Breeze block plugs
One thing ordinary plugs are not good at is gripping in soft or crumbling masonry, notably breeze block and aerated concrete block. Here a special plug is required. It consists of a central core surrounded by tough, flexible fins arranged in a sort of spiral. To use it, drill a hole a little larger than the central core, and hammer the plug in. The fins compress, then force themselves against the sides of the hole to hold the plug even if the masonry does give way.
Wooden pegging
The solution to the problem of fixing into mortar joints – take a piece of wood, preferably hardwood, roughly 19mm in diameter, taper one end, and then drive it into a 12mm (Jin) hole with a mallet. You can then screw into it in the same way as any other piece of timber.
Masonry nails
Masonry nails are used like any other nail. They are just specially hardened, and designed to penetrate and hold in masonry. They come in sizes to suit most jobs – choose a length that will penetrate the wall by about 19mm (Jin) – and, in spite of their tendency to shatter if you don’t hit them squarely, they do offer a fast way to get a fixing. However, the result is not neat, so reserve them for rough constructional jobs, where looks are not important.
Rawlbolts
The thing to use if you need a really heavy-duty fixing – for example, fixing a lean-to roof to the side of a house. Rawlbolts work in much the same way as a standard plug, but are made from metal, and come ready-fitted with a bolt. Various sizes are available, and you can choose between a number of types of head, including a threaded stud to take a nut, a hook, an eye, and a normal hexagonal bolt head.
Plugging compound
For a relatively light fixing in crumbling walls, use a plugging compound; a fibrous material that you mix with water and pack into the hole using the tool provided. Once the hole is full, make a starting hole with the pointed end of the tool, and carefully drive in the screw. As the compound dries, it “cements” the screw in place.
Fixings in hollow walls
Here, getting the screw to grip is even more of a problem than with a solid wall. After all, the screw has nothing to bite on but air. There are a number of ingenious solutions, but virtually all have a snag; remove the screw, and the fixing device is lost inside the cavity.
Petal anchors
Made from plastic, these are twisted onto the end of the screw and pushed through the hole into the cavity beyond. As the screw is tightened, the anchor’s petals open out against the back of the plasterboard, or whatever, thus preventing both anchor and screw from pulling out.
Spring toggles
These use the same principle as gravity toggles. The difference is that two sprung metal wings are used to do the bridging job.
Expanding plugs
Designs vary, but all work in the same sort of way. You push them into the hole, insert a screw – some have a built-in machine screw – and tighten up. The plug bulges out inside the cavity until it is too large to come back through the hole.
Gravity toggles
The toggle is essentially a small metal hinged device fitted to the end of a machine screw (supplied). When pushed through the hole, it flops down inside the cavity, bridges the hole, and so allows the screw to be tightened. This bridging action is ideal for lath and plaster walls.
Screwing into the framework
The only way to make a really strong fixing in hollow walls is to screw directly into the wall’s internal timber framework. This consists of upright “studs” spaced about 400mm apart, and horizontal “noggins” put in mainly where there is a horizontal join between plasterboard sheets. The former offer the strongest support for a fixing. To locate them, tap the wall until it sounds reasonably solid, then drill a series of tiny test holes until you strike wood. If the studs aren’t where you need them, span two with a stout piece of timber screwed in place on the surface, and make the fixing into that.