Monday, April 29, 2013
To Fill or Not to Fill?
By Roy Reichow
I went to an inspection where the client expressed their concern regarding snagging their socks on the wood floor. The inspection showed compressed filler (filler push-up) that was raised above the wood floor surface:
The flooring contractor refinished this floor six months ago and the condition did not exist previously. Who’s at fault? The flooring contractor was the last person to service the floor, therefore he or she carries the liability.
Let’s take a closer look at some aspects of this job:
Sales: Many times when bidding the floor, you are faced with bidding against four or five other companies. Therefore everyone tries to sell themselves and their service to rise above their competitors. One of the biggest statements I hear is, “We’ll make your floor look like new” and trowel fill all the gaps at no charge. The client feels they are getting a premium service for free.
Cause of Concern: The floor was refinished in January when seasonal gapping was taking place, creating many small and large gaps. This would be considered normal. The flooring contractor has to project what dimensional change will take place when installing, sanding and finishing any wood floor.
Cure: The current condition was caused by trowel-filling the wood floor in low-RH season. The floor will have to be re-screened, have stain touch-up on the filler and be recoated at the flooring contractor’s expense.
Prevention: The estimator has to educate the end-user regarding proper HVAC control and seasonal change in the wood flooring. Seasonal gapping is a normal condition. Having an explanation of the results of trowel filling and a photo of filler push-up in your portfolio usually sets you apart from the competitors. On future jobs, there are only three ways to prevent this:
- Wait until high-RH season when gaps close, then trowel-fill all remaining gaps
- Spot-fill only large gaps and leave small ones for normal and required expansion
- Trowel-fill the floor in its current condition with a disclaimer of filler push-up in your proposal and the cost to re-coat floor in August at their expense to correct the condition.
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Tuesday, April 09, 2013
Video: My Thoughts at the End of the Expo
By Roy Reichow
The NWFA Expo in Dallas this year was a great show. Here are my quick thoughts as the show was coming to a close at the Gaylord Texan:
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Monday, April 01, 2013
NWFA’s New ‘Involved Parties’ Definitions
By Roy Reichow
The NWFA has released the 2012 Installation Guidelines, and on page 3 the guidelines now include a statement about “Involved Parties.” This is to help identify the roles of each party when it comes to the wood floor and who is responsible for testing, delivery, acclimation, installation, floor care, etc.
Why was it written? There simply are too many times then someone involved in the sale/delivery or installation of flooring is unaware of what their responsibilities are. Our goal was to identify each level of responsibility so that we can attempt to put a cap on passing the buck. Note that installers are responsible only for flooring installation procedure and site conditions while present on the job.
Here are the definitions included in the guidelines:
Manufacturer: Any individual or entity that physically manufacturers the wood flooring product.
Specifier: Any individual or entity (including, but not limited to, architects, builders, consultants, design centers, designers/decorators, end users, general contractors, flooring contractors, sales professionals) that recommends, specifies, or in any way advises the buyer prior to ordering, purchasing, and/or installing the wood floor products.
Supplier: Any individual or entity (including, but not limited to, distributor, importer) that receives product from a manufacturer and supplies the wood flooring products to a seller or buyer.
Seller: Any individual or entity (including, but not limited to, retail stores, big box stores, internet
sales, interior designers, direct sales) that physically supplies/sells the wood flooring products to the buyer.
Buyer: Any individual or entity (including, but not limited to distributors, homeowners, installers, flooring contractors, general contractors) that is the first to use/handle/possess/receive/deliver the wood flooring material prior to installation of the wood flooring product.
Installer: Any individual or entity that physically installs and places into service the wood flooring product.
End-User: Any individual or entity that physically receives and puts to use the final wood flooring product.
To obtain a copy of the new 2012 Installation Guidelines, contact NWFA at (800) 848-8824 or go to www.nwfa.org.
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Monday, March 04, 2013
Hitchhikers on the Wood Floor Job Site
By Roy Reichow
Through many of our daily jobs, many of us hold off on a final coat until other all other trades are finished. During your final floor prep, though, other trade(s) can sneak across the floor and, unknown to you, leave a grain of sand or two. The next thing you know, you pick up a grain of sand (hitchhiker) with your buffer and this happens…
… one swirl all over your floor. The question is: What is the best protocol for the floor finisher?
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Monday, February 18, 2013
Glass-Smooth: How to Avoid Burnishing & Picture-Framing
By Roy Reichow
Has this ever happened to you? You’re getting the floor ready for stain and the inevitable happens: burnished edges. The next thing you know, the floor is picture-framing when it’s stained. This is a common problem many floor sanders face when they don’t understand the principle of scratch patterns. In many cases, floor sanders will do their final drum sanding on the floor with 100 and their final edge with 100 grit. However, many sanders will use a backup pad under the edger, causing a softer cut. The result? This cut will be equivalent to one grit finer (such as 120) and will polish the edges and close down the grain.
To avoid inspections, floor sanders should either go up one grit for the edger when using a backup pad or drop down one grit on the drum. Secondly, stretching out the paper on the edger will close down the grain. When you are ready to turn the corner on the butt wall, change the paper regardless. Sharp paper usually won’t close down the grain and polish the floor like the one in this photo:
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Tuesday, January 22, 2013
Mold Claims in Wood Flooring
By Roy Reichow
As a wood floor inspector, I was called out to do an inspection regarding possible mold in the wood floor. Upon visual inspection of a light-medium stained wood floor, I could see a definite pattern to the area. Using a floor edger to remove the existing stain and finish, I could clearly see darkening of the grain. However, the area of concern was patterned into a square and confined only to the springwood after edging:
Mold in wood is not confined to springwood alone, and I had suspicion of another source causing this appearance. Upon interviewing the floor sander, I disclosed my floor sanding experience. I explained that either I could do further destructive testing to confirm my findings or he could cooperate with me and disclose what stain color he started with for color samples. He disclosed he had done a sample with Antique Brown, although the floor we were inspecting was a Medium Golden Oak color (about half as dark as Antique Brown). The area where he had done the darker sample on the floor was showing through on the finished floor. The floor had to be fully re-sanded.
This is a common problem many floor sanders run into and are not prepared for. Yet there is a simple answer: building sample panels for stain approval:
Once stain color is approved on the panel, make a final sample on the actual wood floor for acceptance. A second purpose in using the panel is testing the dry time of the stain-coat the panel and try to move the color around; that will tell you if you should proceed on the wood floor or wait another day for the stain to thoroughly dry.
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Wednesday, August 08, 2012
How I Spent My Summer Vacation
By Howard Brickman
It has been a whirlwind of a summer season for me since early in May. This always happens whenever I mix some actual work into my schedule.
This is not to say that consulting and inspections are not real work. But nothing qualifies as real work like dusting off the tools and machines and spending time on a job site installing, repairing, sanding and finishing. You know the deal when you need the “floorman’s special” for breakfast. That’s two eggs over easy, sausage, black coffee, and two extra-strength pain relievers. When you get to a certain age, just being able to put in a decent day’s work is incredibly satisfying.
But enough about me. The really interesting thing I did in July was a nine-day visit to Japan. I have been back about a week and am still not completely over a severe case of jet lag. There is a 13-hour time difference from the Eastern U.S. When it is 8 a.m. Monday morning in Tokyo, it is 7 p.m. Sunday evening in Boston. The non-stop flight time from the Northeastern U.S. to Tokyo is 13 to 14 hours.
My sponsor for this adventure was the Maruhon Company located in Hamamatsu, Japan, which is halfway between the larger cities of Tokyo and Osaka. The experience turned my preconceived notions about Japan and the wood flooring business upside-down. Some quick facts about Japan:
- Land area: 145,902 square miles (California: 155,778 square miles)
- 73% of terrain is mountainous
- Population: 128 million (California: 37.7 million)
- GDP: $5.9 trillion (third-largest world economy)
- Individual single-family houses are typically replaced rather than renovated.
Maruhon has a long history in the hardwood and softwood lumber trade, handling a wide variety of wood products from many countries. In the last 15 years, wood flooring has become their largest product category. They import many construction types and species from multiple countries.
My host was Mr. Noriyoshi Ito, president of Maruhon. He and his staff were amazing—not just in their generosity to me, but in their tremendous knowledge of wood, wood flooring, and the international industry. I would like to give a special thanks to Mr. Ken Goh, their primary flooring buyer. I was also fortunate enough to be assisted in my travels by Elizabeth Baldwin, who writes the Green Blog here. Elizabeth worked for Maruhon for over 20 years, with more than 10 of those years being based in Hamamatsu. She moved me through a bewildering country with ease, explaining food, culture and customs, and keeping me well-fortified with green tea.
The reality at Maruhon exceeds the public image. They walk the walk even better than they talk the talk. And they do one heck of job presenting themselves to their customers. But this is not intended as a puff piece about Maruhon. I was given access to the company headquarters and distribution center in Hamamatsu and their Tokyo Designers Showroom. Additionally we visited a factory that precision-cuts new house framing kits and a number of job sites where wood floors were being installed. It is almost 8 a.m., and I must head over to my local job to put in an honest day’s work but will resume this narrative about Japan until the topic is thoroughly treated.
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Thursday, April 12, 2012
Thoughts as I Travel Home from the Expo in Orlando
By Howard Brickman
I am on my way back home from the 2012 NWFA convention in Orlando and wanted to get some thoughts online before the distraction of being back home starts. It was a lot of fun to be able to say hello to fellow bloggers Scott Avery, Wayne Lee, and Elizabeth Baldwin. But the real news is …
There was a remarkably different vibe this year. A lot of people who had recently been absent were back, and the exhibits looked very busy all day on Wednesday. A number of people commented on how great I looked (which isn't true), which I attribute to the growing optimism about the renewal going on at NWFA. Everyone I encountered was happy to be there, and the negativity that had accumulated in the past half dozen years is gone.
My thrifty travel planning was a rousing success. But I have to admit that it might have been a little nicer to have stayed at the convention hotel/center. Here is the final expense tally:
- My hotel (the Broken Arms _otel—the "H" is missing) was $270
- Air fare $350
- Rental car $110
- Misc $160
For a total = $890. I had several fellow thrifty travelers mention my previous post on this topic and even offer some additional tips on how to further economize. In fact, I was able to save $16.05 on parking Wednesday thanks to a thoughtful tip. :-) That is the first smiley face that I have ever used.
My next effort will be back to our thought experiment on cupping…
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Thursday, April 05, 2012
Going in New Directions
By Craig DeWitt
I have been very remiss in posting blog bits this year. My work has changed and led me in a little different direction. New issues to explore, new people to teach. As my father says, "Too much to do, too little time." My posts and comments over the last couple years may have been a little harsh and pointed at times, and I have never been one to sugar-coat issues. Nor do I shy away from controversy. In all of it, I attempted to discuss some issues that make for better inspections and a better wood flooring industry.
I filled out a personality profile recently. (If you haven't done one, you should. They can be interesting.) Apparently sometimes I follow the rules and sometimes I don't. That may sound disturbing, but it makes sense if you know my background. I worked for about 20 years at Clemson University doing research on issues such as moisture in buildings. Some rules I did follow, such as using the scientific method, filling in time sheets properly, and other university policies and procedures.
But other rules I did not follow. In my research, I uncovered some issues that caused me to investigate further, and even go as far as writing new rules. I helped create what is now called "building science," which has changed a lot of thinking on how buildings work. I then took that approach and information, and tried to bring it to the wood flooring industry. That got me involved with NOFMA and the NOFMA Certified Wood Flooring Inspector program.
Along the way, I have made several new friends and acquaintances, and even made a few people mad. Some quite mad. To those, I apologize. To everyone, I hope my comments, training and other involvement with the wood flooring industry have been beneficial in some form or fashion. I won't be as involved as in the past, at least directly. But I will still do some training, making comments and suggestions here and there, and will always be available for discussions or questions.
A sincere thank you to everyone for your comments, complaints, suggestions, and involvement.
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Friday, March 16, 2012
World Class Networking On the Cheap
By Howard Brickman
It is less than four weeks till the start of this year’s NWFA annual convention. It looks like it will be an improved effort. Truth be told, in spite of all of the whistling past the graveyard from the economists, there is still plenty of room for improvement in the construction business. But here are some things to think about...
- This is a major opportunity to do some world-class networking at the major wood floor event of the year.
- You can attend from the Eastern half of the U.S. for less than $1,000.
More on both of these:
World-Class Networking
Make a list of the manufacturers that you want to get to know. All relationships in business are personal. The more quality relationships you have, the greater your resistance to stresses that naturally occur. If you have preferred brands of wood flooring, finishes, sanding machines, and adhesives, get to know the people who distribute and make them. Otherwise, you are not going to have a chance to get to know the manufacturers who aren’t local. The annual convention is your big opportunity to make and maintain personal connections. If you are good at what you do and a manufacturer needs to give a referral in your area, they are going to call people they know and trust. So plan your time carefully and then try to follow your plan.
NWFA Convention on the Cheap
If you are taking your “main squeeze” to the convention, please disregard the following advice. But if your trip is going to be strictly business, there are a number of ways to reduce your travel expenses. Buy your plane tickets early and be flexible with travel dates and departure times. I just purchased my tickets on Southwest to Orlando from Boston for $345 round-trip. With gas at $4/gallon, I figured the break-even distance for one person to drive to Orlando at 750 miles. If you can carpool, the distance increases for each additional passenger. I am returning home early on Thursday morning to save $125 on my return airfare, plus $95 on my hotel room. Yes. That’s right, $95/night. It’s always better to stay at the main convention hotel. But by the time taxes and other fees were added, the Gaylord was going to be $250/night. I found a Hampton Inn that is a total of $270 for all three nights. And a rental car for $105, plus gas.
Again, it is always better to do the full registration for the convention, but if your budget is really tight, consider the exhibits-only option at a cost of $25 for non-members and $0 for NWFA members. So far the grand total is $828 ($325 + $278 + $105 + $120 = $828). Every penny you spend is a penny of profit that won’t be there at the end of the year.
I look forward to seeing you all at this year’s Wood Flooring Expo. Have a safe and thrifty journey.
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Tuesday, February 14, 2012
The Good Old Days
By Howard Brickman
In 1978 there was no industry-sponsored training or conventions; in fact, there was barely a wood flooring industry. I had just started working at NOFMA in Memphis. Two of us inspected all of the oak flooring mills in the U.S. and did the complaint inspections for those manufacturers. There was a total of 14 manufacturers operating and 12 were full-dues-paying NOFMA members. Hardwood flooring shipments had plummeted from 1.2 billion board feet in 1955 to 75 million in 1982. Here’s a chart from a Hardwood Floors history article (click on the chart for the article with the bigger version) showing the decline:
The NOFMA marketing committee decided to start a wood flooring installation school to replace the rapidly vanishing cadre of wood floor mechanics. So this bunch of manufacturers formed the NOFMA School Committee and picked the junior man in the organization (me) to develop lesson plans with 35-mm slides to illustrate the important steps. It took me months to get everything planned and written and rewritten. March 1979 was our first class. It was a good first effort but something was missing. The missing ingredients were real-world experience, leadership, and a love for the hands-on skills and hard work of the wood floor craft. The next class, in September 1979, became something special when two gentlemen from Dallas and Shreveport were recruited as the lead instructors. Within the next year, a core group of lead instructors formed around Harold Reid and Roland Holder. They were Bill “Mac” McLaughlin, Dick Hradecki, and Warner Tweed. We worked to improve the lessons and course materials, and it was like a vacation for me to participate in the weeklong classes over the next two years.
It is hard to describe the impact on those of us who attended these classes. There was no question that you were getting good, straightforward information that was fun to listen to from men who knew what they were talking about. The ultimate teaching tool is the good example. Roland and Harold exemplified what was possible to accomplish in the wood floor industry. Harold Reid’s legacy lives on in the people lucky enough to have the opportunity to work with and learn from him.
Harold Reid: Gone but not forgotten.
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Friday, January 27, 2012
Fact, Fiction or Opinion (cont.)
By Craig DeWitt
One aspect of an inspection is the background information. This information is usually collected by talking to other parties such as the homeowner, installer or builder. Is this information fact, fiction or opinion? How much of it can be used in reaching a conclusion and cause? If you ever end up in court, you will hear that much of that kind of information is hearsay, and not information you can present. It’s also not something on which you should base a conclusion.
For instance, the builder tells you that he put a vapor barrier under the slab. Now the slab is wet. Can you use the builder's statement to rule out below-grade moisture? You shouldn't, because at this point it may not be fact. Worse even is that the homeowner told you that the builder told her that he put a vapor barrier under the slab. The only way to determine if, in fact, there is a vapor barrier under the slab is to find it out for yourself. Construction photos might work, but cutting a hole and eyeballing the vapor barrier is better.
So basically, everything in the background information is opinion unless you have proof that it is fact or not. In many cases, people don't tell the truth, so some of your background information is fiction. A homeowner once told me that the floors were never wet-mopped. The floor looked like it had been wet-mopped. So I started looking for other possible causes, until the cleaning lady came in and started wet-mopping the floor in front of me.
Sometimes background information can be used, if there is documentation to back it up. Delivery tickets and invoices can support acclimation and installation times. If the homeowner said the floors were left in the house to acclimate for five days, and the manufacturer's instructions call for 10 days of acclimation, can we say the floors were not properly acclimated? Based on her statement, we had better not say, "The floors were not properly acclimated." But we could say, "Based on Mrs. Homeowner's comments, the floors were not acclimated to manufacturer's instructions."
Speaking of which, is acclimation even an issue with the floor you’re inspecting? Or, is it irrelevant (in which case we shouldn't even mention it)? If acclimation is an issue with the floor, does the background information tell us anything? No, the floor tells us whether it was properly acclimated or not.
I rarely use background information in forming a conclusion and cause. When I do use it, I do everything I can to verify that information first. People don't always tell the truth, but floors don't lie. Let the floor tell you what is happening.
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Tuesday, January 10, 2012
Inspector Reports: Fact, Fiction or Opinion?
By Craig DeWitt
Fact, fiction or opinion: In writing and evaluating reports, I am often faced with determining whether something is fact or fiction, or just an opinion. Some "facts," like my "grits come from grit palm" statement from last week's blog, are easy to verify or disprove with a simple web search. On the other hand, we've all faced an unusual name for a product or material, and "grit palm" could be someone's proprietary name for their material.
"The floor is cupped because of subfloor moisture." Is that fact, fiction, or opinion? In my opinion, it could be any of those. In fact, it could be any of those. One of our jobs as an inspector is to collect, analyze, interpret and present data such that we separate fact from fiction. Done correctly, our opinion doesn't really enter into things. Because if you have an opinion, I might have a different opinion.
How about "Using a XXXX moisture meter, the floor was 8% MC, the subflooring was 14% MC and the slab was 80% RH. This exceeds industry standards. The cupping is therefore the result of excessive subfloor moisture." Which of this is fact, fiction and opinion? First, the meter could have read 8% and 14%, but are they actually the MC of the materials? The numbers could easily be false because of the way meters work and how we use them.
Then I dare say that industry standards are opinions. In the opinion of the industry, if you do/don't do this, you will have problems. Some of us have talked about this many times in the past: Just because you violate industry standards doesn't mean your floor will fail. But it can be a fact that you followed industry standards or not.
Then the last statement, "Cupping is the result of…" could be fact, fiction or opinion. If it’s based solely on an industry standard, it is based on opinion (and we inspectors certainly have our opinions). Actually, if it is based on the 8% and 14% numbers, that could be opinion also. A board cups as a result of a top-to-bottom difference in moisture, or possibly, as Howard recently clarified, because of differential movement in a board as it changes moisture content. How about if the MC of the floor and subflooring were still 8% and 14% two months after the floor was disassembled and leaned against the wall? How does that change our facts and opinions?
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Thursday, January 05, 2012
A Closer Look at Bamboo & Palm
By Craig DeWitt
My house has been below 30% RH for over a week now. A couple gaps have opened in my hickory floor, but nothing in the oak floors.
My last post about a floor installed over a slab and this one will set the stage for some upcoming bits about inspections.
A year or so ago, I mentioned seeing palm floors in Fiji. My buddy, Genia, mentioned a palm floor that she looked at more recently in a forum post. Palm is one of those kinds of groups like oak or pine where there are lots of different species in the group. In palms, we have coconut palms (where coconuts come from), and date palms (where dates come from). The SC tree is the palmetto palm. The floor I looked at recently was a grit palm (where grits come from.) If you're not from the South, you may not be familiar with grits. But shrimp and grits are tasty, as are grits with butter or syrup.
Palm wood looks a lot like bamboo, but is big enough that it doesn't need to be glued together to be big enough to use as flooring. Here are photos of the end grain of a piece of bamboo…
… and palm. The pictures are about 10x magnification. Both don't really have growth rings or grain that you would find in typical woods.
The next thing we see will probably be banana wood flooring.
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Wednesday, December 28, 2011
Board Cuts, Moisture Changes & Cupping
By Howard Brickman
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:
(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.
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Monday, December 19, 2011
What Causes Cupping? Experiment 1 Explained
By Howard Brickman
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.
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What's Going on with this Cupped Floor?
By Craig DeWitt
Here's a question related to my fellow blogger Howard Brickman's last post about what causes cupping:
Situation: The wood flooring is cupped with spots that have raised off the slab. The construction from the bottom up is slab, 6-mil poly, two layers of 1/2" plywood stapled together and floating on slab, 15# red rosin paper, 5 & 6" solid red oak stapled to the floating plywood. The slab was 85% RH, the plywood was 14% MC, and the oak was 8% MC. The poly was full of holes from protruding staples.
So, what is happening?
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Sunday, December 11, 2011
What Causes Cupping in Wood Floors?
By Howard Brickman
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.
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Friday, December 02, 2011
When Is Your House Outside the Right Range?
By Craig DeWitt
Friday, December 2, 2011, 9 a.m. in Clemson, S.C.: Conditions in my house were 65 degrees F and 34% RH. It’s Dec. 2 (not even winter yet), South Carolina (classified as a warm, humid climate) and my hardwood floors are exposed to conditions outside what many wood floor warranties and installation and use guidelines allow.
If an inspector showed up then to look at problems with my floors, the report would likely have pinned the floor issues to the house's dry conditions, and therefore owner responsibility. I guess it’s a good thing I have site-finished NOFMA flooring in my house.
So my question today is: When does the RH in your house drop below the 35% RH minimum stated in many wood floor warranties and industry guidelines? Watch your house and let me know.
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Wednesday, November 30, 2011
The Fungus Among Us
By Craig DeWitt
Anyone roller skate these days? I looked at a nice old roller rink recently that would make your teeth chatter. The flooring was cupped pretty badly. The owner made an interesting comment: The floor moved. Or, more precisely, the floor rotated. People skate counter-clockwise. And the force exerted when they made the turns at the ends caused the floor to rotate clockwise. So think about that when you are racking out flooring and doing tongue reversals, and trying to keep the forces pushing the fasteners tighter rather than pushing them loose.
In this situation, much of the problem was related to a wet subfloor. Water from the underside was causing the cupping. And the water was also making the subflooring softer, so fasteners moved more easily. This floor system was very wet. Here's a picture of some fungus I observed under the floor. You can also see a very rusty nail in the upper left corner. We may even have rusted-out flooring fasteners.
Roller skating can be strenuous, which means you warm up nicely… which means you need to keep the place cool for people to be comfortable. And cool isn't a good situation in the warm, humid Southeast U.S. in the summer. Combine that with a big vented crawl space, and we ended up with subfloor moisture issues. The solution is easy, but I don't think the overall repair cost will be very cheap.
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