Purchasing additional flooring is like insurance since the last thing you want is to be 95% of the way through your floor installation only to find that you’ve run out of floor. At that point, you would need to order more flooring, wait for it to arrive, and then get your contractor back and arrange another appointment.
The additional square metreage ordered is commonly referred to as a “waste factor”. During installation, boards are cut to specifically fit your floor. However, once the board is cut (particularly if it is cut at an angle) you may not be able to use the rest of the board less you have a short board that sticks out like a sore thumb.
In addition, real wood floors often have a lot of character to them as they’re a natural product. Particularly during the installation of lighter hardwood floors, you may not always want that character. So you may find yourself not wanting to use a board that is a little darker than the rest.
Finally, you may want to repair a spot of the floor down the road or you may discover that you really did want to put a floor in that hallway closet after all. Since many manufactures discontinue flooring lines now and then, you might find yourself in a situation where you can’t buy the same flooring. By having it on hand, you insure that you can use it in the future. For this reason we recommend you add 10% to your room size to allow for natural wastage.