Restraint straps are also known as bat straps or tension straps, and they can be used for vertical or horizontal restraint. The straps can be used to restrain a roof or floor and will help to prevent the cracking of walls. Without these bars, the walls can move slightly sideways because of, for example, repeated wind pressure. Restraint straps can either be heavy-duty or light-duty, and each type has its application. Heavy-duty restraints should be used for lateral restraint of roof rafters and jolts which are tied into masonry walls. On the other hand, light-duty restraints are used on wall plates on top of masonry walls.
What are lateral restraint straps?
Lateral restraint straps are bars that provide support to walls that are suffering from lateral movements. As noted earlier, the most common factor that causes lateral movements in walls is wind. The straps can be installed during the construction of the walls or can be added to existing walls.
How many joists should lateral restraint straps be attached to?
Lateral restraint straps should be attached to a minimum of three joists or rafters. If the straps don’t exceed 2 metres, you can also fix them to the longitudinal bracing.
How do you fit a lateral restraint strap?
To fit a lateral restraint strap, you should follow these steps:
• Start by drilling a stainless-steel bar through a pilot hole that is drilled into the wall from the outside. You should ensure that the pilot hole self-taps into the floor joists.
• You should then screw additional timber cross members and fit them between the floor joist. This timber will act as the anchor point for the restraint straps.
• Next, you have to resin bond the stainless-steel bar into the external brickwork. You will need to lift the floorboards internally to ensure that the restraint bars are directed into the joists.
Before you install restraint straps, you should ensure that they are suitable for the building and the conditions of the structure. Restraint straps cannot restore a bowed wall to its original state, but they will help to prevent further movement of the wall.
How should straps or bars that provide lateral restraint to outside gable walls be installed?
Gable walls suffer the most from lateral movements, as they tend to be quite high. For this reason, you should ensure that you install the lateral restraints properly. Gable walls should be restrained at the rafter level. You may also need to provide restraints at the ceiling level. To determine whether the straps need to be installed at the ceiling level, you should measure the height of the wall from the foundation of the building, and add this height to half the roof height. If this figure exceeds 16 X the thickness of the walls, you should use restraint straps at the ceiling level.
Modern buildings are usually constructed with restraint straps, but you can also choose to install them on older walls that seem to be moving. The straps can either be heavy-duty or light-duty. It is important to follow the instructions in this guide to ensure that you install them correctly.