Within construction, there are many metal components that act as forms of restraints, supports, and holdfasts. These components are often called for within the specification associated with a job, as dictated by the current building regulations. Mechanisms such as handles and hinges are also classified as ironmongery. Here we shall look at the most common forms of ironmongery and metal components used on site. 

Restraint Straps

Restraint straps are galvanised metal extrusions that are used in restraint applications. The metal is resistant to corrosion and the straps come in a variety of sizes. Common sizes include 0.8m, 1m and 1.2m long. The straps have many holes drilled in them to allow for fixings to be placed where required. These straps have a right angle at one end of them and are intended to be hooked over a component. UK building regulations require these straps to be used in holding down wall plates as well as in the form of gable restraint straps. When in use as a wall plate strap, the hook is laid over the plate and nailed or screwed into place. The long part of the strap then points directly down the face of the internal masonry and is fixed with screws and plugs. In this configuration, the straps along the plate should be no further apart than 2 metres, with a comfortable placement of around 1.8 metres between each strap.  

For use in gable restraint applications, the straps should be no further apart than 2 metres and are to be nailed or screwed to the underside of the rafters. The space in between the rafters behind the strap should be fitted with solid blocking. The hook of the strap should be hooked over the inside skin of the gable. This should continue up the rake of the roof as well as along the joists at the end of the flooring system in order to tie the gable into the roof. Both of these applications are in place to prevent the roof or the gable from being lifted away or blown out due to negative pressure or high winds.  

Straight variations of these straps exist with no hook/bend to them and are intended for any application in which two members are required to be held together with additional mechanical fixings. An example of this would be tying two ridge pieces together in a roof system.

Twist straps

Twist straps are a form of restraint strap that have a 90-degree twist somewhere along their length, allowing for certain components to be mechanically attached to others in a way that would otherwise not be possible. The basic construction of these straps is similar to that of standard restraint straps, though as the name suggests they have a twist in them. As an example of their use, the longer varieties of these straps can be used to tie timber rafters/joists directly to masonry; a scenario that would be common in a garage roof assembly. They can also be used to tie joists to rafters where the specification calls for it.  

Timber Joist Hangers

Timber joist hangers are a form of metal mechanical restraint that are designed to support the ends of joists as they connect into other load bearing components. Joist hangers come in many varieties for use in different applications. Galvanised metal hangers are the most common variety available, and they are used to support the end of a timber at its intersection with another timber. The two straps either side of the hanger have holes drilled in them so that twist nails can be used to attach these straps to the side of a timber or beam. The cradle of the hanger then receives the end of a joist in order to provide additional structural support. Twist nails are installed through the holes in the side of the cradle into the joist end to hold it in place. This variety of strap come in different depths and widths for use with different sized timbers. Another variety of hangers are much thicker stamped hangers that are intended to be used to support joists ends abutting a masonry wall. The hangers are to be built into the wall as it is constructed, with the joist ends then being seated into the cradles of these hangers. The advantage of these hangers is that the ends of the joists are not susceptible to potential rot or water damage through cavity bridging. Another large advantage is that the joists do not need to be installed before the bricklayers can continue to build upwards.  

Variations of these hangers exist, such as skewed or adjustable angled hangers, for use with angled or pitched components.

Timber joist hangers are typically required where any 2 structural timber components meet. They are very cost effective in relation to the utility that they provide. Specialist nail guns exist for use with twist nails and hangers that drastically speed up the installation process, though these guns are on the more expensive end of tools. 

Handles, latches, hinges

When hanging doors there are a few different categories of ironmongery that are employed in modern construction. The common internal door’s ironmongery consists of hinges, handles, and latches. These items are often decorative and are more delicate components in contrast to the other forms of ironmongery used within construction. They typically have a nice surface finish to them and are ordinarily made from brass or stainless steel. There are many varieties of each of these, as well as a few other types of door related ironmongery such as locks and self-closing mechanisms. We shall take a further in depth look at all of this later in the book in the door hanging section. 

External Hardware

As is the case with internal doors, external components like gates also have a selection of associated ironmongery that is utilised in their construction. Specialist hinges and latches are a staple for the construction of gates, with many different styles being available. We will look at all of these in depth later in the fencing and gates section. For appropriate weather resistance, these types of ironmongery are typically made from corrosion resistant stainless steel and are often coated with an additional layer of external paint.  

Strap banding

Strap banding is a form of lightweight mechanical restraint that is normally purchased by the roll. Within construction, strap banding has many applications, such as mechanically tying windows into the surrounding masonry, providing additional restraint to joists that are receiving into steels, as well as restraining rafters over the top of a ridge. The utility of this material is really quite limitless, being a very handy solution to many problems. The banding can be bought in different widths and thicknesses and is easily cut to length off of the roll with tin snips. It is often perforated with holes along its length to allow specific fixings to be installed where required.  

Rebar

Rebar is a form of extruded steel that finds many uses in the foundations and substructures of domestic construction, as well as heavy usage in more industrial and commercial construction. Due to its flexibility and high tensile strength, it can be combined with the extreme compressive resistance of concrete to form structurally sound components. Within domestic construction rebar is typically used to reinforce concrete footings, helping to prevent them from cracking at their weakest points. Rebar may also be used to tie concrete components into existing components when carrying out repair work. Thinner rebar sheets may also be called for during the pouring process of large concrete rafts. There are many more scenario specific applications that rebar is useful for, and the drawings and structural calculations should always be consulted for the correct installation of rebar to be carried out. It is a very cost-effective material which makes it a suitable option for many construction applications.   

Cavity wall ties

Cavity wall ties are a form of mechanical restraint that tie cavity wall assemblies together. They have gone through many design iterations over the years but are all essentially thick shaped wire or stamped steel that is laid in the wet mortar of both the external and internal skin of a cavity wall assembly. This ties the walls together and prevents them from moving apart from each other. Most of the ties have some form of drip that prevents water from bridging the cavity along them. As a cavity wall assembly is built, the courses of the inside skin are laid slightly above the courses of the outside skin, so that the wall ties are angled away from the building during construction. Wall ties should be spaced out at no more than 900mm horizontally, and no further apart than 450mm vertically. There should be two and a half wall ties per square metre of masonry within a cavity wall assembly.  

Timber dogs

Timber dogs in the context of woodworking are temporary mechanical fasteners that utilise a wedging action to bring materials together. Traditionally they are smaller pieces of equipment that are used in finer joinery and woodworking to align the edges of boards as well as hold materials together during the gluing process. In modern site carpentry, larger dogs can be used to hold components in place whilst more permanent fixings are installed - a third hand for lone operators. These dogs are very distinctive in shape and are typically made from spring steel or hardened steel.  

Timber dog tooth connectors

Dog tooth connectors are galvanised steel components that are stamped and bent from sheet metal. They are circular in appearance with sharp teeth that alternate in their direction around the connector. They have a hole in the middle that is intended to be slipped over a bolt in between 2 lengths of timber that are being assembled into a beam. The purpose of the dog is to prevent the two timbers from sliding out of alignment from each other over time. They also work somewhat effectively at keeping the timbers tight together in the event that the bolts loosen over time. Care should be taken when handling these connectors, as they are genuinely sharp and unpleasant to handle. 

Washers

Washers come in a variety of shapes with different hole diameters and are mostly made from stainless steel. Washers act as spacers as well as load distributing components within the context of nuts and bolts. The most common type of washer used in modern carpentry is the square plate washer that is used in conjunction with M10 or M12 bolts when assembling beams. Circular washers are also sometimes used with threaded studs.  

Timber nail plates

Timber nail plates are stamped galvanised steel sheets that have holes predrilled across their face. The purpose of these plates is to connect 2 or more timbers together and provide more structural strength at the intersection of the members. These plates are typically used for assembling custom trusses, as well as at intersections of structural stud walls. The plates are placed across the joint and either nailed or screwed through the holes into the members. They are very cost effective for their purpose and are a very simple yet effective piece of equipment.

Tooth plate connectors

Tooth plate connectors are similar in concept to the timber nail plates, but feature teeth on one face that have been stamped outwards from the main plate instead of drilled holes. As with timber nail plates, the tooth plate connectors are intended to provide more structural strength to the intersection of two or more timber components. The plate is placed over the joint and either hammered or mechanically pressed into the timber, providing more structural strength. This form of connector is most commonly used to assemble truss frames. 

Corrugated fasteners

Corrugated fasteners are galvanised corrugated plates that feature a sharpened edge. These fasteners are intended to be used in smaller wooden pieces to strengthen the intersection of corners and mitres. The plate is hammered into the joint until it is flush with the surface of the timber. The corrugated nature of the plate grabs each piece of timber and keeps the joint tight over time. They can only be effectively hammered into the end grain or between the grain of timber due to the decreased resistance. They can also be fired through the use of a special gun also for rapid yet strong joint assembly.  

Truss clips

Truss clips are special hanger-like pieces of ironmongery that are used for securely fastening truss frames to timber wall plates. The clips feature a series of holes that allow for the installation of nails or screws, the main surface of the clips is installed either on the inside or outside of the wall plate, on the correct layout, with the top internal edge flush with the top of the wall plate. The truss frames can then be dropped into the correct layout in the clips. Fasteners are installed through the holes of the clip into the truss to securely fasten it in place.