Boen Parkett's oiled natural oak floor installed in a diagonal configuration.

Fig. 1

As with all flooring products, precise measurement by the installer is required to properly layout the floor and determine the focal point of the room in which the wood floor will be installed. Probably the best rule of thumb for determining the focal point is to ask yourself the following: When I walked into the room, what do I see first? And after the floor is installed, where must it look its best and how should the rows of strip and/or plank flooring be laid to look their straightest?

It is highly unlikely that any room will be perfectly square. In fact, it is highly probable that the installation will require “rips” of hardwood flooring strips along the installation’s ending wall line.

The most common installation format for linear hardwood flooring products has always been, and will remain, parallel to the longest wall in the room. In addition, the hardwood flooring strips or planks should always bridge the floor joists in perpendicular fashion when the floor is fastened to an existing subfloor.

Without question, the tedious task of maintaining a straight and parallel installation requires frequent checking. The installer must periodically take measurements as he progresses with the job to avoid a crooked installation. It’s also imperative that he establish precise starter rows at the beginning of the installation. Even simple adjustments can become quite complex once you get within three feet of the ending installation wall line.

Remember, although not considered a patterned product, per se, hard wood flooring strips are precisely milled at a specific width and can contain very distinct grain patterns. In particular, eased-edge prefinished products create a visual line between the strips of flooring for ease of detection by the customer. Any irregularity in the straightness of the wall will become apparent only when the opposite, parallel wall proves your expertise as the final components of the floor are laid.

Fig. 2. "P" denotes the primary line, "S" is the secondary line, and "D" is the diagonal line.

Thinking ahead

As in any business, they will always be new angles to learn. In our industry, those angles are diagonal. The key to a successful diagonal strip or plank flooring installation begins with accurately measuring the room to determine that needed square footage of product including a sufficient allowance for waste. Typically, parallel installations require a 5% waste allowance. Due to the fact that angle cuts of hardwood flooring also decrease the lengths of usable cut-off pieces, a minimum 10% waste factor must be incorporated into your measurements. A qualified and prudent installer will utilize the smallest strip length while still maintaining the staggered end joint requirement of 6 inches between rows.

As with all hardwood for installations, the installer must determine the squareness of the room. Ironically, the only reliable method for determining that is by measuring the room from corner to corner. A truly square room will have two identical corner-to-corner measurements.

The next step for the installer is to establish a diagonal working line in the center of the room. To accomplish this, he must first utilize the 3-4-5 method of establishing the primary and secondary working lines that, in turn, will establish the basic 90º angle (see fig. 1). Once the 90º angle is determined, equal measurements of 4 feet then need to be marked on both the primary (horizontal) and secondary (vertical) lines (see fig. 2).

Arcing marks at 4 feet from both the primary and secondary line on opposite corners will allow you to strike the necessary diagonal working line. Remember that the 45º angle line will also intersect the 90º center point that was established with the 3-4-5 method for creating your secondary (vertical) line.

In addition to establishing working lines, the following practices are also required for the diagonal installation procedure.

1. Secure your first starting row on the diagonal line by blocking with a straight scrap of wood to avoid subsequent movement.

2. Install a slip tongue in the groove of the starter row. This will allow you to blind nail both sides of the starter row and install the flooring in opposing directions.

3. Maintain a ¾-inch expansion space along the wall line on all four sides of the room.

Just like you, Wood or Wood Knot will continue to research and share potential directions for the future of the hardwood flooring industry. Why be “a square?” All we need to do is just find our angle for success.