When I describe how to construct internal walls, I take internal walls to be the same as non-load-bearing walls. Note that none of the methods for constructing a wall that are described below are suitable for supporting walls.
Metal framework for internal walls
The most common method of constructing internal walls in France is using plasterboard that is fixed to a metal structure. Glass wool is put in between the two layers of plasterboard to provide some sound insulation.
The metal structures are easy to use, being put together rather like Meccano. They consist of metal ‘rails’ that are securely fixed to the floor and ceiling, and metal uprights (‘montants’) that are placed between rails, usually at 60 centimetre intervals. The uprights are then attached to the rails using self-tapping metal screws. This method of wall construction is easier, quicker and cheaper than constructing a wall structure in wood.
To create door openings a shorter piece of rail is fitted at ‘top of the door’ height between the two uprights. It is easy to cut appropriate lengths of upright and rails (with an angle grinder).
The rails and uprights come in various thicknesses between about 4cm and 10cm – the thicker they are, the more rigid the final wall will be. The strength can also be increased by attaching two uprights back to back every 60cm, rather than just a single upright, or by using the uprights every 40cm instead of every 60cm. 40cm or 60cm gaps are used because plasterboard is 120cm wide and needs to be fixed at both edges, as well as in the middle.
The space between adjacent uprights is then filled with semi-rigid rockwool, which slots easily into place, to improve the sound insulation properties of the wall. Rockwool is sold in standard 60cm width so is very easy to fit. Another recommended technique for improving both rigidity and sound proofing is to use two sheets of plasterboard on each side of the structure, rather than one.
You need to alternate the plasterboard on the two sides of the structure – that is, plasterboard on one side of the wall should never end at the same upright as the plasterboard on the other side. Again, this is to improve the rigidity of the wall.
The uprights have precut holes, so electricity cables and plumbing pipes can be passed through the inside of the wall.
Plasterboard is then screwed on to this metal structure with self tapping screws, the joins are taped (with ‘plasterboard joining tape’)and the indent is filled with skim plaster as usual.
Remember to use green ‘hydrofuge’ plasterboard in bathrooms and wet areas, white in other areas.
Plaster squares for constructing walls
A second common method for building internal walls is to use squares of plaster, about 60 centimetre square and 5 – 10 centimetres thick, which have tongue and groove edges.These are glued together with special glue (available from the same supplier as the plaster squares).
This type of wall is very quick and easy to fit, but is less practical in places where there are numerous wires and cables to be concealed – the method doesn’t leave a cavity in the wall, so cables need to be individually buried by cutting grooves. A common use for these plaster squares is for making ‘low walls’, such as those found in kitchen bars, or in supporting walls for bathroom sinks and so on.
Wooden framework walls
More or less the same as ‘metal framework’ above except it costs more and takes longer, and is harder to sound proof! But you can do it with a saw rather than an angle grinder. That’s slightly unfair perhaps, but I don’t think you would ever find a professional using a wooden frame to make a plasterboard wall.
Covering an existing brick or stone wall
For holding plasterboard to an existing brick or stone wall, there is special glue available. You do not need to build a wooden frame against the wall! You just make sure the wall is dust free, put big blobs of glue on the back of the plasterboard and lift it up to the wall. Press it into place, check it’s straight and vertical, and that’s it. How easy can you get.
There are two ways to lift plasterboard to ceiling level and hold it there while you are fixing it into place.
One is hard, involves two people, a series of struts and supports, and a great risk to life and limb. The other is much easier and involves a machine. I hired the machine, and suggest you do the same.
With the hoisting machine, the plasterboard is placed on a surface that holds it in place while it is vertical, and then this is tipped to the horizontal. A handle is then turned that lifts the plasterboard to ceiling level and holds it there while you fix it in place. Without this machine, as I know from experience, the job would have taken two of us several days. With the machine it took me two and a half days on my own to do 80 square metres of ceiling, including all the cutting to size around the edges and so on. The hire cost for two days was about £20. There is still a bit of effort involved in getting the plasterboard on to the lifter, but it is possible for one person and easy for two. I think that motorised hoists are also available, if you really want the easy life.
Pretty much all towns will have a place where large machines can be hired, and I would certainly check these out before you buy machinery that won’t be used very often. If you can’t find a hire shop, check in the local builders merchants or diy / bricolage store since they will often hire things out, or will be able to point you in the right direction.
Other Ceiling Tips
Use plasterboard screws rather than galvanised nails for fixing the board in place, since these are less likely to work loose over time.
One slight complication is leaving the holes for ceiling light fittings. You will need to cut holes in the plasterboard for these to pass through, before you lift it up. Then you can lift the board close to the ceiling, feed the wires through, and finish raising the board to its final position. Clearly care is needed in getting the hole in the right place in the board!
As with internal walls, the joists to which you are fixing the boards will usually be 60cm apart so that the edges of the plasterboard can be fixed firmly in place.
If the corners of your room are not right angles (I bet you they aren’t) you will need to lower the plasterboard back down, and shape the end as appropriate. This is much easier than putting the board in place and then trying to fill in the spaces later.