This year, the 2015 edition of the International Residential Code is being developed. As an advisor to the North American Deck and Railing Association (NADRA), I represented the decking industry at the code committee hearings in Dallas at the end of April. Nearly two dozen proposed changes that would affect the industry were presented during those hearings.
Even though most jurisdictions have yet to adopt even the 2012 edition of the IRC, these proposals — some minor, others more significant — will eventually have an impact on how PDB readers build decks. Some provisions will limit design options, while others will make decks more costly to build. I've listed them here, along with my analysis of the more important ones and an update on how the code committee voted. More details on these proposals are available on the NADRA code page at nadra.org/contractor-code-guide and at nadrablog.com.
RB264 and RB268 include joist and beam span tables for wet-use environments and post sizing, framing connections, and footing provisions that are intended to fill in holes in the IRC's deck design guidelines. RB268 also includes mandatory provisions for deck guards, stairs, and other features.
Analysis: These proposals are based on the American Wood Council's DCA 6, but contain many compromises (some good, some bad). In particular, the expanded provisions, prescriptive guard and stair assemblies, and hardware connections in RB268 are at odds with many design and construction practices commonly accepted in the decking industry.
Status: Both proposals were disapproved, although the committee encouraged stakeholders to continue to work together and bring modified proposals to the final hearings.
Deflection Limits (RB61-13)
Guards are one of the few (or the only) features for which the IRC currently provides a minimum live-load resistance without also providing a deflection limit. RB61-13 would remedy that, limiting guard-post deflection to about 3 inches and limiting downward deflection of top rails to about 1 inch over 8 feet while under a maximum required design load of 200 pounds.
The proposal is complicated by the inclusion of an allowable deflection for a combined post and horizontal-top-rail assembly. In this case, a guard's top rail would not be allowed to deflect outward by more than about 11/2 inches in the post plus 1 inch over 8 feet in the horizontal rail.
Analysis: How would an inspector apply a 200-pound horizontal force, and — simultaneously — determine the deflection of the post and rails? More likely, deck builders would be expected to use engineered, tested, or standardized guards, as these deflection requirements cannot be verified any other way.
This proposal would greatly impact the design and construction of site-built guards without any evidence of an epidemic of guard failures under the current code. An inspector can always demand a test or analysis of a guard system if there is concern that load requirements are not being met.
Status: Disapproved. The committee felt the deflection limits were too flexible, and the wording for how to measure the deflection unclear.
Height Above Seating (RB145-13)
This proposal would eliminate the current requirement that guard height be measured from fixed-bench seating, rather than from deck level.
Analysis: When the IRC originally adopted the code provision that requires guards adjacent to fixed seating to be at least 36 inches high, it essentially ended built-in deck seating. While the goal — preventing small children standing on the seat from climbing over the rail — was laudable, the requirement is clearly ineffective. With so much moveable seating on decks, it's hard to see the point in regulating fixed seating.
Status: Approved. The committee agreed that building codes cannot stop kids from climbing on furniture.
Deck Height Measurement (RB143-13)
Under current code, deck height — which determines whether or not guards are required — is measured from a point 36 inches horizontally from the edge of the deck. Under this proposal, measurement would take place at the edge of the walking surface. It also replaces the phrase "walking surface" with a specific list of terms, the intent being to exclude landscaping surfaces from regulation.
Analysis: Measuring fall hazards directly at the edge of a deck rather than where a falling person would actually hit the ground creates a greater safety hazard. I think the current language more accurately reflects the intent of this provision and should be retained.
Status: Disapproved. The committee agreed that people fall away from an open platform rather than straight down, and that the horizontal distance contained in the current code is appropriate for the safety hazard.
Several proposals build on the questionable lateral load requirements contained in the current code. Here's a quick summary:
RB260-13 would require that the two hold-down tension devices permitted by the IRC be installed within 24 inches of each end of the deck ledger.
RB261-13 would provide an exception to the hold-down-device provision for decks less than 30 inches above grade.
RB262-13 provides for a second lateral-load-connection method, in which angled brackets connect the bottom of the joists to the wall plates, with loads derived from the 1,500-pound requirement in the current method.
RB263-13 provides an exception to the hold-down-device provision for decks not requiring guards.
Analysis: Lateral-load provisions in the 2012 IRC are poorly written and based on incomplete data. Although the proposals above appear to lighten the burden of existing requirements, they would also inadvertently justify them elsewhere in the code.
While current lateral-load anchor details appear to be mandatory, they are actually not required. Researchers have been testing and analyzing lateral loads on decks, and their findings indicate that standard ledgers bolted to rim joists without lateral anchors perform quite satisfactorily. Modifications should not be made to lateral-load provisions until they can be based on validated data.
Status: All except RB261 were approved by the committee. While these changes complicate the creation of future lateral-load provisions founded on actual data, they lighten regulation by allowing an alternative to the current IRC method of using two hold-down devices, and by exempting decks not requiring guards.
Other Structural Requirements
Blocking Over Beams (RB247-13)
In certain seismic zones, this proposal would eliminate the requirement for blocking over a beam when joists cantilever 24 inches or less.
Analysis: This simple proposal would provide needed flexibility for installing deck drainage systems over dropped beams. As a code administrator, I have seen many engineered designs that allow blocking to be altered or even omitted altogether for this very reason. For short cantilevers, the current code adds an unnecessary cost to many under-deck drainage systems.
Status: Approved, but with slight editorial modification.
Hangers on Beams and Ledgers (RB253-13)
This proposal would prohibit connection of hangers solely to the bottom half of beams.
Analysis: This proposal would restrict design flexibility by prohibiting such common practices as hanging 2x6 joists from the bottom portion of a 2x12 beam or ledger, with little evidence that minimal loads from conventionally sized lumber joists could split a supporting member.
Status: Disapproved. The committee did not feel that ledgers should be included in this connection limitation.
RB66-13 would provide an exception to fire-resistive construction for decks that are more than 5 feet from the property line or the dwelling.
RB74-13 would require exterior stairways to be at least 5 feet from lot lines and other buildings on the lot.
RB75-13 would require accessory structures, such as patio covers and decks, whether attached or detached, to be at least 5 feet from lot lines.
Analysis: IRCTable R302.1 deals with fire separation distances, often referred to as setbacks, which are intended to prevent a fire in one house from spreading to a neighboring house. "Walls" and "projections" (such as roof eaves) are currently listed in the table, but not decks, making it unclear how they should be handled. Under these proposals, decks would be specifically addressed, but in many cases they would be prohibited if located within 5 feet of property lines. Since fire affects decks differently from other structures, more research is necessary for addressing them in the IRC.
Status: All setback proposals were disapproved. The committee felt that the provisions were too inflexible for decks and could have unintended consequences.
RB102-13 would eliminate all requirements for illumination of exterior stairways, both over the stairs and at the top landing. Current illumination provisions for exterior stairways are indeed confusing. However, the illumination at the top of a stairway is critical for the safe use of it, as well as for alerting occupants to the presence of stairs.
RB129-13 clarifies that stairways serving decks, porches, balconies, and sunrooms are regulated the same as any other stairway. Landscaping stairs not serving one of the above features would not be required to meet code, which appears to offer more flexibility to the design of hardscape areas.
RB130-13 would allow handrails to project up to 61/2 inches into stairs, as opposed to the current maximum of 41/2 inches.
RB141-13 would allow all ramps other than ones serving a required egress door to be a maximum slope of 1-in-8 versus the current maximum of 1-in-12.
RB142-13 would require that the minimum width of landings for ramps be equal to the width of the ramp, versus the current 36 inches.
RB187-13 would require exterior stairways and ramps built in flood-hazard areas to be constructed in one of three specifically prescribed ways.
RB115-13 clarifies when safety glazing is required for windows or doors located underneath or at the bottom of a stairway.
RB42-13 includes an exception for decks, sunrooms, and similar spaces to the requirement for protection of glazed openings in regions prone to wind-borne debris, provided some specifics regarding the wall of the home are satisfied.
RB8-13 would require contractors disturbing interior or exterior surfaces on homes built prior to 1978 to submit EPA certificates and a plan complying with 40 CFR 745 to building officials for work on homes, even when building a deck.
RB15-13 restores previous definitions of "balcony" and "decks" in the IRC.
RB31-13 adds a definition for "spiral stairway" in the IRC that allows more freedom than the IBC definition does, by omitting the center column from the description.
RB58-13 removes references to "guardrail" and replaces them with the IRC- defined term "guard."
RB60-13 includes "deck floors" in the floor description for allowable deflection. It officially sets deck-floor deflection limits where they have been previously only assumed.
RB465-13 requires that all swimming pools, spas, and hot tubs comply with the International Swimming Pool and Spa Code (this code has deck provisions not currently required by the IRC).
All the hearing results can be overturned at the final hearings scheduled for this October.
Glenn Mathewson is a building inspector in Westminster, Colo.