What is the typical ground snow load in Illinois?

Typical lowland ground snow loads in Illinois run from about 20 to 30 PSF for planning purposes. Actual jurisdictional values vary by county and elevation — always verify with your local building department.

Do all Illinois counties use the same snow load?

No. Counties commonly adopt different design snow load values based on local snow history and elevation. Confirm the value used on your permit set.

Do steel buildings in Illinois need special snow engineering?

Every North Point Steel steel structure ships with sealed engineering for the permit jurisdiction, sized for local snow, wind, seismic, and code requirements.

Does roof pitch matter in Illinois?

Yes. Steeper pitches shed snow more easily and reduce the ASCE 7 slope factor on smooth, cold metal roofs. Drift, slide loads onto porches, and unbalanced loads still need to be checked by the engineer.

Is this an official code value for Illinois?

No. This is a planning-level reference only. Official design snow load comes from ASCE 7 and the code adopted by the local building department.

Snow Load Reference · IL

Illinois Snow Loads

Typical ground snow load in Illinois: 20–30 PSF for planning. Actual design values are set by your local jurisdiction and confirmed by a licensed engineer.

Planning and educational reference only. Verify final design snow loads with your building manufacturer, engineer of record, and local building department.

Typical Ground Snow Load

20–30 PSF

Moderate · 15–30 PSF

Regional considerations

Chicago and northern Illinois typically design to 25–30 PSF. Southern Illinois trends lower. Roof drift loads matter on multi-level industrial and warehouse buildings.

Designing a steel building in Illinois

Roof framing: purlin spacing and rafter depth sized to the jurisdictional design snow load, not a rule of thumb.
Drift & unbalanced loads: checked against parapets, adjacent rooflines, and rooftop equipment.
Snow slide: smooth steel panels shed snow — slide loads onto porches, lean-tos, and adjacent buildings are part of the design.
Foundations: snow-driven column reactions size piers, anchor bolts, and slab reinforcement.

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Planning reference only — not an official code value. Confirm final design snow loads with your building manufacturer, engineer of record, and the Illinois permitting authority.