WOOD FLOORING EXPECTATIONS

1. What to expect from your new wood flooring
2. Wood specie hardness and stability
3. Effects of ultraviolet exposure on wood flooring
4. DIY vs. professional
5. Solid vs. engineered wood flooring
6. Prefinished vs. site finished wood flooring
7. Crawl space vs. basement
8. Subfloor framing considerations
9. New construction installations
10. The moisture meter

WHAT TO EXPECT FROM YOUR NEW WOOD FLOORING
( transfer of moisture )

Unlike the brick, drywall, or roofing on your home, the wood flooring installed on your floor is breathing.  Yes, it is alive!  The very product that creates the warm homey feeling that you walk across every day, which should last the life of your home, is constantly in change.  Wood is hydroscopic, comprised of millions of tiny open cells which are like sponges.  Depending on moisture in the air, wood fiber is either accepting moisture and growing in dimension, or dissipating moisture and shrinking.  This process is similar to a person inhaling and exhaling, except wood flooring is transferring moisture, not oxygen.  In most parts of the country, wood flooring is inhaling (accepting moisture) in the spring and summer, and exhaling (dissipating moisture) in the fall and winter.  As this occurs, dimensional change takes place potentially resulting in edge compression and swelling in the humid months, and shrinkage resulting in gaps between boards in the dry months.  And this action is not limited to finish floor boards, it also affects the very framed structure the boards are attached to, which compounds the movement. In many wood framed homes, large gaps between floor boards develop over central framing beams in the winter.  This is where two independent floor joist systems meet, and instead of shrinking from the exterior walls, they pull apart slightly at an interior junction. As well, where warm air is forced through floor vents, the vent slightly restricts airflow and forces super-heated air down the tongues and grooves of individual boards, causing gapping around the vent. During the heating season, some of this may be minimized by use of humidification (adding moisture back into the air), however, when outside temperatures are cold, and heat is introduced for comfort, solid wood is going to shrink, and the wider the board, the larger the gap.  Normal seasonal shrinkage is defined as a gap in the heating season which closes during the humid months.  A dime-size gap between 2 ¼” solid floorboards is considered a seasonal gap if it closes in the summer.

WOOD SPECIE HARDNESS AND STABILITY

Although over 90% of wood flooring produced today is red or white oak, many other options are available for you flooring.  American walnut has become a popular option because of its warm rich brown tone and beautiful patina with age.  But how does the specie desired affect the long-term performance and appearance of your new floor?  All wood floors scratch and dent (compress). The finish on your floor is just as hard as the wood under it.  Do not think for a second that more finish will make your wood floor harder.  It just doesn't work that way. Most polyurethane finish systems perform best with only one to three coats applied to unfinished flooring.  If you desire a floor that does not scratch, then consider laminate, a composite material with an image of wood on top.

The domestic hardwoods in order of hardness, from softest to hardest are as follows: AMERICAN CHERRY, AMERICAN BLACK WALNUT, RED OAK, BEECH, ASH, WHITE OAK, MAPLE, and HICKORY.
Exotic species are generally much harder than domestics, are more costly, and offer fewer color options.  Most exotic species are dark. From softest to hardest are as follows: AFRICAN MAHOGANY, TEAK, AUSTRALIAN CYPRESS, SAPELE, ROSEWOOD, TIGERWOOD, SANTOS MAHOGANY, BRAZILLIAN CHERRY (twice as hard as domestic oak), AND BRAZILLIAN WALNUT (IPE).
Other common wood flooring species include BAMBOO, RECLAIMED ANTIQUE HEART PINE, CARRIBEAN HEART PINE, WHITE PINE, and SOUTHERN YELLOW PINE.  Vertical and horizontal bamboo are similar in hardness to oak, but the newer stranded bamboo, which offers a completely different look, is extremely hard.  Reclaimed antique heart pine and Caribbean heart pine are about as hard as oak, but white pine and southern yellow pine, although used in some restaurants, are extremely soft.

http://en.wikipedia.org/wiki/Janka_hardness_test

This may be too technical for most selecting a wood floor specie, but everyone needs to be aware that all species were not created equally.  The differences you can expect between specie may be noticed in the depth of compression marks in the wood from dog claw scratches, a pot being dropped on edge in the kitchen, or the depth of high heel compression marks from a guest with worn off heel caps. Compression will occur, but the depth of the compression mark is determined by hardness of specie.  Normal wear scratching and finish sheen-down is pretty comparable regardless of specie.

As discussed, solid wood flooring expands and contracts as humidity levels change. Species differ in stability as they do in hardness, and the wider the plank, the larger the seasonal gap will be in the heating season.  Antique heart pine and American cherry are the most stable with respect to seasonal movement.  Oak, walnut, and ash are average, but hickory and beech are the most unstable of domestic hardwood species.  Don't allow wood flooring stability to affect your specie selection though, the differences are minor.  As an example, comparing 4” American cherry to hickory, in the dead of winter when the heat system is cranking, a large seasonal gap in the cherry flooring may be the width of a dime, and the gap in hickory might be the width of a penny.

EFFECTS OF ULTRAVIOLET EXPOSURE ON WOOD FLOORING

Just as high sun exposure accelerates the wrinkling of human skin, causes fading of painted surfaces, and breaks down plastic, its direct rays can wreak havoc on interior floor finishes.  Even indirect sunlight will cause fading and discoloration of finishes, and the damage is not limited to the finish system.  Even after floor finish is sanded off by commercial floor equipment, rug lines are still obvious, but more subtle.  The two species which are the most sensitive to UV exposure are AMERICAN CHERRY and BRAZILLIAN CHERRY.  These woods, though some of nature’s most beautiful, darken drastically when exposed to sunlight.  It is well advised for consumers not to place rugs on these floors for a year if the rooms are exposed to direct sunlight. 

Consider the effects of UV exposure when adding an additional room of prefinished flooring of the same color or adding a custom finished wood floor with the same stain as before, it will not be a great match at first, but with time, may age to match.  This image was taken of a custom finished floor with Duraseal stain, two coats of Poloplaz gloss polyurethane, and thirteen years of direct morning sun exposure.

Shadow line is result of UV exposure

DIY vs. PROFESSIONAL

Twenty years ago, a homeowner attempting to install and sand wood flooring was almost unheard of.  Installation and sanding equipment was hard to find, and information on how it was done was even more difficult to come by. Then came the big box stores with rental machines, promoting do-it-yourself and “save big bucks”, even scheduling “how-to” workshops to teach potential customers the bare basics. Then evolved the world wide web which offered not only countless sites for purchasing wood flooring, but almost as many with instructions, videos, and technical information. Now many handy homeowners get an estimate or two, sit down at the kitchen table, and do the math. “Honey, if I buy this prefinished wood flooring online and install it myself, we will save enough to buy that new flat screen for the den.” What a temptation!

Yes, there are some real deals out there if one has all the facts, and many times a homeowner can successfully complete a floor project with most expectations being met, but buyer beware! If the deal sounds too good to be true, use common sense, it probably is.  If you must buy online, most importantly, talk to a salesperson and get all the facts about what you want to purchase, preferably someone who has installed wood flooring previously. There may be some critical issues you have overlooked.

What is the moisture content of the flooring being purchased, and how long does it need to acclimate before installation?
What is the average board length?
Is the product mismilled?
Running inventory or closeout? Will I be able to buy more later?
What will one more carton cost me if I run short?
Can I return unopened cartons, and what is the restock fee?
If I have a problem, will a representative come to my jobsite?
Will the material be dropped of at the street, or placed in my jobsite?
Am I dealing with a BBB accredited business, and what is its track record?

Installation of wood flooring is physically demanding, and will in all probability result in a sore back and stiff legs.  You will use muscles that you haven't used in many years.  Listen to your body, if you don’t, your boss will be calling Monday morning wanting to know why you are not at work. Although installation of wood flooring requires very basic carpentry skills, it does require the use of some dangerous power tools; miter saw, jamb saw, table saw, and possibly a router.  The last thing a homeowner wants to do is start the weekend working on a new floor and end it in the hospital.  Don't take these tools for granted, they are very dangerous and can cause permanent injury! Is losing an eye or finger worth saving $1500.00?  Know your limitations, and use common sense! If you have never used a table saw, this is not the time to experiment.

Sanding a wood floor has become much easier for homeowners with the introduction of some easy-to-use sanders.  Even though the square buff doesn't do a great job of leveling unfinished floor boards, it is a great finish sander.  From start to finish on a new unfinished floor, it will take much longer to sand using a square buff, that an EZ 8 belt sander and edger.  But with a belt sander, you will have to be careful not to leave drum hollows (dips) in the wood.  Unfortunately, you will not see the hollows until the first coat of floor finish is applied. Do not expect your sand and finish job to look professional!  It is sometimes hard for a person to justify sanding his or her own wood floor because of the economics.  By the time all the appropriate tools are rented, and all the finishes, solvents, applicators, sandpaper, screens, rags, scrapers, and there is always more, why not pay a professional with dust containment and be done with it.  And this is assuming you get it right the first time. What if you have to resand or recoat some areas? How about the dust and vapor?

After almost 25 years in the business, here is my advice for installing and/or sanding new or refinishing existing hardwoods:

Get 2 or 3 bids, preferably from contractors referred by your friends or family.            
Pay for dust containment floor sanding if in your budget.
If you want to save money and complete yourself, estimate the total cost of wood products, supplies,  and your time.
Evaluate your limitations, comfort zone, and schedule.
Only install wood flooring if you have experience with power tools.
Do not sand your own wood flooring just to save money.
Put it on paper, remembering that wood flooring contractors do this every day.

SOLID vs. ENGINEERED WOOD FLOORING

Years ago, only solid ¾” flooring was considered a lifetime floor, not engineered (multiple layers of wood glued together with the desired specie on top).  That has changed.  Some of the engineered sold today has a top wear layer as thick as the sandable surface on solid ¾”, so that product can now be sanded and finished multiple times.  The thicker the wear layer, the better the value.  Who wants to prepare a house for sale and find out from the flooring professional that the engineered floors throughout the house cannot be resanded.  The following should be considerations when choosing between solid and engineered wood flooring:

Solid wood flooring

Prefinished or unfinished
Less expensive in the unfinished
Sensitive to humidity gain or loss, can shrink, swell, resulting in finish fracture
Will cup over a crawl space with excessive moisture
Cannot be installed below grade ( basement )
Must be nailed or nailed and glued
Can be nailed over screeds on concrete
Very solid feel under foot
Better insulating value
Heavier per square foot, more costly to ship
Individual cartons may exceed 70 pounds
Lifetime floor, can be sanded and finished numerous times
Can withstand minor water leaks with no need for repair
Requires proper acclimation

Engineered wood flooring

Prefinished or unfinished
Unfinished is almost as expensive as prefinished
Dimensionally stable, not very sensitive to moisture or humidity fluctuations
Can be installed above, on, or below grade
May be stapled, floated, or glued, but glued will result in a more solid feel under foot
Less insulation value
Lighter weight, less costly to ship
Not as water leak friendly, can delaminate with short exposure
Sliced face looks like solid, but rotary peeled has very wide grain
Life of floor is dependent on thickness of top wear layer
More environmentally friendly, less desirable woods can be used under top layer
Generally produced in shorter lengths
Acclimation required, but not as critical

PREFINISHED vs. SITE FINISHED WOOD FLOORING

For years, prefinished flooring was considered by the masses as a less expensive substitute for wood flooring. A real wood floor was one that was installed unfinished, then sanded and finished to a customer's preferred stain and polyurethane or wax finish.  With technology, that has all changed.  Today's manufacturing facilities offer a host of precision-milled floor boards from prefinished engineered reclaimed distressed heart pine to prefinished cabin grade gunstock red oak.  If you can imagine it, it probably exists. And the prices are all over the board, prefinished solid hand-scraped stained hickory flooring retails for $15.00 per square foot, while solid cabin grade oaks can be purchased for a little over $2.00 per square foot.  And with that same technology, finishes have improved to the point where manufacturers are offering 50 year residential wear-through warranties.  There is no wonder that prefinished flooring has overcome unfinished flooring's market share in a few short years.  If you purchase prefinished today, you can go to work in the morning and return home to a completed wood floor with no dust, no fumes, and the finish is totally cured!  Consider these points, though, before making a final decision:

Prefinished flooring

About the same cost installed as site-finished
Most products are micro beveled on the edges (square edge would create overwood, a sharp edge that can snag a sock).
Available in aluminum oxide and ceramic finishes, those that boast 50 year warranties
Board replacement is relatively easy
May be recoated, though may void finish warranty
Most may be refinished, depending on wear layer if engineered
One day completion, after proper acclimation
Solid flooring under moisture compression may develop finish fractures, small white lines running with the grain
Not quite as suitable in new construction because of contractor traffic damage, higher moisture levels
Hand-scraped prefinished flooring will wear irregularly, dulling on the high spots, especially in the kitchen and other high traffic areas

Site-finished wood flooring

Available in widths from 1 ½” to 20+” boards, and specified long lengths
May be plain sawn or quarter sawn, and of any specie
Finished with any stain color, finish type, and in any sheen level
Can be recoated, provided the proper cleaner has been used
Flooring can be installed under cabinets during construction
After flooring is installed, construction traffic will not harm flooring
Time must be allowed for stain and finish drying and curing during construction
Sanding process may produce massive amounts of fine dust, unless dust containment is used during process
The finished product will not be like a table top, will contain some finish flaws (puddle, dry spot, ridge)
Floor finish will contain some debris (trash in finish, possibly an insect or human hair)
Site finished floor will contain sander swirls, minor dips, and other imperfections
Fireplace borders, room borders, medallions, and custom flush mount vents are easy to install

CRAWL SPACE vs. BASEMENT

There are two types of constructed floor systems, slab and framed. Framed systems may be over a heated basement, unheated basement, typical crawl space with ground cover and foundation vents, or an encapsulated crawl with no vents but controlled air. 

Most moisture related flooring complaints are those involving a typical crawl space, and the primary reason is imbalance of relative humidity (moisture).  The air in the typical crawl is uncontrolled.  Ground cover, the plastic sheeting which is supposed to prevent the rise of capillary moisture from the earth to the house, is not always completely covering the soil, might be torn, may not be overlapped, and sometimes may be holding water. And even if the ground cover is in great shape, guess what comes migrating through the vents into the crawl in the summertime?  You guessed it, high humidity!  When the relative humidity rises in the crawl space and remains constant and comfortable inside the house, the result is an imbalance.  This deviation is easily observed in the form of wash boarding or cupping in the floorboards, and to verify this, a small battery-powered tool called a moisture meter may be used.  As little as 4% difference in moisture content between the top of the flooring and the underneath of the subfloor can result in cupping.  Though, this is not an unnatural occurrence.  This takes us right back to the dynamics of moisture and the relationship of its migration into the building products making up the home.  But how could my floor cup with felt under it?  Simple! Felt is asphalt saturated building paper; it is a retarder, not a barrier.  It only slows moisture transfer.

If solid unfinished or prefinished wood flooring is installed over a crawl in an existing house, proper acclimation is critical.  Sometimes even an experienced flooring contractor has difficulty.  If the underneath side of the subflooring reads 16% MC, what does the new wood flooring need to be?  At least 12%!  How does someone bring in 8% flooring and get it to 12 – 13% MC?  This is why many of these floors cup.  Once cupped and stable, corrective sanding will set the stage for long term performance.  The reason the unfinished floors installed during the original construction did not cup is because they were installed during moderately high moisture conditions, went through compression set, then relaxed after HVAC was turned on. The original flooring had already accepted and dispersed lots of moisture, reducing the tendency to grow, even in the summer months. 

Light cupping should be acceptable over conventional crawl space construction.

Basement construction is seldom the culprit for unfavorable wood flooring performance because the air above the slab in a basement is much dryer than that in a crawl, and if an imbalance does exist, a dehumidifier can promptly draw any undesirable moisture in and out of the house.  The most common performance issues over basements occur when flooring is installed too dry(6%) and too tightly, or hairline cracks aren't left during wintertime installations. (If flooring is installed tight in the winter when flooring should contain seasonal gaps, what will happen when relative humidity rises in the summer?) You guessed it again!  I think you get the picture now.

Crawlspace encapsulation is a relatively new building technique, and with time, this system will become more popular each year.  Most homeowners would not want to stick their head in a crawlspace, much less actually enter it. Attics aren't so bad, but who wants to dress in old jeans, pack a flashlight, and literally crawl under the house with potentially uninvited guests like spiders, snakes, mice, raccoons, or God forbid, a skunk! And you might want to hold your breath, because the insulation fiber and musty smell can't possibly be good for you to breathe.  And stay away from the mold flourishing on the floor joists!  Forget it, I'll call a plumber, He can go down there!

Encapsulations are wood floor friendly if performed correctly.  Wood flooring cannot cup if the moisture content underneath the subfloor is equal to or nearly the same as the top surface of the flooring.  Here is how it works:

First, the ground in the crawl must be graded smooth.  Crushed stone and a sump pump with float switch may be installed in the lowest area.  Then the foundation walls are insulated with foam boards or closed cell foam.  Any previous vent opening must be blocked off air-tight.  Then a vinyl-reinforced poly sheeting material is installed on the ground, exterior foundation walls, and structural piers. The pieces are permanently seamed. Now the air in the crawl space is completely sealed off from the outside of the house. Some systems are maintained with dehumidifiers, others are controlled with air forced from the HVAC system creating positive pressure, and some are controlled by recirculating air from the living space through the crawl. There is no need for insulation between crawl space and lower finish floor because the crawl is now totally insulated, and potentially heated and cooled.  No more pests, no frozen water pipes, no mildew, no standing water, no more high moisture contents and rotting joists, and goodbye to cupping forever (provided air quality is maintained)!

Encapsulated crawl space 7% MC floor joists!

SUBFLOOR FRAMING CONSIDERATIONS

Subfloor components have evolved parallel with other building products in the construction industry. In the eighteen hundreds, finish floor decking up to 1 ½” in thickness was installed directly over floor joists.  Today, many of those floors (predominantly pine, poplar, and ash) are still serviceable and are refinished on a regular basis.  In the early 1900's most floor systems were decked with 1 X 6 square edge pine boards installed over the floor joists on diagonal. Plywood became  the common decking in the mid-1900's, and in the 1980's, less costly strand board (pine chips glued together under pressure) came onto the scene, and to this day is the decking of choice by the masses. Not long after strand board became popular, engineered joists were introduced and were a big hit with engineers because they could span wider areas than conventional pine joists.  One type of engineered joist is the “I” joist. It is manufactured with a solid top and bottom, but a plywood core.  These joists are applied on 12”, 16”, and 19.2” center spacing schedules.  The 19.2 spacing, though specified to meet building codes, can cause some subfloor deflection between joists, resulting in a bit more wood floor noise than normal, especially during the winter months when the flooring is relaxed from slight shrinkage. This only applies to flooring nailed or stapled to the subfloor, glued-down flooring will perform just fine.  Excessive noise may also occur if flooring is nailed to some strand boards which are exposed to too many soaking rain events.  This may result in the wood fiber's inability to hold a staple or cleat when the wood flooring swells from construction moisture.

All wood floors squeak some, except for those glued down with the appropriate adhesive and full-trowelled.

  
NEW CONSTRUCTION INSTALLATIONS

New construction environments are temporary. Excessive amounts of moisture are present in the new home from many sources.  To start with, the house framing was exposed to numerous rains.  If the home was built over a crawl space, large amounts of moisture were migrating from the soil upward into the house before the ground cover was placed.  Then many of the products applied inside the structure dissipated moisture into the house such as drywall compound, masonry mix, tile grout, and paint.  And not until the HVAC system became operational, and ground cover placed on the soil in the crawl space, did the two year process of complete dissipation of moisture start to occur. That's right, it takes two years for all that construction moisture to dry up.  So one can only imagine what happens to kiln dried wood products when they are exposed to all that high moisture.  Remember that wood is hydroscopic, and when the surrounding air is full of moisture, the wood grows dimensionally.  A solid 11 ½” oak tread left exposed in a moist construction environment can grow almost a ¼” in dimension.  And then guess what happens to that oversized slab of oak once the heat is turned on for the first time. You guessed it…major shrinkage! Fortunately, stair treads are installed later in the construction process, and the back edge is covered by riser material, but hopefully you get the point. 

Every building contractor and wood flooring contractor has his very own procedure for installing wood flooring in a new home.  I have heard of wood flooring being installed right after the roofing was completed. Imagine how easy installation would be without sheetrock on the interior wall studs. This apparently works for at least one builder, but some builders require the HVAC system to be completely operational before the first stick is laid. Successful timing of the wood flooring installation varies across the country. If the finished product performs as expected at least one year after the house is completed, then the schedule was right on.

In the Central Tennessee region, most building contractors have difficulty obtaining electrical service releases before the building schedule calls for wood flooring installation, so most unfinished floors today must be installed before the HVAC is operational.  This timing allows the flooring to be installed under all cabinetry and baseboards.  Unfinished flooring has been installed that way for years in this area, and most are performing very well.  The key to performance seems to be HVAC operational at least two weeks prior to sanding.

There seems to be no magic scheduling formula for flooring performance, each new construction project has its own moisture related dynamics, and what works in the house across the street may not work in yours. The plywood subfloor may have been four points higher than yours at time of installation, or the flooring may have been two points lower in moisture content before installation.  Contrary to most technical literature, I have found that the following schedules work pretty well in the Tennessee region, though not guaranteed by Jeffco Flooring.  These are general guidelines:

New construction with crawl space, solid unfinished flooring:  After sheetrock finishing, ground cover in place, and MC of plywood less than 12%, install unfinished flooring at 8 – 9% moisture content over felt or Aquabar.  Finish flooring after HVAC is fully operational for at least two weeks. Flooring should be installed at least two months before sanding.  (Special considerations are required for installation over encapsulations in progress. If wood flooring is installed before crawl is controlled, temporary excess moisture from underneath may cause abnormal movement in solid wood flooring such as irreversible compression, cupping, buckling, and broken boards. Prior to controlling air quality in crawl, temporary ventilation must be provided by the builder.)  In the image below, a knowledgeable builder has attached a large fan to the first floor framing in order to force temporary moisture from the crawl prior to encapsulation.

Temporary fan drawing moist air out of crawl space

New construction with crawl space, solid prefinished flooring:  Before carpet is installed, check moisture content of bottom of plywood. Acclimate product to within 3 -4 points MC. Install over Aquabar, felt (butt seams), or no underlayment.  If heating season installation, and flooring is too dry, install a little loose (intentionally leave some hairline cracks).

Existing construction with crawl space, solid unfinished flooring:  Check MC underneath subfloor.  Acclimate flooring to within 3 – 4 points. Install over felt or nothing.  Wait at least two weeks, but as long as possible before sanding and finishing.  Installation followed immediately by sanding and finishing may result in a permanent cup.

Existing construction with crawl space, solid prefinished flooring:  Check MC underneath subfloor.  Acclimate flooring to within 3 – 4 points. Install over felt (butt joints), Aquabar, or nothing. 

New construction over basement, solid unfinished flooring:  Wait until most construction moisture has dissipated, after trim has been installed, and subfloor is less than 10% MC.  Install wood flooring at 6 ½ -8% MC over felt or Aquabar. Sand and finish flooring after two months, after HVAC has been fully operational for at least two weeks.

Existing construction over basement, solid unfinished flooring:  Check MC underneath subfloor.  Acclimate flooring to within 3 – 4% MC.  Install over felt, Aquabar, or nothing.  If felt is used, wait six weeks before sanding and finishing.  Without felt, sand after one week.  

New or existing construction with or without crawl space, engineered unfinished or prefinished flooring:  Acclimate flooring to 7 – 8% MC. Glue, staple, or nail.  For unfinished, wait one week before sanding and finishing. 

THE MOISTURE METER

The professional flooring contractor can't leave home without it.  Jeffco Flooring will not accept solid wood flooring from manufacturers unless use of the meter indicates proper moisture contents.  The moisture meter is used most frequently to determine high contents; most meters will not read below 6%.  Without its readings, interpretation, and application of data, solid wood flooring installation is a gamble, like throwing dice.  Unidentified high moisture content in solid wood flooring before installation is like cancer. One can't see a potential problem at first, and slowly with time, as the product dries, shrinkage gaps become larger and larger, until finally they become offensive.  Then the flooring may potentially have to be replaced.  The moisture meter (the most important tool to the flooring contractor) removes all the guesswork.  Even though some mystery exists when applying nature's products, this tool sets the stage for predictability.

Delmhorst J – 4 moisture meter