Inspecting Residential Interior Doors

by Aaron Miller, CMI®


Doors have been with us for at least 5,000 years. One usually cannot progress from one room to another without passing through them. The average house in Texas, where I live, has about 20 interior doors. Other than windows, no other operable, structurally related component outnumbers them. With these things in mind, one would expect more attention would be given to interior doors during home inspections, as well as greater mention of their condition and function in inspectors’ reports.

Standards of Practice

A perusal of the relevant home inspection protocols and standards of practice throughout the country indicates that little is required from an inspector regarding the doors in a house, other than exterior doors, such as garage overhead doors, fire separation doors, and egress doors. Inspection protocol for exterior doors generally follows building code requirements, as it should. Regarding all doors other than exterior doors, vague references in SOPs, such as “condition” and “function,” are found. The reason for this is that secondary exterior doors and interior doors are afforded almost no consideration in the prevailing prescriptive building codes.

The Texas Real Estate Commission’s SOP says:

535.228(a)(3)(A)(a) Foundations. The inspector shall: (3) generally report present and visible indications used to render the opinion of adverse performance, such as: (A) binding, out-of-square, non-latching doors…

535.228(e)(2)(A)(e) Interior walls, ceilings, floors, and doors. The inspector shall: (2) report as Deficient: (A) deficiencies in the condition and performance of doors and hardware.

The SOP of InterNACHI, of the world’s largest home inspector organization, requires this:

3.10.  I. Doors, Windows & Interior, I. The inspector shall inspect: a representative number of doors and windows by opening and closing them.

3.3.  III. The inspector shall report as in need of correction: cracks, brick cracks, out-of-square door frames, and unlevel floors.

These citations might lead an inspector to wrongly believe that the only significant deficiencies to be discovered regarding interior doors are binding, out-of-square, non-latching doors due to differential foundation movement and poorly defined problems with the condition and performance of door hardware.

Why are they given so little attention during a home inspection? This is probably because, unlike their exterior cousins, almost no mention is made of them in the prevailing model building codes.


Just how critical can the installation of an interior door be? What hazards do they involve? Often, the view of residential door safety focuses almost exclusively on preventing unwelcome visitors, insuring energy conservation, avoiding moisture penetration, and allowing the maximum speed of escape in the event of an emergency. Attention to door safety certainly has much wider implications.

Here are just a few statistics:

  • There are more than 300,000 door-related injuries requiring hospital emergency room treatment each year.
  • Around 45,000 of those involve children under the age of 14.
  • Door injuries result in an estimated 15,000 amputations.
  • In just two cases where the finger was actually re-attached, the settlements had price tags of $725,000 and $600,000.

Glass doors represent a very real concern. While some inspection SOPs may require inspection of safety glass locations, many do not. Some specifically exclude it, while strangely also containing verbiage to the effect that inspectors must make mention of all unsafe conditions. We all have or know someone who has walked or fallen into a closed glass door, hopefully with no injuries. The installation of safety glass or the application of approved glass safety films in all required locations should be strongly urged.

Frequent injuries involve children or adults whose hands or fingers are caught in closing doors. A closing door can exert up to 40 tons per square inch of pressure along the gap between its hinges. Doors frequently inflict bruised, cut, or mashed fingers, torn or cracked fingernails, broken bones, and even amputations on the unsuspecting. Utilization of appropriate pinch-protection hardware may significantly reduce the potential for injury. The addition of after-market anti-pinch door hardware ought to be considered.

Model Codes

The current building codes specify the need for safety glazing in residential doors primarily because of the large number of lawsuits related to safety glazing that were in litigation around the time of the formation of the Consumer Product Safety Commission. The numbers of injuries from other door-related issues have evidently not reached the threshold where the code authors feel compelled to make regulations to prevent such injuries.

The International Residential Code’s silence on the subject of interior doors is also a mystery.  They are not required. Furthermore, their dimensions are not regulated. R311.4.2 states:

Door type and size. The required exit door shall be a side-hinged door not less than 3 feet in width and 6 feet, 8 inches in height. Other doors shall not be required to comply with these minimum dimensions.

I find this both curious and inexplicable in light of the fact that IRC 311.1 appears to require a "continuous and unobstructed path of vertical and horizontal egress travel from all portions of the dwelling to the exterior . . ."  How does this affect the location, size and configuration of interior doors and hardware in rooms without windows and in hallways? The code authors have drawn a blank.

Would a double-keyed deadbolt in a windowless media room’s interior door obstruct the path of horizontal egress? Yes. Would an interior hallway door’s header height of 48 inches obstruct the path of vertical egress? You bet. How about an interior door width of 12 inches? Time for a diet. These may seem to be far-fetched examples, yet I have encountered each of these conditions more than once. Should an inspector inform a client of conditions that are at least very inconvenient and potentially life-threatening? You decide.

There is one other area in the IRC that applies. The catch-all is the R102.4 Referenced Codes and Standards:

The codes and standards referenced in this code shall be considered part of the requirements of this code to the prescribed extent of each such reference, and as further regulated in Sections R102.4.1 and R102.4.2.

Exception: Where enforcement of a code provision would violate the conditions of the listing of the equipment or appliance, the conditions of the listing and manufacturer’s instructions shall apply.


In short, the equipment—in this case, the door and its hardware—and its installation must meet the condition of the listing and the manufacturer’s instructions.

Installation Issues

With the possible exception of a few strictly hand-made custom doors, all doors are manufactured and come with a warranty. The manufacturers’ warranties are voided if the installation instructions are not strictly adhered to.

Beyond the topics of door-related injuries and emergency egress, door condition and function must be more closely explored. Too often, a binding door or out-of-square door opening is not related to differential foundation movement but, rather, to improper door construction, installation and/or maintenance.

Those in the trades are in agreement that the true test of any framing carpenter is the ability to cut stairs, while the ultimate test of a trim carpenter is his or her ability to hang doors. Notice I used the term “hang” and not “install.” When I entered the home construction profession, we usually hung doors from scratch, i.e., built the jambs, mortised and installed the hinges, bored the locksets, and installed the doors in the rough frame openings. We often also built the doors themselves, if they were of rail-and-stile construction. Today, this is almost unheard of. All but the most high-end custom doors are manufactured and pre-hung in their jambs offsite. The trim carpenters have only to install these shake-and-bake units into the walls. This should be simple enough.

The current home building industry’s need for higher profit margins has necessitated the use of second-rate carpenters and inferior doors and hardware. Unskilled and semi-skilled installers who are subcontracted on a low-bid basis rely upon a high rate of production in order to make a profit. This has resulted in slapdash installation of low-grade doors on a widespread basis. Since most remodeling contractors have their beginnings in the new construction market, this model of shoddy workmanship also carries over into the remodeling industry, and even further to the uninitiated do-it-yourselfers. Add to that the consumer-driven need for more square footage and amenities for less money in new homes and remodeling projects, and many builders and contractors feel forced to cut corners at every possible opportunity.

Proper door operation relies on the laws of physics. Gravity, momentum, inertia, resistance, friction, pivoting, energy, and other laws apply. Sadly, when it’s time to install a door, the rules of physics are not always adhered to. This results in doorways that are misaligned, warped, malfunctioning, and sometimes in need of replacement.

The framing of a door opening must be properly aligned, square and plumb. Door frames must be properly secured to avoid movement. Door hinges must be strategically placed and in line with one another. Door hinge screws must be of sufficient size and length to overcome the shear forces they undergo, once installed. Of course, this assumes that quality materials are used. If not, all bets may be off, regardless of proper installation techniques.

Doors should be checked for warping, delamination, rail/stile separation, self-opening or self-closing conditions, binding, uneven reveal between the door and the jamb stop, hardware operation and condition, etc. Clients should be advised to seek the expert counsel of a contractor skilled and experienced in door installations for remedial options.

Another issue that is universally overlooked regarding doors of all kinds is the finish that is applied. This is not merely an aesthetic concern. Finishing all six edges of any door is required by all manufacturers in order not to void their warranties. The reason is that the exposed wood in these areas absorbs moisture. This, in turn, adversely affects the stability of the wood, causing swelling doors to stick. How often do you see the tops and bottoms of doors that have not been painted or stained and varnished? Do you look?

Publications About Industry Standards

In addition to the various door manufacturer installation instructions, some other industry standards are also applicable. Various home builders’ warranty documents apply. While these may not be easily identified or located for older homes, they are all similar, and together make up a body of industry standards from which to draw. They are readily obtainable for new homes.

Here are some of the most notable:

The Residential Construction Performance Guidelines for Professional Builders & Remodelers, from the National Association of Home Builders:  Though these are voluntary standards, they also serve as the model for most home builder warranties.

Architectural Woodwork Quality Standards, from the Architectural Woodwork Institute: These standards are enforceable only if the designer of the house specifies these standards in the construction contract documents. This notwithstanding, they add to the body of industry standards that apply to doors.

Quality Standards for Architectural Stile and Rail Doors, from the Window and Door Manufacturers Association:  These standards apply to all wood stile and rail doors.

Quality Standards for Architectural Wood Flush Doors from the Window and Door Manufacturers Association:  These standards apply to all wood flush doors.

Other publications address door material and installation tolerances, such as the Handbook of Construction Tolerances by David Kent Ballast, AIA

In closing, there are a couple of publications that may be of interest to students of the game or merely inspectors with a heightened sense of curiosity. Doormaking and Window-Making for Carpenters and Joiners is a 100-year old gem that has been resurrected by the Lost Art Press. Its contemporary counterpart is The Doorhanger’s Handbook by Gary Katz.


The information in this article is limited to the installation of interior doors in single-family residential structures in Dallas, Texas, and the surrounding area. While doors and their installation techniques may vary in different parts of Texas and across the country, most of the issues cited are commonly found in the U.S. and elsewhere. This information is not intended to be the definitive treatise on interior doors but, rather, an overview based on the author’s experience installing more doors during more 40 years in the fields of residential construction and home inspection.

About the Author

Following six years in the U.S. Army, Aaron D. Miller began work as a general contractor in the residential building and remodeling industry in 1975, until becoming a full-time home inspector in 1997. A member of InterNACHI and a Certified Master Inspector®, Aaron is also a TREC-Licensed Inspector and Professional Instructor, a Master TPREIA Inspector, and an ICC-Certified Residential Inspector in five areas.  He is a native of Dallas and has lived in the Dallas suburb of Garland for the past 15 years. A full list of his extensive professional credentials can be found on his website at



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