Wall Types and Fixings

There are many types of wall found in houses and choosing the correct fixing is vital if you want to safely hang something on it.

Building techniques have changed over the years with Lath and Plaster being found on most houses built before 1945. After World War 2, builders started to use solid block skimmed with plaster giving the appearance of Solid Walls. This period also saw the introduction of Stud Walls that continue to be used in modern houses. Houses built after 1990 are most likely to have been constructed using the Dry Lining technique.

Dry Lined Walls (1990-Present)

The load bearing walls of most houses built in the UK within the last twenty or so years have been built using a construction method known as dry lining or more commonly called, 'dot and dab' in the trade. This system involved literally sticking sheets of, usually 12.5mm, plasterboard to the walls with dabs of cement based adhesive.

The idea was to leave a gap of about 10mm between the wall and the plasterboard but this will vary a bit to take account of any irregularities in the block work wall. Though still quite a skilled job, dry lining was much quicker than conventional plastering and did not leave walls of wet plaster which take a long time to dry. Thus ‘dry’ lining.

Although this method is quicker for the builder than traditional plastering, it creates a wall that is not compatible with standard wall plugs. The dry lining process starts with adding “dabs” of adhesive to the wall (A), then plasterboard is pressed onto the dabs (B). This quickly provides a smooth surface, however an awkward variable gap (C) is left between the plasterboard and the block work of the wall. The plasterboard is largely unsupported, and this creates the “hollow” sound if you tap the wall (unless you happen to tap over a “dab”).

Dry lined Wall Fixings

DryLinePro to the Rescue

Standard wall plugs do not grip well in the plasterboard, and of course not at all in the air gap. DrylinePro™ was specifically designed for dry lined walls that keys into the block work behind the plasterboard while also supporting and protecting the plasterboard itself.

Solid Walls

Block Work, Plastering and Stud Walls (1945-1990)

The post World War 2 housing boom produced a revolution in the construction industry with the widespread use of both concrete block and the advent of plasterboard. The walls were built with an insulating cavity between brick on the outside and concrete blocks on the inside.

The concrete blocks were changed to a lighter, thermal insulating and the inside walls were plastered, using a sand and cement render skimmed with plaster for a fine finish, giving what appears to be a solid wall.

Plasterboard was used on the non load bearing walls. This gives what is known as a ‘stud wall’. To make these walls, sheets of plasterboard are nailed to a timber frame and then skimmed with plaster to give a final smooth finish.

If your house or apartment walls have been finished with traditional plaster (A), then you have a solid wall with no gaps (B), and you can use traditional wall plugs or an expanding bolt to fix your TVs, shelves, curtain rails, radiators etc to the wall. Solid walls actually sound solid when you tap them. If they sound hollow when you tap the wall, you need to use a different type of fixing.

Solid Wall Fixings

Rawlplugs

‘The original wall plug was invented by John Joseph Rawlings in 1911, and marketed under the name Rawlplug. This brand name has become genericised in the UK, being equally applied to wall plugs from competing manufacturers’ (Wikipedia).The rawlplug has been the workhorse in the fixings world for years and remains a top selling product. It works very well indeed in a solid wall made from brick, concrete, stone or, to a lesser extent, lightweight concrete or ‘aircrete’ blocks.

Rawlplugs come in various sizes. Do not drill too large a hole. Masonary drills in particular often tend to drill oversize holes (the best masonry drill for an 8mm plug is often a 7mm drill ). If you are drilling into a light weight block, use an HSS drill rather than a masonry drill.

The screw used with a wall plug also needs to be the right size so that it can be tightened up firmly within the plug. In our testing, we found that an 8mm rawlplug with a 5mm x 50mm screw into lightweight block we failed at about 50kg tensile (pull-out) load.

Expanding Bolts

We used the DrylinePro™ test rig to measure the maximum pull out load of 6mm and 8mm expanding bolts carefully fitted into lightweight blocks.

6mm Expanding bolt : Maximum pull out load 55kg.
8mm Expanding bolt : Maximum pull out load 200kg+

There was a significant increase in performance going to the larger bolt, although this does require a 13mm hole. The shear strength is excellent.

Note that these bolts are not suitable for dry line walls as they do not support the plasterboard. They can be robustly fitted into the masonry wall behind the plasterboard, but if you then tighten down on them against the plasterboard, the plasterboard will fracture.

Stud Walls

Both solid walls and dry lined walls start with a block work wall. During the last 50 years, many internal walls have been based on a timber frame structure (A). Once the frame is covered with plasterboard (B) this type of wall is visually indistinguishable from the other types. This type of wall is known (in the UK) as a “stud wall”.

A stud wall, like a dry lined wall, will generally sound “hollow” when tapped apart from if you happen to tap over the wooden frame. You may be able to determine if your wall is a stud wall or dry line wall by tapping, but a quicker and more certain way is to drill a small hole where you need to put a fixing anyway, and see if there is a block work wall behind (dry line wall) or an empty cavity (stud wall). Stud wall fixings come in two types. Those that screw into the plasterboard and those that go through a hole in the plasterboard, and expand in some way behind the plasterboard within the cavity.

Stud Wall Fixings

Hollow Wall Anchor

The hollow wall anchor requires a 9 mm hole, and is quite easy to use. It failed at 30kg in our tests due to plasterboard rupture.

Spring Toggle Fixing

The spring toggle requires a 14mm hole, and is not particularly easy to use (fixture needs to be attached prior to fitting the toggle through the hole). It failed at 50kg in our tests due to plasterboard rupture.

Self Drive Plug

The metal self drive plug screws into the plasterboard (rather than fitting through a hole and holding on the back face). It is suitable for only the lightest loads. Our examples pulled out in the range 5kg to 15kg.

Plasterboard Rupture

The very best stud wall fixing will be stronger than the plasterboard which then becomes the limiting factor. This hollow wall anchor failed at 30kg when the plasterboard ruptured.

Lath and Plaster

Pre World War Two

Some of the walls in older properties will be hollow internal non load bearing walls. These are probably made of lath and plaster.Lath and plaster walls were made by nailing thin horizontal strips of wood to both sides of strong vertical timbers. The horizontal ‘laths’ were then covered with plaster to give a smooth finish.These walls can be tricky to fix to unless its possible to find the strong uprights in which case a conventional woodscrew will work well. You may get away with using a spring toggle type of fixing or any one of the many fixings designed to open out behind plasterboard on the hollow bits of wall. Do not be tempted to overload such attachments or the whole lathe and plaster structure might disintegrate.Houses built between the wars will probably have a cavity between two layers of brick for the main wall. The inner brick wall was then plastered. Use rawl plugs to fix to this type of wall.