How To Add Attic Flooring Without Wrecking Your Roof

When converting your attic, incorrectly installing flooring can damage your ceiling and the overall structure of your roof. This can make your attic conversion much more expensive, not to mention creating new repair jobs within your home.

This article delves into everything you need to keep in mind when adding flooring to
your attic conversion and how to avoid damaging your home in the process.

Is My Attic Strong Enough for Storage?

There are several factors that determine whether your attic is strong enough to support a conversion into a storage room. These include:

  • The way the attic was built, i.e. how it is structured (from trusses, rafters, etc.)
  • If it has an existing floor and how strong that floor is
  • If it doesn’t have a floor, whether the attic’s structure is strong enough to support the installation of one.
The best way to find out this information about your attic, and to make sure it’s accurate, is by seeking the advice of a structural engineer or an experienced attic builder. If necessary, they’ll also be able to tell you how to strengthen your attic so it’s suitable for conversion into a space for storage.
The answers to the questions below look into these factors in greater detail.

    Can My Attic Support a Floor?

    Whether your attic can support a floor or not depends on how it was constructed. More specifically, it’s how the roof structure of your house was constructed.
    On one hand, if your attic is constructed out of trusses, it’s harder to install a floor. What appears to be the floor of your attic is actually the ceiling of the room below. These ceiling joists are typically made from 2′′x 4′′ or 2′′x 6′′ beams, which aren’t generally considered strong enough to support the weight of a floor – not to mention whatever is going to be placed on it.
    On the other hand, however, if the attic’s structure is comprised of a ridge board with rafters, it is more suitable for supporting a floor. This is down to the fact that ceiling joists are likely to be made of 2”x 8” or 2” x 10” structural members.
    To get the most accurate picture of how your attic was constructed, consult a structural engineer or an experienced attic builder. If it turns out your existing attic flooring isn’t strong enough, they’ll advise you on how it can be reinforced.

    Can My Attic Floor Support Weight?

    First of all, let’s clear up what you consider to be an ‘attic floor’.

    If your attic floor is no more than a series of beams separated over gaps supported by some plasterboard, that’s actually the ceiling of the room below! Those beams are ceiling joists and it cannot support much weight. If you actually have an attic floor and are unaware of how much weight it’s capable of supporting, it’s best to ask a structural engineer how the floor was constructed. You need to have a clear idea of the support structure the floor was built upon to understand how much weight it can support.

    How Can I Strengthen My Attic Flooring to Support Weight?

    While there are several ways to strengthen your attic floor to support more weight for a conversion, they generally fall into one of three categories:

    • Increase the size of the ceiling joists
    • Reinforce the ceiling joists,
    • Space between the ceiling joists

    Firstly, you can increase the size of the existing ceiling joists so they’re large enough to support the weight of a floor. Most ceiling joists in a structure composed of prefabricated trusses are 2” x 4” or 2” x 6”. In order to support an attic floor, as well as all the objects placed upon it (not to mention people), you need to replace them with 2” x 10” joists or larger.

    Secondly, you could reinforce the existing ceiling joists. There are a number of ways to achieve this:

    • Bridging: Bridging involves installing additional beams perpendicularly between the existing joists. This stabilises the joists and helps to reduce sagging. Bridging may be sufficient If the existing joist system only needs a little extra support.
    • Sistered Joists: This involves attaching new joists, of the same size, next to the existing joists (which is known as ‘sistering’). Sistered joists rest on the same load-bearing walls as the existing joists and attach directly to them, reducing the risk of breakage or sagging.
    • Laminated veneer lumber (LVL): LVLs undergo a process involving heat and pressure that produces beams that are much stronger for their size than those made from regular wood. These can be placed between the existing joists to strengthen the floor.
    • I-Joists: I-joists, which derive their name from the fact they look like a capital ‘I’, are mainly designed to help floors support the increasing weight. They can be installed above or next to existing joists.

    Lastly, there’s the spacing between the joists. Standard joist spacing in attic flooring materials is 16 – 24 inches on centre (OC). This refers to the distance from the centre of one joist to the centre of the one next to it. By bringing the joists closer together, you can increase their load-bearing capacity so they can support a floor.   (FYI in Australia we talk metric measurements for example standard joist spacing is 450mm centres in attics  – same as above trusses are commonly 90mm x 35mm and generally spaced at 600mm – 900mm and 1200mm.)

    It’s best not to come to any conclusions about your attic’s existing joist structure – or make any changes to it – without consulting a professional.

    What Is the Best Flooring for an Attic?

    What you intend to use your attic for plays a huge factor in the type of flooring you should have installed. You need to factor in:

    • Load-bearing capability
    • Noise transmission
    • Insulation

    Here’s a look at different uses for an attic conversion and suitable types of flooring for each:

    Flooring for an Attic Storage Space

    Plywood

    As it’s just for storage, thinner ½-inch plywood is sufficient for flooring. However, if the space were to be habitable, then stronger, ¾-inch plywood would be habitable. If you have an eye on the future and anticipate storing a large amount as time goes on (growing family, etc), you could go for the thicker, ¾-inch plywood sheets anyway.

    Flooring for an Attic Kids’ Playroom

    Laminate

    When it comes to a kids’ playroom, you’re going to need sturdier, more robust flooring. This will ensure it has the increased load-bearing capacity to cope with the constant movement, as well as limiting the amount of noise that can be heard in the rooms below. A laminate, as well as vinyl or linoleum, overlay on a wooden floor will absorb a lot of the sound coming from the attic. Also, laminate flooring is easy to clean – a huge plus when it comes to kid’s room!

    Carpet

    Carpet on top of a wooden floor also provides a comfortable, quiet flooring solution. You have a number of materials to choose from, such as wool, polyester, and olefin, but it’s best to choose one that’s stain-resistant. You can also choose from wall-to-wall carpeting or carpet squares: squares have the added advantage that individual tiles can be replaced if they get dirty.

    Floating Floors

    Floating floors are comprised of interlocking tiles that can be made from laminate, vinyl, and a variety of wood. A floating floor can be installed over plywood planks and padding to create convenient, noise-reducing flooring.

    Flooring for an Attic Home Office

    Hardwood

    For a home office, you could upgrade from plywood to any number of hardwoods, such as pine, oak, cherry, mahogany, beech, or maple, for a more inspiring, professional look. Better still, hardwood flooring is durable – especially in a space intended for adults rather than kids. Hardwood floors are sealed and easy to maintain – and can be refinished whenever necessary.

    Carpet

    Carpet over a solid plywood floor is suitable for home office setup.

    Laminate

    Laminate is another cost-effective option for home office flooring. It’s durable and comes in a huge variety of colours and styles – including those that look like wood. Plus, there are some instances, where you have a workshop as opposed to a home office, where easy-to-clean laminate or vinyl might be preferable.

    Flooring for an Attic Bedroom or Living Space

    Flooring for a living space, such as an extra bedroom, can the same as that of a home office or kids’ playroom: with an emphasis on comfort and durability. Both carpeting and laminate, over ¾-inch plywood can be budget options that are easy to clean, maintain, and even replace if need be. Alternatively, for a higher quality, and pricier option, you can also go for hardwood floors, which are also highly durable and easy to maintain.

    Attic Bathroom Flooring

    Tile

    Tiling, most notably ceramic tiles, are an excellent option for an attic bathroom floor. Tile is waterproof, durable, easy-to-replace – and budget-friendly to boot!

    Can You Put Flooring Over Attic Insulation?

    Yes, you can install flooring over the insulation in your attic, but you’ll have to take precautions as to not compress it – but have to put some sort of structure over it to avoid compressing it. If you put flooring in your attic incorrectly and end up compressing your existing installation, you decrease not only its value but its effectiveness as well. This will lower your home’s energy efficiency while increasing electricity and heating bills.

    The first way to avoid compressing your insulation is raising the height of the joists so they sit above the insulation. You should also do this if your attic’s insulation is thicker than your ceiling joists. The second way to avoid compressing your existing insulation is to reposition parts of it. This is dependent on of your attic’s structure and how the insulation was installed within it.

    Are Attic Trusses Worth It?

    Yes, attic trusses can indeed be worth it, especially if you have plans to convert your attic into a habitable space instead of just for extra storage.

    Standard roof trusses are designed to take the weight of the roof, as well as frequent, periodic load from the elements (snow, wind, rain, etc.). It then distributes said load down and out to the exterior walls of the house. Forcing a roof truss to handle more weight, for storage, let alone for an extra living space, puts you at risk of you weakening the entire structure.

    However, attic trusses, in contrast, are designed to take the extra weight that comes with a conversion. In fact, they actually have an open space at the centre of the structure where an extra room can be built, whether it’s just for storage or designed to be a living space.

    Better still, attic trusses provide this extra living space without the need to change the footprint of your home. It’s generally easier to get local council approval for this kind of extension and it generally costs less too.

    How much does it cost to put floor in attic?

    The cost of installing a floor in an attic can be very considerable. The biggest factors that go into its eventual cost are the structure you already have in place and what you intend to do with the space. For instance, installing a simple floor for a storage space will cost less than a sturdy, stylish floor for an extra room.

    As a very loose guide, you can expect to pay in the region of $700-$800 for subflooring and $1500 -$15,000 for floor joists. You’ll also need to factor in:

    • Renovation labour costs
    • Engineering and design fees
    • Council fees

    If you’d like a more accurate estimate based on your specific situation and plans, contact us for a free, obligation-free quote.

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