English Timbers

Solid Hardwood flooring

Technical Summary

This is intended to explain the basics of the product and introduce any relevant technical information. It is brief, simple and does not attempt any in-depth explanations.

If you need detailed technical information about our products, fixing, site conditions, site surveys etc, please use the Comprehensive Technical Guide.

Laying a floor is not rocket science and we provide instructions with each order. It simply requires the appropriate knowledge, the correct method of fitting and a little care. Make sure that the site is thoroughly dried out and take all precautions. We have seen some extremely competent installations done by amateurs.

However a word of caution for everyone concerned. Floors can go wrong, but this is mainly due to incorrect installation or poor site conditions. Moisture and damp conditions will cause the floor to swell and distort.

It is important to follow instructions and most of all to make sure that the building is thoroughly dried out. A belt and braces approach is best adopted.

Please see the Explanation of Terms which includes some additional technical information.

Type of Flooring

We manufacture the traditional unfinished hardwood floor which must be sanded and sealed after installation.

Lengths - Random lengths up to a max of 1500mm, shortest length depends on grade - see price list. All orders contain a fair spread of lengths, but not necessarily every length. Sorry we cannot select for length.

Width - normally 128mm, sometimes 100, 110, 140 & 150mm. Thickness 20mm. Tongued and grooved sides and ends. Very accurately machined, requires minimum sanding.

Grades - All of our flooring is accurately graded into Classic, Character, Rustic & occasionally Tavern grades - see below.

Moisture content - About 8% to 10% average unless stated otherwise on the relevant web page or price list.

High quality, very accurately controlled product. Manufactured by English Timbers in the UK. Please see the particular web page and the printed price list for details and any variation from normal.

Advantages of Unfinished Floors - Unlike pre-finished floors, they have a smooth uninterrupted surface without any vee grooves. The continuous surface finish is applied after sanding and is hygenic and easy to clean.

There is the widest possible choice of surface finishes, wax, oil, lacquer, matt, silk etc. There are different finishes to match the various end uses - domestic, contract, sports etc and the good quality products will give years of good service.

Although the initial costs are higher due to the extra time to install, this is the best of all hardwood flooring options. In the long term, the floor will cost the same or less than a prefinished floor because the surface finish will normally last much longer.

English Timbers Floors - Timbers and Grades

Classic Grade - In general mostly clear of knots and has a well defined colour range. In certain timbers there may be more than one classic grade where each grade has been sorted on the basis of colour. E.g. White & Olive Ash.

Character Grade - Usually contains small to medium sized knots and more colour variation than the classic grade.

Rustic Grade - Wide colour variation, larger knots, some cracks etc. Shortest average length.

Tavern Grade - A low cost grade rejectedb from the Rustic. Has very rustic features, cracks, machining defects. Limited availability. Mostly all short lengths.

Skirtings - We also produce 130mm x 20mm skirtings in some of the timbers. The grading is different to that of the floors because it is difficult to find long lengths of one grade at a sensible price. The top grade may contain a few knots and colour variation. Small quantities of rustic grades are usually offered as a clearence item. Click here for more info

For more information, please refer to the specific timber page and The Comprehensive Guide.

Pre-finished Floors - We have introduced a small range of prefinished floors in September 2007 and details of these can be found on the prefinished page. These are well made products which are excellent value for money.

The grading is described on the prefinished page using the same grades as our own flooring.

We can offer a 120mm wide x 18mm thick floor and a 90mm x 15mm overlay floor - all with a micro bevel. These are very different from the usual imports in that they are all supplied in 1.82m lengths which are made up of smaller pieces finger jointed together. This makes them easy to lay and they only have an end joint every 1.82m.

Choosing a Floor

Each timber is described in detail on the particular page, but there are few general facts that are worth considering when choosing your floor.

Colour - Neutral colours are more forgiving if the decor is likely to be changed.

Light floors reflect more light and may be more suitable if the rooms are north facing or have little light.

Most timbers change colour over time. Dark timbers tend to fade, especially in direct sunlight, while some of the lighter timbers darken.

b>Wearing Ability - The ability to withstand denting is governed by the hardness of the timber. The resistance to wear also depends on hardness, but also depends on the ability of the lacquer to withstand scuffing, scratches etc.

All of our timbers may be used for domestic floors,if they are treated with respect. However it is best to use one of the harder timbers for areas with heavier traffic Eg hallways, kitchens etc.

For commercial use please ask for advice.

Timber Hardness

Hardness is a measure of a timbers ability to withstand indentation. The value quoted for each timber is the force in newtons(N) required to push an 11.3mm ball into the wood to half its depth. In general all our timbers are suitable for domestic use but cherry should only be used in lightly used areas such as bedrooms.

Resistance to Scratching

Resistance to surface scratching depends on the abrasion resistance of the surface finish. Only use a good quality finish. A two pack lacquer is harder than a one pack. Oil or hard wax finishes are easier to repair. For more advice please call us. See Finishing the Floor below for more info.

Site Conditions/Moisture Content/Storage

Our hardwood flooring is accurately kiln dried so that it can be used in fully heated buildings. Careful wrapping, monitoring and delivery ensures the moisture content is correct when delivered.

Flooring should only be accepted onto site when the conditions are correct for laying. If conditions are not correct, it should remain fully wrapped & stored in a dry building.

Site conditions refer to the state of the building fabric & the internal atmosphere where the floor is to be laid.

The site conditions for storing unwrapped flooring, laying the floor and during use are essentially the same.

The correct site conditions are:- The building must be weatherproof, warm and dry and at normal living conditions. New build or renovations must be thoroughly dried out and heated before installation. All masonry, plaster and concrete floor slabs must be thoroughly dry

Relative humidity of the air to be 35% to 50%. Temperature to be 15 to 25C.

For more information see Site Conditions in the Comprehensive Technical Guide

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Checking Conditions Before Laying

The site conditions should be checked before installation to ensure that the building is thoroughly dried out and that the ambient air conditions are within the limits above.

This is particularly important for new builds, renovations & old unoccupied buildings. If it is a dry existing property which has been occupied for some time, this is not so critical

If in doubt, the best approach is to be scientific and check these conditions with the correct survey equipment. For full details see the Site Survey section in the Comprehensive Technical Guide.

Timber Moisture Content

The moisture content is extremely important. Our flooring is dried so that it is stable in normal heated and dry buildings. If the conditions in the building are significantly different from those specified above the floor will expand or contract.

The moisture content of the timber will adjust to its surroundings. This means that if the site conditions are, say too damp, the timber will absorb water from its surroundings and expand.

It is impossible to choose a moisture content which is suitable for all conditions and types of buildings. We aim for about 8 to 10% for most heated buildings.  Where underfloor heating is to be used the moisture content needs to be about 8% or below - depending on the building - and we try to produce some batches of flooring with this lower value.

However, these very low moisture contents may cause problems if the flooring is used in normally heated buildings or some older properties and therefore an average of 8.5% to 10% is the norm.

See Moisture Content in the Site Conditions section of the Comprehensive Tech Guide for more info & the notes below.

Movement of Timber

Assuming site conditions and moisture contents are about right, the new flooring will adjust easily to the conditions in the building. It will then continue to expand and contract from summer to winter with the change in seasons and the use of heating.

You can expect to see small gaps towards the end of winter and these will close up in summer.

Underfloor Heating

We generally advise that considerable care should be excersised if our normal flooring is to be used over underfloor heating.

The type of building, level of heating, type of heating system and moisture content of the wood are all critical. The moisture content of the flooring should be about 8% or below.

However, if the moisture content is a little above 8%, it can be acclimatized by placing the floor, without fixing, over the heated area while the flooring is running for about a month. It may then be laid in the usual manner provided that the conditions in notes 1 & 2 below are met.

We also produce some drier batches of flooring and these may be used provided that:-

  1. The building is very well insulated up to the latest standards, has the minimum heat loss and reasonably uniform conditions throughout the year. Old houses with little insulation are not suitable.
  2. The heating system is correctly designed to accommodate a solid wood floor with adequate fixings and an appropriate heat output to maintain comfort without damaging the timber. Poor design or installation may damage the floor.
    Please ensure that the provider of the system understands the technicalities of solid wood flooring, has designed the system with wood flooring in mind and is aware of the moisture content of our flooring.
    In general, expect more seasonal expansion and contraction with these systems.
  3. The moisture content of the particular batch of flooring which you buy is low enough for use over underfloor heating. Please discuss this with us well in advance and notify us, when ordering the floor, that it is to be used with underfloor heating. We will then advise you accordingly.

Sustainable Buildings - Some modern buildings are being constructed with very high levels of insulation, are designed for solar gain, high thermal mass & heated with low level underfloor heating powered by heat pump technology. The conditions are more or less constant and wood flooring may be used provided that all the usual conditions are met and the floor installed correctly.

Conservatories with glass roofs

In general, solid wood flooring should not be installed where the conservatory is exposed to the sun for long periods. The temperature may be excessive. A north facing conservatory may be acceptable.Please call for advice.

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Basic Laying Guidelines

Option 1 - Secret nailing

Nailing through the tongue with a floor nailer or pneumatic nail gun. This is the best method as it allows the floor to move. Nail at 200 to 300mm intervals at 45 degrees into sub floor. First and last 2 or 3 rows are fixed through the face with a face nailer or by fixing with screws and plugs.

Nailing to existing boards fixed to joists - Punch in old nails. Ensure the existing floor is securely fixed, sand off level. Lay a damp proof membrane (DPM) of building paper & fix the new floor at 90 degrees to the direction of the existing boards.

Nailing to chipboard or plywood fixed to joists - As above but lay at 90 degrees to joists.

Nailing to floating chipboard over insulation - Such floors are not fixed securely & may cause problems when the new floor expands in summer.  If possible, replace with battens fixed to concrete ( See below ), or fix down the existing floor to the concrete with anchors.

If the conditions within the house are very stable from summer to winter it may be possible to fix the new floor with a large expansion allowance and hope this is sufficient. Always use building paper DPM under the new floor.

Fixing to Dry and Level Concrete - Fix kiln dried treated battens (Min thickness 25mm) to concrete at 250 to 300mm centres and ensure level. It is preferable to insulate between battens.

Always use a DPM. Options are polythene sheet, epoxy resin and building paper depending on the humidity of the concrete slab. See the Comprehensive Guide for more details. Fix floor at 90 degrees to battens.

Fixing to Existing Ground Floor Joists - Not recommended because the damp air under the floor will be absorbed into the new floor causing severe expansion and distortion. It is difficult to seal a building paper laid over joists and polythene sheet should not be used because it may sweat. Floor joists are normally set at 400 to 500 centres and this spacing is too wide. It is very important to both fix and support the new floor at 300mm centres or less. The more fixings per square metre, the more stable the floor.

The best option would be to fix 20mm exterior plywood or chipboard to the joists, lay a DPM and fix the new floor to this.

Option 2 - Using Adhesives

The flooring may be glued to the subfloor provided that the correct adhesive is used and the site conditions are correct. Many contractors use this method successfully to fix hardwood flooring to a variety of subfloors including concrete.

We recommend using an MS adhesive. This is a new type of flexible adhesive which was originally designed for bonding teak decking to steel for boat decks. It is very safe to use and contains no water or solvents. It will bond timber to almost any other material and can be used to fix the floor to concrete, steel, ceramic tiles, plywood, chipboard etc. There are one or two materials which may require additional treatment such as new ashphalt.

There are number of points to consider for a successful installation:-

The subfloor must be sound, clean & free from polishes/wax, be firmly fixed.

Site conditions must be correct and the subfloor dry.

Because hardwood flooring is normally secret nailed, the boards are cramped together and held down by the action of the nailer. During gluing, it is important to keep the floor in contact with the adhesive and it may be necessary to weight it down. Some fitters fix the floor at 500 to 600 centres with screws and plugs. The adhesive does have a good "grab" and will usually hold the floor in place.

Some floors are machined at very high speed and are often bent or distorted. These will be difficult to hold in place.

However our floors are machined very slowly and they are mostly flat and straight. This means that it is relatively easy to lay the boards without obvious gaps. A few small gaps will aid expansion within the floor.

The existing concrete may not be level enough (3mm over 3m) or dry enough and would require a self levelling compound to remove irregularities. These must be compatible with any suface DPM (See below) and laid either under or above the DPM in accordance with the makers instructions.

Regardless of the age of the concrete slab, a surface damp proof membrane should be applied to the surface to prevent excessive moisture being absorbed by the timber.

There are 2 options:-

A). For most slabs it will be adequate to apply 2 coats of Creom to the surface and leaving overnight. This is a safe, easy to apply, water based product which soaks into the top 5mm of the concrete and forms a barrier to the moisture in the concrete. The flooring can be then glued to the slab with Proflex.

Creom cannot be used in every situation. The slab must have a maximum humidity of about 90% and must contain an integral DPM under the site main slab. Creom should not be used if the surface has been power floated unless the surface is first shot blasted or abraded.

B). Where the slab has an RH over 90%, or is power floated, or is an old slab without a DPM, 2 coats of an epoxy resin DPM should be used.

In all cases and regardless of the RH, the slab should have dried sufficiently prevent further shrinkage. This is usually 2 to 3 months.

The only exception to this may be a screed over an underfloor heating system which has been running for some time. However, we would still recommend that 2 coats of Creom is applied to the surface.

Allowance for Expansion

All timber will expand in summer, when the humidity is high, and contract in winter when the humidity falls due to cold external conditions and central heating.

A new floor with a moisture content will normally expand at some point in the 12 months after installation.

To accommodate this, an allowance must be made around the perimeter of the floor - usually about 15 to 20mm. In addition, with a particularly large floor area, some intermediate allowance should be built in when installing the floor. This can be achieved by intermittently placing spacers between lines of flooring every 600 to 1000mm or using an appropriate pneumatic nailer which does not cramp the flooring during nailing and introduces a little slack.

If the floor is glued to concrete, there will be less accumulative expansion at the edges of the floor and the allowance can be reduced. Most of the expansion will occurr within the floor because it is laid more loosely and not cramped the nailer. The fitter should try to estimate the likely movement and make due allowance as he lays the floor. This is more important with a large area.

Finishing the Floor

English Timbers floors are very accurately machined and require far less sanding than most mass produced floors. The rustic and tavern grades will, however require a little more work.

After installation, the floor should be first sanded with a large floor/drum sander with a 60 or 80 grit paper (no finer) at 45 degrees, followed by sanding along the grain with progressively finer grits until it is finished with a 150 or a worn 120 grit. Edges are done with an edge sander and corners with a scraper. If available, a rotary finishing sander may be used with an abrasive screen to finish.

Vacuum up any remaining dust carefully - some will remain even though modern sanders have effective extraction. It is a good idea to wipe over the floor with a damp cloth. As well as remove any final bits of dust, this will also show up any sanding errors which can then be remedied. The surface can then be treated with the chosen surface finish.

Types of Finishes

With the exception of oil based polyurethanes, there are two types of finish:-

Junckers Hard Wax Oils which are absorbed into the surface of the timber. Two coats are normally required. Easy to apply and repair. Faster to cure than many other oils. Reasonably resilient to wear and spillage. Click here for a link to the Junckers website.

Advantages of oils - More natural appearance with soft sheen. Scratches and scuffs less obvious and easy to repair.

Disadvantages of oils - Slower than water based lacquers to cure - 6 days. More maintenance required. May permit more transmission of moisture through the surface than lacquers and hence more seasonal movement. Can be rather dull in appearance. Darkens and changes the colour of the floor. Not suitable for light floors where natural appearance is required. Consider Junckers HP Matt as an alternative.

Water Based Lacquers

Junckers Profinish is a one pack lacquer. 3 coats are normally required & it is easy to apply and gives a fine matt finish.

Dries in 3 to 4 hours. Fully cured in 3 days.

Junckers HP is an excellent product. It is a 2 pack water based polyurethane lacquer which gives a modern matt finish. It looks like an oil finish but is much tougher & easier to maintain. Suitable for domestic or heavy contract use. Very durable, dries within 3 or 4 hours and fully cured within 3 days.

Advantages of water based lacquers - Fast drying & curing. Easy to clean and maintain. Seals surface and helps stability. Hard wearing, especially Junckers HP. Silk or matt finishes. Does not radically change the colour of the floor.

Produces a continuous surface coat over the surface.

Disadvantages of water based lacquers - Very few except for appearance which some find less natural than an oiled finish.

Effect of Direct Sunlight - Most timbers will bleach in direct sunlight and where this is likely to happen, a light timber should be chosen. Heat treated timber may be more susceptible than untreated timbers. So far the use of this type of timber is new and little is known of the long term effects. Our only advice at this stage is not to use it in direct sunlight.

Full fitting instructions are supplied with the floors & these contain technical info and explanations how to install and finish.

For further info on finishes Click Here

Revised 07/01/08