Every day I have conversations with people who are thinking of having a wood floor and want help in making the decision.
These conversations often take the same pattern and I thought it would be useful to follow that pattern here.
The first question is not really technical at all.
What do you want your floor to look like?
You may know this and be able to describe it to a supplier. Or you may find an image on our website, another website, a magazine etc. which shows what you hope to achieve. Answering this usually decides, or narrows down, what wood is best. It can also affect what finish the floor has.
The next question is ‘WHAT IS THE EXISTING BASE?’ I’ve written this large because it is the most important technical factor and I’ll spend a little time in explaining the options.
You will probably have one of the following:
A Concrete Screed.
This is the most common base for newer houses, extensions and renovations. The ‘screed’ is a smooth concrete layer that is usually laid over a rougher and thicker concrete slab. These days insulation is likely to be installed between these two layers.
The slab should have a polythene membrane underneath it and there is often another membrane between the slab and the screed.
It is essential that the concrete is dry before laying a wood floor. If the building is old it is probably OK but if concrete has been recently poured you should allow a month for every inch of concrete above the membrane and the area should be heated for about two weeks before laying the wood floor. If in doubt get the base tested – a damp base is the single biggest reason for problems in a wood floor.
Traditionally only parquet or narrow strip floors would be bonded directly to concrete. Modern adhesives offer more flexibility but we still suggest a maximum width of 120mm for boards in this situation.
Engineered boards can be bonded directly to the screed.
It is important that the screed is flat enough for the blocks or boards to sit flat and have sufficient contact for the adhesive to work. A latex leveling screed can be used to achieve this without introducing a lot of moisture.
For wider boards of solid wood we suggest they are fixed by secret nailing and this requires a timber sub-base to be installed on top of the concrete. This can consist of battens or a chipboard or plywood base. This sub-base needs to have a minimum thickness of 18mm (it can, of course be thicker if you need to raise the floor level).
As most solid boards are about 20mm thick the combination of the sub-base, adhesive and the wood floor is a minimum of 40mm on top of the screed. This does not usually cause insurmountable problems in sitting rooms or dining rooms. Doors may need to be adjusted, solid wood threshold pieces can be fitted which are sloped to even out any difference in height at doorways etc..
The raising of the floor level can be more of a problem in kitchens where the units are already fitted as it effectively lowers the height of the worktop by 40mm and can also ‘trap’ washing machines, dish washers and fridges under the work top. It can also be an issue in bathrooms and cloakrooms if the fittings are installed and cannot be removed. Hallways can also be problematic as they may have a number of doorways each requiring a threshold piece and the door to be adjusted.
In situations where you want to have a plank floor and the raising of the floor is a problem it is worth considering using an engineered board (we often use an engineered board with a thick top surface of real wood which is fished on site in the same way as a solid hardwood floor) or our solid Oak overlay.
These will usually be a softwood such as pine. In older houses they will probably not be tongue and groove which means that drafts can come up between the gaps. This is especially the case when the floor is fixed to joists over a ventilated void, this is a common system in older houses and is indicated by the presence of air bricks in the external walls allowing air flow under the floor. The tendency for drafts is increased if there is an open fire in the room as this tends to suck in air through the gaps.
There are two options for fitting a wood floor in this situation.
1. Lift the existing boards.
The new floor, assuming it is thick enough to be structural, can be fixed by secret nailing to the joists. A membrane should be laid over the joists to protect the underside of the new boards from damp and to help in reducing drafts. It is also possible to introduce insulation between the joists before laying the new floor. The new floor is likely to be Tongue and Groove and End Matched (i.e. the ends of the planks are also Tongue and Groove) which also eliminates draft. While the floor is lifted we often install insulation between the joists which improves the thermal efficiency of the house. This approach has the advantage that the new flooring will be the same height as the old one allowing it to be eased under the existing skirting board and is likely to finish flush in doorways. When removing the old floor care must be taken in situations where features such as staircases, fire hearths, walls etc have been built on top of it.
2. Fit the new floor on top of the existing
This is probably slightly easier. A thin board (flooring hardboard or plywood) should be laid on top of the existing boards. The new floor can be secret nailed to the existing floor. It is best if the new floor is laid at right angles to the old, but very often the old floor is laid in what looks the ‘right’ direction and we have found that with care the new floor can be laid the same way. As the new floor will be higher it is likely that doors will need adjusting, the floor may need to be ‘eased down’ in doorways and the expansion gap at the edges will need to be covered by moving skirting, fixing bead etc. (see later)
Existing Board (e.g. plywood or chipboard)
So long as the board is sound the new floor can be fitted directly to the board base. If in any doubt a moisture barrier can be laid over the base board. The same issues exist regarding height as in fitting to existing floorboards.
By now, having decided what you would like and what is possible you should be in the position of being able to choose what type of floor you are going to have. Apart from one thing……..
If you do not intend to have underfloor heating then you can skip this bit but it is becoming increasingly popular and has implications for wood flooring.
The most common form of underfloor heating consists of warm water being pumped through pipes. These pipes are often set in a concrete screed which is then heated by the warm water. Another common system has the heat being transferred to metal spreader plates which are fixed to joists. In both cases the new wood floor is fixed to be in direct contact with the screed or spreader plates, avoiding any air gaps which can act as an insulator. The wood floor thus becomes part of the heating system.
The first thing to check is that the heating system has been properly specified i.e. it can yield a comfortable room temperature without the floor surface becoming too hot – usually a maximum of 27°C. A building that is drafty, badly insulated or with high ceilings may not be suitable for underfloor heating.
It is possible to have real solid wood flooring over underfloor heating but great care needs to be taken.
If the system is in a concrete screed then only a wood block or narrow strip can be bonded to the screed. It is possible to set battens in the screed and then a plank floor can be secret nailed to the battens. It is essential that the screed is completely dry and that the heating has been running for at least ten days before the wood floor is laid. There are liquid membranes available which can be applied to a screed but it is our opinion that these should be used as an added precaution and not a substitute for drying the screed. Make sure that the moisture content of the screed is checked before the wood floor is laid.
The metal spreader plate system does not have the same moisture issues as the concrete screed approach but care must still be taken that anything (such as new timbers) which will be under the wood floor is completely dry.
It is also important to ensure that the wood floor is at the right moisture content at the time of laying. This is recommended to be 6%-9% moisture content. Some companies can offer to supply flooring kilned to this level. Others recommend conditioning the boards on site but this can be difficult (see Site Conditions). The moisture content of a wood floor over underfloor heating is attained by it being in direct contact with the heat source and it is difficult to mimic this before laying.
Engineered flooring can be used in the situations described above and while they are more stable the same principles regarding moisture content apply. Engineered board can be bonded to a screed or nailed to battens. It can also be laid as a floating floor but it is our preference to fix it.
There are also electrical systems of underfloor heating. Electric underfloor heating is not as common as the warm water systems as it is more expensive to run.
The most common form of this type is where electric elements are contained within a thin foil that is laid over insulation on top of a solid base. The manufacturers of these systems usually recommend a floor covering of a laminate or engineered board which is laid as a floating floor (i.e. the boards are glued to each other but are not fixed to the base). If the foil is laid as a continuous mat then a floating floor is the only option. It is however possible to arrange for gaps between the mats and if there is timber to nail into – either a board base or battens set in screed – then a timber floor or an engineered wood floor can be nailed. We have been involved in just a very few projects like this but they have been successful.
If you have specific questions regarding underfloor heating and wood floors then please email us at firstname.lastname@example.org We are also keen to increase our knowledge in this relatively new area so please email us with your comments and experiences.
If you buy wood flooring it is very likely the supplier will advise you to acclimatize the flooring by storing it on site for two weeks before laying. But what if, as is often the case, two weeks before laying the site is unheated and damp? Does it make sense to acclimatize the floor to that environment? The issue looks more complicated than the suppliers suggest.
But it is, in fact, very simple and it’s all to do with EQUILIBRIUM.
What you are trying to avoid is the wood floor shrinking, expanding or distorting after laying. Wood will only do these things if its environment i.e. temperature and humidity changes.
So this is all you need to know about site conditions & acclimatizing.
1. Get the site to the conditions that will exist when the area is in use - usually a centrally heated environment.
2. At the time of fitting ensure that the wood flooring is at a moisture content that is in equilibrium with that environment – for a modern centrally heated environment that will be 8%-10%.
Those are the simple principles. Understand them and get them right and you’ll have no problems.
But be aware that:
If you have a new concrete base this must be checked for its moisture content before laying a wood floor.
The environment in your house will change over the year and all the wood in your house will adjust accordingly (small gaps between boards should not be considered a problem)
Areas in front of fires, cooking ranges, south facing windows may experience extreme conditions and show larger gaps.
The Clever Bits Around The Edges
One of the big advantages of using real unfinished wood flooring and employing fitters with woodworking skills is that details such as mitred surrounds to matwells and hearths, thresholds at doorways, finishes to steps, ferrules to radiator pipes and other details are carried out as part of the job.
You will need to decide what to do at the edges of the new floor. A wood floor needs to have an expansion gap around the sides (especially across the width of the boards). Traditionally this gap is covered by skirting boards.
If new skirting is to be fitted and this can be done after the floor then this is ideal.
When an old floor is removed and the new floor is put in its place it is usually possible to ease the new floor under the existing skirting.
In other situations it may be best to remove and refit the existing skirting (usually possible but dependent on how it has been fixed).
If the skirting board is left in place a cover bead can be fixed at the join between the new floor and the skirting. It is usually desirable to make this as unobtrusive as possible.
Where radiator pipes come up through the floor wood ferrules can be fitted to give a neat finish.
Most wood flooring is sold pre-finished. This avoids the requirements to have the skills and equipment to finish the floor after fitting. The trade off is largely aesthetic. Pre-finished boards will have beveled edges which gives the floor a ‘factory product’ look. If you are going for something very contemporary this may be OK but if you want a more traditional wood floor appearance this will be a compromise.
Most of our customers are looking for a real wood floor, fitted and finished on site.
Whether you go for finished on site of pre-finished you will need to choose what type of finish you want. These broadly fall into two types:
Lacquers & Varnishes
These are coatings which offer protection to the wood. They tend to keep the colour of the wood looking like it did when it was laid. The coating will gradually wear and though good maintenance can extend its life it will at some point need to be sanded back to bare wood and recoated. Because of this we tend to recommend this type of finish for lighter floors such as Maple, Ash and American Oak. Because of the ‘lifetime’ issue we suggest using a good quality lacquer which has a high durability to wear.
Oils & Waxes (and combinations of the two)
It is possible (and has been done for centuries) to use just oil or wax, this is hard work in the first place and needs quite high maintenance, but the end result is a magnificent looking floor.
A modern development of this approach are products known as Hardwax Oils. These work by containing oils which seal the wood by saturating the pores and leaving on the surface a modified wax. This surface wax coating is more hard wearing than a traditional wax coating but will let the wood age and mellow and can be buffed. It is also reparable in a way that a lacquered floor is not. If you want a floor with a traditional look we would recommend this approach.
THAT'S ABOUT IT.
To give a guide price the questions I need answers to are:
How big is the area
How is this made up i.e. number of rooms and rough idea of layout.
What do you want your floor to look like?
What is your existing base?
Are you having underfloor heating?
Bearing in mind the above what type of flooring do you want?
How will the floor be fixed
Wwhat works to the base are needed?
How many threshold pieces are needed?
How many doors need adjusting?
What is to happen at the edges e.g. move skirting, fix bead, have new skirting etc.?
Do you want details such as surrounds to matwells and hearths, pipe ferrules etc.?
What type of finish do you prefer?
Where are you?
I hope you have found this helpful. If you have specific questions then please email us at email@example.com
We are keen to make this information page as helpful as possible. If you have suggestions as to how we may improve it then please tell us at firstname.lastname@example.org
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