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Board Cuts, Moisture Changes and Cupping

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Cross posted from Howard Brickman's article on Hardwood Floors Magazine: Inspector Blog.

This blog will explore simple moisture content changes of individual S4S RO boards and how that would be related to changes in shape and how that could be related to cupping. But first…

A quick review of the initial article: Cupping = boards that are concave on the face. I have initially proposed six experiments where variables are limited to see which actions cause which reactions. The list of experiments is summarized below, but you can see the more complete explanations in my Dec. 11 blog link.

Experiment 1: 10 S4S RO boards ¾” x 4” x 72” edge-to-edge into a panel ¾” x 40” x 72”. Place and tighten pipe clamps at 3” intervals across the 40” dimension. What happens?

Experiment 2: 10 pieces RO flooring ¾” x 4” x 72” edge-to-edge into a panel ¾” x 40” x 72”. Place and tighten pipe clamps at 3” intervals across the 40” dimension. What happens?
 
Experiment 3: 10 pieces RO flooring ¾” x 4” x 72”, MC 6%-8%, nailed to ¾” plywood with a MC of 6%-8%. Put a wet towel on the face of the boards with 6-mil ploy over towel. What happens?
 
Experiment 4: 10 pieces RO flooring ¾” x 4” x 72”, MC 6%-8%, nailed to ¾” plywood with a MC of 14%-16%. 6-mil poly on underside of plywood. What happens?

Experiment 5: 10 pieces RO flooring ¾” x 4” x 72”, MC 14%-16%, nailed to ¾” plywood with a MC of 6%-8%. 6-mil poly on underside of plywood. What happens?

Experiment 6: 10 pieces RO flooring ¾” x 4” x 72”, MC 14%-16%, nailed to ¾” plywood with a MC of 14%-16%. 6-mil poly on underside of plywood. What happens?

We are going to discuss the effect of a simple change in MC of individual RO boards. Since I did not include this in my original list of experiments, we will call this Experiment 1A. There is a cool graphic in the Wood Handbook that shows shape changes in boards with varying grain orientations:

Wood Handbook Figure 4-3.jpg

(Note that you can download the chapters of the Wood Handbook for free here; you can download Chapter 4: Moisture Relations and Physical Properties of Wood by clicking the illustration above.)

We are going to keep this simple and use a very slow and gradual change in MC with very small differences in MC within the board, which eliminates the effect of having large differences in MC on opposite sides of the board. Again, we are controlling conditions, so that we will only see what happens when a single factor causes the individual boards to change shape. These boards are unrestrained so that we don’t have any additional factors related to installation to worry about.

The intent of this experiment is to see what effect a simple gradual change in MC would have on the shape of individual boards without any other compounding factors such as:

  • configuration of the tongue and groove edges
  • mechanical fasteners along the edges or into the face
  • gluing of the boards to a substrate
  • configuration of the relief cuts on the bottom surface

We can see that changes in shape after individual solid boards are manufactured are to be expected and would vary depending on the amount of MC change and in conjunction with differences in growth ring orientation between the opposite faces of the boards. Quartersawn (radial) boards shrink and swell less than plainsawn (tangential) boards, so if opposite faces have different shrink/swell factors, voila. If just the occasional board is cupping, then it might be caused by a grain-orientation-related effect. If every board is cupping, it is extremely improbable that it is a grain-orientation issue.

Bonus information: Now remember that we are talking about boards that are completely unrestrained (that means not installed). So if you were to allow wide-plank flooring to “acclimate” under high RH conditions, the individual boards would definitely change size (swelling), and there could also be significant changes in shapes. Would the boards be cupped? Yes and no, because flooring is fed into the molder/matcher with the best-looking face as the exposed face, the orientation of grain would be random. Some boards would be cupped (concave) and some would be convex. Unless there was a really big change in MC, these shape changes would probably not be that noticeable other than some complaints from the installers about varying width and difficulty banging the tongue and groove together.

On a separate note, on Saturday, January 21, I am putting on a one-day seminar on Dyeing Dark Floors at the Bona Regional Training Center in Bridgewater, Mass. Topics will include mixing and applying aniline dyes and which finishes can be applied over dye. E-mail me for information. I need to limit the class to 15. Lunch will be served.

What Causes Cupping? Experiment 1 Explained

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Cross posted from Howard Brickman's article on Hardwood Floors Magazine: Inspector Blog.

We are going to start deconstructing some of the variables related to cupping and what many people believe are the causes of cupping.

A quick review of the initial post about this. Cupping = boards that are concave on the face. I have initially proposed six experiments where variables are limited so we can see which actions cause which reactions. The list of experiments is summarized below, but you can see the more complete explanations in my Dec. 11 blog post.

Experiment 1: 10 S4S RO boards ¾” x 4” x 72” edge-to-edge into a panel ¾” x 40” x 72”. Place and tighten pipe clamps at 3” intervals across the 40” dimension. What happens?

Experiment 2: 10 pieces RO flooring ¾” x 4” x 72”  edge-to-edge into a panel ¾” x 40” x 72”. Place and tighten pipe clamps at 3” intervals across the 40” dimension. What happens?
 
Experiment 3: 10 pieces RO flooring ¾” x 4” x 72”, MC 6%-8%, nailed to ¾” plywood with a MC of 6%-8%. Put a wet towel on the face of the boards with 6-mil ploy over towel. What happens?
 
Experiment 4: 10 pieces RO flooring ¾” x 4” x 72”, MC 6%-8%, nailed to ¾” plywood with a MC of 14%-16%. 6-mil poly on underside of plywood. What happens?

Experiment 5: 10 pieces RO flooring ¾” x 4” x 72”, MC 14%-16%, nailed to ¾” plywood with a MC of 6%-8%. 6-mil poly on underside of plywood. What happens?

Experiment 6: 10 pieces RO flooring ¾” x 4” x 72”, MC 14%-16%, nailed to ¾” plywood with a MC of 14%-16%. 6-mil poly on underside of plywood. What happens?

We are going to discuss Experiment 1 in greater detail this week. Here is the expanded description from Dec 11.

Experiment 1: We place 10 S4S red oak boards ¾” x 4” x 72”  edge-to-edge, which approximates a panel ¾” x 40” x 72”. Then place pipe clamps at 3” intervals across the 40” dimension and tighten the clamps until a pressure of 200 pounds per square inch is reached. What do you think is going to happen to the shape of the individual boards?

The intent of this experiment is to see what effect pressure would have on the shape of individual boards without any other compounding factors such as:

  • changes in moisture content
  • configuration of the tongue-and-groove edges
  • mechanical fasteners along the edges or into the face
  • gluing of the boards to a substrate
  • configuration of the relief cuts on the bottom surface

If you were to place adhesive on the edges of the boards before clamping them, you would end up with a pretty good rough panel for fabricating a table top. This is the procedure for making any edge-glued panel out of solid wood (for example, stair treads, shelves, top-bottom-side panels, etc.). A bazillion of these solid wood panels are made this way every week. If the individual boards don’t change shape because of this pressure across the width of the boards, this goes a long way toward refuting the argument that pressure by itself causes cupping. It may be that pressure in conjunction with some other factor(s) may cause cupping. However, based on Experiment 1, which has eliminated all other factors, pressure is not the cause of cupping.

After having proved that cupping is not caused by pressure, we need to start adding some new variables one at a time to see what effect the individual variables have. So, next week we will add the tongue-and-groove to the edges. After all, if you can’t make something happen on purpose, how do you really know what caused it?

Bonus information:
In the Wood Handbook Table 5–3a. Strength Properties of Some Commercially Important Woods Grown in the United States (metric) lists the “Compression Perpendicular to Grain of Red Oak” at 12% MC in the range from 6,000 to 8,600 kPa, which converts to 870 to 1247 psi (Pounds per Square Inch) using the conversion factor of 1 kPa (Kilopascal) = 0.145037738 psi. If the force applied to the pipe clamps is limited to 200 Psi, there should be no crushing where the jaws contact the edge of the panel.
 

What Causes Cupping in Wood Floors?

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Cross posted from Howard Brickman's article on Hardwood Floors Magazine: Inspector Blog.

The official topic of this blog will be an excruciating discussion of the term “cupping” for your consideration. But first…

My apologies for taking so long to get another submission ready, but for me writing is very hard work and extremely time consuming, and I marvel at those gifted individuals who can churn out wonderful written content on a regular schedule. I must admit that I’m not certain that I would be able to increase my output even if I were offered bushel baskets of legal tender to do it on a full-time basis. Time is finite and moves at an increasingly rapid pace. I remember watching the classroom clock as a youngster on Friday afternoons thinking that 4 o’clock would never arrive, and now Friday afternoons pass by faster than the pickets on a fence. But I digress…

If I were going to give an official definition for cupping it would be, “boards that are concave on the face.” There is a common misconception in the wood flooring bidness that all cupping is moisture-related and that pressure that develops due to swelling is the primary cause. Let’s explore some thought experiments.

Experiment 1: We place 10 S4S red oak boards ¾” x 4” x 72” edge-to-edge, which approximates a panel ¾” x 40” x 72”. Then we place pipe clamps at 3” intervals across the 40” dimension and tighten the clamps until a pressure of 200 pounds per square inch is reached. What do you think is going to happen to the shape of the individual boards?

Experiment 2: We place 10 pieces of red oak flooring ¾” x 4” x 72” edge-to-edge, which approximates a panel ¾” x 40” x 72”. Then we place pipe clamps at 3” intervals across the 40” dimension and tighten the clamps until a pressure of 200 pounds per square inch is reached. What do you think is going to happen to the shape of the individual boards?

Experiment 3: We nail 10 pieces of red oak flooring ¾” x 4” x 72” at a MC of 6-8% to a ¾”-thick plywood panel 48” x 72” at a MC of 6-8%. Then we place 1½” deck screws at 3” intervals into the first and the last boards so that they will be prevented from moving. We predrill the oak so that there will be no splitting. Then we place a bath towel on the face of the boards and saturate it with enough water to completely wet the towel but not have water puddling onto the surface of the flooring. Then we put a piece of 6-mil polyethylene over the towel to keep the water from evaporating. What do you think is going to happen to the shape of the individual boards?
 
Experiment 4: We nail 10 pieces of red oak flooring ¾” x 4” x 72” at a MC of 6-8% to a ¾”-thick plywood panel 48” x 72” at a MC of 14%-16%. Then we place 1½” deck screws at 3” intervals into the first and the last boards so that they will be prevented from moving. We predrill the oak so that there will be no splitting. Then we put a piece of 6-mil polyethylene covering the underside of the plywood to keep the water from evaporating. What do you think is going to happen to the shape of the individual boards?

Experiment 5: We nail 10 pieces of red oak flooring ¾” x 4” x 72” at a MC of 14-16% to a ¾”-thick plywood panel 48” x 72” at a MC of 6-8%. Then we place 1½” deck screws at 3” intervals into the first and the last boards so that they will be prevented from moving. We predrill the oak so that there will be no splitting. Then we put a piece of 6-mil polyethylene covering the underside of the plywood to keep the water from evaporating. What do you think is going to happen to the shape of the individual boards?

Experiment 6: We nail 10 pieces of red oak flooring ¾” x 4” x 72” at a MC of 14-16% to a ¾”-thick plywood panel 48” x 72” at a MC of 14%-16%. Then we place 1½” deck screws at 3” intervals into the first and the last boards so that they will be prevented from moving. We predrill the oak so that there will be no splitting. Then we put a piece of 6-mil polyethylene covering the underside of the plywood to keep the water from evaporating. What do you think is going to happen to the shape of the individual boards?

The great thing about these thought experiments is that we could actually do them. If you had a university or commercial testing company do these for you, it would cost many thousands of dollars. If someone wants to send me $12,479.00, I will do the experiments and send you a report on the results with cool pictures. In my next episode we will start to discuss the individual experiments. I want to thank Don Sgroi for the very thought provoking e-mail, which is the inspiration for what will I think be a very interesting series of blogs.

Calculating Shrink/Swell and Why It Matters

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Cross posted from Howard Brickman's article on Hardwood Floors Magazine: Inspector Blog.

Wood shrinks and swells when it loses and gains moisture content (MC). For example, if a piece of 2¼" wide plainsawn red oak flooring were to decrease in MC from 8% to 5%, the net change in MC would be 3%. Using standard values from the Wood Handbook Table 4-3 Shrinkage Values of Domestic Woods, the net change in dimension would be .021" (2.25" x .086 x .03 / .28 = .021"). Expressed as a fraction, .021" would be between 1/64" (.015625") and 1/32" (.03125").

How is this information useful? Let’s take a real-world scenario and show how a quantitative understanding of dimensional change helps us perform an analysis.

SCENARIO:
We look at a wood floor that we installed last year where the customer has called to complain about gaps between boards. As part of our normal procedure, we look at the surface of the floor to see if individual boards are flat, cupped (concave), or crowned (convex). In this case, the boards are still very flat. Then we determine the size, frequency and distribution of the gaps. We note the minimum and maximum gaps, then we eliminate the smallest and largest gaps to describe the range, which characterizes the majority of the gaps (80-90%). In statistics this is referred as “eliminating the outliers." Now we choose several locations where the gapping is the most severe and begin a series of accurate board-width measurements, along with MC of the individual boards. Our results are:

MC of all of the boards is less than 6%. We estimate the MC at 5% based on interior RH for the last three weeks using Wood Handbook Table 4-2 Moisture Content of Wood in Equilibrium With Stated Temperature and Relative Humidity. The widths of individual boards range from 1/64" to 1/32" less than the manufactured width of 2¼". The gaps are located between every board and range in size from 1/64" to 1/32".

Danger! FORMULA ALERT: IF YOU BECOME SHORT OF BREATH, BREAK OUT IN A COLD SWEAT, AND HAVE DILATED PUPILS WHEN YOU READ FORMULAS, please skip this section of the blog. For you brave souls, let’s proceed.

FIRST FORMULA (Change in Dimension)
Δ D (change in dimension) = Manufactured Width x St (Shrinkage factor from Wood Handbook) x Δ MC / .28

SECOND FORMULA (Change in Moisture Content)
Δ MC = [Δ D x .28] / [ Width x St ]

With these two formulas we can:

1 – Predict the amount that a board will swell or shrink (Δ D) and
2 – Estimate the magnitude of change in MC (Δ MC) based on the current width of the board.

IT’S SAFE TO START READING AGAIN. Danger over.

Now it’s time for some SHRINKAGE RULES:

Rule Numero Uno: If a board is less than its manufactured width, it has lost MC since it was manufactured.

Rule Numero Dos: If a board is exactly its manufactured width, it is at the same MC as at the time of manufacture.

Rule Numero Tres: If a board is greater than its manufactured width, it has gained MC since it was manufactured.

Applying Rule Numero Uno, we know that our boards that are smaller than the manufactured width have lost MC. Using the SECOND FORMULA for Δ MC, we can pretty accurately quantify the change in MC.

For boards that are 1/64" narrower than 2¼", the Δ MC is 2.26%:

Δ MC= [Δ D x .28 ] / [ Width x St ] Δ MC= [ 1/64" x .28 ] / [ 2.25" x .086 ] Δ MC= [ .015625" x .28 ] / [ 2.25" x .086 ] Δ MC= [ .004375 ] / [ .1935 ] Δ MC= .0226 = 2.26%

For boards that are 1/32" narrower than 2¼", the MC is 4.52%:

Δ MC= [Δ D x .28 ] / [ Width x St ] Δ MC= [ 1/32" x .28 ] / [ 2.25" x .086 ] Δ MC= [ .03125" x .28 ] / [ 2.25" x .086 ] Δ MC= [ .00875 ] / [ .1935 ] Δ MC= .0452 = 4.52%

If we add the Δ MC to our current 5%, the boards that are 1/64" narrow were originally at 7.26% (5% + 2.26% = 7.26%). The boards that are 1/32" narrow were originally at 9.42% (5% + 4.52% = 9.53%). This allows us to estimate MC at time of manufacture between 7.26% and 9.52%.

I find these quantitative methods to be useful tools when working through the analysis of a wood floor that has evidence of a change (or changes) in MC. In new construction there are frequently several MC changes, starting with the adsorption of excessive moisture from the subfloor, then the eventual drying during the following winter heating season.

Let’s explore how doing all this rigmarole calculating helps with analysis. Let’s change our scenario by a single factor: instead of gaps that range from 1/64" to 1/32", how about gaps that range from 1/32" to 3/64" with individual board shrinkage that ranges from 1/64" to 1/32"? We have already done the calculations on the board shrinkage, but that doesn’t account for the additional size of the gaps. SO… something besides seasonal low interior RH would have to be the cause of the increased size of the gaps. Maybe the flooring was left on the job to “acclimate" and picked up some excessive moisture before it was it was installed? Or… (to be continued)
 

Do You Need An Alibi?

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Cross posted from Howard Brickman's column in Hardwood Floors Magazine: Inspector Blog.

Only a guilty man needs to have an alibi prepared. Well, you are all guilty of being wood floor guys, so let’s get those alibis ready for prime time. And maybe the process of getting those alibis prepped will also provide a framework for preventing the need for an alibi.

Tool/Equipment List:

  • smartphone with camera
  • pin-type moisture meter
  • black Sharpie Marker
  • hammer
  • 6d and 8d finish nails
  • thermohygrometer
  • flashlight
  • spiral notebook
  • pencils and pens
  • string (fluorescent red, blue, green, or yellow)

Stuff To Do (or Not Do):

BEFORE WOOD FLOORING DELIVERY:

  • Do not sign a confession, err, I mean contract provided by the general contractor without carefully reviewing the provisions regarding warranties and terms of payment.
  • Check moisture content (MC) of the subfloor and inspect the crawl space. Use the Sharpie to write the MC readings directly on the subfloor with the date and your initials. Check MC near windows, plumbing, and doors, and by obvious signs of water staining or moisture intrusions. More readings are better. Record the readings in your notebook.
  • Make a label that lists the date, job address, and your name in large block letters for identifying pictures.
  • Take pictures of the high-MC readings with your smartphone. It will automatically time, date, and location-stamp the individual photos.
  • Take pictures of other non-compliant issues (e.g., missing windows or doors, tile saws on subfloor, unvented torpedo gas/kerosene heaters, etc.)
  • Check MC of joists and subfloor in basement and crawl space. Look for water, mold, and mildew, and take pictures.
  • Politely request that the GC or building owner correct any problems noted in a brief and concise e-mail (or using another method that documents the content and delivery of the request).

AFTER WOOD FLOORING DELIVERY:

  • Check subfloor MC again and verify the any problems observed during previous visits were corrected. If not, document them again.
  • Check wood flooring MC on at least 40 boards. Use the Sharpie to write MC and date on the back of boards. Record the readings in your notebook. Reject the flooring if it is outside the range from 6% to 9% MC.

BEFORE INSTALLING THE FLOORING:

  • Verify that you document everything that could negatively impact the wood floor. Use the list from the NWFA Installation Guidelines (the PDF is available free online for all NWFA members).
  • Communicate one last time to the GC if there are any issues. This is the point at which you need to present your disclaimer or waiver document for the GC to sign or at least acknowledge. This can be a delicate time in the job. You may want to tread lightly, because there is a fine line between being a concerned wood floor professional and being a pain in the neck who aggravates everyone else on the job, especially the GC. You know the deal. There are 10 flooring guys waiting on the sidewalk to come in and do the work without even “noticing” the all of the potential problems.
  • If you are called to help out a GC at the “last minute,” take a deep breath and try to figure out why the other floor guy that has been doing his work for the past three years is not available. Is there a money issue? Or what?
  • If you are installing a nail-down solid floor, there are some critical steps that help to inoculate you from problems during an inspection: 1) fasteners every 6”; 2) #15 asphalt-saturated felt; 3) Expansion space around the perimeter of the floor.

The typical inspector will check MC, expansion space, nailing, and will want to see your documentation. If you have done due diligence with your prep work, the chances of a job going South are greatly reduced. If it goes South, you should be certain that a really qualified person performs the inspection. The same qualities that make you a competent craftsman apply to the inspection craft: experience in the wood floor craft, experience in performing inspections, referrals from really knowledgeable people in the industry, and the proper temperament to stand up to the pressure from all of the associated parties. In addition to doing everything right, you have to be able to prove that you did everything right. Here’s to hoping that you never need that alibi. Good fortune favors the well prepared.

Carolina(s) On My Mind

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Cross posted from Howard Brickman's article on Hardwood Floors Magazine: Inspector Blog.

HowardBrickman_SurvivorMan.jpg
I hope that my loyal fans will forgive the temporary lapse in blogging. Hurricane Irene blew through town, taking with her our electricity for almost a week. On the plus side, I got to break out my “Survivorman” skills and lived to tell the tale. Wood has many other uses besides wood flooring. With my handy new Rocket Stove I was able to cut up the fallen branches and heat water for coffee and tea and also cook some one-pot meals.

By the time my power was restored, I was off to Charleston, S.C., to attend a wood floor class organized by Selva Lee Tucker featuring faculty from North Carolina State University. I must say: The class was yet another home run by Lee. With 10 years of instigating wood floor technical training under his belt, Lee has a knack for seamlessly combining hard-core practical and scientific knowledge.

The four-day class was instructed by two North Carolina State wood science professors and a wood floor guy from the Boston area. (Guess who the latter was?) The fee was $495, and those in the know can appreciate what an incredible value that is. It was a sell-out crowd, with over 50 attendees flying in from all over the U.S.

This was the sixth collaboration between Lee and NC State Wood Science faculty, several of which I have attended. Two of NC State’s finest taught fundamentals regarding the effects of moisture on the building envelope. An all-encompassing body of information was presented regarding the effect of temperature on relative humidity, how moisture moves through building components, and how fungi develop when exposed to moisture.

Dr. Phil Mitchell, wood products extension specialist and associate professor, has extensive experience working at major universities (Mississippi State, North Carolina State), and international wood products manufacturers (Weyerhaeuser). Dr. Phil is an acknowledged authority on the wood-moisture relationship with regard to academic as well as practical applications.

Dr. David C. Tilotta, associate professor and housing extension specialist, has a great deal of experience with contamination of buildings from chemicals and water, with extensive research and teaching background at the University of North Dakota and North Carolina State University. Dr. Dave introduced a software program from Oak Ridge National Laboratories that models temperature and moisture movement in exterior wall, floor, and roof systems.

On a personal note, do you remember how intimidated you were by your professors in college? This couldn’t have been further from the case with these two fun-guys who taught about fungi (pun intended). Tilotta and Mitchell are two of the best-natured and engaging college professors, and they took some fairly complex material and made the concepts much easier to digest (another fungi pun). The presentations were excellent, and the ease with which they answered questions worked to support true understanding. I left wishing that they had been my professors when I was an undergraduate (back when dinosaurs roamed the earth).

It has been exciting to see a major university put some effort into supporting the wood floor industry. Those of you out there who need studies, research, or laboratory testing should have the folks at the NC State Wood Products Extension Department on speed-dial. Dr. Phil’s email is phil_mitchell@ncsu.edu.

Last year, I had the opportunity to attend a three-day Wood I.D. class at the NC State Wood Anatomy Lab led by two of the leading wood anatomists in North America. The class was my personal favorite, and I’m hoping that it will become an annual event or at least every other year. I could see myself making a pilgrimage to attend. Even after 33 years in the wood flooring industry, I’m always pleasantly surprised to take away new insights about my specialty.

Stay tuned for my next blog: a step-by-step checklist to minimize installer liability when there are problems on the job.

Ignorance, like Mr. Know-It-All

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Cross posted from Howard Brickman's article on Hardwood Floors Magazine: Inspector Blog.

Do you remember “Mr. Know It All” from “Rocky and Bullwinkle”? Bullwinkle would make some ridiculous remark that was completely wrong, but he said it with ultimate self-confidence and an assertive manner.

Do you know any “Mr. Know It Alls”? You know the type. They use their self-confidence and an assertive manner to bluff their way through every situation. The customers don’t know enough about the wood floor business to know if they are being given the straight scoop… or not. As long as everything goes as planned, the misinformation doesn’t seem to do any harm.

But let’s think about another approach that transforms Mr. Know-It-All into Mr. Knows-It-All. Think about how effective it would be to combine self-confidence and an assertive manner with actually knowing what you are talking about. This is done with some hard work by learning the important fundamentals. It starts by learning the technical vocabulary of 300 words… Learning how to properly spell and pronounce the words and their definitions… Then reading and reading and reading…

“The man who does not read good books has no advantage over the man who can't read them.” — Mark Twain. It’s a little late to be handing out a summer reading list, but here are some good books to put on your recommended reading list.

– Wood Handbook, published by the Forest Products Laboratory (PDFs of the chapters are available free here.)
– Drying Eastern Hardwood Lumber by John M. McMillen and Eugene M. Wengert (also available free on the Forest Product Laboratory website)
– Understanding Wood by Bruce Hoadley (Taunton Press)
– Identifying Wood by Bruce Hoadley (Taunton Press)

E-mail me when you get through these and need some more titles. Don’t get discouraged. Google the words that you don’t understand, or use a dictionary. I think that we still have dictionaries in the 21st century. I have been reading and rereading these and other books for over 30 years, and you never seem to really “Know-It-All”.

The Peril of Using Averages

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Cross posted from Howard Brickman's article on Hardwood Floors Magazine: Inspector Blog.
 
I’m going to start by answering the question Wayne Lee asked in his latest blog post: Wayne, the short answer on this job is NO. The 18% moisture content of the subfloor is the deal breaker. This is a complicated scenario when you toss the crawl space into the mix. You mentioned that the average MC is 18%, and I would like to take this opportunity to share some thoughts about using averages with moisture content. Averaging is a statistical method for making erratic data more uniform in appearance. But averaging also takes accurate data with a great deal variation and mathematically makes it a single number. With variable accurate data this is often quite misleading in that it can hide some very important information. It is much more informative to use the following format to describe accurate data. The minimum is ___. Maximum is ____. The majority of the measurements are in the range from MIN to MAX (which are adjusted to remove the outliers-extremely low or high data).  Let’s look at an example from our friends on Wall Street.

The advertising literature from Amalgamated Super Rich Guy Growth, Income, and Value Fund trumpets an “average” annual rate return of 9% for the past four years 2007-10. But as usual the devil is in the details. In 2007, the ASRGGIV Fund lost 90% of it value, but had returns of 42% in 2008, 2009, and 2010. (-90% + 42% + 42% + 42% = +36% / 4 years = 9%/year). Let’s look at $1,000 invested in January 1, 2007.

$1000 + (-90%) or -$900) = $100 balance on Dec. 31, 2007
$100 + (42%) or $42 = $142 balance on Dec. 31, 2008
$142 + (42%) or $59.64 = $201.64 balance on Dec. 31, 2009
$201.64 + (42%) or $84.69 = $286.33 balance on Dec. 31, 2010

The normal assumption with a 9% average would be that at the end of the four-year term $1,000 would be worth at least $1,360. That “average” IS hiding some very important information. Our original $1,000 is now worth $286.33, for a net loss of $713.67. So you call the fund manager, Kineon Goodhue Beelzebub and demand an explanation to which he replies, “But dude, the average annual return is 9%”. NOTE: Please don’t post any comments that I didn’t compute the annual return in accordance with SEC regulations. Dude, this is wood floor blog, and I am trying to make a point about how averaging may not always be a useful data analysis tool.

Now back to Oak Street from Wall Street. Flooring contractor Harry Picoides takes 30 moisture content readings of the plywood subfloor at a 1,500-foot job. If Harry is using a meter that gives accurate readings, he should evaluate each individual MC reading. For instance, the reading by the slider in the family room is 19% and all of the other readings are between 11% and 12%. This tells Harry that there is a water intrusion by the slider but the remainder of the job is good to go. So he asks the GC to fix the leak and dry out the subfloor. If Harry had averaged the 29 readings of 11% to 12% with one reading of 19% there would be no alert about the high MC location and Harry would be back at the job within the first year doing an uncompensated major repair and refinish.

But we didn’t discuss the issue of the crawlspace and the temperature and RH readings… yet. Wayne, thanks for presenting this scenario which will keep me thinking and writing for the remainder of the summer. Some quick thoughts about temperature, relative humidity and crawlspaces: While we should know and understand how these things work, HVAC contractors and general contractors are responsible for this piece of the puzzle. That being said, we own that subfloor once we install a wood floor over it and ignore high subfloor MC at our own peril and bank account.

Is Believing the Same as Knowing?

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Cross posted from Howard Brickman's article on Hardwood Floors Magazine: Inspector Blog.

Is believing that something is true or correct the same as knowing that a fact is true or correct because of rigorous objective examination? Said another way, “Don’t believe everything you think.” (Bill O’Hanlon.) Does this mean that we should stop thinking? Of course not. But it means that we should develop the ability to think critically and carefully evaluate the information that is presented to us. We all know individuals who can never really make a decision as they agonize over every minute detail of a proposition, so-called “analysis paralysis.” On the other hand, we also know people who will believe anything that they read or hear. This is called being gullible. There is a sweet spot somewhere east of gullible and west of analysis paralysis that thoughtful people search for.

Consensus is an extremely important tool for facilitating agreement. How do we decide which house to buy? Or what to have for dinner? Or how do we manage our private and public institutions? But this whole consensus decision-making process is not the most effective tool for determining actual facts or scientific truth. That’s right! Just because almost everyone “agrees” on something does not necessarily make it correct. We are bombarded continuously with polling data and statistical “studies” that are surrogates for consensus. This constant repetition can be very convincing even when it is not accurate or factual. How do we sift through this avalanche of information and figure out what is true?

Be skeptical! “If you can’t make something happen, you don’t know what caused it.” (Howard Brickman.) The greatest opponents of a good experiment are unknown, uncontrolled or irrelevant variables. It is analogous with trying to pick out the important remark whispered by an individual who is part of a very noisy gathering. If you are not looking directly at them you won’t even see their lips moving. And if you are not within several inches you might not be able to distinguish the words being spoken. Even if you do hear the remark you may not realize how important it is. Scientists often refer to all of this extraneous data as “noise” that drowns out the really important stuff. Once the correct data is recognized and introduced into the collective consciousness, we forget how much effort it took to figure it out.

Don’t believe everything you hear or read on the Internet! As individuals we greatly enhance our ability to recognize good information by developing our fundamental understanding of the physical world around us. But in our wood floor business, we have the added necessity of learning about wood and psychrometrics. Develop the habit of reading and rereading “quality” source materials. That way when someone takes cow manure, forms it to the shape of an apple and paints it red, we will have enough sense to figure out what it really is before we try to make an apple pie with a bag full of bull $#!+.

Dispatch from NWFA Prefinished School in the Big Apple

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Cross posted from Howard Brickman's article on Hardwood Floors Magazine: Inspector Blog.

I just attended a three-day NWFA class on the installation of prefinished flooring in New York City. These classes can be a lot of fun and a great learning experience. Most of us work in a vacuum. By that I mean we work within our own little groups of personal and professional associations. There is a tendency to decide that there is one way to do the work, and those habits become deeply ingrained. These classes are a wonderful opportunity to meet new people, learn some new things, experiment with new techniques, and try some different equipment and tools away from our normal cast of characters. We can also make mistakes without any bad financial outcome. The major limitation is the short time horizon.

This particular class is the first NWFA hands-on training event that I have attended in the last 10+ years, and it was a great deal of fun, with many learning opportunities. Daniel Boone (a real wood flooring contractor from Jacksonville, Fla.) was the lead instructor. If you have never been to one of Daniel’s schools, you owe it to yourself to do it at least once. The corny jokes and skills that Daniel uses don’t get old. As charismatic and skilled as Daniel is, the real star of this event was the host, The New York District Council of Carpenters, Labor Technical College’s floor covering instructor, Ron Zimmerman.

This is the Carpenters’ Union training school in New York City, which is a permanent facility that is similar in size to the typical urban community college. But the similarity ends at the front door. Ron Zimmerman runs the Floor Covering Department, which has jurisdiction over wood floors. There are classrooms, demonstration and work areas dedicated to the installation of wood floors. For union carpenters who want to learn the skills required to work for wood flooring contractors, training is available that is structured to teach the skills and tools of the trade for wood flooring. Knowledge and hands-on is a powerful combination. But we all know that you don’t have a relationship with an organization. It is the people who answer the phone, do the work, and make things happen that we have to deal with.

Ron provides a great deal of support to run these classes in NYC in a manner that is comparable with the training provided in St. Louis at NWFA headquarters, although on a slightly smaller scale. This training partnership between NWFA and The United Brotherhood of Carpenters and Joiners of America is delivering a high-quality learning environment for anyone willing to take advantage of the opportunity. There is another class scheduled for August 3-5, with a few spaces still available, so be there or be square.