Sliding door cage systems over the last few years have become more and more popular. SWD’s fitting teams have installed most of the cage systems that are available on the market.

So what is a cage system? A cage system is a complete kit which includes the top track, the guide pin and the framework for the pocket itself which is boarded over and then plastered.

The alternative to a cage system would be just to build 2 walls with a gap between them. The walls can be constructed either from stud work or block work. In this case you would need to buy just an appropriate top track to support the weight of the door and a guide pin. The only main advantage of doing a sliding door this way is that the double wall construction is quite robust and solid. The down side is that the double wall could take up 300mm or more.

Fire rated sliding door cage systems

In the event your sliding door needs to be fire rated, the above method is not an option. You will need to purchase and install a fire rated cage system. The cage systems have been tested to resist a fire for 30 minutes and come with all the jambs and intumescent materials installed into them. Additional features can be purchased which are soft closers and touch latches which enable the door edge to be pushed in so the door pops out of the pocket.

We have installed most of the cage systems on the market and have our preferred supplier. When installing a cage system they can either be installed against an existing wall or within a stud wall or block wall opening. On installation of the cage it is vitally important that the cage structure is not compressed. This can happen if the plasterers or dry wallers apply too much pressure onto the cage when installing the plasterboard.

The cages we predominantly use come with a 95mm width cage and can be single boarded to give a total width of 125mm or double boarded both sides to give a wall thickness of 145mm. We would recommend the latter if you have the space as the wall will be more solid. We would also recommend the first layer to be plywood as the wall will be stronger.

Diagram of the sliding kit – please click to view

The cage systems can cater for quite large door leafs. The maximum door leaf size for a single fire doors is 2850×1500 giving a visual opening size of 2828×1425. The double sliding kit will take 2 leafs of 2850×1111 which give a visual opening of 2828 by 2142 wide. The link below shows the specification diagram for the fire rated cage systems.

SWD fire rated sliding door cage systems diagram – please click to view

For the fire rated sliding cage systems in particular, when the door is closed, on the back edge of the door that comes out of the pocket, 40mm must remain inside the pocket so it is surrounded with intumescent. Also the leading edge goes into a rebate that is 35mm deep which again is surrounded by intumescent material.

Double sliding doors intumescent strips need to be installed into the meeting styles, the specification of these can vary depending on the system you have installed and the manufacturers guild lines. On the system shown on the link above 2 x 15x4mm strips need to be put into 1 leaf 4mm apart.

There are some important things to consider with fire rated doors and their design.

1 – The door has to be a 44mm fire door and can’t be wider than 44mm including beading as there is only 5mm clearance inside the cage. Therefore bolection beading can’t be used which protrudes from the door face. We have a number of recessed beading profiles we use for this purpose.

2 – If the door has a panelled design with side stiles, we will extend the stiles on both sides as 35-40mm is hidden when the door is closed.

There are 3 main styles of sliding door cage systems:

1 – Visible Frame – with wood reveals where architrave is required, this would make the sliding door look like a normal door set.

The main system we install at SWD is the visible frame which requires architrave. If the client has for example walnut doors with matching frames and architraves, we will supply additional architraves and reveal pieces to over clad the white primed frames or jambs that come with the kits. This is so that the sliding doors will have the same appearance and finish as the hinged door sets in the project. If the frames in the project are just primed then the jambs supplied with the system can just simply be painted on site.

How to work out the structural opening size for the visible frame system

Below is a table on sizes to make the structural opening for a certain door leaf size.

2 – Concealed Frame with plastered reveals.

3 – Shadow gap design

Ironmongery

Lastly the door handles that best suit sliding doors are flush pulls. These are available in different sizes and finishes and can work in combination with hook locks if the door needs to be locked in the case of a bathroom.