1. Case Introduction

The following image shows an oak engineered flooring project in Thailand in June 2024. It is evident that both ends of the flooring have noticeable bulging, which is a typical complaint case.

End bulging can be considered a form of swelling in length after aborbing moisture.  This article will analyze cases of deformation occurring in practical application scenarios.

2. Inspection Record

This batch of products was completed in April 2024. Before loading and shipment, the customer-designated personnel conducted an inspection at the factory. The following are photos of the inspection records.

Installation Inspection
Length Inspection
Width Inspection
Thickness Inspection
MC Inspection

It is evident from the inspection records that the products meet the standards in terms of width, thickness, length, moisture content, and joint flatness.

3. Analysis

As all the products passed the factory inspection, it is inferred that the cause of the end bulging of the flooring results from moisture absorption at the installation site.

To ensure dimensional stability and joint flatness of the flooring, the moisture content is restricted to 7.0% to 10.0% before packing and shipment. If the moisture content is too high, the flooring may result in shrinkage deformation or surface cracking in dry space or humidity fluctuation.

It was the rainy season with high relative humidity in Thailand during installation. This induced the flooring to absorb moisture at the installation site, leading to swelling along the length direction and resulting in end bulging.

4. Solutions

4.1 Soaking up the humidity

Since wood have shrinkage and swelling characteristics, a certain range of bulging deformation is reversible. Dehumidification can be achieved by turning on the air conditioner at the installation site or using desiccants to actively reduce the relative humidity of the space. As the wood desorbs moisture, the flooring will gradually return to flatness.

4.2 Expansion joints

When installing the flooring, a 5mm expansion joint should be reserved at the ends near the corners. Expansion joints are widely used in buildings, bridges, furniture, flooring, and wall finishes. They are the most effective method to prevent deformation from causing damage to the structure.

4.3 Baseboard

In regions with high humidity or arid areas, flooring is prone to shrinkage and swelling. Birch plywood as baseboard material of multi-layer engineered flooring can largely reduce deformation. Compared to eucalyptus plywood, birch plywood has a finer texture, higher strength, and better dimensional stability, thus resulting in less deformation after moisture absorption.

Regarding to the flooring in this case, it used birch plywood as baseboard, but there is still slight warping. To further improve flatness, other methods should be used in conjunction with optimal baseboard configuration.

4.4 Installation Method

The installation methods for flooring include glue-down, nail-down, and floating. This project adopted the floating installation method, which involves laying EVA soundproofing mats under the flooring and directly placing the flooring on the mats. This method is highly efficient but does not constrain the flooring. Therefore, using the glue-down installation method is recommended as it can effectively reduce flooring deformation or displacement.

The above is an analysis of the causes and solutions for flooring bulging at the installation site. Guolian is committed to providing reliable flooring services to our customers.

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