Oklahoma Snow Load Calculator
Enter your ground snow load, roof pitch, and roofing material. Results update instantly — the calculator converts the ground snow load to a roof snow load using the ASCE 7 formula and compares the total against a 30 psf design load.
Total roof load (dead load + snow load) vs the 30 psf design check.
Dead load
Permanent weight of the roofing system
Roof snow load
Converted from the ground snow load
Slope factor Cs
Snow-shedding credit for steep pitches
Design check
Typical Oklahoma residential design load
How the snow load was calculated
Ground snow load (pg) = 20 psf (Oklahoma, OK — IBC Figure 1608.2).
The check uses a 30 psf total design load, common for Oklahoma residential roofs (10 psf dead + 20 psf live in many older designs; newer engineered homes are often 40 psf). This is an estimate for homeowner planning — a licensed professional must verify actual structural capacity.
How Roof Loads Work: What's Safe for an Oklahoma Roof
Dead load is the permanent weight of the roof itself — shingles, underlayment, decking, and framing. Snow load is a live (temporary) load: the weight of accumulated snow and ice. Building codes add them together and compare the total against the roof's design capacity, because the worst case is a fully loaded roof during a heavy Oklahoma winter storm.
The International Building Code maps Oklahoma's ground snow load (pg) at 15–20 psf (IBC Figure 1608.2, based on ASCE 7 snow maps) — Tulsa and Oklahoma City sit at 20 psf. For a typical sloped shingle roof, the code converts that ground load into a roof snow load of about 14 psf (0.7 × exposure × thermal × importance factors). Flat and low-slope roofs get a 20 psf minimum per ASCE 7, and very steep pitches shed snow, so their snow load drops.
Many Oklahoma homes — especially those built before the 2000s — were designed to a 30 psf total load (10 psf dead plus 20 psf live). Newer engineered homes are often designed to 40 psf. A typical asphalt shingle roof comes in around 29 psf total, which is why Oklahoma roofs handle normal winters without issue. The situations that deserve attention: heavy tile or slate roofing, flat roofs (ponding and drifting), older homes with undersized framing, and snow drifts piling against walls, valleys, and mechanical units.
| Roofing material | Typical dead load | Notes |
|---|---|---|
| Asphalt shingle | 15 psf | Most common in Oklahoma — includes framing + shingles |
| Metal | 10 psf | Lightest common option — great for snow shedding |
| Wood shake | 20 psf | Heavier than shingles, still within typical designs |
| Flat / low-slope (TPO, modified bitumen) | 15 psf | 20 psf minimum snow load applies — watch for ponding |
| Tile / slate | 25 psf | Often requires engineered framing — verify capacity |
If your result says Safe, your roof is within the 30 psf design check. Needs Review means the total exceeds 30 psf — have a professional inspect before the next heavy snow. Not Safe means the load is well above the check and the roof should be evaluated immediately.
Oklahoma Snow Load FAQ
Most of Oklahoma, including Tulsa and Oklahoma City, uses a ground snow load (pg) of 20 pounds per square foot (psf) under the International Building Code and ASCE 7 snow maps. Some areas of the state are mapped at 15 psf. This calculator lets you choose 15 or 20 psf (or any value in between) to match your location.
Many Oklahoma homes — especially those built before the 2000s — were designed for a total roof load of 30 psf (commonly 10 psf dead load plus 20 psf live load). Newer engineered homes are often designed to 40 psf. This calculator checks your roof load against the 30 psf baseline as a conservative rule of thumb; if you know your home was engineered for 40 psf, treat the result as extra conservative.
A foot of fresh, dry snow weighs roughly 3-5 psf, while a foot of wet, heavy 'heart attack' snow can weigh 15-20 psf or more. That is why drifting, wet snow is the real concern in Oklahoma winters — a few inches of wet snow can put more load on a roof than a foot of powder.
Only if you see warning signs: sagging or creaking roof members, doors or windows that start sticking, cracks in drywall near ceilings, or ice dams at the eaves. Never climb onto a snow-covered roof — use a roof rake from the ground on shallower pitches, or call a professional. Proof Construction offers winter roof inspections across the Tulsa metro; call (918) 734-4444.
If your result lands in Needs Review or Not Safe — for example a tile roof, a flat roof with ponding, or an older home with undersized framing — have a licensed roofing contractor or structural engineer inspect the roof before the next heavy snow. Proof Construction offers free roof inspections for Tulsa-area homeowners: call (918) 734-4444 or request one online. If you see active leaking or sagging, that is an emergency — we provide 24/7 emergency tarping. Get a free roof estimate from Proof Construction. Explore all roofing solutions from Proof Construction. Try the roof cost estimator for a ballpark figure.