Building for Oklahoma weather.
Oklahoma sets some of its own values on top of the national residential code, and Oklahoma City sets more on top of those. This guide gathers those values in one place, with the documents they come from.
The design criteria Oklahoma City builds to
The residential code carries a table of local values that each municipality fills in for itself. Oklahoma City has filled it in by resolution, and this is what a house inside the city limits is designed against.
Wind exposure category is determined for each individual site, so it doesn’t appear in the city’s table. A house on open ground falls in a different exposure category from the same house behind mature trees, which changes the loads it’s designed for.
Storm shelters are held to 250 mph, statewide
This is one of the clearest examples of Oklahoma setting its own standard. The state amendment reads that “for storm shelters, the minimum design wind speed for the entire State of Oklahoma shall be 250 miles per hour”.
For comparison, the house around the shelter is designed to the 115 mph in the table above, and the shelter within that house is designed to a far higher standard.
A storm shelter in Oklahoma is defined as a structure built in accordance with ICC 500, the national standard for storm shelters, and designated for use during a severe wind event. There’s a distinction in the code between a residential storm shelter and a community one.
A shelter installed in the garage floor
Oklahoma adds a specific requirement for in-ground shelters installed in a garage slab, which addresses water intrusion. The rim of the shelter has to be raised not less than 1 inch above the highest point of the adjacent garage floor, and the floor around it must form an apron that slopes away from the shelter.
This detail keeps the shelter dry and usable, and it must be set before the garage slab is poured.
Hail and roof impact ratings
Impact resistance for roof coverings is graded by laboratory test from Class 1 to Class 4, with Class 4 the highest. The test is a steel ball dropped onto the same spot twice without the material cracking or splitting.
Two points are worth understanding. A class rating describes performance in a laboratory test, and actual storm performance can vary. Whether an impact resistant roof reduces your premium is determined by your insurer. Insurers in this state commonly offer a credit, the amount varies by carrier, and your own carrier can confirm the value before you select a roof.
This page doesn’t provide insurance advice. The Oklahoma Insurance Department answers consumer questions directly on 405-521-2991, and your carrier can confirm any discount available on your own policy.
Expansive ground
Much of central Oklahoma sits on clay soils that swell when they take on water and shrink as they dry. That movement is seasonal and more pronounced here than in most of the country, which is why foundation design receives particular care in this state.
It’s also why Oklahoma City requires an Oklahoma licensed engineer to design a pier and grade beam foundation or a post-tension foundation. If either is proposed for your lot, ask to see the engineer’s drawing.
These values changed on 14 September 2026
Oklahoma has adopted the 2024 editions of the residential and building codes with state amendments, in force since 14 September 2026. The 2024 rule keeps the storm shelter standard and the garage shelter detail above, renumbered from Section R323 to Section R307.3, and it fills in one value of the design criteria table statewide: ice barrier underlayment isn’t required anywhere in Oklahoma.
The other values in the table remain each city’s to set. Oklahoma City’s resolution for the 2024 edition hadn’t been published when this page was checked, and the city’s list of adopted codes still named the 2018 editions, so the values above stand until the city acts. Ask which edition your permit is reviewed under.
What the energy code requires of a new house
Oklahoma City is in Climate Zone 3A, the warm and humid zone that covers most of central Oklahoma. Since 14 September 2026 the energy requirements for a house have been Chapter 11 of the 2024 International Residential Code, adopted with Oklahoma’s own amendments. The amendments matter, because several of them set a different value from the model code.
Walls: the model code asks for R-20 cavity insulation, or R-13 with R-5 of continuous insulation outside it. Oklahoma sets the wall at R-15, and accepts full depth open cell spray foam in a 2 by 4 wall as meeting it. Ceilings: R-38, the model value, which Oklahoma leaves unchanged.
Windows: a U-factor of 0.35 or lower, where the model code asks for 0.30, and a solar heat gain coefficient of 0.25 or lower.
Slabs: the model code calls for insulation along the edge of a slab in Zone 3. Oklahoma deletes that requirement for an unheated slab, so a standard slab on grade here needs no edge insulation. A heated slab keeps its insulation, and where that insulation runs down the inside of a stem wall with a ledge, a half inch thermal break is permitted so the slab can still bear on the ledge.
Air leakage: the model code requires every new house to be tested with a blower door. Oklahoma makes the test apply only where the city has adopted it, allows a visual inspection of the air barrier in its place, and where a house is tested, sets the limit at 5 air changes per hour at 50 pascals in Zone 3, against the model code’s 4. Duct testing works the same way, required only where the city requires it, with visual verification allowed. The ductwork, air handler, return air and filter boxes must be sealed in any case, and the plenums, start collars, coil connections, wyes and supply boots with mastic.
The certificate: whichever path a house takes, a permanent certificate must be posted in the furnace space, a utility room or another approved place inside the house. It lists the insulation values, the window ratings, the results of any tests, the heating, cooling and water heating equipment with its efficiencies, and the code edition the house was permitted under. It is the document to ask for when you buy a house built after this date.
What the amendments leave alone: the ceiling, floor and crawl space values, the skylight and solar heat gain limits, and the two compliance paths, prescriptive and performance, remain as the model code sets them.
The commercial energy code is older, and under review
For commercial buildings, the state’s building code refers to the 2006 edition of the International Energy Conservation Code, and the 2024 adoption kept that reference. The commission created a technical committee in October 2025 to review the 2021 and 2024 editions, and its own minutes record that the earliest a new commercial energy code could take effect is 2027.
We build across the Oklahoma City metro, and we walk every property first.
Share the address and a brief description of your project, and we’ll review how your site’s exposure and soil conditions will shape the design.
Codes and city procedures change, and the issuing office is always the authoritative source.