The 2024 International Residential Code (IRC) is the current edition of the model code that governs single-family homes, two-family homes, and townhouses in most of the United States. If you're building or remodeling residential in 2026, the 2024 IRC is either already in effect in your jurisdiction or it's coming. The biggest changes affect deck builders, framers, and stair builders. Knowing them before your first failed inspection is cheaper than learning them after.
This article covers the most relevant 2024 IRC changes for residential carpenters. Codes vary by jurisdiction, so always verify with your local authority having jurisdiction (AHJ). The principles below are widely applicable, but specific requirements differ.
The big picture
The 2024 IRC was released by the International Code Council and is now being adopted by jurisdictions across the country on rolling schedules. Some states are still on the 2018 or 2021 IRC. Most are moving toward 2024. The 2024 edition includes 69 significant changes from the 2021 edition, and they touch decks, stairs, framing, energy efficiency, and electrical safety, among other areas.
For residential carpenters, the highest-impact changes are in deck construction (Chapter 5 / Section R507), stair construction, and a major reorganization of Chapter 3 that affects how you find provisions in the code book.
1. Decay-resistant wood requirements clarified
This is probably the most controversial change in the 2024 IRC for deck builders.
The rule. All deck joists, beams, posts, decking, and stair stringers must be made from either pressure-treated wood (in accordance with AWPA U1 standard) or a "naturally durable" species. The 2024 IRC defines naturally durable species as redwood, cedar, black locust, or black walnut, with each piece having no more than 10% sapwood on each face.
Why it matters. Previous editions allowed decay-resistant wood without specifying species or sapwood limits. The 2024 IRC tightens this. In theory, this eliminates many hardwood decking species (ipe, mahogany, etc.) from use under the IRC, although market enforcement may vary.
What you need to do. For deck framing, structural members, and stair stringers, default to pressure-treated lumber rated for ground contact unless you're using one of the four named species. For decking, the same rule applies. Premium hardwood decking that doesn't fit the four named species may not be allowed in jurisdictions strictly enforcing the 2024 IRC. Verify locally.
2. Bottom landing exception for low decks
This one is a quality-of-life win for deck builders.
The rule. Previously, exterior stairs at a deck required a landing at the base that was at least as wide as the stairs and made of an approved hard-surface material (concrete, flagstone, etc.). This created problems on low decks where homeowners wanted grass or gravel at the bottom of the steps.
What changed. The 2024 IRC adds an exception: if the stairway has 3 or fewer risers and no handrail is required, the bottom landing can be reduced to 36 inches wide. This exception does not apply to required egress doors.
What it means in practice. A low ground-level deck with two or three steps down to a backyard no longer requires a wide concrete pad at the bottom. The landing can be 36 inches wide, which can sometimes be incorporated into existing patio or walkway. Customers happy, code happy.
3. Beam span tables simplified
The 2021 IRC added complex calculations for beam sizing when joists cantilever less than the maximum allowable distance. It worked, but it was confusing and led to oversized beams in many cases.
What changed. The 2024 IRC reformats the beam span tables (R507.5) to show various combinations of joist span and cantilever for equivalent beam loads. For example, a beam supporting a 10-foot joist span with a 2.5-foot cantilever, a 12-foot span with a 1-foot cantilever, and a 14-foot span with no cantilever all fall in the same column.
What it means. Beam sizing is now straightforward. Look up your joist span and cantilever in the table; the column tells you the beam size. No calculations required for typical residential decks.
4. Ledger flashing detailed
Improper ledger flashing has been responsible for some catastrophic deck failures, and the 2024 IRC tightens the requirements significantly.
The rule. Flashing over a deck ledger must be installed flush to the weather-resistive barrier (WRB) and extend at least 2 inches above the ledger. The 2024 IRC includes detailed written and illustrated requirements for various ledger flashing conditions.
What fails. Flashing tucked behind the siding only at the top edge but not properly integrated with the WRB. Flashing that doesn't extend high enough above the ledger. Flashing that's installed before the WRB instead of integrated with it. Each of these is a citation under the 2024 IRC.
What to do. Plan the ledger flashing as part of the WRB integration sequence. Install the flashing so water draining down the wall above gets directed out over the top of the ledger and away from the band joist behind it. The 2-inch minimum height above the ledger is the new explicit standard.
5. Guard deflection limits
Guards (railings) on decks have been under increased scrutiny in the 2018 and 2021 IRC, and the 2024 IRC continues that trend by establishing clearer deflection limits.
The rule. Guards must withstand a 200-pound concentrated load applied in any direction at the top rail. The 2024 IRC adds an explicit deflection limit so the connection can be properly evaluated.
Why it matters. Previous editions left deflection ambiguous, which made it hard to evaluate whether a particular guard installation actually met code. The new explicit limit gives builders and inspectors a clear test to apply.
What to do. Use guard systems and connections that have documented load and deflection ratings. Off-the-shelf composite railing kits typically include this documentation. Custom-built wood railings need to use code-prescribed details for posts, post-to-deck connections, and rail connections.
6. Stair opening framing (R502.11)
A new section added to address wood framing around stair openings.
The rule. The 2024 IRC includes prescriptive requirements for the framing around stairwell openings in floors. This addresses a gap in earlier editions where the framing around stair openings wasn't clearly specified for floor trusses, I-joists, and conventional dimensional lumber.
What it means. If you're framing a new floor with a stair opening, follow the prescriptive details in the new R502.11. For floor trusses or I-joists used as edge members supporting a guard at a stair opening, the design must specifically consider the guard load.
7. Chapter 3 reorganization
This isn't a new code requirement, but it changes how you find things in the code book.
What changed. Chapter 3 has been reorganized. Sections related to structural and fire resistance are now grouped first, followed by fire and CO detection and fire sprinklers, then room and space configurations, then means of egress and accessibility, then indoor environment, then solar and on-site provisions.
What it means. If you're upgrading from a 2021 IRC to a 2024 IRC, your bookmarks, tabs, and section numbers from your old book are wrong. Plan time to re-familiarize with the new layout. This affects how you cite code on permit applications and inspection responses.
8. Appendix reorganization
Similar to Chapter 3, the 2024 IRC reorganizes nearly all appendices with new section numbering and order. Appendices are now grouped to make related provisions easier to find.
What it means. If you reference appendix provisions (storm shelters, swimming pools, manufactured homes, etc.) in your work, the section numbers have changed. Update your references.
What this means for your pricing
Code-compliant residential carpentry in 2026 costs more than it did in 2018. Some specific cost drivers in the 2024 IRC:
- Decay-resistant wood requirements may eliminate cheaper non-treated framing options in deck construction.
- Ledger flashing details require more time and the right materials to do correctly.
- Guard deflection requirements push toward documented railing systems and away from quick custom wood railings without proper details.
- Stair opening framing may add slightly to floor framing scope on homes with stairwells.
Your prices should reflect the actual current cost of code-compliant work. The contractor who's still building decks the way they did in 2015 isn't your competition; they're playing inspection roulette.
Common 2024 IRC violations on residential inspections so far
Early data from jurisdictions that have adopted the 2024 IRC show these as the most-common citations on residential carpentry work:
- Improper ledger flashing. Flashing not extending 2 inches above ledger, or not properly integrated with the WRB.
- Wrong species or grade of decking material. Hardwood decking that doesn't meet the new 10% sapwood limit, or non-treated framing in deck structural members.
- Guard connections without documentation. Custom wood railings without code-compliant connection details.
- Footings not to frost depth. Always a leading citation but worth flagging again because it doesn't go away.
- Missing hold-down tension devices on attached decks. Hold-downs at proper spacing along the ledger, with documented load capacity.
All of these are 100% preventable with planning and attention to the prescriptive details in Section R507.
The bottom line
The 2024 IRC reflects continued tightening of deck construction requirements, including clearer rules for decay-resistant wood, simplified beam span tables, detailed ledger flashing requirements, and explicit guard deflection limits. The biggest practical changes for residential carpenters are around decks and stairs.
Verify which IRC edition your jurisdiction has adopted. Update your reference materials. Train your crew on the new ledger flashing details and the species requirements for decay-resistant wood. Price the work to reflect the real current cost of code-compliant residential carpentry. The contractors who handle this transition smoothly will own the residential market by 2027. The ones who don't will be playing catch-up.
Frequently Asked Questions
How do I know which IRC edition my jurisdiction has adopted?
Call your local building department and ask. Most state code adoption websites also list the current edition. Don't assume the newest is in effect; some states are still on 2018.
Can I still build decks with ipe or other hardwood decking under the 2024 IRC?
Strictly read, the 2024 IRC limits naturally durable species to redwood, cedar, black locust, and black walnut. Many jurisdictions accept third-party documentation showing decay resistance for other hardwoods, but enforcement varies. Verify locally before bidding a hardwood deck.
What if my state hasn't adopted 2024 yet?
Build to whichever code your AHJ enforces. But know that 2024 IRC provisions are coming, and starting to use the better practices now (proper flashing, documented railings, correct species) means you won't have to relearn habits later.
Do I need an engineer's stamp for residential decks under the 2024 IRC?
For prescriptive decks within the size and load parameters in Section R507, no. For decks outside the prescriptive limits (very large, very tall, unusual loads, complex geometry), yes. Most residential decks fall within prescriptive rules and don't require an engineer.
How often does the IRC update?
Every 3 years. The current edition is 2024. The 2027 IRC is in development now. Most code changes are incremental and reflect new technology, materials, or safety improvements, but each cycle has a few significant updates worth tracking.