We wrote the book
"HARDWOOD FLOORS" and the two accompanying video
tapes/DVDs (“Laying Hardwood Floors”) & (“Sanding
and Finishing Hardwood Floors”) published by "Taunton
Press and Fine Homebuilding Magazine" perceived by many
throughout the wood flooring industry as the definitive text
for the last 20 years on the installation, sanding and
finishing of wood flooring. The book HARDWOOD FLOORS can be
found in nearly all public libraries throughout North
America. It can be purchased directly from us, or through
the publisher, Taunton Press/Fine Homebuilding Magazine, or
from any of the various wood flooring associations, or at
book resellers including those online such as
BUY IT NOW on www.amazon.com.
and Associated Products Wholesale Supplier to the Trade/Retail to Do-It-Yourselfers.
READ MY LATEST
We're a manufacturer/distributor for all manner of wood flooring types and sizes
including Custom Designs and Custom Milled Products.
All products associated with wood flooring trade from stair parts to trim, inlays,
medallions to floor and wall vents, fillers, finishes, abrasives,.
Complete installation tools and supplies as well as everything to sand, scrape,
stain, seal, fill, finish or refinish including abrasives, masking tools and
supplies, safety tools, supplies, equipment and maintenance tools, supplies
opinion and topical commentary
from an industry expert
Flexible Fillers for Expansion Gaps
(December 21, 2007
To leave a gap or not between a hardwood flooring border and a stone fireplace hearth, entry pad or other feature raises the age old question of when and where do you allow for the expansion in a wood floor when you have a fixed header or border in your installation? This can be a very important issue, often more than many installers, builders and architects expect.
Many ancient installations of stone and wood left these gaps “open” where they collected dust and dirt that then solidified over time if the space was never taken up or utilized by movement of the stone or wood. If one or both of the two mediums expanded into the gap, the dust or dirt collected simply crumbled, allowing for free movement. Others were filled with dry sand or dry wood dust. Occasionally this sand or dust was sealed or packed with linseed oil or tung oil as a flexible binder. I have also been privileged to encounter installations similar to these where ground nut shell or ground cork were utilized in lieu of sand or sawdust.
The allowance for movement (in the design and arrangement) can literally make or break the beauty of an otherwise stylish or ingenious layout and installation. Of course the amount of expansion space that may be required varies with every wood flooring style and product, where it’s being installed, the structure’s design and heating/cooling scenario and last but certainly not least, the locale or area (i.e., rain forest, desert, tropical, variable, etc.). Structures differ substantially even in the same region or locale in the degree of expansion space needed. Finally, and an often overlooked category, is the size of the installation. The greater the area or size of the installation, the more expansion it will need.
Some floors are completely ringed in by a border or fixed perimeter. This is a whole other issue and I’ve written volumes about it in the past. Look for more on this in future issues of “Bollinger on Floors”.
Here’s a tip I learned many years ago when I first started setting a lot of stone and wood together. If you decide to leave an expansion space but want to fill it in with something that will help blend the two mediums, consider leaving flexible filler between the two instead of using grout or wood filler. Grout is meant for stone. Wood filler is meant for wood. The seam of either of these two between a section of stone and wood often (usually) fractures or crumbles leaving an ugly-looking seam that begs for attention. In my perspective, this draws interest away from an otherwise joyful union of two very beautiful but different mediums.
First, to help avoid any unnecessary intrusion of moisture, thoroughly seal any exposed edges or seams of the wood flooring adjacent to the stone interface, including any exposed subflooring. For site finished floors, simply make sure you apply several heavy coats of the sealer/finish you are using to all the exposed sides of the flooring. If you’re using prefinished wood flooring, after you’ve completed the installation of the wood, apply several coats of any inexpensive wood finish or sealer prior to installing the stone. If you install the stone first, be sure to seal all the exposed edges and ends (including the bottom) of the wood planks or pieces that will border the stone prior to their installation.
Next, tuck-point a layer or two of “flextubing” (available at most good hardware stores under a variety of different names) into the cavity between the wood and the stone at their interface. This tubing generally comes in a roll that can be cut to length (on the job) as needed. Tuck each layer into the gap as tightly as possible. Make sure the first layer completely fills the bottom of the cavity. If you need a second layer of tubing (generally needed for cavities ¾” or deeper), make sure it is squeezed well down into the cavity tight to the first layer. You will need to leave approximately ¼” of open space or gap between the top of the tubing and the top of the cavity for your filler to bond to both sides of the wood and stone.
Have a bag open and ready with some presanded grout of a color you have pre-selected to match both your stone and your wood. Using a caulking gun loaded with clear silicon, finish filling your gap(s) with a bead line of the silicon. Carefully “dress” the edges of the silicon line with a clean cloth dampened with the silicon’s solvent (i.e. water, mineral spirits, etc.) to remove an excess material from adjacent sides of the wood or stone. Now, before the silicon sets, carefully sprinkle a fine layer of the grout on to the silicon line. You can use a flour sifter if you don’t feel comfortable sprinkling it on by hand. You can carefully blow the excess grout away with a hair dryer as it sets. You now have a flexible grout line that looks and functions like the real thing. You may find the some of the loose grout may come up in the days after installation, but once it totally cures, it works great.
If you’re unsure whether or not it will look right or work well with your circumstances, mount a scrap piece of flooring and stone to a spare piece of plywood and use the above procedure on it. It’s always a good idea to get your customer’s advanced approval on the final look of any project.
You can always fill a deep void or gap with just silicon, but this procedure is highly problematic. You’ll have to contend with sags and overfilling and God knows what else unless you’re very good and very careful. Then of course you’ll have to be quite lucky as well, at least in my opinion. I’ve never been able to make it work right every time without using some type of flextubing as a “prefiller” to the silicon. What is it they say about a “professional”. A really proficient craftsman will keep doing it until they get it right. A professional will keep doing it until they can’t get it wrong.
Another technique, similar yet different from the preceding method, is to add supplementary polymers (i.e. substitute latex binders for the water called for in the mixing instructions) to the grouting compound you’re using. Be sure to check with your grout supplier if this is acceptable first.
You can also use clear silicon without adding anything to it. Its clear color is often enough to bring the two mediums color and texture together in a harmonious blend. Whatever you do, if you choose to use silicon as flexible filler, keep in mind that not much will stick to it after it dries and that you should always allow several days for the filler line to cure before permitting foot traffic across it.
Wood Floor Products, Inc.
If you want more information on these products, please contact me
directly or Wood Floor Products, Inc. (206) 622-6996 (7-4:30 PST)
(Monday – Friday)
© The above material is intended for the exclusive use of visitors to http://www.woodfloorco.com and http://wwwtheoakfloors.com and clients of Don Bollinger, Wood Floor Products, Inc. and The Oak Floors of Greenbank, Inc. The copying, transmission, distribution, use, retransmission, redistribution or reuse of all or a portion of the above material without the expressed written permission of Don Bollinger, Wood Floor Products, Inc. and The Oak Floors of Greenbank, Inc., is expressly prohibited.