Let’s start here by explaining shrinkage for those that aren’t sure. In the construction industry, shrinkage is noted when materials lose moisture or in other words dry out. The material will then shrink or reduce in dimensions.
To give a practical and relevant example, when timber joists are installed in a property, they often have a high moisture content or higher than normal (normal being in the region of 8 to 12% mc). This can be put down to the elements. As a property in being constructed, there will often be a period of time where the property is left open to the elements i.e. no roof or windows etc. This allows rain to enter the property. Thus, certain materials will become wet to differing degrees. Even when the materials haven’t been rained on, simply being exposed to the elements is enough to raise the moisture content.
This isn’t an article assigning blame towards the construction industry. Of course, properties can’t be built roof and windows first.
Shrinkage is a perfectly normal phenomenon in this context.
When materials shrink, they can often separate from another adjoining material and/or warp. Especially timber joists. When timber joists warp, they change shape. To keep within the context of this article, the top of the joists (where the joist meets the chipboard flooring) tilts. This leaves a ‘void’ between the joist and chipboard. Essentially, there will now only be a very small point at which the chipboard is coming into contact with the joist (see picture below). As foot load is applied – on the side where the void is – the chipboard will flex downwards. However, the fixings (nails or screws) will stay where they are. As this independent movement occurs between the chipboard and fixings over a period of time, it’s relatively easy to see how the two materials will rub. This is where one of the classic squeaks happens. The ‘Fixing’ squeak! Adding more fixings or screws does not solve this issue, indeed doing so often increases the noises.
This phenomenon isn’t solely down to shrinkage/warping of course. It’s almost impossible to install every single joist absolutely water level perfect. However, excessive warping/’tilting’ of joists is something we often see on particularly noisy floors.
There are many reasons that cause floors to squeak, but to answer the question ‘Does Shrinkage Cause Floor Squeaks?’. Yes.
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