Counter Battens
In some instances before the installation of plasterboard sheathing, additional depth may need to be added to existing surfaces in order to bring certain components into the same plane as one another. Sometimes an existing surface may not be suitable for boarding in accordance with local regulations, and counter battens may need to be installed.
What are counter battens?
Counter battens are timber pickups that are installed just before the plasterboard stage in order to achieve a handful of desired outcomes. As mentioned above, the most common reason for counter battens to be installed in modern construction is to form a flat fixing surface over the face of an insulated slope. Counter battens are also sometimes installed on the underside of joists in order to add a consistent depth to a ceiling assembly, typically to encompass a steel that slightly projects below the ceiling line. They can also be installed in order to create a new OC layout for the installation of plasterboard, where a regular OC layout may not have been attainable with the structural members. Additionally, counter battens can be implemented in combination with spacers/packers in order to overcome poor internal work during renovations.
What are the criteria for the installation of counter battens?
Counter battens are typically 2”x1” battens. In most scenarios, they should be installed at 400mm centres in order to accommodate the plasterboard that is being hung from them. Care should be taken to ensure the overall surface created is plumb and level where applicable. Appropriate fixings should be used in order to ensure stability over time, especially in ceiling applications - where the force of gravity and load of the plasterboard will forever be pulling downwards on the battens.
How are counter battens installed?
Counter battened ceilings
Counter battens are often installed on the underside of timber joists during renovation operations in order to overcome certain obstacles. Utilities that run underneath the joists, in addition to deep RSJ’s that project below the ceiling line are often a cause for counter battening. By installing these battens, we can achieve additional depth within the joist system in order to facilitate a flat ceiling surface, without boxings. Alternatively, a consistent 400mm OC layout may have been disrupted or unachievable during the installation of the structural joist components. In order to overcome this, and make the installation of the plasterboard easier, counter battens can be installed at 400mm centres.
Installing these battens is very straightforward. In most cases, the counter battens run perpendicular to the run of the joists. A measurement of this run should be taken, with the battens being cut with a small tolerance for ease of installation. The battens can then be installed on the underside of the joists to a 400mm OC layout. They should be fixed in place with the use of screws or appropriate nails - at least 2.5x the thickness of the batten. A 50mm ventilation gap should be left around the perimeter of the battens to avoid bridging. Where the battens come parallel to a steel, a batten should be installed either side of the steel if the OC layout is disrupted, to provide adequate support for the boards. Care should be taken to ensure the battens provide a level and flat surface once installed, especially when installed over the top of existing structural members. Packers may be required to facilitate this.
Counter battened insulated slopes + rooflight trimming
As a part of the modern insulated slope system implemented within loft conversions, counter battening plays a staple part in creating the final finished timber surface ready for receiving the plasterboard. Installed over the face of both reflective blanket and rigid foam insulation, the counter battens re-introduce an appropriate layout for the plasterboard to hang from. For the general installation, the procedure is much the same as previously mentioned, with the addition of the insulative layer between the two solid timber components. A 1200mm rod can be used to determine the centre of the battens that will support the edges of the board. This trick works especially well in this scenario as the insulative layer inhibits our view of the rafter, with the surface layer moving around a lot before it is fully battened back. As such, accurately marking the face of the insulation is impossible, and thus a rod should be used. Quite often during this stage though, there are roof lights installed within the slopes that must be trimmed out as a part of the counter battening procedure in order to accommodate the plasterboard. Here are a few methods for framing out the structural opening to receive finished plasterboard.
Pack out all the sides of the structural opening up to the plasterboard line and install the board long, then install the surrounding boards up to it and cut off the excess/ alternatively, install full packing around, then install the board over the opening, cut out and cut the side pieces in on top, then cut away the excess.
All in one go with the batten. Install the battens long and hang them into the opening. Plumb down inside the roof light for the board and install timber on top of the long battens to accommodate the board. Then cut off the excess battens and install the board. A timber ground will need to be installed at the top to prevent the long batten from sagging over time.
Counter battened walls
Vertical surfaces can be counter battened in much the same way as ceiling surfaces can be, in order to overcome obstacles or out of plumb surfaces. Whilst modern plastering techniques can mostly resolve these issues, especially bad cases, in combination with lead times, can call for counter battening to overcome these issues. Some examples of when counter battens may be required include out of plumb internal walls, an uneven surface across a wall, as well as exposed services on the face of a wall. These battens are also installed at 400mm centres to accommodate the installation plasterboard and should be packed where applicable to overcome any obstacles.