One-Half Inch Is All It Takes to Cause a Fall

by Bruce Montgomery Ph.D. February 13, 2017

One-Half Inch Is All It Takes to Cause a Fall


Even the slightest change in floor elevation can result in a disastrous trip and fall. We expect to raise our feet when we climbing stairs and getting in and out of tubs and showers. When we encounter an elevation change at an entry door and especially between rooms, the result may be a stubbed toe or loss of balance.

Between rooms. The height of the floor should not change between rooms. If it does, then someone made a mistake. When a home is first built, a subfloor is at the same height. The smart builder accounts for different height floor coverings by adding underlayment to compensate for a lower height covering.

A tripping hazard results when a new floor covering is added to one room but its height is different than the height of the floor covering in the adjacent room. This is especially common when carpet is converted to hardwood or tile which can add ¾” or more to the originally height.

Per the Fair Housing Act Design Manual, (page 4.5) “Within the interior of the dwelling unit, thresholds should not be used or they should be thin and installed flush with the flooring surface. If a threshold must be used, it must not have a level change more than 1/4 inch without being beveled or tapered. When a tapered threshold is used, the level change may be a maximum of 1/2 inch. If an interior door threshold represents a change in level greater than 1/2 inch, it must be ramped and must slope at 1 inch in 12 inches maximum (1:12).”

Although the Fair Housing Act was enacted for the design and construction of multifamily housing covered by the Act, it is just as important to be safe in single residential or any other kind of housing.

My advice: When you are replacing a floor covering in one room and it is currently level with the adjacent room(s), keep the height the same. If you plan to change the height by adding tile or hardwood, change all floor coverings to the same level at the same time. This can be done by adding an additional subfloor to a room with a lower height floor covering.

Entry doors. Although we may tolerate and somewhat expect a slight change in floor height when we enter or exit the home, the ideal is for a no-step primary entrance. The Fair Housing Act Design Manual (pages 4.11 and 4.12) offers the following guidelines for the primary entry door:

“If the primary entry door to a dwelling unit has direct exterior access, the landing surface outside the door, as part of the accessible route, must be level with the interior floor, unless the landing is constructed of an impervious material, such as concrete; in which case, the landing may be up to 1/2 inch (but no more than 1/2 inch) below the interior floor of the dwelling unit. However, to prevent water damage, the finished surface outside the primary entry door may be sloped at a maximum of 1/8 inch for every 12 inches.

The Guidelines allow limited changes in levels at exterior doors along accessible routes. In addition to the change in floor level between the interior floor and exterior landing discussed on page 4.11, the Guidelines specify that thresholds at these exterior doors, including sliding door tracks, shall be no higher than 3/4 inch. The Guidelines further state that changes in level at these locations must be beveled with a slope no greater than 1:2.

In the case of primary entry doors where the exterior landing surface is impervious, the exterior landing surface is permitted to be below the finish floor level by 1/2 inch. Therefore, the Guidelines allow an overall change in level of 1-1/4 inch on the exterior side of the primary entry door. Note, however, as already stated, these changes in level must be beveled with a slope no greater than 1:2.”

The ideal primary entrance to allow the safest access into and out of the home is as follows:

  • No step – outside level even with inside level
  • A large landing area of 5 feet by 5 feet or more to allow for maneuvering
  • Covered entry or overhang to protect against weather
  • Non-slip floor surface
  • Proper lighting
  • Easy to grip door handle
  • A shelf or hook on the wall adjacent to the door 12 inches below the door handle to hold packages
  • A grab bar or handrail – especially if there is a step

Stubbed toes and loss of balance due to uneven floor surfaces can be prevented. If you are going to change your floor coverings, remember that carpet, tile, hardwood, engineered wood and laminate are of different heights. With proper advanced planning, you can be sure that your floor surfaces are all the same height.


Bruce Montgomery Ph.D.
Bruce Montgomery Ph.D.


Dr. Bruce Montgomery is a licensed building contractor in Michigan and Florida. He is a Certified Aging-in-Place Specialist as designated by the National Association of Home Builders. He has also achieved an Executive Certificate in Home Modification from the University of Southern California. He has a wide ranging educational background, including a Master of Science degree in Entomology, with a Master of Science degree in Forestry and a Ph.D. in educational administration.