How to lay laminate flooring on cement
To lay laminate flooring on cement, first ensure the subfloor is clean, dry, and level. Install a vapor barrier and underlayment, acclclimate the planks, and then click them together, leaving expansion gaps around the perimeter. Finish by installing baseboards and trim.
Laying laminate flooring directly over a cement subfloor is a common and achievable DIY project. Cement is a stable base, but it requires specific preparation to ensure your new laminate floor lasts. You’ll need to address moisture and flatness concerns before you even think about clicking the first plank into place.
Before starting, gather your tools and materials. You’ll need the laminate flooring planks, an underlayment (usually a vapor barrier and cushioning layer), a measuring tape, a utility knife, a tapping block, a pull bar, a rubber mallet, safety glasses, a dust mask, and a saw (miter saw, jigsaw, or circular saw).
The most critical step is preparing the cement subfloor. It must be clean, dry, and level. Sweep and vacuum thoroughly to remove all dust and debris. Check for any high spots or low spots. Low spots can be filled with a self-leveling compound, and high spots can be ground down. If your cement is poured directly on a ground slab, a moisture test is essential. You can use a plastic sheet taped to the floor for 24 hours; if condensation forms underneath, you have a moisture issue that needs addressing with a proper vapor barrier.
Install the underlayment
Once your cement subfloor is clean, dry, and level, it’s time to install the underlayment. Most laminate flooring manufacturers specify a particular type of underlayment, so check your product’s instructions. Typically, you’ll need a moisture barrier (a plastic sheeting, often 6 mil polyethylene) if your slab is on-grade or below grade.
Roll out the plastic sheeting over the entire floor, overlapping the seams by at least 6 inches and taping them with construction tape to create a continuous barrier. Run the sheeting up the walls about 4-6 inches, as this will be trimmed later.
On top of the vapor barrier (or directly on the cement if it’s above grade and has no moisture concerns), lay down the laminate underlayment. This is usually a foam or felt material that provides cushioning and helps with sound dampening. Roll it out and cut it to fit the room, butting the seams together without overlapping, unless the manufacturer specifies otherwise. Some underlayments come with built-in vapor barriers.
Acclimate the laminate flooring
Laminate flooring needs to acclimate to the room’s temperature and humidity before installation. This prevents the planks from expanding or contracting excessively after they are laid, which can lead to buckling or gapping.
Store the unopened boxes of laminate flooring flat in the room where they will be installed for at least 48-72 hours. Ensure the room is at its normal living temperature and humidity levels. Do not store them in a garage or basement unless that’s where they will be installed and maintained at consistent conditions.
Lay the laminate planks
Begin laying the planks in the longest, straightest run of the room, usually along an exterior wall. Start with the first plank with the tongue side facing the wall. You’ll need to remove the tongue on the side facing the wall using a utility knife or saw, as it won’t be used.
Place the first plank against the wall, leaving an expansion gap of about 1/4 to 1/2 inch around the perimeter. This gap allows the floor to expand and contract with changes in temperature and humidity. Use spacers between the planks and the wall to maintain this gap consistently.
Connect the next plank by angling its tongue into the groove of the first plank and lowering it. For the short ends, you’ll usually need to use a tapping block and rubber mallet to gently tap the planks together until they are snug. Ensure the seams are tight and flush.
Continue this process, working your way across the room. Stagger the end joints of the planks from row to row by at least 6-8 inches to create a stronger and more visually appealing floor. You can achieve this by using the offcut from the previous row to start the next row, provided it’s long enough.
When you reach the last row, you may need to rip (cut lengthwise) the planks to fit. Measure the width needed and cut the planks accordingly, remembering to leave the expansion gap at the wall. Use the pull bar to connect the last row of planks to the previously laid row, as there might not be enough space to use the tapping block.
For doorways and around obstacles like pipes, you’ll need to cut the planks to shape. For pipes, cut a hole slightly larger than the pipe diameter to allow for expansion. The cut pieces can then be reassembled around the pipe.
Finishing touches
Once all the planks are laid, trim the excess underlayment that extends up the walls. Install your baseboards and quarter-round molding to cover the expansion gaps around the perimeter of the room. Ensure the baseboards are nailed to the wall studs, not into the laminate flooring itself, to allow for movement.
If you have transition strips (like T-molding or reducers), install them at doorways or where the laminate meets another type of flooring. These strips also need to be installed according to the manufacturer’s instructions, typically screwed into the subfloor through the underlayment.
Common Mistakes When Laying Laminate on Cement
| Step/Tool | Typical Mistake | Consequence |
|---|---|---|
| Subfloor Preparation | Skipping moisture test or not addressing unevenness | Buckling, warping, mold growth, or squeaking floors |
| Underlayment Installation | Overlapping seams of vapor barrier, or not using one when needed | Moisture seeping through, damaging the laminate and subfloor, leading to mold |
| Expansion Gaps | Not leaving adequate gaps around walls and obstacles | Flooring buckling or lifting due to expansion in temperature/humidity changes |
| Acclimation | Installing planks immediately after delivery without acclimation | Planks shrinking or expanding after installation, causing gaps or buckling |
| Cutting Planks | Cutting too close to walls or obstacles | Inability to achieve a tight fit, visible gaps, or flooring pressing against surfaces |
FAQ
What is the proper expansion gap for laminate flooring on cement?
You should leave an expansion gap of approximately 1/4 to 1/2 inch around the entire perimeter of the room. This includes walls, doorways, cabinets, and any other fixed objects.
Can I lay laminate flooring on a concrete slab that has radiant heating?
Yes, but you must use a laminate product specifically designed for radiant heating and follow the manufacturer’s guidelines carefully regarding subfloor preparation, underlayment, and acclimation.
How do I know if my cement subfloor is dry enough for laminate installation?
Perform a moisture test. A simple method is to tape a 2 ft x 2 ft piece of plastic sheeting to the concrete for 24 hours. If condensation forms on the underside of the plastic or the concrete appears dark, it’s too wet. You may need a vapor barrier or more time for drying.