How to board a loft – 3 different methods

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Boarding out your loft is a great way to add extra storage to your home. For most people, this is an area that is not utilized, and is essentially wasted space.

However, boarding out your loft is relatively easy and can add a large amount of usable storage to your home.

Every loft is going to be different, so the amount of space and the layout will vary. However, if the area is just being used for storage, then the process will be very similar.

how to board a loft

In most lofts, you will have trusses and supports running through the space. If this was being converted into a usable room, there would need to be adjustments made. For example, you would need to remove certain timber supports. These would need replacing with new forms of support, to open up the floor space, whilst ensuring the roof is still safe.

However, for storage purposes, this is not necessary, and you can simply fit the flooring around these timber supports.

Most common boards used in a loft

The most common floorboards used in lofts, are tongue and groove chipboard flooring. Although other options are available, such as OSB (orient strand board) and also plywood. Both of these can be purchased with tongue and groove, meaning they can be fitted identically to chipboard flooring.

However, chipboard is usually the cheapest option, and it is also more readily available.

Chipboard flooring comes in two main sizes, the largest is 2400 x 600mm. You can also buy smaller boards at 1200 x 320mm.

Larger boards are preferred. However, they are sometimes hard to get into some lofts. Smaller boards are much easier to fit through a smaller hatch into the loft space.

Chipboard also comes in two main thicknesses. These are 18mm and 22mm. For this type of job, 18mm is completely acceptable and will give more than enough support.

Finally, you have the choice between standard boards and moisture resistant boards. This is entirely up to you. Moisture boards will be more expensive, but they will also hold up better if you do have a roof leak onto the flooring.

Fitting methods and insulation

When it comes to fitting your boards, the first thing you want to do is check the joist spacing. In most cases the joists will be fitted at either 400mm or 600mm centres.

Sometimes, you may also find joist at 450mm, and occasionally, in older properties, there may be different spacing.

In the vast majority of cases they will be 400 or 600mm. Of these two, 400mm is the most common. The advantage of standard spacing, is it will allow you to fit 1200 or 2400mm boards without cutting. This is because a whole board should land halfway on a joist.

In this scenario, the only time you will need to cut is when you reach a wall.

Boards should run perpendicular to the joists, and this will add strength to the flooring. Also, you should stagger the boards. For example, your first row of boards would start from the left of your loft, and your second row would start from the right. This will ensure that all the joints are staggered. Again this will strengthen the floor.

If you can see the joists and they have insulation in the middle, you can simply board straight onto the joists. To fit your boards, use 30-40mm wood screws. This will give a secure fixing and ensure that you don’t suffer with squeaky boards. It will also make the chipboard easier to lift at a later date

You can also glue the tongue and groove joint, with a standard wood glue, for a solid fixing between the floorboards.

Solutions for thick insulation

For a loft that has thick insulation that is much deeper than the joists, you may need to raise the boards up above the insulation. This can be done with additional timbers, or you can use a solution such as loft legs, to raise your floor above the insulation.

Loft legs are basically small plastic legs, they form a support to raise your floorboards above the insulation. This will require a little more time and you will need to measure and space them out properly. However, they do offer an affordable solution for raising your lofts floor level.

You can see some instructional videos on there website here. The process is very simple, and you just screw the legs in place and then fit your boards on top.

This type of solution is strong enough to walk on and can support around 25kg per square meter. Therefore, if you are just using the loft for basic storage, it is a fairly decent option, that will allow you to not compromise on insulation.

If you do need more support, whilst still covering the additional insulation, then you will need to use timber to raise the floor level.

This can be done with 4×2, running perpendicular to the existing joists. By doing this, it will also allow you to run your two layers of insulation in two different directions.

This process is more time consuming and slightly more expensive. However it will produce a stronger floor. It will also mean adding additional support between the floor and roof is easier. This may be something to consider, if you ever intend to use the room for anything other than storage.


Essentially you have 3 potential ways of fitting boards in your loft:

  1. Attaching straight to joists
  2. Loft legs
  3. Adding additional timber to raise the floor level.

Obviously, the first option is the easiest. Also, according to energy advice portal The Green Age, the heat loss difference between 100mm and 270mm of loft insulation is only around £13/. So it’s not massive.

With that said if you already have insulation. Or if you do want to add more, then loft legs are definitely a cost effective and easy solution to raise your floor above the insulation.

Timber is more expensive and more time consuming. However, it will add more strength and might be a better solution if you need more solid support.

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