Floor Prep Guide

How this guide is made

Every limit on this site is a sentence a manufacturer or NWFA published, read in the document itself and kept with the page it is on and the date it was read. This page says what that record holds and what the site does with it.

What is a row?

A row is one test, one floor type and one document. It holds the document’s own sentence, word for word, the page and section it is on, the figure that sentence gives, any condition attached to it (an adhesive, a grade level, a mitigation step), and the date the document was read. A document that gives different limits under different conditions has one row per condition, and still counts as one document.

What does “verified” mean?

A row is verified when its sentence was found, word for word, in the text of the document as it was fetched on the read date. The document is fingerprinted with a cryptographic hash at that read, a PDF on its bytes and a web page on its extracted text, so a file later replaced at the same address can be told apart from the one that was read. Only verified rows reach a page. Documents whose rows have not been checked this way are listed on the sources page as not yet verified, and nothing from them is shown anywhere else.

Why does a range need two companies?

A limits table shows a range for a floor type only when documents from at least two different companies publish a limit for it, and the row says how many documents it comes from. Two documents from one company count as one source. A limit from one company alone is that company’s number, not a range, so it stays out of the table: the row says so, and the limit is quoted under the table with the document’s name.

Where meters read on different scales, the row does not put them on one range. It lists each document’s figure with its own scale.

What does an empty row say?

A floor type with no published limit stays in the table, with this sentence, where N is counted from the documents read:

“None of the N documents read publishes a limit for this floor type.”

A hidden row would read as “there is no limit”. What the record supports is narrower: none was found in the documents read.

What does this guide never say?

No page grades a report. The guide does not tell a reader that a reading is acceptable, that a slab can take a floor, or that a floor can go down. A wrong verdict can cost a reader the warranty, and the figure that decides it is not on this site. What a page says instead is how far the published limits spread for a floor type, followed by one sentence:

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

Why NWFA and the product document can differ

NWFA’s installation guidelines are an industry guideline for wood flooring. A manufacturer’s installation document is the document for one product. The two do not always agree. Where they differ for the same test and floor type, the page shows both figures, neither weighted over the other, and the product document is the one named as binding.

Where do the procedure facts come from?

How deep a probe hole goes, how long to wait, how many tests an area needs, what the room should be like while a test runs: these are quoted from NWFA’s installation guidelines and say so (“per NWFA’s installation guidelines”). The ASTM standards are named as the methods. Their texts are sold, none was bought for this guide, and no page paraphrases a text nobody here has read.

What is left out