While they may look like the same thing once installed, Engineered and Solid timber floors are 2 very different things. Solid timber flooring has been used since the dawn of time, but engineered flooring is only an invention of the last 30 years, but incorporates scientific principles that were used in the making of Composite Bows by laminating several different types of timber together that would in theory balance each other out.
Engineered Flooring was developed to allow floors to be floated as it is quite common in Europe that people take all of their fittings (lights, kitchen and Floor included,) with them when they move house. The theory was that the floor could be packed up and reinstalled in a new home if it was floated, but could not be if it was direct stuck.
Let’s have a look at the 2 different kinds of timber flooring (and their sub-categories,) so you can see which will be the right choice for you.
Solid Timber Flooring
Solid Flooring is as it’s name suggests solid timber all of the way through. It is a single piece of timber that is usually profiled with a Tongue and Groove join to help with installation, although historically this was not always the case.
If the solid Timber is 19mm in thickness or greater, it means that this can be used as a structural floor laid over top of joists. Anything less than this is considered an overlay and must be laid over top of another kind of sub-floor. A Solid Timber floor is usually coated on site and not supplied pre-finished. This means in the vast number of cases an experienced timber installer is required to do the job and a floor sander to sand, seal and finish the product. Sometimes this is the same person.
The product is supplied raw and kiln dried usually in random lengths, and requires a period of acclimatization before it is laid. Because the timber is supplied, there is an array of finishes that can be used from polyurethane lacquer, Oil, Hard Wax Oil and others. In Australia, floors are typically Lacquered as this requires less regular maintenance.
Engineered Timber Flooring
Engineered timber flooring is a lamination of several different kinds of timber to make a lighter, more stable type of hardwood flooring that would have less environmental impact. This is achieved through using a veneer (or Lamella,) of Hard wood that is on average 3.5mm in thickness. This is then laminated to either a Ply core, or a stave core of about 8mm, with a 2mm backing, making for a finished product that is usually between 13-15mm in thickness depending these layers.
In the case of the Ply core, the kind of ply that is used depend upon where it is made. This can be made of many different types of timber with fewer thicker or more thinner laminations that are cross laminated. This is because as Timber wants to grow more on it’s with than its length, these laminations control each other to a degree. The veneer is then added to the surface of the core, and the backing (or balancing layer,) is added to the back of the board to try to counter the forces of the veneer.
A 3-layer floor uses a Stave core made of Staves of white Wood (commonly Hevea, Birch or Spruce,) working on the same principle as the Ply core. In this case the veneer and the Backing Layer run in a North/South Direction while the Staves in the core run East/West. This achieves the same principles of cross lamination as the ply core does.
A Solid Timber Floor is always fixed to a Sub-floor and cannot be floated. In the case of it being used as a structural floor, it is usually nailed to joists. In the case of it being used as an overlay, it generally requires that Ply sheeting first be screwed to the floor and then the Solid Timber be either Glued or Secret Nailed to this. This means that you will almost always need to engage the services of a timber flooring professional.
Engineered Timber Floors can for the most part be direct stuck (many are designed to be,) but do not require the layer of ply unless they are going onto upper level Yellow Tongue style sub-floors. Additionally, these floors can be floated, eliminating the need for adhesives with a mostly glue-less installation. This means that a Floating floor can easily be dismantled and removed.
Solid Hardwood flooring will grow much more than an engineered floor. This is planned for by acclimating the floor on site prior to installation. Additionally, small expansion joints of Cork must be added periodically through the floor during installation to accommodate expansion in the floor. These are not a negotiable option and are required for all timber floors. Studies conducted by the ATFA showed that a solid timber on average will expand and contract about 4 times as much as a solid timber with a Hevea Core. This movement must be planned for, and cannot be ignored.
For an Engineered Floor, the Acclimatization period is still required, but the amount of expansion breaks is not. Most suppliers allow a floor to be 10m on the length and between 7-8m on the width before a break is required. These breaks are usually positioned in places where they are less obvious, such as doorways. Trims are used to conceal the expansion break, and around the perimeter either skirting boards or scotia are used to hide the perimeter expansion. Additionally, most suppliers will allow their Engineered Timber to be direct stuck which greatly reduces the need for internal expansion breaks in the floor.
A Solid Timber floor is installed, and then sanded and coated on site. This gives you not only a greater option in the coating that goes on your floor, but allows for better coatings to be applied. When polyurethane Lacquer is applied on site, it is generally done in 2 thick coats. This forms a solid protective shield across the top of the timber and does not leave any sort of micro space for dirty humid air to be sucked down into and stain the ends of the boards. Additionally, while not really very popular in Australia, Oiling is a viable option. While this is more regular maintenance, you will never have to go through the process of sanding he floor, and scratches can be instantly buffed out with a small amount of oil. Because Oil nourishes a timber, a floor coated this way has an indefinite life if it is maintained.
Engineered timber is mostly pre-finished although raw versions do exist that give you the same options as above. With an engineered floor, you are generally limited to a Lacquered finish (in Australia,)and these factory finishes are applied differently. As any over run of coating over the side of the board can prevent it going together properly, these coatings are sprayed on in several thinner layers. The bottom layers are thinner to allow them to penetrate the wood, and then they are gradually thickened to build up over this. While this is very convenient, the fact that there is a micro space between boards that is unprotected can often overtime cause a ‘Dirty’ appearance in the timber as moisture is drawn in through these spaces and the wood is stained over time. Once this coating is removed though, all of the options for a solid floor apply.
Solid Timber is a more expensive option. This is because you are using more of the most valuable wood in it’s makeup, and dealing with a far more expensive installation process which requires ply-wood sheeting and the correct adhesives.
Engineered Timber is a less expensive option because it uses less of this most valuable timber, and uses plantation grown alternatives below the top veneer where it is not seen once it is installed. Additionally, because it can be floated, there is a great cost reduction here, and also the ability to do the job as a DIY project.