When embarking on finding a new hardwood floor for your interior, you will be faced with many choices in terms of species, colour and the type of finish to name a few.
One of the most important of these decisions is whether you have an engineered or solid construction.
First of all from an aesthetic point of view there will be absolutely no difference, but from a technical point there will be.
As shown in the images below, solid boards will be made from a solid piece of hardwood from top to bottom.
Engineered boards will consist of a hardwood top layer that is adhered to plywood or a soft wood core.
There is often a misconception, one I had myself when I first started in the industry, that a solid board will last longer than an engineered board as you can sand it more.
This is incorrect, you can only ever sand down to where the tongue and groove profile is, regardless of the construction.
This top layer is an important feature to take note of.
The thickness of the top layer of a board will be determined by the overall thickness of the plank.
Solid planks are usually constructed in a 20mm thickness and will have a 6mm wear layer.
With engineered boards, they normally range between 13mm - 21mm in thickness and the wear layers will range from 4mm - 6mm.
This will vary depending on manufacturer and where the wood is sourced from.
Watch out for poorly manufactured floors, they will have a lesser hardwood top layer to save on costs. These product's can't usually be sanded and refinished as the top layer can be as little as 1.2mm.
See example below.
What is important for you as a buyer is the longevity of the board.
On average 1/2mm - 1mm is taken off the top layer every time you have the floor sanded.
Meaning that even opting for a 15mm board with a 5mm wear layer, will get you 4 sands from it comfortably.
If you base that on an average of sanding it every 8 years, the floor will last 32 years at a minimum.
Depending on what finish you opt for, hard wax oiled or lacquered, will determine how often you need to sand and refinish.
With the correct maintenance, you shouldn't need to do this often.
It's for this reason that I often steer my clients to selecting a thinner board such as a 15mm thickness, especially when having to meet project resources.
Unless they need to lay a structural board, in the event they are installing directly over joists, then an 18mm or thicker is required.
Different Types of Engineered Construction
Within the construction of engineered boards, you will come across 3 main different options depending on the manufacturing.
Hardwood with a Multi Layer Plywood
As shown in the image below, the most economic engineered board is produced on a multi layer plywood board.
Constructed from layers of thin veneer sheets on top of each other, with each grain running at right angles to the next layer to enhance the strength of the board.
Now, there is absolutely nothing wrong with this construction, however if a cheap plywood is used, they are known to delaminate easily.
Ensure that if you do go for this construction, that the plywood is called flooring grade plywood or birch plywood and that its described as WBP - this refers to it being water and boil proof.
Hardwood with Softwood Core
The second option is to have the hardwood top layer sitting on a softwood core such as birch.
Birch is very stable and the construction is composed of an inner void-free core of cross-banded birch plywood.
It is among the strongest and dimensionally most stable plywoods.
This construction is often referred to as a 2 layer engineered board.
Birch Plywood Core Between Hardwood
The third option is a 3 layer engineered construction and can be referred to as a counter balance board.
As shown in the image below, the construction consists of hardwood top layer, a birch wood core and hardwood bottom layer.
Its structure of 3 crossover layers of real wood guarantees exceptional stability over time, especially for extra long and extra wide boards.
This robust construction enhances both the visible top layer and the quality of the bottom layers resulting in a board with superior strength.
Under Floor Heating & Relative Humidity
If you have decided on having under floor heating, electric or water system, you will have no choice but to go for an engineered construction.
This is where the plywood core of the engineered construction comes into its own.
Plywood is highly resistant to expanding or shrinking, it is less likely to split when nailed at the edges, and the sheet strength is consistent in all directions.
Wood flooring must be allowed expand and contract naturally through the four season cycle.
Wood is hygroscopic, which means it will absorb, hold and then release moisture over time, depending on moisture levels in the surrounding environment.
Changing relative humidity (RH) and temperatures levels influence the shape and size of wood flooring on a daily basis.
Without the ability to expand and contract freely, the risk is that your wood flooring will bow, causing squeaking, lifting and joint stress.
When it's Winter, we all have the heating on and this dries up the relative humidity in the atmosphere causing the floor to contract.
In Summer we don't have the heat on and so they expand.
This kind of movement is fine and I bet you that you won't even notice it.
However, were you to whack your under floor heating from nothing to maximum, this will shock the wood and it will contract quickly, leaving visible gaps in your floor.
I would recommend a maximum surface temperature for under floor heating of between 22° - 24°c (72° - 75°f) and turn it on slowly to reach that temperature.
The opposite will happen should you have a flood for example.
The sudden impact of humidity into the floor will cause the floor to expand, sometimes very quickly, taking the skirting's with it!
Because a solid plank doesn't have the plywood to stabilise it, it will warp very quickly to environmental changes and not be able to return to its original size.
Engineered wood is extremely resilient when its comes to sudden changes.
However, because London is so built up, it meant that we had a flat above us.
On a couple of occasions, I'd walk in on a Monday morning to find the neighbours above washing machine had caused a leak and as a result the entire showrooms floor was under water.
Even now I remember walking over the 21mm engineered planks we had and you could hear the water being squished under the boards.
We immediately brought dehumidifiers in to dry up the relative humidity in the showroom and get rid of the moisture.
Admittedly it took a few weeks, but slowly the boards contracted and went back to their normal width.
We would not have been so lucky with solid planks, we would of had to replace the entire floor.
Even with all this said, there is no guarantee that an engineered board will survive a flood or under floor heating being switched up too high, it will depend on the damage and how long it's been left in that condition.
Always make sure your installer leaves a perimeter expansion gap of approximately 6-10mm, which will be covered by skirting boards after installation.
Are you thinking of installing hardwood in your kitchen? Check out my article:
You Might Need a Floating Installation
Planks are glued together along the tongue and groove profile and no nails are used.
This installation is not possible with solid planks as they are not stable enough.
Going Wide with Engineered Flooring
Trends have dictated over the last few years that going wide with flooring planks makes your space feel more spacious and modern.
Keep in mind that if you want to have a wide board installed over under floor heating, British Building Regulations state no wider than 130mm, this isn't very wide considering that you can now get engineered boards that are 500mm wide.
I would err on the side of caution and discuss your requirements with your installer.
Boards that have a width between 180mm - 240mm are consider wide. Boards that have a width between 260mm - 500mm are considered to be super wide and you should only be buying these a 3 layer construction as described earlier in the article in ensure stability.
In order to keep a solid board's construction stable they are usually manufactured to a maximum width of around 200mm and the lengths are keep to a maximum of 2.5m.
As mentioned above, engineered boards are produced in wider widths and lengths can reach up to an impressive 5meters.
In order to get a superb installation it always starts with a perfect subfloor.
The more level your subfloor the better your floor you with behave over the coming years.
Engineered boards will be slightly more forgiving than solid boards when it comes to an uneven subfloor.
Now, your subfloor unevenness cannot deviate more than a 3mm difference over a 2m space, but because engineered floors usually have a micro bevel profile this masks slight unevenness.
Some engineered boards are manufactured with slits cut into the back of the board, allowing for some flexibility.
Solid flooring doesn't always carry a micro bevel and can have a profile called a square edge. This will show up height differences very easily.
It's important to note that solid floors require an acclimatisation period of at least two weeks on site. Engineered boards do not require this but if the installation is taking place over the colder months,
I recommend leaving the boards on site for a few days.
Check out my article entitled The 5 Questions I Get Asked Most About Hardwood Flooring for more information on choosing a hardwood floor
So Why Go For A Solid Board?
Personally I would always choose an engineered board.
With 20 years experience in the industry, I can count on one hand the amount of solid planks floors that I've sold.
It's not that I've got anything against solid floors, I just feel that manufacturing has moved on and with under floor heating and acoustic requirements becoming the norm for most refurbishments, engineered floors have become more popular.
You can also get parquet floors such as herringbone, chevron and panels in engineered formats now, but where solid is beneficial is if you opt for going for a 10mm overlay.
Solid overlays are often produced for parquet flooring such as herringbone and can be a great economic choice for a project.
Solid overlays typically don't have a tongue and groove profile and so they are glued down, usually to a plywood subfloor.
They will often have a distressed edge, which masks any height differences between pieces and adds character to the floor.
This post is packed with technical information, but the main thing to remember is that your subfloor and property type will dictate what type of floor that you can have.
Please visit my consultation page should you be embarking on a flooring project and would like detailed advice and product suggestions.