Hardwood flooring is becoming very popular again in modern-day home building. There is a separate article on this blog about the history of hardwood floors so I won’t write much about that here. This article is intended to share some info I have gained about hardwood floors and how to ensure that you make the right decisions when choosing your hardwood floor.
There are a number of hardwood flooring specialist companies in Durban to choose from when installing hardwood floors in your home. A few important points to consider when choosing a hardwood flooring company is their track record and their knowledge of wood, its characteristics and how it behaves.
There are broadly speaking two ways to install a hardwood floor. It will either be suspended on battens or joists, or be glued to the substrate which is normally concrete.
Suspended Floors vs. Glue Down Floor Boards
Suspended or sprung floors are exactly that. They are floor boards that are fixed to joists or battens with a cavity between the bottom of the floor board and the substrate. They are useful when there is no substrate or the substrate is below the desired height of the floor and filling with concrete is not an option due to cost. One can then simply run beams and joists, or battens if the height to be gained is not that great, at specified centres and then attach floor boards to the joists. The distance between joists will be determined by the type of wood being used as floor boards and its density and hardness. They will generally be between 400mm and 500mm. Anything less is a waste of wood and anything more may result in the floor boards being “spongy” and “bouncing” with slight movement up and down. Despite being annoying when walked on, this will also put strain on all joints and failure of the hardwood floor may be premature.
This substructure, or substrate, must be completely flat and level on the top in order to get a flat and level floor. Shimming and notching are practices used in suspended floors to achieve a flat and level substructure. Skimming or screeding may be necessary when making use of a glued down method. Either way that substrate or substructure MUST be completely flat and level otherwise you will have boards popping or unnecessary strain being placed on suspended boards resulting in nails pulling out or breaking. Once the substructure is completed and you are happy with it you can start installing floor boards.
If the concrete substrate is 20mm or so below the desired height of the top of the floor, then one has no option but to glue the wood down to the substrate. A batten is typically 25mm to 35mm thick and a floor board is typically about 20mm. So one would need at least 45mm between the desired top of floor height and substrate in order to make use of this method. Most older houses made use of suspended floors and the ground was typically 500mm to a metre below the floor and was sand. Columns were built up to support the beams and joists. In these older houses a suspended floor is the only option. In most modern-day homes the concrete substrate is set at about 20mm to 25mm below the door frames so that any floor can be utilised (i.e. wood or carpets). In these homes a glued down floor is the only option as the height of the substrate won’t allow for battens and floor boards as it will result in the top of the floor being higher than the door frames. It’s not impossible but also not preferable to have your floor 20mm or 30mm higher than your door frame.
One should be careful of glueing floor boards to a substrate that moves itself. If for instance the substrate is ply wood, installed on top of joists, then a suspended floor should be the method as the substrate will also be moving, thereby creating problems with the floor boards.
All wood “moves”, that is it expands and contracts with seasons and humidity. A suspended floor will allow the wood to move more freely as it is nailed down as opposed to being glued down. Being able to move a bit more freely will result in less boards splitting, popping or cracking over time. A suspended floor will have a hollow sound to it, which some people prefer while a glued down floor will have a more solid sound to it as it is glued directly to a concrete substrate.
Wood should always be allowed to acclimatise before being installed. This applies to both glued down and suspended methods. If we take teak for instance. It will originate probably in Zimbabwe, be machined there and exported to South Africa. It will arrive and will spend some time in Gauteng and then be shipped to Durban and then to its final destination. The changes in humidity and temperature between all these places affect the overall size of the wood. In more humid environments the wood will swell, expand slightly and in drier environments it will shrink, or contract slightly. It should be allowed to “rest” for at least two weeks, at its place of installation before being installed, to acclimatise to the local climatic conditions. Thin pieces of wood should also be placed between boards to allow for movement of air while it is acclimatizing.
The best time to install a floor is in the summer months. The wood would have (excuse the pun) swelled slightly due to heat and humidity (assuming of course the local conditions are more humid in summer than winter, such as Durban). The boards will be installed in this slightly swelled state and in winter they will contract slightly. If we do it the other way around, install in winter, then the wood will be contracted when being installed and will expand in summer and the boards will push up against each other, on the sides, and may pop. If winter is the only time one can install them, then allowance needs to be made for this and small gaps need to be left between boards to allow them to swell in summer. The size of the gap will depend on the type of timber being used. Harder woods will require less than softer woods as they will move less between seasons. When I say gaps I mean very slight gaps and I should rather refer to it as loosely laid as opposed to tightly laid.
Types of wood
There are various types of wood one can use for flooring. Some work better than others and the imported exotic hardwood such as Oak and Walnut are very expensive as opposed to locally grown timber such as pine or Saligna. Softer woods such as pine and Saligna (gum) can be used but will not be as durable as a hardwood such as teak or oak. They may split or crack sooner and will expand and contract more. Pine and Saligna work best being suspended rather than being glued down because they expand and contact more easily due to their lower density. Also the floors life span will be shorter because with every maintenance interval the soft wood will lose about 2mm from the surface when sanded. A hardwood such as teak will loose considerably less than that and as such its life span will be longer (i.e. it can be sanded many more times).
The different types of wood also vary in colour from dark to light and then some with varied colour like brown and white teak or Kiaat. Some of these variations in colour are due to heart wood and sap wood being present. Brown and white teak for instance is made up of heartwood and sap wood, heart wood being the timber close to the middle of the tree and sap wood being that close to the outside of the tree. Heart wood is by far the best as it is older and therefore harder and more resistant to attack by insects and rot. It is unavoidably more expensive.
Types of floor boards
There are various types of floor boards available on the market today. Most are tongue and grooved so that one side has a tongue and one side has a groove. When installing the tongue of one floor board is inserted into the groove of the board next to it to provide a tight fit and stop the boards from moving in a vertical direction against each other. The result being that your floor will remain flat for longer, if not forever. There are various different types of tongue and groove too which makes installation easier and results in less problems. Normally the tongue is slightly shorter than the groove to allow it to slide into the groove and not be prevented from being inserted all the way in so that the boards butt up flush with each other. Sometimes the tongue swells and the inside of the grooves swell, when moving into an area of more humidity, which makes it near impossible to get the tongue into the groove. A good floor board manufacturer will allow for this by making the tongue slightly thinner and shorter than the groove.
With locally grown timber such as pine or Saligna the boards come in longer lengths, typically 3m or so. With these longer boards they are normally only tongue and grooved on opposite sides along the length of the board. When installing, one will either cut the end of the board to reach a joist or batten, resulting in a small amount of waste or one will install an extra batten on that board only to support the end of the board. With imported timber such as teak, the boards will come in much shorter lengths as the longer stuff carries a premium price tag and is normally reserved for other uses. These are commonly known as maxi planks and vary in length from 450mm to 1m. If the same method as above was used one would be inserting extra battens all over the place which would not be feasible. So what the manufacturer does is to tongue and groove all four sides of the board. When the end of the board is reached there is no need to install an extra batten as the ends are tongue and grooved and fit snugly into each other without any vertical movement.
There are specialised tools for hardwood installation. We make use of an angled floor nailer. The nailer drives a nail at a 45° angle through the tongue and into the batten or joist. It also counter sinks it so that the nail does not impede the next board from butting up tight against the first one. The nail is now invisible and cannot be seen from the surface of the floor. The nail is also flat in that it is thinner than it is wide. This allows the nail to be driven through the timber between the grain on it’s thinner side so as not to split the tongue. It is hook shaped and ribbed so that it does not pull out over time.
I hope I have shed some light in the pros and cons of hardwood flooring and what to consider when installing hardwood floors and that you enjoy your hardwood floors for many years to come.
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