Vacuuming the existing carpet before laying down a new layer of carpet is not recommended and generally unnecessary. In fact, it's better to avoid vacuuming the old carpet right before the installation of the new one for several reasons:
Debris and dust: Vacuuming the old carpet can stir up dust and debris, which might settle back onto the subfloor or get trapped between the old and new carpets. This can create an uneven surface and affect the new carpet's appearance and performance.
Uneven surface: Vacuuming might not completely remove all debris or flatten the carpet fibers. If there are any lumps, bumps, or debris left behind, they can cause the new carpet to have an uneven surface, affecting its smoothness and longevity.
Residue and moisture: If the old carpet has recently been shampooed or steam cleaned, there might be some residual moisture left in the fibers. Installing a new carpet on a damp surface can lead to mold and mildew growth and damage the new carpet.
Instead of vacuuming, it's best to follow these steps before laying down a new layer of carpet:
Remove the old carpet: If possible, remove the old carpet entirely, including the padding, to ensure a clean and even surface for the new carpet installation.
Inspect and prepare the subfloor: Once the old carpet is removed, thoroughly inspect the subfloor for any damage or irregularities. Repair and level the subfloor as needed to provide a stable foundation for the new carpet.
Clean and dry the subfloor: Sweep or vacuum the subfloor to remove any loose debris, dirt, or dust. Make sure the subfloor is completely dry before laying the new carpet to prevent mold or mildew growth.
Install new carpet padding: If the old carpet padding is worn or damaged, it's a good idea to install new padding before laying the new carpet. Quality padding can enhance the comfort and durability of the new carpet.
Install the new carpet: Follow the manufacturer's instructions and best practices for installing the new carpet. Proper installation ensures the carpet lays flat and lasts longer.
By skipping the vacuuming step and properly preparing the subfloor and carpet installation, you can achieve better results and prolong the life of your new carpet.