Case Study on Wood Flooring in Commercial Applications

By Carol M Goodwin

Wood flooring can give a commercial office, loft or retail space a warm and inviting look. Often there are additional specifications to consider from the sub floor, to sound, to even the color and matching components that may be more intensely specified than in a home.

Questions to consider:

How do you attenuate the sound transmission for 2nd floor or above installations?

What if your client wants the floor to have specific or long lengths on a concrete sub floor?

How do you match cabinetry or other color considerations on antique reclaimed wood?

When a holding company for an old family lumber company wanted antique heart pine on the 3rd floor the specs included:

– control the sound transmission

– match the color of the furniture

– match the height of doors at 1″ overall

– include long lengths not practical in engineered flooring

Sound transmission can be attenuated using several different methods; from gluing cork to the sub floor and the wood floor to the cork using the same strength glue, to a whole solution system such as Sika. All require craftsmanship beyond a typical installation.

The National Wood Floor Association recommends the Sika system; a sound dampening mat with slots for sound dampening glue. The mat and/or glue must also fill all joints around the perimeter of the room to avoid sound traveling.

Some choose to ‘float’ an engineered floor over a sound dampening mat, perhaps using a ‘click and lock’ tongue and groove system. Most flooring professionals cannot achieve a quality and lasting installation with these systems. They are more appropriate for ‘do it yourself’ or where the floor is not planned to last the lifetime of the building.

There are many, many ways to achieve a particular color; natural penetrating hardening oils with no VOCs, aniline dyes that aren’t so environmentally friendly, paints or stains that are ‘floated’ onto wood that has been sealed first or combination systems. Sanding differences will often make the floor take stain differently. Therefore, the person who provides the samples should be the person who will do the coloration.

Plywood over concrete with ¾” solid wood on top was too high. Engineered wood flooring wasn’t practical given the lengths desired. Solid wood had to be glued to the concrete to meet height and length specs.

The Sika system is designed to achieve this; however, all boards must be straight. Any crook means that board has to be saved for a nail down job where it can be levered into place. Antique heart pine is fairly straight. Most species require 30-35% extra wood.

Engineered wood floors shrink and swell 5 times less across the face; however, they do so 5 times more down the length of the board. Most engineered wood floors are fairly short pieces with a much shorter average length.

You can purchase a well-made engineered wood floor with the same average length as a solid wood floor; however, it won’t have the longest lengths possible in a solid wood floor. In this case, the owners required very long lengths to emulate an old, old floor; requiring highly stable solid wood flooring.

Ref: Buck Lumber Co, Charleston, SC.

Carol Goodwin, CR, MCR, is President of Goodwin Heart Pine and holds Craftsman and Master Craftsman degrees from the National Wood Floor Association. She is also a Certified Hardwood Flooring Inspector, and an accredited CEU Provider. She is a frequent blogger and can be found giving lots of good advice on green building, and using reclaimed wood at

Solid Wood Floors Over Concrete

There are many questions about gluing down solid wood flooring to concrete.  The traditional industry standards for wood floor installation limited the direct glue down of solid wood flooring over concrete to short pieces or parquet patterns.  A well made engineered wood floor looks like a solid floor but avoids some of the installation difficulties.  The backer of the engineered flooring helps reduce the movement with moisture changes.  For many applications this is the best solution.

Flooring insert

Small Flooring Insert Including Antique Heart Pine

With the advent of elastomeric adhesives gluing solid flooring directly to concrete has become more common.  NOFMA produced a technical publication outlining recommended procedures for installing solid wood floors to concrete about five years ago.  Despite the inherently higher risks of gluing solid to concrete it has become an accepted practice for many people in the industry.  This installation method takes more effort to manage the risks.  Moisture issues are the primary concern.  Test to see if the concrete is dry enough.  The ASTM F2170-2 test is a widely accepted procedure which measures the relative humidity inside the concrete.  It is often prudent to apply a sealer to the concrete just in case moisture is introduced into the concrete at a later time. Then if the concrete gets wet in the future a trowel on moisture cured urethane vapor barrier or penetrating sealer such as Bone Dry which was applied prior to installing the floor can keep the water away from the wood. An alternative to a glue installation is to install a plywood subfloor over the concrete then nail down the flooring.

Subfloor Preparation Tips

River Recovered Heart Pine Log

River Recovered Heart Pine Log showing water errosion

Starting with a flat subfloor is essential for a good wood floor installation.  Older homes often have areas where the subfloor is irregular. Refasten any areas of loose subflooring.  It is sometimes advisable to renail the entire subfloor using ring or screw shank nails. Renailing can also be needed in new construction where the subfloor was left exposed to the weather. Sand any small high spots flat. Small depressions can be filled with layers of thin plywood.  Cut the plywood to progressively smaller pieces (like a contour map) then feather the edges by sanding.  Plaster based floor patch is not recommended. If the floor joists have sagged in an old house removing the subfloor and sistering new joists to the old ones can be a good solution. Adding stiffness to the framing is better than reducing stiffness. If you are not doing a large area and the plywood is sound you can use 2x4s turned on edge. Cut them to follow the floor contours and create a flat top.  We used to use a metal rail system and a router to trim the tops of the 2x4s to a flat plane.  Install the floor as you would over a sleeper system.  This is still a lot of work

Be Aware of Water in Concrete

Wood Floors are Beautiful in the Bedroom TooWhen a client’s water heater flooded their Goodwin Heart Pine engineered wood floor the insurance company called in a restoration contractor. The contractor pulled up half the floor to the point where they said the water had gone in the concrete. After three days of dehumidification they declared the concrete dry.

Following the National Wood Floor Association’s procedure we used a concrete meter that requires drilling a small hole 40% of the depth of the slab. The meter readings were much higher than recommended to install a wood floor over concrete.

We pulled up the remainder of the floor so that the entire slab could be dried. And we provided the restoration contractor with the meter readings and a study on water movement through concrete. Fortunately, they agreed to bring back the dehumidification system and get the slab to the proper moisture content.

Wood floors are not rocket science; however, they do demand a scientific approach to water and subfloors of all types. Call if you would like us to send you the research paper on how to properly test concrete for moisture content.

Best wishes for great wood floors all the time for the longterm.

Heartwood vs. Sapwood

Words can have a variety of meanings when used by different people.  Wood science textbooks tend to agree on the definition of the words heartwood and sapwood.  Trees transform sapwood into heartwood by depositing additional chemicals in the wood.  The color and durability of heartwood make it preferred for many products.

In informal speech ‘heart pine’ (or sometimes ‘heart of pine’) is often used to describe wood products containing the heartwood of southern yellow pine trees. Traditional heart pine floors were all heartwood. Now many products labeled heart pine actually contain a mixture of heartwood and sapwood.   As the color of the wood matures the heartwood develops a much deeper color whereas the sapwood remains yellow.  The contrast increases between the heartwood and sapwood as the wood ages.  According to the Southern Forest Products Association  website ” there is no set ratio of heartwood vs. sapwood in the grading rules that defines heart pine lumber.”   The site goes on    “Of the 10 Southern Pine species, longleaf pine is most commonly referred to in the trade as “heart pine”. It is generally characterized by tighter growth rings, higher density and greater proportion of heartwood. Longleaf lumber is so prized it merits a special quality classification within the grading rules.”

The superior qualities of longleaf pine heartwood enhance both the appearance and durability of products made from this wood.

Hello Wood Floors… Goodbye respirators and meds!

Hopefully…   When our grandson was born his bedroom had new carpet and fresh paint. I gave my wonderful daughter the Lung Association’s Healthy House book and thought we were doing better.

Two weeks before our granddaughter was born her room suddenly had to be painted pink. And the paint store didn’t offer my daughter the low VOC paint!

This spring the family replaced the carpet with Precision Engineered River Recovered Antique Heart Pine wood floors in both grandkids rooms.

We are all breathing easier… literally. So far, so good. I’ll keep you posted.

Love wood floors and grandkids!

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