Swis Wood Products Ltd
There are a few things to consider before starting installation
1.Check your relative humidity using a hydrometer or humidity meter. If the humidity is higher than 50% or lower than 40% at 20 degrees Celsius, you need to climatize the flooring. The sub floor should be with in 2% moisture content of the flooring. ie. The flooring is 8% the sub floor should be 6 - 10%
2. Do you have the supplies required?
a) Craft paper is put on the sub floor, to prevent wood on wood squeaks. This is an untreated tar paper.
b) Finish. It is best to apply the top coat of finish as soon as the flooring is installed. Decide what kind of finish you are going to use. Water based finishes are easy to apply and clean up, but do little to bring out the grain. Oil based finishes tend to darken the white wood slightly and enhance the grain.
c) Applicators. Generally there is a mop type to do the large open areas and a brush type to cut in around the edges. There are several types to choose from. Make sure that your applicator is designed to work with your finish.
d) Sandpaper. It is best to start with a course grit and gradually work your way towards a finer grit. Start with 36 grit, then 50, then 80, then 100. If are using a palm sander 120 grit is a good finishing grit. Some 220 grit will be needed to scuff between coats.
e) Nails. 2" nails are generally used to nail 3/4" thick flooring. Each nailer uses a different type of nail. If you plan on doing hand nailing use 2" finishing nails.
3. Do you have the Tools?
You will need saws that can cross cut and rip. This can be done with mitre saw, table saw, skill saw, jig saw, or a hand saw. Other misc. tools are needed like a String line, hammer, punch, tape measure, pencil, drill, floor sander, lint free rags, and a vacuum for clean up.
4. What direction to run the flooring?
If the sub floor is springy or appears to wave over the floor joist the flooring should be layed across the floor joists. This will level and make the floor solid. Generally flooring is run the length of hallways. Running the flooring 90 degrees to large windows can reduce the visual effect of the seams.
Wood flooring will only expand in width if exposed to high humidity, it does not expand in length. There needs to be a 1/2-3/4" gap between the wall and the edge of the flooring. The ends can be run tight to the wall. To reduce this gap, you can cut away the paneling so that you expansion gap is hidden. You need to establish a straight line. Roll out 1 width of paper and staple down. Measure approx. 20" from 2 points from the starting wall and run a string line between the 2 points. Put the first piece of flooring down with the 3/4" expansion gap and measure to the string line. Cut 2 pieces of flooring to this length. Use these as your measuring sticks. Carefully place measuring stick up to the string at either end of the piece of flooring to be nailed and hold the flooring against them and face nail with the brad nailer, near the wall, about every 10". These nail holes may need to be filled if the baseboard molding doesn't cover them. Then nail at 45 degree angle into the top of the tongue. Make sure that these nails are fully counter sunk, or the next row of flooring will not fit tight. Continue this until the first run is complete. Use medium length, straight pieces. The last piece of every row will need to be cut. When cutting the last piece, take a piece of flooring and place the tongue towards the other tongue and put a mark where it needs to be cut. This puts your cut against the wall. Take the left over piece and start the next row.
The second row will need to nailed with the brad nailer in the tongue. Make sure to lap the end joints by about 1/2 way on this second row. This will give the strongest straight line to work from. Be careful not to bang the flooring into place at this point. You can distort the first row.
The third row can be nailed with a flooring nailer. Nail about 3" from each end and every 12". Still try not bang the flooring hard, to keep the straight line. The ends can now be lapped a minimum of 3".
Open a few bundles and lay them out in rows so that you can adjust the end lapping and color variation. This gives you chance to adjust the look of the floor. Set aside the pieces marked with a lumber crayon on the tongue edge. The last row needs the tongue cut off. These pieces have slight defects that can be ripped off.
If you nail in a piece and notice that it has a defect or doesn't fit right, take the time and remove the piece. It is much easier to remove it now.
Use short pieces for the last few rows. They are easier to get tight together. The bottom lip of the groove can also be ripped off to allow the piece to be dropped straight down into place and then face nailed.
Before sanding, you will need to fill any nail holes or gaps. Choose a wood filler that has similar color to the flooring and that is compatible to the finish you are going to use. You can make you own filler from sanding dust and glue, or it is preferred to make a paste from the finish you plan to use and sanding dust. Take a small amount of finish in container and add sanding dust until it makes a thick paste. This way it will be compatible. Press this into the gaps with a putty knife, remove as much of the over spread as possible. Wait for the filler to dry and then start to sand.
When sanding, move the sander slowly, this will make the scratches from the sand paper less noticeable. Overlap each pass by about 1/3. Clean the floor well between each grit change. The sand paper breaks down as it is used, leaving sand on the floor. Start sanding with 36 grit. Continue to sand with this grit until the floor is flat. Switch to 60 grit, then 80, then 100. There still maybe scratches, if you can't see them in the standing position, in average light, you are ready to apply finish.
The first step to achieving a good finish is cleaning. Plug any heating ducts to prevent dust being blown into the room. Vacuum the floor and clean up any dust that may fall on to the floor. Wipe the floor off with a damp lint free rag. Dampen the cloth with water if the finish is water based, or if it is an oil based finish, then use mineral spirits (paint thinner). Scuff sand with 220 grit paper in between coats and tack off before applying the next coat.
A moisture meter can be used to take a reading MC of the flooring and the of the sub floor. If you are checking a plywood sub floor sometimes the glue will give you a false reading. Your sub floor should be the same MC% as the flooring. When climatizing the flooring, it needs to be exposed to air on all 4 sides. Take the flooring bundles apart and pile it with spacers (you can use flooring for spacers) and use a fan to blow air through the pile. The longer you can do this for the more acclimatize the flooring will be to your room. Usually 1 week will be enough. Make this pile where you plan on finishing laying the flooring to avoid moving it again.
Wood Flooring and the Effects of Humidity
Wood Flooring will perform best when the interior environment is controlled to stay within a relative humidity range of 30% to 50% and a temperature range of 20 degrees Celsius. Fortunately that is about the same comfort range that most humans enjoy. It is the responsibility of the homeowner to keep the relative humidity within a constant acceptable range.
- Wood is a natural product and its limits must be respected. Because extremely low humidity has drying effects on properly manufactured and installed wood flooring, manufacturers do not consider some plank separation or cracking to be defects.
Cracks and Separation Between Boards
Every floor in a heated space will endure some separation. This seasonal movement is a normal characteristic of wood flooring, and it never stops, regardless of the age of the wood. In the winter when the heat is on the humidity indoors decreases. This change causes the wood to shrink and cracks get larger. The gaps in floors of light colored wood or white stained floors tend to show more than gaps in darker or natural colored wood floors. Radiant floor heat and flooring around heating ducts can be more affected. Controlling the humidity is one way to minimize the seasonal shrinkage of wood. Normal relative humidity levels of 30%-60% should be adhered to in order to avoid cracking and drying of the wood.
Swis Wood Products dries our flooring to a moisture content (MC) of 6-8%. If floors are dried down below 6% (by dry room climate, low relative humidity, improper use of in-floor radiant heating systems, excessive heating etc.) it may cause cracks on the surface and more gapping.
Generally, the wider the flooring, the larger the gaps.
- Maximum surface temperature must not exceed 82° F. In-floor radiant heating systems must have thermostats set accordingly.
- Installation must be performed in accordance with the National Wood Flooring Association guidelines and must be followed for sub floor preparation, sub floor moisture content and radiant heat control
Installing Our Flooring Over Radiant HeatSlab and sub floor conditions
The most important factor in a successful wood flooring installation over radiant heat is a dry slab and a dry sub-floor. The only sure way to dry a slab and sub-floor system is to turn on the radiant heating system before installing the wood flooring. If this isn't done, moisture left in the slab will enter the wood flooring as soon as the heat is turned on. The result is floors that will expand, contract, shrink, crack, cup and bow excessively.
Opinions on the amount of time required vary widely. Some say the heating system should be turned on at least 72 hours before installation, with a preferred time of five to six days. That assumes that the slab has been in place for at least 60 days. If the slab is relatively new, the recommendation is to have the heating system turned on for 30 to 60 days before installing wood floors.
To be completely sure that the slab is dry enough you must always test for moisture content before installation.
Just as important as a dry slab and sub floor is the proper drying of the wood flooring you are about to install. When our products are being installed over radiant heat we kiln dry to 6% moisture content. Before installation we recommend no more than 2% difference between the slab or sub floor and our flooring.
With radiant heat, the heat source is directly beneath the flooring, so it may gain moisture or dry out faster than a similar floor in a home with a conventional heating system. Wood flooring can be successfully installed over radiant heat as long as you understand radiant heat and how it can impact wood flooring, what precautions to take, and what type of wood flooring to use.
In the past, adhesives used to install wood flooring created a rigid bond between the flooring and the substrate. With seasonal shifts in ambient air humidity the flooring is constantly adapting through expansion and contraction while the rigid adhesives restrain this natural movement creating shear stress in the wood, in the adhesive layer, and in the substrate. This shear stress can cause the adhesives to tear loose from the flooring planks or the substrate, weakening the bond.
This problem has been solved with the creation of new elastic adhesives that remain flexible and allow the natural movement of wood to occur without undue stress placed on the flooring or substrate.
The advantages of elastic adhesives:
- Controls expansion / contraction
- Minimizes gaps between planks
- Compatible for use with in-floor radiant heat installations
- Eliminate sleepers and plywood for gypsum or concrete installations
- Perfect for large dimension projects - seamless floors
- Impact sound reduction / greatly reduces footfall noise
- Improves room acoustics
- Comfortable to walk on
- For solid wood to 8" wide and engineered flooring to 14" wide
Installation over in-floor heating
For a number of years wood floors have been glued and floated as alternatives to nail down installation on all types of sub floors, including concrete and gypsum based.
But there is still potential for improving these installation methods so that all solid and engineered wood floors can permanently keep their appealing characteristics without damage or problems with the floor even over radiant heating.
The solution is elastic adhesives for wood floors.
Full surface bonding
With elastic adhesives the wood flooring is installed directly onto the slab eliminating the need for sleepers and plywood. This bond is permanently flexible allowing planks to expand and contract without damage to the adhesive or substrate. Using this system you can effectively install solid wood flooring up to 8 inches wide and engineered planks up to 14 inches wide directly to concrete with no length limitations.
Acoustic bonding system
Acoustic bonding uses a specially designed synthetic foam mat containing oblong slots which when laid out onto the slab the elastic adhesive is applied into the slots and then the floor is laid. This system combines the benefits of a full surface glue with those of a floating floor. While each plank will expand and contract individually, there will also be some expansion and contraction across the entire floor.
The combination of a foam mat and elastic adhesive makes the wood particularly resilient, considerably improves its impact noise deadening and sound transmission capacity, and reduces noise caused by walking.
The acoustic bonding system is ideally suited for installation in residential and commercial buildings when using solid wood up to 3/4" thick and 8" wide or engineered floors with three or more layers.
We are not a professional floor installer. This information is provided as practical advise. We are currently developing this page. Please check back.