HOW TO AVOID GAPS, CRACKS AND SPLITS WITH HARDWOOD FLOORING

By Jeff Hosking – Hosking Hardwood Flooring Inc. All Rights Reserved

If the Relative Humidity in the home goes below 30% for any extended period of time which usually happens during the cold, dry heating season, it can cause the wood boards to dry out to less than the original 6-9% Moisture Content. This loss of Moisture Content will cause the boards to contract in size, leaving open gaps between the installed boards. Depending on the severity and length of time of this moisture loss, these gaps can close once the humid spring and summer months take hold and the boards absorb the moisture it has lost during the dry heating season.  Loss of moisture content can also cause the boards edges to curl upward or "Dry" cup. 

The reverse can also happen when excess humidity levels within the home exceed 50% Relative Humidity for an extended amount of time. This usually happens during the humid spring and summer months and can cause the floor boards to absorb excess moisture. This results in the edges of the boards swelling and cupping upward or, in extreme cases, it can cause the boards to swell against each other and to buckle up in areas. Relative Humidity levels higher or lower than the recommended 30-50% range can also cause face checking within the surface of engineered flooring and or checking within the wood surface. Floors that are improperly cleaned or soaked with water or other liquids can also cause these issues also.

PRIOR TO THE FLOORING BEING INSTALLED it is recommended to bring the flooring into the home as soon as it is delivered and to allow the wood flooring to acclimate to its new environment for at least 3-7 days prior to it being installed.  Manufacturers warranties require compatibility moisture readings recorded for both your flooring and your subfloor prior to it being installed. Do not store wood flooring in garages or sheds or where temperatures or moisture levels can vary greatly from where the flooring will be installed. Doing this may cause the 6-9% moisture levels within the flooring at time of milling to change causing excessive twists and bowing within the boards.

To reduce the effects of contraction and expansion within wood flooring we recommend:

1. To purchase a small digital Hygrometer ($25.00) that can give you a daily digital read out of what the Relative Humidity level is within the home. This Relative Humidity should be maintained between 30-50%.
2. When you purchase any wood flooring you need to acclimate the wood to its new environment for 3-10 days or more before it is installed. For nail/staple down floors we also recommend using 15 lb. black hardwood flooring underlayment paper, which slows down possible moisture migration up through the subfloor from damp basements. During installation of the 15 lb. black felt paper, overlap the seams by 4-6 inches.  For floating engineered floors or even Laminate flooring an underlayment pad with a  moisture retarder film attached is recommended. 
3. To help maintain this 30-50% Relative Humidity during the hot humid spring and summer months, you may need to run air conditioning or de-humidifiers.
4. To help maintain this 30-50% Relative Humidity during the cold, dry heating season, you may need to run humidifiers. Homes that have forced hot air heating systems can cause severe dryness within the home and should have a humidification system built into the furnace system. Additional Humidification may still be needed to maintain a healthy Relative Humidity levels.

Using a higher quality engineered wood construction will help to minimize gaps, cracks and splits within the wood and they can withstand a slightly wider range of Relative Humidity level changes before showing problems. It is sometimes difficult to be able to always maintain 30 – 50% relative humidity levels, but if you make a valid effort then you can virtually eliminate or at least minimize potential problems later.   The information contained within this article is only meant to be general information, and not a substitute for any particular flooring manufacturers specifications you have purchased. 

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