What ice density does ASCE 7 use?

ASCE 7 §10.4.1 specifies a minimum glaze ice density of 56 pcf for atmospheric (freezing-rain) ice.

Does the design ice thickness increase with height?

Yes. The height factor fz = (z/33)^0.10 increases the ice thickness above 33 ft above grade, up to 900 ft where a site-specific study is needed.

Atmospheric Ice Load

ASCE 7 Ch. 10 Preliminary estimate

Freezing-rain ice load on a round member per ASCE 7 Chapter 10 — design ice thickness with the height and topographic factors, and the resulting ice weight per foot of member.

Results update as you type. These are educational estimates — confirm against the governing code and a licensed engineer before design use.

Method & references

Atmospheric (freezing-rain) ice load per ASCE 7 Chapter 10. The design radial ice thickness is:

t_d = t · I_i · f_z · K_zt^0.35 , f_z = (z/33)^0.10

The ice forms a uniform glaze around the member, so the iced cross-section and weight per foot on a round member are:

A_i = π·t_d·(D_c + t_d) , w_i = (A_i/144) · 56 pcf

t — nominal map ice thickness (in), 500-yr MRI from the ASCE 7 ice maps
f_z — height factor, 1.0 at or below 33 ft, valid to 900 ft
56 pcf — minimum glaze-ice density (§10.4.1)

Reference: ASCE 7-16/22 Chapter 10. Concurrent wind-on-ice and the combination load cases are separate checks; map thicknesses are site-specific.