Generally, it is not recommended to install new VCT (Vinyl Composition Tile) directly over existing VCT, particularly in certain environmental conditions.
For areas located below grade, such as basements or other sub-level spaces, it is specifically advised against installing VCT or Premium VCT over existing VCT or Premium VCT. Adhering to this crucial guideline is essential for ensuring the long-term performance and durability of your flooring installation.
Why Overlaying VCT is Not Recommended
Beyond the specific caution for below-grade applications, installing new VCT over an existing layer generally presents several challenges that can compromise the finished floor:
- Adhesion Issues: The surface of existing VCT might be contaminated with waxes, finishes, or dirt, which can prevent new adhesive from bonding properly. This can lead to tiles lifting, shifting, or developing hollow spots over time.
- Subfloor Imperfections: Any irregularities, indentations, or old adhesive ridges on the existing VCT layer are likely to "telegraph" through the new tiles, resulting in an uneven, unsightly, and potentially uncomfortable walking surface.
- Moisture Management: In below-grade environments, concrete slabs can allow moisture vapor to rise. An existing VCT layer can act as a barrier, trapping this moisture between the two layers. This trapped moisture can degrade adhesives, promote mold or mildew growth, and cause damage to both the old and new flooring materials.
- Increased Floor Height: Adding a new layer of VCT will increase the overall floor height. This seemingly minor change can create significant issues with doors (preventing them from opening/closing freely), transitions to adjacent flooring types, and the fit of baseboards or other trim.
- Structural Integrity: An underlying VCT layer that is loose, damaged, or otherwise compromised will not provide a stable foundation for new flooring, leading to a compromised new installation.
Best Practices for VCT Installation
To achieve a durable, aesthetically pleasing, and long-lasting VCT floor, consider the following best practices:
- Complete Removal: The most effective approach is to completely remove all existing flooring, including old VCT, adhesive residues, and any underlayment.
- Thorough Subfloor Preparation: Once the old flooring is removed, meticulously clean, repair, and level the subfloor. This may involve scraping, grinding, patching cracks, or applying a self-leveling compound to create a smooth, sound surface.
- Moisture Testing: Especially in below-grade areas, conduct accurate moisture tests on the concrete slab. Address any detected moisture issues using appropriate mitigation strategies before proceeding with installation.
- Acclimation: Allow the new VCT tiles to acclimate to the room's temperature and humidity for a minimum of 48 hours prior to installation. This helps prevent expansion or contraction after installation.
By following these guidelines and avoiding the installation of new VCT over existing VCT, particularly in below-grade locations, you can ensure the optimal performance and longevity of your flooring investment.
