Specification and design-Hardwood flooring

Under floor heating systems need to be well thought out in advance. Common mistakes at the design stage cannot always be rectified and can lead to substantial embarrassment and cost. If you are uncertain about any elements of under floor heating or Hardwood flooring we are only a phone call away. The heating design will leave certain areas of floor without heating such as under kitchen units, walk in larder, baths, showers, toilet pans, pedestals and under stairs cupboards. Bear in mind when redesigning after the heating has been installed that you may be having heating where it is not suitable and cold spots where floor space is exposed but not heated.

 

Existing buildings may need a review and most certainly upgrade of their current insulation to reduce heat loss on which calculations of output for the heating system will depend. In areas such as hallways and corridors where multiple heating circuits are on rout to their destinations it is necessary to insulate some of the heating pipes to reduce uneven heat build-up where the heat source is gathered. This is particularly required by the manifolds. This will ensure that all areas of the floor produce an even output which intern produces more even expansion and contraction rates of the Cathedral flooring  reducing problems that might otherwise occur.

 

BS EN1624 guideline figures for maximum floor temperatures are: occupied areas 29ºc, peripheral areas 35ºc and bathroom or similar 33ºc.

Cathedral flooring has been tested 100% positive to withstand a variance of combined temperature in the same floor area exceeding the parameters of these figures. When fitted to our guidelines Cathedral flooring will withstand fluctuating moisture contents of 6.5% to 11%. When installed over any type of under floor heating system it is critical that Cathedral flooring Cathedral flooring is bonded to a suitable substrate sheet. The purpose of the substrate is to strap the individual boards together for greater lateral stability and eliminate possible rotational force on individual boards.

 

This sheet also helps to disburse heat more evenly to the hardwood floor reducing hotspots and also eliminates any air from venting up between individual boards. The bond of the sheet material to the screed is much less likely to fail than individual boards but if it did the floor would still survive as a floating diaphragm. Many a time we have surveyed floor failure where the adhesive has kept its bond to the screed but the screed surface has failed. Trying to take up individual boards and re-bonding can be a nightmare as adjacent boards come loose in the process and you end up chasing your tail. We do not recommend bonding (CF) direct to screed even when UFH is not present.

 

Cathedral flooring can be laid as a floating floor without a substrate only when UFH is not present. The combined Cathedral flooring bonded to a wood substrate can be floated over UFH but the best option is a fixed down system. Until tests have been approved we do not advise to float Cathedral Flooring bonded to Fermacell over UFH.

If the UFH design uses metal diffuser plates these must be in full contact with the overlaid floor for best efficiency. The best methods of using these plates are for them to be set in grooved ridged insulation. This helps to prevents them being damaged when walked on and ensures they are in contact with the underside or the floor covering.

 

Some less expensive UFH designs have standard of the shelf insulation on which the pans rest. This leaves an air void under the plates, which we would not recommend. 25mm quilt insulation between the pans and the rigid insulation would help to eliminate some of this and support the pans to ensure they are in contact with the floor.

Another less expensive method of using plates is to nail then to joist or batten with rockwool slab or quilt beneath. Again air voids are present, not good. Often on site these plates get trod down and replacing them is not simple once the pipe has been laid. The result will be poor heat transfer, inefficient heating. A suitable underlay compatible with UFH can be installed between the plates and underside of the wood flooring to eliminate possible sound of the plates creaking against the flooring. UFH works best when all air gaps are eliminated and heat transfer is by direct conduction.

 

Air gaps present in a design rely on higher operating temperatures and only create low floor output temperature. If the air gaps are not totally sealed the heat can be vented out of the floor into cavities etc taking away any possibility to warm the floor. If air is allowed to vent up and between floor boards floor failure will surely follow owing the severe uneven drying of the boards. Underfloor heating in screed is at most risk during the screeding process.

 

It is important that the screeders are supervised to make sure the pipework remains where it was positioned to ensure the correct even output. If the pipe gets bunched up or randomly placed after coming free from its fixings the heating design will suffer. Wheelbarrows with poorly inflated tyres are not to be used.  Photos of the laid pipe should be taken prior to covering. These can be compared to an infrared image at a later date if a problem is found with the floors performance. Any leaks can also be pinpointed by an infrared image.

Beware if a pumped screed is to be used (not to be mistaken for a flow screed). The pipe will deliver a bucket full of screed on each pulse. When the pump pulses its shear weight whips the pipe and can rip the heating pipe up in large sections.

 

The screeders will not normally be too careful how they replace the pipe as long as it is covered. If they are made aware that is will be possible to see the placement of any disturbed pipe they will take more care.

 

An Anhydrite flow screed is the best option, incredibly fast to lay, faster drying and easy to level. This application is less likely to damage the pipework as long as the preparation work has been done to make sure the pipework does no float up.

 

After the heating system has been connected to the manifold the engineer will fill the system and prepare a pressure test to 6 bar. After confirmation that the installation is free of any leeks he will reduce the pressure to 3 bar and leave the system under test to be monitored during screeding.

 

Thermostats should be wired to floor probes to ensure the floors do not over heat causing damage to floor coverings. It is advisable to specify that a second floor probe is installed with each thermostat that can be wired in at a later date if the first probe fails. If the thermostats work on air temperature only the floor may be trying to heat more than one zone. If a connecting room with the door open is at a lower temperature or if an external window or door is left open.

 

The result will be overheating of the floor.

 

It is important that from the start of any project the relevant trades and professional are made aware under floor heating is to be installed and the types of floor coverings intended. Details of intersecting floor coverings, finished floor levels and expansion provision need to be taken into account.

Site supervision and scheduling of works will play an important factor in the safe care and usage of the heating system, protection and performance of the floor coverings.

Instruction on the correct use of the heating system should be passed on to the end user.