Dado Rails
Another installation variety of internal mouldings, dado rails are aesthetic option when creating stylized interiors. Dado rails are sometimes referred to as chair rails, particularly in the US.
What is a dado rail?
Dado rails are a variety of moulding that are installed during the second fix process. This moulding is installed on the walls horizontally around a room, at a typical height of around 800mm-1m off of the finished floor. Dado rails are not installed as a standard feature in modern residential properties, but can be installed at the request of the client. Traditionally, dado rails were installed as the top moulding of lower wall panelling assemblies, creating an aesthetic finish between the upper and lower wall finishes. They also served the functional purpose of protecting the delicate plaster wall finish from damage caused by the backs of chairs and low furniture. Rebated varieties of this moulding are available that receive over actual panels or tiles that are installed on the lower section of the wall.
What are the criteria for the installation of a dado rail?
Whilst installed at a different height within a room, dado rails are similar in approach and criteria to skirting boards, coving, and picture rails. As the moulding is installed horizontally around the room at a specified height, its imperative that the dado rail is installed perfectly level. The internal and external corners are formed through the use of mitres and internal copes. The moulding should be fixed suitably to the wall at regular intervals through the use of appropriate fasteners and adhesives.
How are dado rails installed?
Dado rails are installed following the same general approach as the installation of other mouldings such as skirting boards and picture rails. The height of installation should be determined and subsequently marked around the room. The specific height of installation will depend primarily on the height of the room from the finished floor to the ceiling surface. When installed with or without lower wall panelling, the dado rail sections the walls of a room into an upper and lower part. From an aesthetic perspective, its important that the two sections feels proportionate to one another. A common height of 1/3 to 2/5 of the total height of the wall provides an aesthetically balanced outcome. For standard 2400mm/8’ ceilings, this creates an acceptable range of between 800mm-1000mm. Its important to assess other components in the room such as window boards or sockets when deciding the height of the rail, so as to avoid having to install around them.
Once the height has been determined, reference marks can be made around the room to aid with a level installation. This can be done with a spirit level, or much quicker with a laser level. From here, the installation is much the same as for skirting boards. The longest lengths are installed first, fixed suitably in place. Seeing as the rail is installed in the middle of the wall, the chances of uneven plaster are far less likely than with skirting, and so the moulding should sit suitably flat against the wall. Any joins in the lengths are achieved through the use of a splayed joint, to maximise overlap between lengths for fixing purposes. The internal corners are coped much the same as skirting boards are, and the external corners are mitred as usual.
Depending on the exact type of moulding, the thickness of the dado rail can sometimes be deeper than that of the architrave. This is quite normal, though a straight butt joint into the side of the architrave can look a little odd. To smooth the transition between the two mouldings, a 45 degree bevel can be cut on the end of the length so that the remaining thickness matches the thickness of the architrave. This creates a nice detail that can be easily decorated. This detail may also be used where the dado rail returns around a window reveal and comes into the face of the window frame. Alternatively, a return can be cut on the end of the rail before it returns around the reveal to stop the rail in place. This is achieve by cutting a mitre with a small mitred return piece in order to return the dado in the wall.
Where dado rail is installed within an area consisting of 2 or more separate floor height, the rail can be raised in relation to the elevation of the finished floor in order to maintain a consistent height from finished floor. The transition between two separate height rails can be achieved through a mitring process as can be seen in the illustration.
When dado rails must be joined between separate storeys, such as from the bottom to the top of the stairs, the transition between the two separate elevations are joined through a separate piece of rail that runs up the wall at an angle parallel to the stairs/stair stringer. To mark out the location for the angled rail, simply measure the previously determined rail height perfectly plumb from the front of the tread nosing at the top and bottom of the stairs. These marks can be connected, and extended slightly further until they meet the horizontal height marks on both storeys. The point at which the markings meet is the intersection of the dado rails, and the joints between the angled rail and the horizontal rails are cut as bisected angles.
Regular checks should be made during installation to ensure that the rail is being installed level, and that all of the standard criteria are being met.