Rendering over aluminium blind box

[Mr Blobby]

We plan to install aluminium blind boxes (about 250mm high) above some windows for external blinds.  What is the best way (if there is a best way) to render over the aluminium?

The front face of the box has 15mm lip at the bottom but otherwise the front face is just smooth aluminium. 

 

Two challenges then.

First challenge is how to get the render to stick to the aluminium.  Mesh, scrim cloth, something else?

Second challenge is to do this in a way that will not crack given that aluminium may expand in the heat. 

We intend to use a silicone render like sto which will hopefully provide some elasticity but welcome any suggestions as to render choice.

 

Has anyone rendered over a smooth surface like this before, and if so how?

 

[Conor]

One for @nod but I'd expect you'll need to mechanically fix a suitable substrate first, e.g. cement based render board. Aluminium will have different thermal expansion properties to most render systems I'd expect.

[nod]

8 minutes ago, Conor said:

One for @nod but I'd expect you'll need to mechanically fix a suitable substrate first, e.g. cement based render board. Aluminium will have different thermal expansion properties to most render systems I'd expect.

As always Conor 

Spot on

[Alan Ambrose]

+1 suggest either leave the aluminium showing, powder coat a different colour if you need to or ... cement board over and render on that.

 

If there's a chance you need to get at the blind mechanism and can't maintain it solely from below, then the 1st option or some kind of removable rendered board would be good.