What actually needs to go under vinyl flooring? The honest answer: It mainly depends on whether you're installing click vinyl (floating) or adhesive vinyl (fully glued). This is because both systems require completely different sub-structures. Here's an overview, including a table to help you decide.
Last updated: June 2026
Key Points
- Click Vinyl: level, dry subfloor + possibly vapor barrier + impact sound insulation (unless integrated).
- Adhesive Vinyl: NO underlay, instead primer + leveling compound, then glue directly.
- Always: Subfloor must be clean, dry, and level.
- Vapor Barrier: usually mandatory on mineral subfloors (screed) for click vinyl.
- Integrated Insulation? Then NO additional underlay.
Table of Contents
- The Answer at a Glance
- Under Click Vinyl (Floating)
- Under Adhesive Vinyl (Glued)
- Prerequisite: The Subfloor
- Frequently Asked Questions
- Conclusion
The Answer at a Glance
| Layer | Click Vinyl (Floating) | Adhesive Vinyl (Glued) |
|---|---|---|
| Vapor Barrier | yes, on screed/mineral (unless integrated) | not applicable |
| Impact Sound Insulation / Underlay | yes, unless integrated | no (solid bond) |
| Primer | no | yes |
| Leveling Compound | for unevenness | almost always |
Under Click Vinyl (Floating)
Click vinyl is not glued, but lies freely on the subfloor. Depending on the situation, the following goes underneath:
- Vapor Barrier: On mineral subfloors like screed, residual moisture can rise, so a PE vapor barrier film protects the floor. Some underlays have it integrated.
- Impact Sound Insulation / Underlay: makes the floor quieter and compensates for minor unevenness. Important: It must be pressure-stable, not too soft, otherwise the click connection will suffer. If your vinyl already has integrated insulation, NO additional underlay is needed. Details in the guide Impact Sound Insulation under Vinyl Flooring: When It's Needed and When It's Not.
Under Adhesive Vinyl (Glued)
Adhesive vinyl is fully glued, so there is no underlay and no insulation underneath, but rather a cleanly prepared subfloor. This means specifically:
- Primer: binds dust, regulates absorbency, creates adhesion, see Primer Before Adhesive Vinyl: When It's Mandatory.
- Leveling Compound: makes the surface perfectly smooth, because every unevenness will show through the thin covering, see Leveling Compound for Vinyl Flooring: How to Choose the Right One.
Prerequisite: The Subfloor
Regardless of the system, the subfloor must be clean, dry, load-bearing, and level. Before installation, check three things: flatness (with a straightedge), stability (is it sandy or crumbling?), and moisture (especially with fresh screed). Only when the base is correct can the layers be built upon it. Still unsure whether click or adhesive? Then Click Vinyl or Adhesive Vinyl? will help you decide.
Frequently Asked Questions
What needs to go under click vinyl?
On a level, dry subfloor: if necessary, a vapor barrier (on screed) and pressure-stable impact sound insulation, unless the product already has integrated insulation.
Do you need a vapor barrier under vinyl?
For floating click vinyl on a mineral subfloor (screed), usually yes, to prevent rising residual moisture. Some underlays have the vapor barrier integrated.
What goes under adhesive vinyl?
No underlay and no insulation; instead, primer and leveling compound for a firm, smooth subfloor. Adhesive vinyl is glued directly and fully.
Does vinyl with integrated insulation need an underlay?
No. An additional underlay would make the floor too soft and overstress the click connection. On a mineral subfloor, a thin vapor barrier may still be necessary; observe manufacturer's instructions.
Conclusion
What needs to go under vinyl flooring depends on the system: Click vinyl may need a vapor barrier and pressure-stable impact sound insulation, while adhesive vinyl requires primer and leveling compound instead of an underlay. Common to both is a clean, level, dry subfloor. Browse Click Vinyl and Adhesive Vinyl, or get your free sample in advance.