There Is a Thumping Sound in the Walls of My House When It Is Cold Outside

Cold Air

• As winter temperatures fall below freezing, the air touches wood on the outside and within the walls of your home. As the wood becomes colder, the moisture within the wood freezes, causing a slight expansion of the wood. This freezing is most readily observed with wooden decks at night in the wintertime.

Warm Sun

• During the day, you may notice that same thumping sound happening again. This time, the sun’s rays are rewarming the wood, causing the moisture to melt and the wood to slightly shrink.

Why the Noise

• As wood expands, it presses against the other boards and especially the nails and screws that are holding it into position. The thumping sound you hear is the wood sliding across its surrounding surfaces as its pressure increases. Over time and after years of wear, the repetitive expansion and contraction of the wood will lead to gaps between wood panels and even possibly mildew under the wood.

Prevention

• While there is no guaranteed way to prevent the noise, there are some steps you can take to reduce it. First, seal any exterior woods with an outdoor wood sealant. By sealing the wood, you are preventing it from absorbing any additional moisture during the wet season which could contribute to further expansion. Finally, insulate inside the walls of your home so that the beams in the walls are less exposed to the cold air.