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Should Flooring Go Under The Door Frame?

Floorboards or floor laminates are typically installed as late as possible in a building project to protect the surfaces from being damaged during construction. The junction of the walls and door frames to the floor requires careful installation to ensure the best finishes.

Floorboards should be fitted under the door frames to ensure the best finish and prevent damp from getting access to the open grain at the bottom of the door frame. A gap must be cut into the door frame for the flooring to be slid into, and the joint filled with caulking.

The best technique to achieve an excellent finish between the door frames and the floorboards or laminates is to lay the floors up to the door frame and establish at what height the gap underneath the door frame is to be cut. Use a Japanese Saw, or an Oscillating Tool to cut the door frame to the correct height. Let’s look at the process for installing flooring under door frames correctly.

Do You Install Door Frames Before Flooring?

The sequence to install drywall, flooring, hang doors, install trim and paint is essential to minimize the need for touch-up repairs or clean paint spills. The best practice for sequencing the installation and finishing of the interior of your building project is to leave the installation of flooring until last.

Once the dry walling has been completed and finished with the undercoat and final coat, the installation of door frames and trim can be done. It is much easier to paint door frames and trim before installation and caulking holes and gaps before a final touch-up paint layer.

NOTE: Leaving the flooring installation until the last possible stage prevents the flooring from becoming damaged or having paint splatter on it. Whether it is hardwood floors, laminate floors or carpeting, cleaning paint of these textured surfaces could be difficult if not impossible.

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The result of this installation sequence is that the door frames will need to be cut to create a space for the flooring to fit underneath it. Trying to cut tiles or wood to the exact shape of the door frame profile is tricky. It is far easier to cut the door frame so that the flooring will slide underneath it.

Gaps that may still exist between the flooring and the door frame can be filled with caulking to prevent dirt and moisture from entering the end grain of the door frame when the floor is cleaned. 

To allow for the expansion or contraction of the wooden flooring, the gap underneath the door frames and quarter-round trim will prevent gaps from developing. Any expansion or contraction of the floorboards will be invisible. 

Considerations When Installing Wooden Floors

The wooden floors will most likely be the most costly finish in most rooms in your house. Selecting the correct type of wood will give the room its most visible and tangible quality. Ensure that you consider the following aspects before commencing with the installation.

The Direction Of The Wooden Floor Boards

To allow for the best appearance of the wood flooring, the angle at which the natural light falls into the room is essential. Ideally, the light should fall along the length of the room and towards the direction of the natural light. Houses in the US are built facing south to allow the maximum sunlight from falling along the east-west path across the sky.

The floorboards should be laid along the longest side of the room and parallel at the door opening. Also, consider the direction of the flooring in the main hallway and other rooms of the house.

How To Match Floor Board Patterns Best

In the case of natural wood flooring or wood laminate flooring, some repetitive grain features may be present that will make each board’s selection and placement important during the fitment process. First, place the boards loosely and move them about to get the best matching of patterns and features.

Decide in which way you want to spread out the natural variations in a way that will best suit the appearance of the floor.

If you have an installer doing the floorboard installation, make sure to agree on this aspect before installation starts. Removing and relaying floorboards are to be avoided at all costs.

Making Sure, The First Line of Floor Boards Is Correct

All the boards that are laid subsequently will be aligned to the first line of boards. If you are nailing, screwing or gluing down the floorboards, check and double-check that the first line is correct and square before proceeding.

An easy-to-use laser alignment tool like this one from Amazon will help make sure that the first line of boards is square and securely fitted before proceeding.

Keep moving up the laser plumb line as you proceed with laying the boards, and make sure you keep your installation remains plumb and that all the gaps between boards are consistent. Ask someone else to double-check your progress and make corrections before using the nail gun or glue gun.

How To Stagger The End Joints Of Your Floor Boards

During the layout of floorboards to match grain patterns, also decide how to stagger the end joints of the boards to achieve a consistent and best-looking result.

Ideally, the minimum distance between end joints should be 250 to 300mm apart (10 to 12-inches). Try to make the staggering of joints random so as not to introduce any unwanted pattern from forming.

The best practice is to consider the staggering of end joints when you do the dry fit layout of the floorboards. Get a second opinion and move boards around before you commence with the final fitment. The removal of floorboards once nailed or glued in place is never easy without the risk of damage to the board surfaces.

How To Obtain Consistent Gaps Between Floor Boards?

Allow small, consistent gaps between floorboards to compensate for potential shrinking and expansion of natural wood floor planks. Ensure that the floor planks that you are laying have been allowed to dry and acclimatize well before being laid.

NOTE: Natural wood will contain some moisture and may expand and contract with the seasonal variations in humidity and temperature. Check all the floorboards for straightness before laying them down during the dry-fit process.

Use a spacing tool to ensure that all gaps are even and consistent over the entire floor. This spacing tool on Amazon is ideal for laying out positions quickly and accurately. Cut curved floor planks straight and use them only along the final edge of the floor where the trim can hide any bowing.

How Much Space To Allow Around The Floor For Expansion?

The natural tendency for wood is to expand and contract as the temperature and humidity vary during the extremes of summer and winter. The same is true for tiling and artificial laminates. An expansion gap of 5/8-inch (16mm) is required around the perimeter of the room.

Plan for the gap to be around all features of the room, like fireplaces and doorways. For natural wood floors wider than six meters, an additional 1 mm per meter of width must be added. Install temporary spacers around the entire perimeter to maintain a consistent gap between the walls and the floorboards throughout.

The skirting boards cover the expansion gap and the quarter-round beading trim fixed to the walls once the flooring has been laid. When butting up against hard thresholds such as fireplaces, tiles or staircases, the gap can be filled with a cork strip to close the gap neatly.

How To Marry Floor Levels At The Door Frames and Thresholds

Maintain the ability for the floorboards to expand around door frames and between rooms with different floor types or levels. The door frames need to be undercut to allow the floorboards to fit underneath them. A threshold must be fitted to cover the gap between the floorboards between the doorway.

Where there is no change in the level of the floors, a level threshold or T-bar strip is used to cover the expansion gap in the floorboards between the rooms. Where the floor levels differ in height and adjusting threshold must be used to accommodate the transition.


The floorboards must be fit into an undercut at the bottom of the door frames to allow for the thermal expansion of the wood. Fitting the floorboards into an undercut will also make for a better-looking finish and be easier to caulk.

The fitment of floorboards is one of the final steps in completing a build. Cutting door frames to allow the floorboards to fit underneath the door frame uprights is best done using a Japanese Saw (Amazon link) or an Oscillating Cutting tool.

Use a floorboard as a guide to ensure that the undercut is at the correct height to allow a good fit of the floorboard.