There are many circumstances when you’ll be faced with the need to fit flooring directly over joists, in new builds, for example, as well as in certain situations where you’ve extended your property. There are few reasons why you shouldn’t fit engineered wood flooring directly over joists (unless in a ground floor situation where you have a ventilated cavity: see below), but there are certain things that you need to take into account.
Firstly, you need to make sure that your joists aren’t too far apart. The general rule of thumb is that joints should be no more than 45cm apart if you’re expecting them to support an engineered wood floor. This is the maximum recommended measurement from the middle of each joist to the middle of the next one. If your joists are further apart than this, you shouldn’t consider laying engineered wood flooring directly on them; instead you should cover your joists with plywood or chipboard to create a stable and solid sub floor. The other option is that you can introduce noggins and, or braces to take the weight of your new floor. Noggins are additional pieces of wood that go between your joists, and braces are pieces of steel that go between the joists to create a more stable laying surface.
If you are planning to lay a plywood or chipboard layer in between your joists and your engineered wood floor, you should choose a ply that is at least ½” thick and preferably 5/8 of an inch thick. This will ensure that the sub floor that you create is solid and stable.
Other things that you need to take into consideration include insulation for heat and for sound. If you are fitting an engineered wood floor over joists that are over an outside space, for example a garage, it is important that you take heat retention into account; otherwise your room will take on arctic temperatures in winter very quickly. If the room you’re planning to re-floor is over an outside space, then you will need to introduce insulation, either over a ply or chipboard sub floor or on a suspended basis between the joists below.
If you are fitting a new engineered floor to joists that are over a bedroom or a living room, then you should also take into account the passage of sound from the room above to the room below and vice versa. Noise can be an extremely irritating factor if wood floors aren’t correctly insulated. Nowadays there are a whole host of effective and economic insulators that will save money in heating and hassles with noise. Making the right decisions before you lay your flooring, particularly in a situation where you’re laying flooring directly over joists is always time well spent.
If you are planning an engineered wood flooring installation on a ground floor, it is important not to install your flooring directly over a ventilated cavity. This is because the flooring will absorb the moisture from the air in the cavity and will expand and contract too much as moisture levels fluctuate, eventually causing damage to your floor. In this case you should introduce an exterior grade plywood or chipboard over the joists, complete with a moisture barrier to stop moisture from passing to your new floor.
Finally, it is important to be aware that any wood flooring that is being used as a structural support in this way ie. being laid directly over joists needs to be thick enough to support the furnishings and footfall it will need to put up with, without risking damage. The general rule of thumb is that your engineered wood flooring boards should be no less than 18mm thick if you are planning to lay them directly over joists and you should fix them using nails or staples at a maximum of 300mm spacing.
If you’d like advice on the installation of your engineered wood flooring, why not get in touch? At Wood and Beyond we have years of expertise that we’re more than happy to share with you. We want your wood flooring project to be a huge success and will do all we can to make sure it is.
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FAQ
Q: Can I fit engineered wood flooring directly over joists?
A: Yes, you can fit engineered wood flooring directly over joists in many circumstances. However, there are certain considerations to keep in mind.
Q: How far apart should the joists be for fitting engineered wood flooring directly?
A: The general rule of thumb is that joists should be no more than 45cm apart to support an engineered wood floor. If they are further apart, you should cover the joists with plywood or chipboard or introduce noggins and braces for added stability.
Q: What thickness of ply should I choose for a subfloor between joists and engineered wood flooring?
A: It is recommended to choose ply that is at least ½” thick and preferably 5/8″ to create a solid and stable subfloor.
Q: What should I consider regarding insulation when fitting engineered wood flooring over joists?
A: If the joists are over an outside space, consider heat retention and introduce insulation either on top of the subfloor or suspended between the joists. For rooms above or below, also consider sound insulation to prevent noise transmission.
Q: Can I install engineered wood flooring directly over a ventilated cavity on the ground floor?
A: No, it is not advisable to install flooring directly over a ventilated cavity as the moisture levels can cause damage. Instead, introduce an exterior grade plywood or chipboard with a moisture barrier.