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Fitting Guidelines

Fitting Guidelines

An Important Note For All Installers & Homeowners

Although it’s obviously more common for an experienced fitter/installer to confirm site conditions as being suitable for installation to begin, the homeowner needs to share some of the responsibility with regards how conditions are maintained thereafter.
Because oak flooring is hygroscopic (moisture absorbent) its moisture content will vary when the flooring is forced to adjust to changes within its surrounding conditions, the 2 biggest contributing factors being the Relative Humidity and temperature of the room.
Due to the fact that as its moisture content changes, so does the size of the oak plank, it’s important to control and maintain conditions during the different seasons of the year, so that your flooring remains at a constant size and performs well.Too often during the cold winter months, we receive calls from homeowners who are experiencing issues with their floor shrinking, cracking, splitting or cupping, who immediately blame the product, instead of realising that the causes are down to the air being colder with less moisture content (humidity) and that they’ve turned their heating up a few notches and for longer periods.
Without compensating for these actions, both will cause the floor to lose moisture and decrease in size, thus causing structural changes within the floor.

We’re all aware that a natural product like oak flooring requires a period of acclimatisation to allow it to ‘do its moving’ before installation rather than afterwards, but it seems many of us are not willing to accept that it remains being a natural product when installed within a finished floor, so will continue to mover thereafter when forced to do so.Any changes in temperature and humidity within the room will affect the finished floor and the size of each board within, which can cause all of the problems noted above.We recommend continually monitoring the conditions with one of our Thermo-Hygrometers and then, if required, introducing appropriate measures such as humidifiers or de-humidifiers to control and maintain the environment that your oak floor is expected to ‘live’ within.

Please note: If you allow the conditions of your rooms to change too much after installation, your floor will show defects and possibly fail. This has nothing to do with the product or its quality, apart from the fact that it’s responding to the conditions that it’s being forced to endure, as any natural timber product will do.

NB: The following installation methods only cover the installation itself. Please understand that whatever the quality of oak flooring you buy, it will only perform as well as the subfloor beneath it, along with how it is maintained after installation.

If the subfloor is not prepared sufficiently, while the finished floor may look great for a while, it will no doubt fail prematurely.

FITTING METHODS
Glue Down Method (Suitable for Solid and Engineered)
  1. Moisture test the subfloor and the flooring with a Moisture Meter and record the results. Proceed when both readings are the same for 3 continuous days, thus proven as acceptable. Continue acclimatisation if not.
  2. Temperature and Humidity readings should also be tested and recorded using a Thermo-Hygrometer, so that they can be maintained thereafter. Relative Humidity should be between 35-60% before installation begins, and then this level should be maintained, during and after installation.
  3. Using a piece of the floor that is to be fitted as a guide for thickness, cut the bottoms of the doorframes and architraves in the room to suit. Chisel out as much of the cut pieces as possible because this will make the fitting of the floor easier.
  4. Once the direction in which the floorboards are to be fitted is decided, measure the width of the room and divide the distance by the face width of the planks to be fitted. This will determine the size of the final row of boards. If the result is less than ¼ of the face width you will need to reduce the width of the first row to increase the size of the last.
  5. Working from 4-5 boxes of flooring at any one time to ensure an even mixture of colour and shade, cut and lay the first 3 rows without adhesive for now, and place plastic wedges between the floor and the wall to maintain the required expansion gap. 1.5mm expansion for every linear metre should be allowed with a minimum of 15mm at all times.
  6. The joint spacing should be random and no closer than 200mm in an adjacent row, with the first and last plank in a row being no smaller than 200mm long.
  7. Once assembled, use a string line to make sure the floor is straight and adjust the expansion wedges if not.
  8. When satisfied, mark the floor at the edge and carefully lift and stack the boards to be fitted in order. Any boards that have obvious and unacceptable defects should have those defects ‘cut out’ and that board should then be used as a starter or end board for another run.
  9. Using a suitable flooring adhesive such as SikaBond T54, apply to the marked area using the correct sized notched trowel. Then place the first row of boards into the adhesive and tight up against the expansion wedges, making sure to apply a suitable joint adhesive to the grooved end of each plank. Locate the tongue and groove correctly and then press down into the adhesive to ensure good contact. Continue this process until the first 3 rows are installed, making sure that the floor is straight by using the string line.
  10. Continue to install the floor but remembering not to spread too much of the flooring adhesive to the extent of it ‘skinning over’. This will depend on the site conditions. It is good practice to occasionally lift a plank back out of the adhesive to ensure good adhesive transfer.
  11. Always make sure that any excess adhesive on the surface of the floor is removed immediately because it will be extremely difficult to remove later.
  12. When you reach the other side of the floor, measure and cut the planks lengthwise remembering to allow for the expansion gap. Use the expansion wedges to tighten up the floor and allow the adhesive to set.
  13. When the adhesive is completely set, remove the expansion wedges and fit your beading, skirting board, pipe covers and door threshold profiles to cover the expansion gaps.

Floating Method (Suitable for Engineered only)

  1. Moisture test the subfloor and the flooring with a Moisture Meter and record the results. Proceed when both readings are the same for 3 continuous days, thus proven as acceptable. Continue acclimatisation if not.
  2. temperature and Humidity readings should also be tested and recorded using a Thermo-Hygrometer, so that they can be maintained thereafter. Relative Humidity should be between 35-60% before installation begins, and then this level should be maintained, during and after installation.
  3. Using a piece of the floor that is to be fitted as a guide for thickness, cut the bottoms of the doorframes and architraves in the room to suit. Chisel out as much of the cut pieces as possible because this will make the fitting of the floor easier.
  4. Once the direction in which the floorboards are to be fitted is decided, measure the width of the room and divide the distance by the face width of the planks to be fitted. This will determine the size of the final row of boards. If the result is less than ¼ of the face width you will need to reduce the width of the first row to increase the size of the last.
  5. Lay out the underlay (we recommend to always use one with an integrated DPM like our Comfort Silver Underlay or Sonic Gold Excel underlay) and preferably tape the joints
  6. Working from 4-5 boxes of flooring at any one time to ensure an even mixture of colour and shade, cut and lay the first 3 rows without adhesive for now, and place plastic wedges between the floor and the wall to maintain the required expansion gap. 1.5mm expansion for every linear metre should be allowed with a minimum of 15mm at all times.
  7. The joint spacing should be random and no closer than 200mm in an adjacent row, with the first and last plank in a row being no smaller than 200mm long.
  8. Once assembled, use a string line to make sure the floor is straight and adjust the expansion wedges if not.
  9. When satisfied, take the 3 rows apart and stack in order. Any boards that have obvious and unacceptable defects should have those defects ‘cut out’ and that board should then be used as a starter or end board for another run.
  10. Place the first plank in position ensuring you have the required expansion gap and then, using a suitable joint adhesive, apply a constant bead of adhesive to the underside of the groove along the length and at the end of the next plank.
  11. Align the planks and tap them together using a suitable tapping block at least 30cm long, remembering to only ever tap against the tongue and never against the groove. Continue this until the first 3 rows are assembled. Remove any glue from the surface of the planks immediately with a damp cloth and make sure the floor is straight with a string line.
  12. Allow the adhesive to set for about 45 minutes and then continue to install the floor until you reach the opposite wall. Measure and cut the last row of planks remembering to allow for the expansion gap. Then use the expansion wedges to tighten the floor and allow the joint adhesive to set.
  13. When the adhesive is completely set, remove the expansion wedges and fit your beading, skirting board, pipe covers and door threshold profiles to cover the expansion gaps

Nail Down Method (Suitable for Solid and Engineered)

  1. Moisture test the subfloor and the flooring with a Moisture Meter and record the results. Proceed when both readings are the same for 3 continuous days, thus proven as acceptable. Continue acclimatisation if not.
  2. Temperature and Humidity readings should also be tested and recorded using a Thermo-Hygrometer, so that they can be maintained thereafter. Relative Humidity should be between 35-60% before installation begins, and then this level should be maintained, during and after installation. .
  3. Using a piece of the floor that is to be fitted as a guide for thickness, cut the bottoms of the doorframes and architraves in the room to suit. Chisel out as much of the cut pieces as possible because this will make the fitting of the floor easier.
  4. Once the direction in which the floorboards are to be fitted is decided, measure the width of the room and divide the distance by the face width of the planks to be fitted. This will determine the size of the final row of boards. If the result is less than ¼ of the face width you will need to reduce the width of the first row to increase the size of the last.
  5. Working from 4-5 boxes of flooring at any one time to ensure an even mixture of colour and shade, cut and lay the first 3 rows without fixing for now, and place plastic wedges between the floor and the wall to maintain the required expansion gap. 1.5mm expansion for every linear metre should be allowed with a minimum of 15mm at all times.
  6. The joint spacing should be random and no closer than 200mm in an adjacent row, with the first and last plank in a row being no smaller than 200mm long.
  7. Once assembled, use a string line to make sure the floor is straight and adjust the expansion wedges if not. Any boards that have obvious and unacceptable defects should have those defects ‘cut out’ and that board should then be used as a starter or end board for another run.
  8. Carefully lift and stack the first 2 rows and place some sacrificial blocks against the back edge of the third row and screw them to the sub floor to ensure the row is held straight. Apply a bead of joint adhesive to the grooved end only of the planks in row 3 and then place back in position.
  9. After making sure the row is straight, the row can be nailed using suitable flooring cleats inserted using a suitable flooring gun. Barbed cleats should be used to prevent them working loose over time after installation.
  10. The planks should be nailed 50-75mm from each end and every 200-250mm along their length. Continue to install the floor remembering to apply the joint adhesive until you almost reach the other side of the floor at a point where you can no longer use the nail gun. At this point you need to pre-drill a 3mm hole and secret nail the planks by hand using a punch to ensure the nails are in far enough.
  11. Measure and cut the final row that will need to be face nailed along the edge closest to the wall. A 3mm hole needs to be pre-drilled every 150mm and the plank must be hand nailed down.
  12. The sacrificial blocks can now be removed and rows 1 and 2 hand nailed as described above. You can now fit your beading, skirting board, pipe covers and door threshold profiles to cover the expansion gaps

INSTALLATION ABOVE UNDER FLOOR HEATING

IMPORTANT NOTE: We cannot guarantee our Engineered Oak Flooring when installed over UFH because we have no control over what happens after delivery and installation.

There are special guidelines on how it’s stored, acclimatised, installed and maintained, and these must be followed for successful installation and performance thereafter. Oak, like all timber, either absorbs or loses moisture from the environment into which it’s installed and it will undergo dimensional changes as it does so.In some situations, especially when UFH is present, the oak will ‘give off’ moisture that results in shrinkage.This can continue to happen after installation when the surrounding conditions are not maintained, even when all the correct preparation procedures and guidleines have been followed, thus causing dimensional changes and sometimes appearance and structural defects.Because of this possible expansion and shrinkage, it is vital that the moisture content of the subfloor onto which your Oak Floor is to be fitted is at the correct level, and that the surrounding conditions are maintained after installation.
Changes in the moisture content of the floor, or the relative humidity of the room, after installation, may have an effect on the dimensional stability of the flooring itself, so it’s very important that conditions during installation are maintained thereafter. When considering these facts, an underfloor heating system can have a dramatic effect on the moisture levels of the room and also on the stability of the Oak floorboards fitted above it.

Specific installation instructions are below for a more detailed report on how to fit an Oak Floor above UFH and which boards are recommended.

Is It Guaranteed?

Many people ask why we cannot guarantee our flooring above UFH and the answer really is because we cannot guarantee that the flooring will be stored, fitted and then maintained correctly after installation. We have every confidence in our product, it’s just that we have no control on how it’s acclimatised and installed after it gets delivered. In some cases when the UFH system is operated without a suitable humidifier being used, the flooring can continue to ‘dry out’ after installation (even when our guidelines have been followed), so this can create dimensional changes and sometimes a ‘de-laminating’ effect where the oak layer ‘pulls away’ from the strong plywood base (this is down to the relative humidity of the room becoming too low, so drying the face of the board faster than the underside). Due to the variables involved and the specific requirements when UFH is present, it’s virtually impossible for us to prove weeks or months after installation that our fitting guidelines were not adhered to at time of installation.

Although we are very proud of the quality we provide, we cannot guarantee installation over UFH systems because we have no control over the fitting methods used, the amount of time allowed or methods used for proper acclimatisation, and the progressive increase of output from the UFH after installation is complete. Another reason is that we have no control over the actual use of the UFH system after installation and how the room conditions are controlled and maintained.

We recommend using our Self-Regulating UFH System under our 15mm ThruFlow engineered oak flooring for optimum performance and efficiency.

Our unique and exclusive ThruFlow products are specifically designed for installation with UFH and will outperform any other flooring product of a similar thickness in this situation where efficiency is concerned.

All our engineered products are suitable for installation over UFH but we never recommend fitting Solid Oak above such ambient heating systems because of the dimensional changes it will cause.

Our 15mm board is more efficient than the 21mm board because it has a lower thermal resistance but both require on-going maintenance of the surrounding conditions to ensure stability and performance.

Our 21mm board is suitable for this type of installation as long as surrounding conditions are maintained but having experienced many situations where individuals have chosen to not follow our guidelines and advice about acclimatisation, installation and ongoing maintenance…we now prefer to recommend using the 15mm product in an effort to reduce costly site challenges.

Our plywood backed Engineered Oak boards are the only boards that we recommend for installation above UFH systems, and our ‘standard’ Eucalyptus plywood backed boards perform very well in this situation, and provide excellent stability when maintained correctly.

Supplied T&G on all 4 edges for minimal waste and easy fitting, we know that due to its construction method that our plywood backed engineered oak flooring is the most stable and suitable product to install above UFH systems.

This method of multiply construction minimises the risk of surface cracks and movement under normal varying levels of humidity, moisture and heat.

Rooms fitted with our 15mm Engineered Oak Flooring above UFH must be maintained at a humidity level of between 35-60% and the UFH output must not exceed 27 degrees centigrade at floor.

This may seem low to some people but the warmth generated from an all-floor ambient heat system is much greater than the warmth generated from wall-hung units, even when running at much higher temperatures.
Should you want more durability and strength than provided on our 15mm boards (that have a 4mm oak wear layer) then we advise using our 22mm ThruFlow UFH Efficient oak flooring, a unique and specifically designed 22mm board with a full 6mm wear layer of oak that provides 25-35% better efficiency than the standard 21mm board because of its construction.
IMPORTANT NOTE
After installation and during the different seasons of the year, the use of an appropriate air humidifier and temperature control is recommended in rooms with varying conditions because failure to control and keep them consistent will increase the risk of shrinkage or expansion, which can cause cracking or de-laminating of the oak surface.
When an installed floor shows dimensional change after installation, it is always down to the change in conditions from when it was installed, and not a fault within the board itself. Acclimatisation is a complete waste of time if the conditions that the flooring is installed within are then allowed to change after installation.
Maintaining the temperature and relative humidity of the room (that the flooring was acclimatised to before installation) is vital to prevent dimensional change after installation and we recommend using a Thermo-Hygrometer to monitor these surrounding conditions..

When our 15mm Engineered Oak Flooring is stored and fitted in accordance with our instructions and recommendations, the floor will reach equilibrium with the room itself before installation, and maintaining this thereafter will result in minimal movement and optimal performance of the oak floor.

UFH Installation Guidelines

Prior to Installation

The subfloor must be structurally sound, clean, dust free and thoroughly dry. To ensure the subfloor is properly dried, it must be allowed to dry naturally for as long as is necessary.

Then the underfloor heating should be turned on to maximum for a full 10 days, so that any accumulated moisture is dried completely.

Then, and only then, the Oak Flooring should be introduced into the room and stored for a further 10-14 days with the UFH system running ‘as normal’ (meaning as it will be when used when the property is lived in). The cartons should be opened and stacked in a way to allow the air within the room to circulate them fully. There is no need to remove all the boards from the cartons for this.
IMPORTANT NOTE
DO NOT RUSH THIS PART OF THE PROCESS IN AN EFFORT TO SPEED UP INSTALLATION. If you do, you will no doubt regret it at a later date when your floor begins to fail, and when you contact us to complain about the product, I’m afraid the reasons for failure will be strikingly obvious and due to no fault of the product itself.
The oak flooring we supply you with will arrive with a moisture content of approx. 6-9%, so this may need to be reduced for installation over UFH by sufficient acclimatisation and suitability of installation must be proven by moisture checks.
These moisture readings should be documented and stored for future reference if required, as should the Relative Humidity readings, so that they can be maintained thereafter.
Relative Humidity should be monitored and maintained after installation, making sure that it drops no lower than 35% during the Winter months and goes no higher than 60% in the Summer. We can supply you with a Thermo-Hygrometer that will provide constant readings for you.
Installation
The heating system should be turned off and must not be operating during installation, and should only be turned on after installation has been completed. Depending on site conditions, it may be necessary to use portable units to maintain consistency of conditions within the room, especially if the job is expected to take more than 24 hours to complete
After the UFH is turned back on, it should then be increased in small steps of 2 degrees every 8-12 hours (starting from Zero degrees), until it reaches a maximum of 27 degrees.Then it should be reduced in steps of 2 degrees every 8-12 hours until the temperature has reached Zero degrees again. After this has been done, the underfloor heating system can be used normally up to a maximum of 27 degrees, ensuring that there is no great change in temperature (over 6 degrees) in any single 24 hour period.

This process is simplified with our Self-Regulating UFH System because the digital thermostat can be set to automatically make these small adjustments of heat output as and when required.Summary:

  • The concrete screed must be completely cured and dry
  • Moisture content and humidity levels must be checked and proven as acceptable
  • The underfloor heating system must be fitted correctly and working as manufacturers recommendations
  • The UFH system must be confirmed as being suitable for use with wood flooring by the manufacturer
  • The underfloor heating system must be turned off during installation but the room temperature and humidity level must be maintained by using portable units
  • 15mm or 21mm ply-backed Engineered Flooring must be installed, preferably the ThruFlow because it’s been designed for installation over UFH.
  • If the floor is installed by the ‘Glue Down Method’, Sika T54 Flexible Adhesive must be used.
  • An expansion gap of 10mm minimum must be left to all perimeters of the room
  • If your floor is installed using the floating method, we advise using an underlay with low thermal resistance (our Comfort Silver and Sonic Gold underlay are designed for this) between the flooring and the subfloor.

So, Back To – Can We Guarantee It?

Now you’ve read the fitting guidelines, I’m sure you can understand why we cannot provide a full guarantee for all installations above UFH. In this modern day of rush-rush-rush, we are concerned that some fitters (not all) will try to speed up the process and make short cuts, which will ultimately effect the way your floor performs. Also, we have no control over how the UFH system is used after installation, which can have an effect on room temperature and humidity.

Unfortunately, because we have no way of making sure that the above instructions were adhered to at time of installation and after, should a floor fail after installation above UFH, we cannot be held responsible. Although our plywood backed engineered boards provide excellent stability after installation, they are still constructed from all natural hygroscopic materials, so will react or respond to the conditions they are subjected to, and forced to endure.

In some cases, an oak floor installed above UFH will continue to ‘dry out’ after installation when forced to do so by the surrounding conditions, especially if the UFH system is being run continuously for long periods during cold seasons, so this can cause dimensional movement and sometimes create cracking or a de-laminating effect where the wear layer will ‘pull away’ from the plywood base because of moisture loss (de-laminating can also occur due to the relative humidity of the room becoming too low, even when UFH is not present).

We must insist on the following: If the flooring is accepted ‘on site’ as being in a satisfactory condition for installation by the fitter/owner, after having been allowed to acclimatise for the necessary period of time, any changes such as cracking, splitting, lifting or cupping within the floor after installation can only be due to ‘on-site’ conditions beyond our control.

By fitting the flooring supplied, acceptance of suitability for installation above UFH is determined by the fitter and the owner of the property.

Although it seems obvious to most, it is still worth emphasising that if our flooring was in an acceptable condition when installed, to change in shape, size or structure afterwards means that the conditions present during acclimatisation have changed since, or it has been subjected to excess heat or moisture, or it simply hasn’t had sufficient acclimatisation time to reach equilibrium with the room.

We Recommend…
We recommend either to install our engineered flooring over under floor heating systems by using the stick down method (especially the 15mm) with the Sika Flexible T54 Adhesive because this method is said to provide the best thermal efficiency for the floor, or by the Floating method above a suitable underlay with low thermal resistance (low TOG). When the flooring is fitted using the floating method, we advise implementing our Sonic Gold Excel or Comfort Silver underlay between the UFH system and the flooring.

When a wood floor is fitted above UFH, it is not unusual to experience some dimensional movement due to the extreme varying heat levels, especially if the UFH system is being operated continuously or at high output levels. This can cause dimensional changes and structural defects, which can obviously change the appearance of the finished floor. For successful performance of any oak floor above UFH, its surrounding conditions should be controlled and maintained after installation.

Unless our Self-Regulating UFH System is used (or a similar self-regulating system), rugs and mats should be avoided if possible because they can create ‘hot spots’ in the flooring.

In sun rooms and conservatories, care should be taken to protect your flooring from excess direct sunlight when UFH is being operated to avoid overheating.

DO WE RECOMMEND A SPECIFIC UFH SYSTEM FOR USE WITH OUR OAK FLOORING?

Yes, take a look at our ‘intelligent’ self-regulating UFH system.


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