Solid walls are generally made of either brick, concrete, or lightweight cellular or aggregate building blocks. Attaching objects to brick and concrete is usually straight forward, and a secure fixing can be made with masonry nails or any of the standard types of plug and screw fixings in the case of cellular blocks, an adequate fixing can be made by simply drilling and driving in a screw. Care is needed, however, when fixing to aggregate blocks as these do not provide as secure a bedding as the other materials.
These can be used to fix such things as shelving battens, picture rails, skirting boards and studs for wall panelling to most types of solid surface in the home. They are tempered to prevent bending and can be nailed straight into the wall with a hammer. Special cartridge tools which fire the nail into the wall can be obtained. These are particularly useful where large quantities of nails need to be driven. Two types of nail are available. One has a straight shank and the other a twisted one, which improves penetration into hard materials and helps keep the nail firmly in place. When nailing, always drive the nail in at right angles to the wall and ensure that the nails are long enough to penetrate at least 13mm and not more than l9mm in into the masonry. If the wall is plastered add the thickness of the plaster to the length of the nail required. To prevent them from snapping, nails with straight shanks should be gently driven into the wall with light hammer blows aimed to hit the head of the nail straight on. With twisted shanked nails, start the nail off with light hammer blows, and then use heavier blows to drive the nail home they are stronger than straight shanked nails and will not break so easily if possible, wear goggles as protection from flying chips of masonry or broken nails.
Most household objects can be firmly attached to solid walls with one of the many types of plug and screw fixings available. They all require a pre-drilled hole, which can be made with either a hand boring tool or a tungsten carbide-tipped masonry drill. To make a hole with a hand tool, first tap the tool with a hammer through any plaster and then use firmer blows when the masonry is reached. Twist the tool slightly after each blow to ensure a neat hole and to stop it jamming. Once the required depth for the plug has been reached, remove the tool and blow out any dust. If you are using a masonry drill, you must use either a hand brace or an electric drill with a speed reducer. With some drills this is built in but an attachment is available to reduce the revolutions of a fixed speed drill. As you drill, press firmly so that the bit bites into the masonry. Remove it from the hole a few times and clear away any debris. Take care to keep the drill steady or the hole will become larger than required. If this does happen, you will have to pack it with a suitable filler. A percussion drill is desirable for use with concrete as it saves time and wear on the drill bit. This can be hired but, again, an attachment for converting an ordinary drill is available.
Second, the screw shank must never be allowed to enter the plug; this would weaken the fixing and the masonry. If the thickness of the article to be secured is less than the length of the screw shank, sink the plug further into the wall. When the hole has been made, first insert the screw a couple of turns into the plug and then push the plug into the wall. Then tighten the screw until the shank is about to enter the plug. Withdraw the screw, attach the fixture and then screw it up tight. Plastic wall plugs are also available and come either as strips which you cut yourself, or in pre-cut lengths. They have the advantage of being rotproof and waterproof, and are colour coded for size.
The main problem encountered when attaching objects to walls made of aggregate building blocks is obtaining a firm anchorage for the fixing. Although light objects can often be adequately fixed with standard plugs and screws, it is safer to use one of the many nylon plugs designed for the purpose. These have ‘teeth’, or ridges, which grip the surrounding material, and ‘fins’ which prevent the plug rotating while screwing. They will also take screw shanks with little distortion, and can be used in normal masonry. Another device that is useful for fixing to aggregate blocks is the’Rawlnut’. This has a rubber sleeve which, when the bolt is tightened, expands and compresses against the surrounding material. lt can also be used for fixing to other types of masonry and is suitable for hollow surfaces.