insulated cavity closers - space allowance ?

[sm_jamieson]

If using insulated cavity closer, (e.g. thermabate etc), rather than closing with the inner blockwork, do you need to allow some space for the closers ? E.g. when leaving an opening of some fixed dimension for a window, should you increase the brickwork opening by some millimetres, in order to allow for the closers ? Thanks, Simon.

[Jeff]

If they are anything like mine then 1mm should cover it

Regards Jeff

[Alex]

Why not install with the brickwork as they are meant to be.Problem then solved