings you add, so there is no separate toggle.
Add openings to a wall
- On the Design tab, select a shear wall and open its Properties panel.
- Click Wall openings to open the openings dialog.
- Enter up to 3 complete openings with width, height, start position from the wall end, and sill height (all in feet). A live elevation preview shows the layout.
- Close the dialog to save. The wall is now designed as FTAO for both wind and seismic.
Remove all openings to return the wall to Traditional design.
Limits the calculator enforces
Rook checks each opening configuration against the T555 / SDPWS limits:
- Piers must be at least 18 in wide (T555 permits 18 in where SDPWS 4.3.2.2 requires 2 ft)
- Sheathing above or below an opening must be at least 12 in tall
- Pier aspect ratio (h/bs) may not exceed 3.5:1 (SDPWS 4.3.3.3 / T555)
Openings that violate these limits are flagged in the Properties panel.
Run the design
Run the wind or seismic design as usual. For FTAO walls Rook solves the Diekmann force transfer around each opening and reports:
- v<sub>max</sub> — governing unit shear demand in plf
- Governing h/bs — the worst pier aspect ratio, with any capacity reduction applied when h/bs exceeds 2:1
- An equilibrium check confirming the force transfer sums balance (within tolerance)
Results appear separately for wind and seismic in the Properties panel and on the Wall Table.
Read the calc sheet
The exported calculation sheet includes an FTAO Design – APA T555 (Diekmann) section for each FTAO wall, showing the full force column for wind and seismic: drag forces around each opening, pier unit shears, and strap forces, step by step. See Export calculation sheets.