NASCLA Accredited Commercial General ContractorFinishesEasy
A commercial contractor is installing a new floating laminate flooring system in a retail space. The concrete subfloor has been cleaned and leveled, but the project is in a region known for high humidity and potential moisture issues. To prevent moisture from affecting the laminate, what critical component MUST be included in the flooring system installation?
- AA sound-deadening underlayment.
- BAn additional layer of plywood underlayment.
- CA radiant heating system.
- DA vapor barrier.
Show answer & explanationAnswer & explanation
Correct answer: D. A vapor barrier.
A vapor barrier is essential under laminate flooring, especially over concrete slabs or in high-humidity areas, to prevent moisture vapor from migrating upwards and causing warping, swelling, or delamination of the laminate.
Why the other options are wrong
- A. A sound-deadening underlayment reduces noise but does not prevent moisture migration.
- B. An additional layer of plywood underlayment might improve subfloor stability or flatness but does not act as a vapor barrier against moisture from concrete.
- C. A radiant heating system provides warmth but does not inherently address moisture vapor issues.
Vapor Barrier (Flooring)
A material, typically a polyethylene film, installed beneath flooring (especially laminate or engineered wood over concrete) to prevent moisture vapor from migrating from the subfloor into the finished flooring.
- Protects moisture-sensitive flooring from warping, swelling, and mold.
- Essential over concrete slabs, in basements, or high-humidity regions.
- Usually a 6-mil or thicker polyethylene sheet with seams taped.
Memory trick: High humidity, concrete slab? Vapor barrier saves your laminate from going bad.