Add interior walls and ceilings

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.

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.

They consist of metal 'rails' that are securely fixed to the floor and ceiling, and metal uprights ('montants') that are placed between the rails, usually at 60 centimetre intervals. The uprights are then attached to the rails using self-tapping metal screws or simply clamped with a special tool that attaches them together by forcing the metal together.

This method of internal wall construction is easier, quicker and cheaper than constructing a wall structure in wood.

The same method is used for external walls - typically you will allow a 10 centimetre space for insulation (usually sem-rigid rockwool) and then construct the wall as described above. A further metal fixture called a fourrure is fixed hirizontally half way up the wall, and special clips used to hold this to the new wall - this makes the new plasterboard wall more rigid.

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 a special tool available for cutting these or with an angle grinder).

I highly recommend you fit the door frame at the same time, this is far easier to install at this stage and also ensures your space is exactly the right size.

The strength of the wall 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.

You will notice that plasterboard has small crosses marked on it, so you can always be sure you are screwing through into the metal framework in the right place.

The space between the adjacent uprights (for internal walls) or the space behind them (for externl walls) 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 technique for improving both rigidity and sound proofing of internal walls 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 upright montants have precut holes so electricity cables and plumbing pipes can be passed through the inside of the wall, after the insulation is in place but before the plasterboard is attached.

Plasterboard is then screwed on to this metal structure with self tapping screws, ad the joints are taped (with 'plasterboard joining tape').

You will need to cut round holes in the plasterboard where necessary to allow the cables to pass through - typcally these are 72mm across, but must be the same size as the plastic pieces that get inset in the plasterboard for sockets and lightswitches to attach to. Drill attachments of these szes are available in your briclage store.

The indent between two boards is now filled with skim plaster - the edges of the plasterboard are slightly recessed to make this process much easier. This is quite a specialist task and will take some practice before you can confidently create an invisible joint, made easier if you:

  •  pass a very wide metal spatula (much wider than the joint) over the join when you have added the plaster, to smooth the surface
  •  use a broad flat sanding block on the surface when it is dry

Remember to use green 'hydrofuge' plasterboard in bathrooms and wet areas, special fireproof plasterboard when the wall will be close to a source of heat, and white in other areas.


Plaster squares for constructing walls

A second 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. I don't think you would ever find a professional in France using a wooden frame to make a plasterboard wall but in some other countries these are still common.

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.

Plasterboard ceilings

The same method of metal rails and montants can be used to make a plasterboard ceiling. Usually the ceiling will be installed before the walls, so that the walls provide extra support to the ceiling.

You can also fit special fixtures to the existing ceing or josts to add further support to the metal framework of the ceiling.

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 many days and probably caused various injuries. 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

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 metal 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.