Hanging Rectangular Duct with 1" wide Hanger Strap

Rectangular Duct is hung with 1″ wide 22 gauge (or 20, or 18 gauge) Galvanized Strips that is supplied to the field along with the fabricated ductwork.

The most common option is 10 ft strips that are cut and bundled. Some shops use 100 lb coils, but any savings in "drop" are negated by the much higher cost of the coiled strip.

Typically, the field will put a hanger on every duct section (which means every 5 ft or 4 ft). One vertical strip on either side of the duct.

What Gauge to Use?

When spaced every 5 ft, 1″ 22 gauge strap is SMACNA approved all the way to duct that is 144″ in total perimeter (adding up all four dimensions 144″ or smaller) and 20 ga is approved on duct with total perimeter of 192″. Shops that use 18 gauge might be doing so for one of three reasons:

• It’s their established standard ("what they have always done").
• To cover all bases, even for the largest ducts.
• They hang every other section, spacing the hangers every 8 ft or 10 ft.

The Gauge of Hanger Strap that a shop uses therefore depends on the spacing that the field uses to hang the duct, the size of the rectangular duct and also whatever the shop standards are (whatever has been passed down over the years).

Whether to Cut in House or "Buy Out"?

Many shops cut their own hanger straps in-house using 5 x 10 (or 4 x 10) flat sheets and a 10 ft power shear.

Typically, shops will cut 1" strips along the width of the sheet 48 or 60 times to produce 10 ft strips. Multiple sheets are cut, and then the strips are bundled in groups of 25, secured with duct tape near each end. If you’re cutting your own hanger straps, here are a few questions to determine if buying pre-cut, bundled straps might be more valuable:

A. Do you account for the cutting and bundling cost when calculating in-house costs? (i.e., do you calculate the cost per foot of hanger strap based on the cost of the 5 x 10 sheet divided by 600?)

B. Are you cutting straps from prime sheets? (unless the shop has white rust sheets to use up, there’s little to no drop from a 10 ft sheet)

C. Is bundling the worst part? (typically, bundling is more of a hassle than cutting)

D. Is labor becoming an issue? (finding good help in the shop seems to be a challenge in many areas)

E. Do you have to flip or sharpen the blade on your shear occasionally?

If you answer "No" to A and "Yes" to B, C, D, and E, consider switching from cutting in-house:

And try buying out your Hanger Strap in strips, already cut and bundled.