The cost of boarding a loft will depend on quite a few factors.
- Do the water pipes need insulating?
- Do electrical cables need rerouting?
- Do you need more loft insulation?
- Do you need StoreFloor supports?
- What area do you want to cover?
- Are you fitting a new loft hatch and ladder?
Cost of Boarding Out A Loft & Insulation
For the purposes of this section we will only be dealing with the number of boards and their associated costs.
A typical semi-detached loft space in the UK will have an area of between 40m2 to 50m2. Although this can be done quite simply by someone who is used to DIY projects and has the correct tools, a professional and labourer (it is a two-man job) will cost in the region of between £1,000 to £1,500 including materials.
Always get two or three quotes from professionals before you decide who to employ and remember that there may be other factors such as access and headroom that will make boarding out your loft even more difficult. If you need other work done at the same time such as the loft ladder, hatch, insulation and support legs mentioned earlier it will be cheaper and more efficient if you get them all done at the same time. Something that may take you months while working only at weekends in your spare time will soon get done if you employ a professional.
You really don’t know how much loft or attic flooring is needed until someone climbs up into the loft and measures the available space. Remember that you don’t have to lay loft boards over the whole of the floor area, just do those parts that are easy to reach.
Why do I want to board my loft?
If you want to make a living area or a home office or even somewhere to set up a model railway, you will have to strengthen the floor considerably. Remember that laying loft floor boards will give you a better storage area it will not provide a floor for walking on.
Remember when you are in the loft that the lengths of wood you are standing on are there to support the ceiling down below. These are called ceiling joists and in a modern house are designed to carry a load of 25kg per m2. In older houses, this load may be even less so be careful. An average person weighs about 64kg (10 stone) and all that weight is concentrated on the area provided by your feet. If you want to use a loft for working or playing in you will have to strengthen the floor to support a minimum of 150kg per m2, that is six times the weight supported by a loft storage area. You can see therefore that the purpose of boarding out a loft is only to provide a platform for storing light objects such as empty suitcases or the Christmas decorations, nothing else.
That isn’t to say that you can’t have a model railway or a home office in the loft, but you will have to strengthen the supporting floor timbers considerably before laying a floor. You will have to notify the local planning authority and find out if planning permission is required. You will also need to have a Building Regulations inspection to ensure all the necessary work has been done to comply with the regulations.
Loft insulation considerations
Let us assume that we aren’t turning the loft into an office, a playroom for the kids or anything else that needs to have the flooring strengthened. Depending on the type of roof design we have, the downstairs ceiling joists we intend to cover up will probably be of a depth somewhere between 50 to 100mm. There will also be some insulation between the joists too and unless the house is brand new this will probably be fibreglass of about 100mm deep. It may be deeper and that is great because the more insulation you have the warmer your home will be. In fact, at present, the Building Regulations recommend an insulation thickness of about 270mm. This is great too, but what happens if you intend laying boards on top of this?
- The fibreglass will be compressed, expelling the trapped air from between the fibres, rendering the insulation useless.
- The compressed fibreglass will push against the plasterboard below resulting in the ceiling billowing out and cracking or even working loose and falling into the room below.
- The compressed fibreglass will prevent air circulation and cause condensation on the plasterboard ceiling.
The obvious answer is to increase the height of the joists to make room for the required thickness of insulation. DON’T DO IT!
Unless you can somehow support the new, thicker joists on something that will transfer the weight down the external walls into the foundations, you will find that the there is even more weight being supported by the ceiling joists. Wood is very heavy and this combined with the weight of the flooring and any storage items may cause the ceiling to collapse.
How to support loft flooring?
The most important thing to say when fitting flooring into your loft or attic is to ensure that the insulation is not compressed. Therefore, the only other way to fit flooring is to raise the flooring above the insulation. There is a system of supporting loft flooring called ‘StoreFloor’ from LoftZones. There are other board lifting systems available such as Loftleg and Loft Storage Stilts but StoreFloor is the only raised loft decking system that has the necessary BBA certificate for use in buildings in the UK. To put it simply it is a system of lightweight steel supports that fit to the existing joists with screws and provides enough clearance to raise the loft boarding over the insulation. It gives enough clearance for 270mm of insulation plus an air gap to allow fresh air to circulate freely preventing condensation. An advantage of using StoreFloor is that it can be done in sections meaning you don’t have to clear out your loft before starting the job. It also works with all types of insulation, from insulation boards through fibreglass to loose granular insulation. For full instruction on how to install this system it is better to visit the website.
How about electrical cables and water pipes?
Let’s take these separately as there are two different problems.
- Water pipes. There is no problem covering water pipes with insulation as we want the pipes to be kept above freezing point and covering them with 270mm of fibreglass will do that job perfectly. However, laying that amount of insulation and having floorboards will make the loft space a bit colder so if any of these pipes are exposed above the flooring, they will need to be lagged with lengths of pipe insulation. These are hollow cylinders of foam that slide over the pipes and must be tied in place. Pipes also need to be left accessible for future maintenance work. It is always worth drawing the route of any pipes and electrical cables onto the top of the floorboards using permanent marker pen so that an electrician or plumber knows exactly where the services are.
- Electrical cables. Electrical cables have exactly the opposite problem. They mustn’t get too hot. The surface area of each electrical cable has been carefully calculated to prevent the cable overheating by allowing the correct amount of heat to escape from the surface. If the cable is covered by 270mm of insulation, then it obviously won’t be able to lose the correct amount of energy and may overheat. On cables servicing lighting and standard electrical sockets, this usually won’t be much of a problem but if there are appliances such as electric showers that need heavy duty cables, then this might become a problem. Ideally, all cables should be rerouted above any insulation so that they are not covered but if this isn’t possible then an electrician must inspect the installation to see if it is safe. Remember that working on a high current appliance like an electric shower is classed as ‘notifiable work’. You must inform the Building Control officer and any work must be done by a qualified electrician.
Ok. We have finally got there. Although the only reason you started reading this was to find out about laying loft boards, you will surely 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 far too large to carry from the front garden, up the stairs and through the loft hatch. In fact, you would have to cut them to size while still in the garden. This is obviously far too much trouble when you can buy flooring grade chipboard that is ready cut to convenient sizes and has a tongue and groove profile along the edges so they can slot together.
The recommended flooring panels are purpose made for boarding out a loft. The boards are 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.
By the way, it might be a good idea to fit a new loft hatch and ladder while we are working on the loft. New loft hatch doors are fully insulated and the ladder will make it so much easier to carry those items back up into your new storage area after the floor is finished. But working on a loft ladder installation is a task that needs its own article so we will leave that for another time.
The loft flooring boards we were talking about previously usually come in packs of three or five boards. DIY stores often have special offers when selling loft flooring so have a look around at the various stores before you decide on one specific brand. Remember that all loft flooring boards should be the same size so it won’t matter if you mix and match from various brands. The boards have a tongue along one long edge and one short edge and a groove along the other two edges. This means that the boards will slot smoothly together and strengthen each other along the joints.
Start laying the first board at 90 degrees to the direction of the joists. (if you are using the StoreFloor System follow the instructions given by the manufacturer). This means that each board will be laid across a number of joists. Cut the board to the correct length so that it finishes halfway across the width of the joist. Continue doing this until the boards reach as far as you want them to, remembering each time to end a board halfway on a joist so that the joint is supported. Carry on with the next board run slotting together the tongue and groove on the long edge and cutting the boards to length to join on a joist. Each time the board goes over a joist, drill pilot holes in the board and fit screws near both edges to hold the board firmly in place. Do not use nails because the vibration from the hammer will damage the ceiling below. Carry on covering the floor with boards until the entire area is covered.
Fitting floorboards in your loft will give you lots of storage areas for those items that you only use once or twice a year. Ensure that the new boards don’t interfere with the efficient operation of the insulation you will already have in your loft and remember that the new space is only for storage not for a model railway or a home office. Do the job properly taking into account all the points mentioned here and you will have a useful storage space that will give good service for many years.