Wood Floors: Why do They Squeak?

National Wood Flooring Association (NWFA) certified inspector René Rocheleau explains the various possible reasons why wood floors squeak. The expert in the matter classifies the reasons into five major causes: 

1. Friction of the anchor points of the planks in the subfloor;
2. Friction between the anchor points of the subfloor and the joists;
3. Friction between the wood planks of the flooring;
4. Friction between the joists and their anchor points; 
5. Friction coming from the joists themselves. 

1. Friction of the anchor points of the planks in the sub-floor 

Without a doubt the most common cause, this is also the most costly to repair, though so simple to avoid. 

 The main reason for this type of squeaking is related to the anchoring of the wood planks and to the inability of the subfloor to retain the anchors (nails or staples). In this particular case, the noise comes from a vertical movement of the anchor points (nails or staples) in the subfloor.

 It is also possible that the anchors used were too small, or that not enough were used during installation. In this case, the squeaking often comes from where the floor abuts the wall, resulting from a lack of anchors for the final rows.To avoid this type of squeaking, the Mr. Rocheleau suggests to glue the final rows (approximately the last five) and not to put a vapour barrier paper in this area. 

 2.   the anchor points of the subfloor and the joists

 This type of friction happens less frequently than it used to, since subfloors are not glued to joists. This procedure greatly helps to reduce the risk of movement between the anchor points and the joists. To further avoid movement, you can add glue and screws between the two elements. 

 This being said, when we renovate a house where the subfloors are not glued to the joists, the solution is to anchor the subfloor where it isn’t already. 

 3. Friction between the wood planks of the flooring

This is the most difficult cause of squeaking to anticipate, because it is primarily due to a manufacturing defect. So, it is impossible to correct this situation because the product itself is defective.

Installation may also be a problem, either from installing the planks too loosely or too tightly, which means a poor adjustment between the tongue and grooves on the planks. The difference between the two is very simple.

• Loose:the movement comes from the groove of the plank.
• Tight:an isolated cracking sound that rarely occurs. 

 4. Friction between the joists and their anchor points

The floor plank joists are made to adapt to the weight that they will support. As a result, the anchors affixed to them can also move. It is possible to avoid this movement by gluing the anchors to the joists. 

5. Friction coming from the joists themselves

Since the floor joists are made up of several pieces of wood glued together, it is possible that one of them isn’t as well secured as the others and makes noise when it moves. This would create a sound in a very specific place. To correct it, you can glue the floor where the sound comes from. 

 To avoid having a floor that squeaks, Mr. Rocheleau suggests the following:

•  Choose a plywood subfloor which is at least 5/8 of an inch thick;
• An underlayment(pontage) that is screwed and glued to the floor; 
• Add a paper membrane over the underlayment;
• Nail the subfloor every 8 to 10 inches at most.

Overall, according to Mr. Rocheleau, flooring that has been installed according to established norms should never squeak, unless it has been exposed to extreme humidity.