installation guidelines

INSTALLATION OF HARDWOOD FLOORING FOLLOWING NATIONAL WOOD FLOORING ASSOCIATION (NWFA) GUIDELINES

ACCLIMATISATION

On delivery your PlankCompany Solid Hardwood floor boards must be acclimatised on site for a minimum of 14 days in the ambient heat and humidity conditions which will be present when the building is occupied prior to installation.

The boards will be carried on site.  They will be stacked and stickered in bales of no more than 1 metre in height with a space of 100mm between bales to allow free flow of air during acclimation.  Although The Plank Company store and stabilise our timbers in the best possible conditions by heating our premises 24/7/365 using  recycled wood waste to fuel a huge wood burner, it is still imperative that the boards we deliver to another premises are allowed to reach the ambient conditions in situ.

An open and/or unheated  building site is not suitable for acclimatising solid wood which may be damaged by the ingestion of moisture from damp new builds or renovations. Delivery of solid hardwood should not take place until the building is completed, totally dried out and tested, then heated and ready to live in.

Properly acclimatised boards will remain stable when installed, and exhibit no visible signs of contraction in the weeks & months following installation.

SUB FLOOR PREPARATION

Preparation of Cement Screed

Screed must be level to within a maximum tolerance of 3mm per 2 l linear metres in all directions.  A maximum screed moisture level of 4% or less and a site Relative Humidity (RH) level of between 40 – 60% must be recorded prior to delivery of flooring.

Upon delivery, the boards should be allowed to acclimatise (see above)

CONCRETE SCREED MOISTURE TESTING

The Plank Company are flooring manufacturers, not surveyors, and all new build or renovation floor screeds must be tested by a fully qualified professional equipped with accurate testing kit and meters who will issue a test result certificate for the installation site. Please ask your surveyor to inform the Plank Company which meters and methods they will use for the testing

We do test for our own information, and our experienced floor fitters also carry full testing kits which they will use prior to fitting to ensure that the conditions as tested are still extant. 

INSTALLATION OVER JOISTS

We do not recommend that our solid hardwood floors are installed directly to joists if there is a substantial vented void underneath.  In this situation a premium quality exterior grade plywood sub floor must be fixed to the joists.  The resulting sub floor should be level to within a maximum tolerance of 3mm per 3 linear metres in all directions.

In all other joisted situations eg first or  succeeding floors, timbers may be fixed directly to joists or battens.  However where height permits it is always preferable to fix plywood or chipboard to joists or battens first, before fixing the flooring.

Chipboard  must be tongued and grooved, and have a minimum thickness of 18mm.  It may be screwed to the joists at 300mm centres, and the joints must be staggered.

In all ground floor installations, exterior grade Plywood must be used.

PLYWOOD

The Plank Company recommend, and always use SmartPly OSB3 plywood for all flooring installations which require plywood in the structure.

Plywood must have a minimum thickness of 18mm for a fixed floor &/or with underfloor heating. (see Underfloor Heating Guidelines)

Plywood should be laid where possible at 90% to the anticipated direction of the flooring timbers, leaving10mm? between plywood sheets.

INSTALLATION DIRECTLY TO EXISTING FLOORBOARDS

This is not the ideal base for the installation of a new solid hardwood floor.  But in certain circumstances is the only solution for the house owner.

Existing floorboards above joists must be level to within a maximum tolerance of 3mm per 2 linear metres in all directions.  They must be fixed with 2 screws per board at each joist fixing point.

Any damaged or decaying floorboards must be replaced.  Where there has been damage to the floorboards or excessive shrinkage, 6mm plywood should be nailed to the floorboards prior to fitting the new hardwood. 

If the new boards can only be fitted directly to the existing boards, then they should be fixed at a right angle to the existing boards to eliminate any risk of stress gaps caused by the different expansion and contraction rates from two different wood species (usually new hardwood over existing softwood)  If it is necessary for aesthetic reasons to run the new boards in the same direction as the existing boards without a plywood base, then it must be accepted by the client that stress gaps may (not necessarily) appear.  But if they do the boards can be tightened.

UNDERFLOOR HEATING

 If you have chosen or are considering installing solid hardwood floors over underfloor heating (UFH) in your new build house or extension, it is imperative that you consult the
Plank Company in the very early stages of planning your home build.  It is surprising how many people only think of the floor covering at the completion of the build when all sub floors and ufh systems are in place without considering the suitability of their chosen solid hardwood with the ufh system installed.  It is then impossible to change the structure to comply with internationally recommend methods of installing solid hardwood floors over ufh.  The Plank Company have installed 1000’s metres of solid hardwood flooring over UFH for almost 15 years using methods tried and tested in the United States & Europe, and recommended by the National Wood Flooring Association (NWFA)

The United Kingdom & Ireland have only recently started to catch up with the United States & Europe in using ufh to heat their homes.  Therefore it is not surprising that there is very little knowledge and much confusion among home builders on the subject of solid wood & ufh.  The Plank Company began fitting our solid hardwood floors over ufh 15 years ago.  The first five years in research, development & testing, and the past ten years successfully installing 1000’s yards of hardwood floors up to 230mm wide over ufh.  From the start, we realised that the Americans had more experience of this method than anyone else, and we use the tried, tested and recommended National Wood Flooring Association methods.
It is not necessary to use a semi solid (engineered) board in order to have a wood floor over ufh. (please refer to our links on Engineered/Mulitlayer floors for more information) Timber which has been thoroughly and slowly kiln dried, laser line edged and parallel sawn, then  properly machined to almost zero tolerances all round is better in every way than a man made board of thin layers of inferior wood with a sliver of veneer on top.  There is no comparison aesthetically & in performance.   What can be more impressive and beautiful than a traditional solid hardwood floor except a traditional solid hardwood floor which can be installed & guaranteed over ufh.  We like to say to our customers “why install an inferior semi solid engineered floor, when you can install a solid hardwood floor crafted  by engineers”

THE PLANK COMPANY “WARMWOOD” METHOD FOR INSTALLING SOLID WIDE PLANK BOARDS OVER UNDERFLOOR HEATING (UFH)

Following  concrete screed moisture tests which should read 4% or less.    

Lay a minimum 1000 gauge DPM.

Over this lay 40mm* insulation board  (* variable subject to new build or existing) We use KIngspan.

Fit The Plank Company “WarmWood” 40mm* heating platen system which carries the heating pipes.

Lay sheets of 18mm OSB3 Plywood (NWFA recommends up to 2?mm, but we prefer
18mm)

Secret nail The Plank Company “WarmWood” solid hardwood planks to the OSB3  Plywood.

THIS METHOD

 Eliminates any risk of residual moisture which may remain in the new build concrete screed, and is not picked up by the meters. (nb rare, but does occasionally occur)

 Reduces the waiting time to install our hardwood floors from 3 – 6 months to 1 week.
 Allows easy access to piping in the event of any failure of the system.

 Allows for re piping with the minimum upheaval in the future if government legislation or 
 lenders) required re piping of ufh systems in the same way as re plumbing & re wiring.

The build completion and handover can be guaranteed within a small time frame window instead of taking a minimum 3 months to possibly 6 months or even more in a wet Winter.

The surface temperature of the wood can be held safely at 26%.  This is the temperature The Plank Company solid hardwood has been tested thorough an 18mm OSB3 Plywood & 22mm solid hardwood “sandwich”  The recommended maximum surface temperature for protecting hardwood floors from excessive contraction or heat damage is 27%

WOOD, CONDUCTION & RADIATION

Wood has traditionally been considered a poor conductor of heat.  While it is not quite as good as  tiles, it is an excellent alternative. It is certainly not the worst conductor.  It makes up for its lower conduction figures by being an excellent radiator of heat.   Your floor will take a little bit longer from a cold start than tiles, but once it reaches the 26% surface temperature wood will hold & radiate the heat most efficiently. And when the system is turned off, wood will hold the heat for a long time.  Provided your solid wood floor is not allowed to exceed 27% in surface temperature,  most Plank Company floors will remain close without any perceptible contraction gaps.

SOLID HARDWOOD DIRECTLY TO CONCRETE INSTALLATION

The Plank Company have successfully installed solid hardwood flooring directly to DRY concrete screeds for 15 years.   However we always stress that this Is not the ideal or perfect way to install solid hardwood floors.  It is always preferable to lay a 1000 gauge DPM first, and fit OSB3 Plywood before secret nailing the hardwood planks to the plywood.

Many clients, particularly those whose homes are not new build and the concrete screed is old, dry & mature have no option because they are limited in available height.  In these circumstances, fitting the boards directly to the concrete with a special adhesive is effective, safe and successful.

But with new build, where there are massive quantities of water in the building( nb please refer to the table in our brochure) it is always preferable to use a DPM and Plywood before fitting the floor.  Some ufh companies are not convinced that the heat from their systems will travel up through a 40mm layer made up of 18mm Ply & 22mm solid board.  But we have  never had a case where an underfloor heating system was properly installed and controlled that  there was any perceived lack of surface temperature or comfort.  On the contrary, we are continually getting feedback from clients who tell us how efficient our flooring system is, and they run their boilers on the lowest comfortable setting.