8 Subfloor Checks Before Carpet Is Laid

Author : TEAM RPM LIMITED | Published On : 24 Feb 2026

Introduction

A properly prepared subfloor can be the difference between a good install and an awful install when it comes to carpet. This will cause visible imperfections and also shorten the lifespan of carpets if the first step is not prepared accurately. Before a new carpet is laid, it is important to check the status of the subfloor. A meticulous inspection will ensure that things are a smoother transition going forward and that a proper, smooth finish can be made a comfortable process. So here are a few important checks you must perform before laying any carpet.

1. Surface Cleanliness

This starts with ensuring that the subfloor is as clean as possible. Any dirt, dust, glue, or muck that may be remaining will affect the comfort and finish of the new carpet. Be sure to sweep and vacuum thoroughly, especially corners and edges. An unsoiled surface allows the carpet to lie flat and look uniform, which is why professional carpet laying services always prioritize proper surface preparation. Over time, even tiny debris is capable of creating bumps or abrasion in well-defined areas, reducing both the appearance and lifespan of the flooring.

2. Moisture Levels

Inspect for any visible moisture or dampness in the subfloor. When dampness gets stuck below the carpet, it leads to the growth of mold or mildew, both of which carry health risks. To determine how dry your subfloor is, run a moisture meter. Both timber and concrete require the site (or the area where carpet is to be laid) to be dry. Repair any leaks and dry the area thoroughly if any damp spots are discovered.

3. Level And Flatness

Look for areas that bulge near the subfloor. An imperfect and uneven surface of the ground will cause the carpet laid above to look bad and wear down quickly. Using a straight edge or level, check for dips or humps. Where there are uneven areas, sand high spots down or use a suitable compound to fill any lower areas. A flat surface helps to avoid wrinkles and prolongs the life of the carpet.

4. Structural Soundness

Check the sub-floor for damage or weakness. Boards should not creak or wobble beneath your feet. Inspect for loose nails or screws because of sound and discomfort. Patch the damaged area and use nails to hold down the loose sections tightly. In turn, a solid base limits motion and provides comfort for anyone who steps onto the carpet.

5. Smoothness And Splinters

Run your hand over the subfloor to check for rough areas, splintering, or nail heads protruding. Poking edges underneath the textile might affect the backing or add lumps. Then, before moving forward, sand down rough spots and remove any sharp objects. This is important as a smooth base will prevent injury and wear the carpet evenly.

6. Old Adhesive or Flooring

Get rid of any old glue or old flooring remnants. The remnants of old glue or underlayment might not allow the new carpet to settle properly and create lumps. Ensure to remove all remaining substances, as even a thin layer contains remnants that can later on become visible. New carpet really should always go down to a bare, clean subfloor.

7. Gaps And Seams

Check in the areas between floorboards or at joints in the subflooring. The main disadvantage of wide spaces is that the carpet can eventually sag or shift. Use appropriate filler to fill all gaps and let it dry completely before carpeting. To look professional, seams should be tight and continuous surfaces are necessary.

8. Height Differences

Verify the height of the subfloor against the adjoining spaces or thresholds. A big difference of heights can cause tripping hazards or look messy when transitioning. Fill in the low spots with leveling compounds to ensure a gentle slope or an at-grade floor slab. Having an even set height provides easier transitions and makes walking safer.

Conclusion

If you want your carpet installation to turn out great, inspect the subfloor and prepare it before calling in the pros. How the carpet looks and holds up all depends on every step of the process, from cleaning to leveling. Missing sound planning will normally lead to poor carpet fitting, but by ensuring these eight checks, anyone can have a carpet that is perfectly fitted to its location, providing a comfortable and beautiful space. Good prep work is essential to ensure that the new floor covering will last for years to come.