The ultimate wood floor installation guide

This wood floor installation guide is split into three main parts:

• Part 1: Preparing for installation
• Part 2: Installation best practices
• Part 3: Wood floor finishes

Part 1: Preparing for installation

Preparing for an installation job is probably the most important step in the entire process. If you get the preparation right, you’ll likely enjoy your floor for many, many years to come.

Getting the preparation phase wrong could be detrimental to the success of your floor. We’ll take you through everything you need to know about preparing for your wood floor installation, as well as common pitfalls to avoid.

What we mean by preparing for installation

The first thing to pay attention to when having a new wood floor installed, is what’s below the surface. The most common scenarios are:

• Existing floor boards
• Concrete / tiles
• Timber joists
• Plywood / chipboard

What we are most interested in here is the condition of the material below the wood floor to be installed. There are a few things to look out for.

Moisture or humidity

Moisture is the single most serious issue that needs to be addressed before a wood floor can be installed. In most cases, moisture is only a problem where a concrete or tiled floor is present. But other surfaces may also contain high levels of moisture.

If the floor is to be installed directly over a concrete floor where moisture is present, it will result in certain failure. This is because wood flooring products are kiln dried to reach a certain moisture content level. If the surrounding areas are significantly wetter that the wood flooring product, the floor will begin to absorb the surrounding moisture, which leads to all sort of problems such as:

• cupping (the boards begin to deform and warp
• expansion (the boards begin to expand and start pushing on walls and doorways)
• wood rot

To determine whether the sub-floor is within safe moisture/humidity levels, a hygrometer reading is necessary. Hygrometers read the Moisture Content (MC) of a surface as a percentage value. Ideally, the sub-floor should be between 6 to 8%

If you do have high moisture levels, there are fortunately some precautionary measures you can take. If there is a leak, this will obviously need to be fixed first. If the moisture is caused by a missing damp-proof barrier, there are products available which can be applied to form a surface barrier.

If a ply or chipboard sub-floor is to be installed as part of the installation job, a PVC membrane can be used to form the barrier. It is important not to protrude the PVC membrane by using screws or nails as this will cancel out the effectiveness of the membrane. The sub-floor should float on top of the membrane.

Dehumidifying the area

In certain cases, it is recommended to use a dehumidifier to extract moisture from the surrounding area. The most common cases are when rendering has taken place within a short period of time before the flooring is to be installed.

In the same way that moisture in the surface below can cause issues, moisture in the surrounding walls can cause just as many issues.

If you have had any rendering works carried out in the premises recently, these should also be checked with a hygrometer.

Acclimatisation

Acclimatisation is the process of allowing the wood to settle, or acclimatise to the humidity levels in the surrounding area.

Failing to allow for acclimatisation can cause serious issues with solid wood products. While most engineered products are less prone movement, it is still recommended allow these products to acclimatise, especially if the laminates are more than 3 or 4 millimetres in thickness.

Acclimatisation does not mean placing wrapped packs of wood in the installation area. To properly acclimatise the timber, the planks or blocks must be unwrapped, and loosely stacked in a criss-cross fashion with space in-between the boards. This will allow the air to circulate and will enable the wood to settle.

Levelling the sub-floor

In most cases the sub-floor will be sufficiently flat and shouldn’t require additional work. However, there are cases when the sub-floor will require some attention.

The recommended standard for flatness is no more than 3mm deviation per square meter. Depending on the installation method, anything beyond 3mm should be looked at.

In most cases, plastic packers can be used to level out the sub-floor. In cases where more extreme deviations are present, thin sheets of ply wood can be used to achieve the desired results.

Separating old floorboards from new floorboards

When installing a new floor over existing floor, it’s important to pay attention to the direction of both the old floorboards and the new floorboards.

If the new floorboards are to be fitted in the same direction as the old floorboards, the two need to be separated by a layer of ply.

This is because as the floor settles and moves around (expansion and contraction during seasonal change), if no barrier is created the new floorboards could eventually become loose.

Part 2: Installation best practices

Now that you have a good understanding of how to prepare your floor for installation, let's look at how we go about installing the floor.

In this section, we explore engineered / laminate flooring, solid timber flooring, parquet flooring and panel flooring. We also go through some of the design decisions that need to be taken to get the job completed.

Engineered / laminate flooring

Engineered flooring is quite a popular choice these days due to a few benefits that come with this type of flooring.

Stability

Engineered flooring is far more stable than solid wood floorboards. By stability, what we mean is that the lateral movement is much less. This becomes more apparent as the widths of the boards increases. For floorboards approaching the 150mm width mark, lateral movement can be up to 1mm per board during seasonal change. This can have undesired effects, which is why consumers tend to choose engineered flooring at the wider widths.

Fitting methods

When selecting an engineered floorboard, you’re spoilt for choice when it comes to installing the product. You have the following options:

• floating (required when sound proofing is required)
• nail fix (when sub-floor is a wood product)
• glue fix (when fitting directly to concrete or tiles)

Please note, nail fixing engineered flooring is only possible with certain types of engineered flooring.

If you have moisture concerns, engineered flooring would be a good option to reduce the possibility of warping and cupping.

Solid timber flooring

Despite the benefits that come with engineered flooring, solid floorboards remain a popular choice amongst consumers. Because of the way in which engineered floorboards are constructed, there is a small risk of delamination. One cause of delamination is water seeping through the joins, which is caused by incorrect cleaning methods as described in our maintenance guide.

Due to the lateral movement common in solid flooring, it is unsuitable for floating.

Thicker usable surface

Engineered flooring is comprised of a base material (usually a softwood or hardwood composition), with a surface laminate measuring anywhere between 2 to 5 millimetres.

Durability may become a factor after restoring an engineered floor. This is generally not the case with solid timber boards due to the thicker wear strip that comes with traditional tongue and groove flooring. Traditional solid timber flooring usually has a wear strip of 6 to 7 millimetres.

Fitting methods

Solid wood flooring is unsuitable for floating over sound dampening material, unless the sound dampening material is installed beneath a ply or chipboard subfloor.

With solid timber boards, you have the following fitting methods available:

• nail fix (when sub-floor is a wood product)
• glue fix (when fitting directly to concrete or tiles)

Parquet flooring

There is a certain quality that parquet flooring brings to any interior. It is an elegant, timeless design style that can really transform your home or work space.

Stability

Because a traditional parquet floor is comprised of many small blocks of wood it is unlikely that you will witness lateral movement with a parquet floor, provided you follow the correct acclimatisation guidelines. This is particularly important when installing a new floor over underfloor heating.

Even small blocks of wood can shrink which is why we still recommend the full acclimatisation period for parquet flooring.

Things to look out for

Parquet flooring tends to work better in larger areas. Small rooms and hallways may sometimes look smaller after a parquet floor has been installed due to the busy appearance of a parquet floor.

The exception to this rule is when the floor flows through multiple rooms/areas and there is at least one large room connected to the smaller areas. The reason for this is that continuity of the floor will give the illusion of space.

Another thing to look out for with parquet flooring is the flatness of the subfloor. If there is a large deviation across the floor it may be recommended to address this issue to achieve the desired results.

If you have chosen a tramline (border around the edges) this may also reduce the appearance of the size of the room. Borders and tramlines are typically recommended for larger areas.

Fitting methods

With parquet flooring you are typically limited to glue fixing. The most common installation procedure involves running a chalk line down the centre of the largest room. This is used to lay the spine of the floor.

The spine can then be used to fill out the rest of the area. After the body of the parquet floor has been installed, it may be necessary to let the underlying adhesive set before sanding and sealing the floor to avoid any movement.

Part 3: Wood floor finishes

Once the floor has been installed, there is one more decision to make, and that is how the floor will be finished. The finish protects the timber from wear and spills, but it also has a big say in how the floor looks and feels, so it’s well worth taking a bit of time over this step.

If you’ve chosen a pre-finished floor, the manufacturer has already made this decision for you. Everything below applies to floors supplied pre-sanded or un-sanded, which are sanded and sealed on site once the installation is complete.

Sanding the floor

An un-sanded floor is sanded in stages. The first pass uses a coarse abrasive to flatten the floor and level out any uneven joins. Each pass after that uses a finer abrasive, which takes out the scratches left behind by the one before. A pre-sanded floor will generally only need a light sand to remove any marks from the installation.

Before the final pass, any small gaps between the boards are filled using a filler made with dust collected from the floor itself, as we mentioned in our style guide. The floor is then vacuumed thoroughly, so that no dust ends up trapped in the finish.

Hardwax oil

As we explained in our maintenance guide, Hardwax oil is the most frequently used oil based finish in the United Kingdom. The oil soaks into the timber and protects it from within, while the wax forms a water-resistant seal on the surface.

The look

An oiled floor has a natural, matt appearance that brings out the grain and colour of the wood. A lot of our clients choose oil for exactly this reason, because the floor looks and feels like real wood rather than wood with a coating on top.

Repairs

One of the biggest benefits of an oiled floor is that worn or scratched areas can be repaired on their own. A worn walkway, for example, can be cleaned and re-oiled without having to sand back the entire room.

Things to look out for

An oiled floor needs a little more looking after than a lacquered floor. Depending on how much foot traffic the floor gets, a maintenance oil will need to be applied every so often to keep the surface protected.

Hardwax oil also takes a while to cure fully. The floor can usually be walked on the day after it has been sealed, but we recommend going easy on it for the first week or two. Rugs in particular should be kept off the floor until the finish has fully hardened.

Lacquer

Lacquer, in most cases a water-based polyurethane, forms a protective layer on top of the wood rather than soaking into it. Bona is the most frequently used brand in the United Kingdom, and their lacquers come in a range of sheen levels, from extra matt through to gloss.

Durability

Lacquer is generally the harder wearing of the two finishes, which makes it a good choice for busy areas such as hallways, kitchens and commercial premises. It also needs less ongoing maintenance than an oiled floor.

Things to look out for

Because lacquer sits on the surface of the wood, a deep scratch or a worn walkway can’t be patched in the same way as an oiled floor. To keep the finish even, the whole floor (or at least the whole room) will usually need to be sanded and re-lacquered.

A gloss lacquer will also show dust and scuff marks more easily than a matt one. If you like the durability of lacquer but not the shine, a matt lacquer is well worth considering. With the right primer underneath, it can even give the floor a slightly more natural look.

Changing the colour

If you’d like the floor to be a different colour, a light fast stain or a tinted oil can be applied before the finish. We always recommend trying the colour out on a spare board or a small area of the floor first, as the same stain can look quite different from one type of wood to the next.

Oil or lacquer?

This is one of the most common questions amongst our clients, and there isn’t a right or wrong answer. It mostly comes down to how much traffic the floor will get and the look you’re after. As a rule of thumb:

• choose oil if you’d like a natural look and the option of touching up worn areas
• choose lacquer if the floor will be well used and you’d rather spend less time maintaining it

Whichever finish you go for, the way the floor is looked after afterwards will make a huge difference to how long it lasts. Our guide to extending the life of your floor covers the cleaning products and routines we recommend for each.