How much to reinforce loft floor UK

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In this article, we will be looking at how much it costs to reinforce a loft floor in the UK. This will look at the rough costs for materials. As well as the cost you can expect to pay for labour on this type of work.

Lofts are quite often wasted space in a property. However, they usually have good head room, and because they span the whole of your house, they often have a decent amount of usable space.

Even areas where the head room reduces, as the roof comes down to meet the floor, can still make for great storage space.

Due to this extra space, it is quite common for people to try and utilise the area. Lofts can potentially be converted into habitable rooms, but more commonly, they are just used for storage.

how much to reinforce loft floor

Storage is particularly useful for items that are used less frequently, such as Christmas decorations. As well as older items you want to keep, but don’t currently use. Putting these items in the loft, can help to de-clutter the main areas of your home.

If you just want to reinforce the loft floor, this will usually involve adding thicker joists. Quite often, loft joists are not intended for walking on and are thinner than required. In order to know the size you need; you will need to look into regulations for joist span requirements.

You can also have a structural engineer advise on the size of joists that you need.

Cost of materials to reinforce a loft floor

There are quite a few things that can affect the cost of reinforcing a loft floor. However, assuming you just need to add better structural joists, this will be one of your biggest costs. There are other things to consider, such as:

  • Insulation
  • Fixings
  • Joist hangers
  • flooring

Potential joist cost

Let’s use a hypothetical example. If we assume the loft is in a 3-bed semidetached property, and we have around 48m2 in total loft space (8m x 6m).

In this loft the largest span of unsupported joist is less than 3 meters, and the joists are spaced at 400mm centres. Based on this, you would need joists that are 47 x 147mm.

For joist this size, you would be looking at approximately £5 per meter. Based on this, the cost for joists would be £630. Obviously, the cost will vary depending on where you buy.

Other things to consider, are whether the timber is treated, which will cost slightly more. Also, the timber grading could affect the price slightly.

As a general rule, timber with a grade of C24 will be more expensive than C16. However, both would be acceptable for this work. The only difference is C24 will be slightly higher quality, with less visible defects.

By far the biggest factor that effects price, is where you buy from. Ideally you should shop around to find the best price.

Potential flooring cost

The next expense is your flooring, and the most common material for this is chipboard. The cost of this will vary slightly based on the thickness, which comes in two sizes, 18mm and 22mm.

18mm will generally cost you around £12, whereas 22mm will usually be around £15. Assuming your joists are spaced at 400mm, then 18mm chipboard should be fine. For wider joist centres, you may want to upgrade to a thicker 22mm board.

For a 48m2 loft, using 18mm chipboard flooring, your cost will be roughly £408 + £15 for fixings and wood glue.

Insulation cost

The next expense will be insulation, and based on current building regulations, this needs to be 150mm thick. This will provide a U-value of at least 0.16W/m2K.

You should expect to pay around £3.50 per square meter for mineral wool insulation at this thickness. Therefore, a cost of around £168 for your insulation.

Fixings and hangers

Potentially, you could nail the joists manually or use a nail gun. You will also need joist hangers and the nails to fix the joist hangers.

Joist hanger nails, and some decent 4-inch nails, will only set you back around £40 for a few hundred of each.

A pack of 10 hangers for this size joist will cost around £10 and you will likely need around 8 packs, so this would be £80.

Total cost of materials to reinforce your loft floor

Based on all of the amounts listed above, the full breakdown can be seen below:

  • Joists – £630
  • Flooring – £423
  • Insulation – £168
  • Joist Fixings and hangers – £120

Total cost = £1341

Total cost per m2 = £27.94

It is important to point out, these numbers are a rough guide. The actual cost could vary quite a bit based on where you buy. However, if you assume anywhere between £1200-£1600, this would definitely be in the ballpark for materials.

How much to reinforce your loft floor professionally

We already have a rough idea for the cost of materials. The cost you pay for labour will vary on your location in the country. However, for simply adding a reinforced floor, you are probably looking at around £1500 for the labour alone.

This is based on two workers and 2-3 days’ work.

You may also need to consider the cost of a structural engineer to advise on the joist requirements, and any other structural supports needed. This could run anywhere from £500 – £1200.

Therefore, based on materials, structural advice, and labour, you should expect a total price of between £2700 and £4300.

Even at the higher end of this range, the space you gain will be well worth the money spent. It will provide lots of storage, and the potential to convert the loft further at a later date.

Obviously, a full loft conversion would be far more expensive. Even a basic conversion with a couple of Velux windows would cost at least £10k. Anything more complex could cost significantly more

In order to get the best price, you should definitely shop around. You can compare quotes online pretty easily. This will enable you to see the best prices in your local area.

It’s actually very simple to do, and you can get rough estimates online within a couple of hours.

Click Here to get no obligation online estimates


We hope you have found this article useful. The details provided should give you a rough idea of the cost to reinforce a loft floor.

All the expense for materials are based on average prices, from popular UK building merchants, and large DIY stores.

Labour costs are based on the average day rates, for this type of work throughout the UK.

Obviously, this is just a guide, and it is based on a theoretical example. Therefore, prices may vary depending on a number of factors.

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