A typical semi-detached loft space in the UK will have an area of between 40m2 to 50m2. Although someone who has the correct tools can easily board out a loft, it’s simpler to hire a professional. Bearing in mind it’s a two-man job, the cost of boarding a loft sits between about £1,000 to £1,500 including materials.
The tables below give you estimates of how much you’ll pay a professional. Don’t worry, I’ll explain about ‘Loft floor stilts’ and ‘Timber Subframe’ later. By the way. These estimates don’t include VAT and may vary depending on where you live in the country. Prices in London and surrounding areas cost far more than anywhere else .
| Area size (m2) | Estimated cost (labour & materials) | |
| using Loft floor stilts | Using timber subframe | |
| 10 | £260 to £280 | £230 to £250 |
| 20 | £520 to £560 | £460 to £500 |
| 30 | £780 to £840 | £690 to £750 |
| 40 | £1040 to £1120 | £920 to £1000 |
| Job | Estimated Cost |
| Top up insulation | £10 per m2 |
| Install pull-down ladder | £350 |
| Modify loft hatch for ladder | £100 |
| Relocate hatch to a better location | £250 |
| Install loft light and switch | £75 |
| Remove old water tanks | £50 |
| Add additional shelving | £15 per m2 |
Other work
Always get two or three quotes from professionals before you decide who to employ. We’ll tell you how to do that later. Remember, factors such as access and headroom can make working in the loft very difficult. Furthermore, if you need other work done at the same time such as a loft ladder, hatch, and insulation, do it now. After all, it’ll be cheaper if you get them all done at the same time. Installing insulation is always worthwhile as it’ll significantly reduce your energy bills.
You might do this work as a DIY project, but it’ll take forever working at weekends. So, get it done much quicker by employing a professional.
Benefits of boarding out a loft
If you want to make a living area, office or hobby room, you must strengthen the floor. Remember that laying boards gives you a better storage area but it won’t provide a floor for walking on.
Unfortunately, the joists in the loft only support the ceiling below plus a bit extra. Not something heavy above. They’re called ceiling joists and in modern houses, can carry a load of 25kg per m2. Furthermore, in older houses, this load might be even less. An average adult weighs anything above 64kg (10 stone). And, all that weight concentrates on your footprint. So, if you want a loft for work or play you must strengthen the floor to support at least 150kgper m2. That’s about six times the weight that it’ll support now. So, boarding a loft only provides a platform for storing light objects.
Don’t worry, you can have a model railway in the loft. But, you must strengthen the supporting joists before laying a floor.
Types of loft insulation
You’ll probably need some more loft insulation, so let’s look at the different types. They all have pros and cons, and you’ll have to choose the best for your situation.
Blanket Insulation
This is the most common type that comes as a roll of glass or mineral fibre. Usually, it’s the cheapest to buy and it comes in pre–cut widths to fit between standard joists. Although it’s the easiest to install, it creates a lot of mineral or glass dust when you handle it. So wear a dust mask.
Loose-fill insulation
This type usually comes as loose, lightweight fibre. It’s made from a variety of materials. Usually, cork granules, cellulose fibre, mineral wool, or recycled newspaper. The main problem is that it might get blown about in the loft if you have draughts and get very messy.
Sheet insulation
These are solid boards of synthetic foam. Usually with foil on one surface for added insulation. They are best used for insulating between the rafters rather than between the joists. Problem is that this is usually the most expensive.
Blown fibre
This is good for getting into hard–to–get–at roofs. It consists of loose fibrous material that’s usually blown into the loft. Like the loose–fill insulation, it’s no good if you have a draughty loft. It’s also expensive and a professional mustinstall it.
Loft insulation considerations
Let’s assume we just want to keep the Christmas decorations in the loft. Therefore, the joists don’t need strengthening. Depending on the type of roof design we have, the joists will probably be somewhere between 50 to 100mmdeep. Probably, you’ll already have some insulation between the joists. So, unless the house is brand new this will be about 100mm thick fibreglass. It may be deeper, and that’s great because thick insulation means you have awarm home. In fact, at the time of writing, the Building Regulationsrecommend an insulation thickness of about 270mm. This is fantastic as far as saving heat goes. But, what happens if you intend laying boards on top?
- The boards compress the fibreglass, expelling the trapped air from between the fibres. The insulation becomes useless.
- Compressed fibreglass pushes against the plasterboard ceiling forcing it to bow out, crack and fall into the room below.
- The compressed fibreglass prevents air circulation and causes condensation on the plasterboard ceiling.
You might think you can increase the height of the joists to make room for the deep insulation. Unless you know what you’re doing, DON’T DO IT! The ceiling joists will end up supporting even more weight. The extra joist weight, combined with the flooring and any storage items may cause the ceiling to collapse.
If you use this method, you must place the new, thicker joists onto supporting walls. This will transfer the weight into the foundations. Simple for a professional but tricky for an amateur.
But, there is another way.
Loft flooring support methods
Your loft insulation mustn’t be compressed when you install loft boards. We’ve just said that installing extra joists is difficult. But, we must ensure the flooring lays above the insulation. What do we do?
Use loft flooring stilts. There are quite a few different brands available. But, the system called ‘StoreFloor’ from LoftZone is probably the best in the UK. StoreFloor is the only raised loft decking system to have the necessary BBA certificate for use in buildings in the UK. It’s a system of lightweight steel supports that fit onto the existing joists with screws. They raise the loft boards above the insulation plus enough air gap for free air circulation. Furthermore, you can install StoreFloor in sections. This is so you don’t have to clear out your loft before starting the job. You can also use it with all insulation types. From insulation boards through fibreglass to loose granules.Then, you use standard-sized chipboard loft storage panels, bought from any home improvement store.
Handling electrical cables and water pipes
Now, these are two different problems. So, let’s take them separately.
- Water pipes. We need pipes kept above freezing point. So, cover themwith 270mm of fibreglass and they’ll be fine. However, laying that amount of insulation and having floorboards will make the loft space a bit colder. So, if any of these pipes have to be above the flooring, they’ll need extra lagging, using lengths of pipe insulation. Pipes often need to be accessible for future maintenance work. So, it’s always worthwhiledrawing the route of water pipes and electrical cables onto the top of the floorboards using a permanent marker pen. This makes it easy for an electrician or plumber to find the services.
- Electrical cables. Electrical cables mustn’t get too hot. You see, the cable manufacturers calculate the surface area of each electrical cable to prevent the cable overheating. So, if 270mm of insulation covers the cable, it won’t lose the correct amount of energy and may overheat. Usually, this won’t matter too much on cables servicing lighting and standard electrical sockets. But, with heavy-duty shower and cooker cables, this might become a problem. Ideally, reroute all cables abovethe insulation so they’re not covered. But, if this isn’t possible then an electrician must inspect the installation to see if it’s safe. Remember, you must inform the Building Control office of any ‘notifiable work’ on a high current appliance like an electric shower. And, you must use a qualified electrician.
Chipboard Flooring
At last, we’ve finally got there. Probably, you only started reading this to find out about fitting loft boards. But, you’ll agree that you needed to know all this other stuff too.
What can we say about chipboard flooring? Firstly, you can buy large sheets of chipboard, but these are too large to carry up the stairs and through the loft hatch. In fact, you would have to cut them to size while still outside. Obviously, this isn’t necessary if you buy flooring grade chipboard, pre-cut to size. It also has a tongue and groove profile along the edges so they can slot together. Suddenly, a loft flooring installation project became a whole lot easier.
By the way, it might be a good idea to fit a new loft hatch and ladder while we’re working on the loft. New loft hatch doors come fully insulated and the ladder makes it easier to carry items up into the loft. But, installing a loft ladder isn’t easy for an amateur so we’ll ask the professional to do it.
Flooring panels
Flooring panels are purpose made for boarding out a loft. They’re moisture resistant and are 18mm thick, 1.2m long and 320mm wide. Just the correct size to get through a standard loft hatch without too much trouble. Often, many DIY stores have special offers, so look around at various stores before you buy. Remember too, all loft flooring boards are a standard size so you can mix and match from different suppliers. Their tongue and groove profile allows each board to slot together with its neighbour thus strengthening each joint.
Start laying the first board at 90° to the direction of the joists. You should beusing the StoreFloor System so follow the manufacturer’s instructions. Because each board has a tongue and groove on all sides, each edge will be supported and you don’t have to cut any to length except for the last in a run.Continue joining the boards until they reach as far as you want them to. Once you’ve completed one board run, carry on with the next run slotting together the tongue and groove on the long edge too. Make sure you stagger each short edge joint with its neighbour so that you have maximum strength. If you have to fix surfaces together, don’t use nails, only screws. Otherwise, you’ll vibrate and damage the ceiling below. Continue covering the floor with boards until you cover the entire area.
Planning Permission & Building Regs Requirements
OK, you don’t need to ask the local council if you just intend boarding out your loft for lightweight storage. Unless you’re interfering with heavy–duty electrical cable of course.
But, if you want to make your loft into another living room, bedroom, hobby room or office you have to get permission. Your loft joists aren’t strong enough and you’ll have to strengthen them before laying a floor. So, notifythe local authority and find out if you need planning permission. You’lldefinitely need a Building Regulations inspection at various stages, to check you’ve done the necessary work. Oh, and don’t forget the structural engineer’s calculations too.
Loft Boarding FAQ
Does boarding a loft add value?
Oh yes, very much. Most people like a lot of storage space. So, if your loft already has an access ladder, floor and light, then it’ll definitely make your home worth buying.
Can I put boards over loft insulation?
You can, as long as you don’t compress the insulation. Either use floor support stilts on your existing joists (we recommend this). Or, install a timber subframe. This is more difficult, needs a qualified builder and might need building regulations.
Can you board a loft yourself?
Yes. If you can do most DIY jobs and have the tools, you should be able to board your loft. Just follow the installation instructions on the support stilts.
How long does it take to board a loft?
Usually, a professional takes about a day to install support stilts and loft boards in a 30m2 loft.
How do I strengthen my loft joists?
Your existing joists will bend under load and need strengthening. You can glue and screw additional timbers to the top of the joists (liberally use PVAglue). Your existing joists are probably 100mm deep so, add at least either 50mm or 75mm timber on top.
Whatever you do, make sure you support the extra timber. Use the load-bearing external walls otherwise, the whole installation will crash down under its extra weight.
Does boarding a loft help to insulate?
Yes and no. The boarding itself doesn’t have any insulating properties. However, the boards trap a layer of still air between their underside and the insulation. So, it’s this layer of still air that helps make your existing insulation more efficient.
To finish
Fitting floorboards in your loft will give you lots of storage space for those items you only use once or twice a year. You can do the job yourself but we recommend using a professional. So, fill out the form on this page to receive 3 or 4 estimates from local builders based near you.
