USG Domed Ceilings and Barrel Vaults - Manual (Page 4)

Page 4 of 12
Part 1:
Installation
Instructions
Domes
Step 4 Assemble and hang The first row in Table 1.2 of the Construction Specifications indicates the arc length required for each of the
primary spokes primary spokes (dimension D). Prepare each spoke by measuring along the arc of the tee and trimming
the end to the required length. Depending on the size of the dome, several tees may need to be connected
to form the length required.
Tip: The vertical slots between the hanger holes are not used in dome applications but will be useful later to
gauge the correct position of headers and cross tees. The slots are exactly 8 apart along the arc of the tee.
Hang the primary spokes from the hanger wires by connecting curved tees to the hub and to each other
(Figure 5) using splice plates provided. Grid face elevations (measured from perimeter) are shown in Table 1.1
of the Construction Specifications to aid in the leveling of spokes (Figure 3) (dimension E).
Figure 5 – Connect curved tees to hub and other tees
Figure 6 – Connect curved tees to hub and other tees
Important! The integrity and accuracy of the primary spokes will ultimately determine the quality of the
completed installation. Check the integrity of the completed spokes. Extra care at this point will prevent
troublesome alignment problems later.
1. Check the elevation difference between the hub and the end of each primary spoke to make sure it agrees
with the construction specifications. If elevations need to be adjusted, adjust them now.
2. It is important that the main spokes are hung in the proper position relative to each other. Check for proper
position by measuring the distance between the ends of the spokes. These distances should all be the same.
The correct distance between the ends can be calculated by multiplying the dome diameter (ceiling
opening size “L”) by 0.8
(Figure 6) . If hanger wires need to be relocated, move them now.
3. Examine each completed spoke from one end. Hanger wires should be in line. They should hang straight
and plumb within 1:6 (about 10 degrees). The spokes should be straight with no waves. If hangers need to
be relocated, move them now.
dome hub
main-tee splice plate
primary spoke S1
dome diameter "L
"
hub
distance between ends = L x 0.8
spo
ke a
rc le
ngth
"D"
Technical Service 800 USG.4YOU
Samples, Literature 888 874.2450
Customer Service 800 950.3839
usg.com