Floor Prep Guide

The floor tests behind your installer’s report

Before a new floor goes down, an installer or a testing firm may check what is under it: how much moisture is in the concrete or the wood, how flat it is, how the room is conditioned. This guide explains each test, what a complete report shows, and which number or missing item to ask about. It does not grade a report. Who publishes it, and what that company sells, is on the about page.

Why is there no single limit?

The same test carries different published limits from one floor type to the next. The concrete RH probe is the plainest case: these are the limits manufacturers publish in the documents read for this guide, by floor type. Each range spans at least two companies’ documents. The method and the report are on the concrete moisture test page.

Concrete moisture test: the RH probe (ASTM F2170): published limits by floor type, from manufacturers’ documents.
Floor type Published limits Documents Conditions
Rigid core vinyl from 80 to 95 % RH 6 documents 1 2 3 4 5 6 above it the warranty requires moisture mitigation 5 6
Glue-down LVT from 90 to 99 % RH 5 documents 7 8 9 10 11 with Karndean K-99 HM adhesive 7 with Karndean DrySet adhesive 7 with Karndean K-Spray adhesive 7 with Karndean 2-part Epoxy adhesive 7 with K-99HM adhesive 8 with Mannington M-Grip adhesive 9 above it the document requires MS007 or MS009 adhesive 10 with MSI MS001 adhesive, on or above grade 11
Laminate from 75 to 80 % RH 4 documents 12 13 14 15
Engineered hardwood 75 % RH in each of the 2 documents 2 documents 16 17 tests listed as required in residential/commercial applications; if both are run, both must pass 16 stated as ideal conditions 17
Solid hardwood from 75 to 80 % RH 2 documents 18 19 the document lists the tests as required in commercial applications 18 above it: vapor retarder or further curing; concrete under an added wood subfloor; the floor may not be installed directly over concrete 19

Engineered hardwood

NWFA guideline
80 % RH20

above it: wait for drying or install a Class 1 membrane20

Manufacturers’ documents
75 % RH in each of the 2 documents

tests listed as required in residential/commercial applications; if both are run, both must pass16

stated as ideal conditions17

Solid hardwood

NWFA guideline
80 % RH20

above it: wait for drying or install a Class 1 membrane20

Manufacturers’ documents
from 75 to 80 % RH

the document lists the tests as required in commercial applications18

above it: vapor retarder or further curing; concrete under an added wood subfloor; the floor may not be installed directly over concrete19

The limit that binds you is in your product's installation document.

NWFA’s installation guidelines are an industry guideline, not the document for your product. Where the two differ, both are shown above.

Which test is on your report?

  1. Concrete moisture test: the RH probe (ASTM F2170)
  2. Calcium chloride test (ASTM F1869)
  3. Concrete moisture meter
  4. Wood subfloor moisture
  5. Subfloor flatness
  6. Acclimation
  7. Vapor barrier
  8. Radiant heat
  9. Concrete pH test
  10. Old floor removal and asbestos

Which floor is going down?

For each floor type, the tests whose limits manufacturers publish for it in the documents read.

Rigid core vinyl
Glue-down LVT
Laminate
Engineered hardwood
Solid hardwood
References (20)

References

  1. 1 Armstrong/AHF Rigid Core SPC Locking Installation. Armstrong Flooring (AHF). https://www.armstrongflooring.com/cdn/installation/afi/AF-Rigid-Core-SPC-Locking-Installation-System.pdf. Read . ↩
  2. 2 COREtec Pro SPC Residential Installation Guidelines (Shaw/USFloors). Shaw (USFloors COREtec). Revision: 11052024. https://pdmsview.shawinc.com/USFloors/COREtec-Pro/Installation/Residential-Installation-Guidelines-for-SPC-Produc. Read . ↩
  3. 3 Mannington ADURA Max Install Guide. Mannington. rev. 05.16.2024. https://assets.ctfassets.net/r69d9lchftro/qCw4Uqxa3cq2fI1bKVby9/76c789d4ccc805eb4069ffb98068d7b4/ADURA_Max_InstallGuide2024_01F.pdf. Read . ↩
  4. 4 Mohawk SolidTech Installation. Mohawk. Rev. October 2018. https://mohawk.blob.core.windows.net/mohawkflooring/pdf/install/SolidTech_Installation.pdf. Read . ↩
  5. 5 MSI Everlife Rigid Core flyer. MSI. https://cdn.msisurfaces.com/files/flyers/rigid-core-everlife-lvt-flyer.pdf. Read . ↩a↩b
  6. 6 MSI Hybrid Rigid Core Installation Guide. MSI. https://cdn.msisurfaces.com/files/flyers/hybrid-rigid-core-installation-guide.pdf. Read . ↩a↩b
  7. 7 Karndean Gluedown Installation Guideline USA. Karndean. KD80333GLO | October 2023. https://karndeancommercial.com/globalassets/karndean/b2c-blocks/b2c-document-listing-block/usa/installation-guides/karndean-gluedown-installation-guideline-usa.pdf. Read . ↩a↩b↩c↩d↩e
  8. 8 Karndean K-99HM Adhesive Installation Guide. Karndean. 240902. https://www.karndeancommercial.com/globalassets/karndean-commercial/blocks/b2b-brochure-listing-block/usa/install-guides/us-karndean-k99-hm-adhesive-installation-guide-240902.pdf. Read . ↩a↩b
  9. 9 Mannington ADURA Flex Installation Instructions. Mannington. Copyright © 2026. https://assets.ctfassets.net/r69d9lchftro/72wp40QH7Sjze2rfjb2mBs/eda3a968f13c3aebe68000069be092bd/ADURAFlex_Installation_Instructions_2026.pdf. Read . ↩a↩b
  10. 10 MSI Everlife Acclima Glue-Down Installation. MSI. https://cdn.msisurfaces.com/files/flyers/acclima-gluedown-installation.pdf. Read . ↩a↩b
  11. 11 MSI MS001 Adhesive TDS. MSI. revision: 081522. https://cdn.msisurfaces.com/files/flyers/ms001.pdf. Read . ↩a↩b
  12. 12 Mannington Restoration Collection Laminate Installation. Mannington. Copyright © 2026. https://assets.ctfassets.net/r69d9lchftro/4DiXQqXdjMnyAJ4HL02eit/d9d8899188d5e7b4d8d8f0236622add0/Restoration_Collection_Laminate_Installation_Instructions_2026.pdf. Read . ↩
  13. 13 Mohawk RevWood Plus Installation Instructions. Mohawk. https://mohawk.blob.core.windows.net/mohawkflooring/pdf/install/Revwood_Plus_Installation_Instructions.pdf. Read . ↩
  14. 14 Pergo Installation Essentials Guide (Mohawk). Pergo (Mohawk). https://mohawk.blob.core.windows.net/pergo/pdfs/Installation_Essentials_Guide_Combined.pdf. Read . ↩
  15. 15 Quick-Step Studio installation (Unilin). Quick-Step (Unilin). Edition Date: 04/01/2020. https://pdf.lowes.com/installationguides/604743166056_install.pdf. Read . ↩
  16. 16 Bruce Engineered 3/8-9/16. Bruce (AHF). LA-295727-422. https://www.bruce.com/cdn/content/sites/2/210049.pdf. Read . ↩a↩b↩c
  17. 17 Hallmark Engineered Wood Installation. Hallmark. 05-2026. https://hallmarkfloors.com/pdfs/Installation-Instructions-Eng-Wood-WEB.pdf. Read . ↩a↩b↩c
  18. 18 Bruce Solid 3/4" Strip and Plank. Bruce (AHF). LA-295726-120, © 2020. https://www.bruce.com/cdn/installation/212080.pdf. Read . ↩a↩b↩c
  19. 19 Mullican Solid Wood Flooring Installation. Mullican Flooring. https://www.mullicanflooring.com/jm-resources/tech-docs/installation/SolidInstallationInstructions.pdf. Read . ↩a↩b↩c
  20. 20 NWFA Installation Guidelines. NWFA. Revised © 2025. https://nwfa.org/wp-content/uploads/2026/02/NWFA-Installation-Guidelines.pdf. Read . ↩a↩b↩c↩d