Render Not Sticking To Reveals After Window Replacement.

[Whitespirit66]

A few weeks ago, I helped the brother in law to install a couple of UPVC windows to replace old wooden ones. As usual, the rendering on the reveals had to be removed to make this possible.

I left him to make good, but he has since said that he can't get the render to stick to the brickwork reveals. I'm not sure what materials he used, but would appreciate any tips. Eg, is it recommended to PVA the brickwork first?

Thanks for any advice, as I'm going around to see what a dog's breakfast he's made of it this weekend and hope to help him finish it.

 

[noseall]

The problem is that the original render was applied in one hit and subsequently set as a one piece render with no joins. Its strength was in the large mass of render.

What there is now is a joined on bit with no strength. As soon as the window flexes with any thermal movement, that render is gonna pop.

Apply plenty of water and don't fuss with it too much.

 

[joe-90]

And don't make the mix too strong.

 

[Whitespirit66]

Ok, thanks for the tips. I now understand the problem. Would it help to screw some of that metal mesh that reinforces render edges to the brickwork to help with grip? Use some washers so that the mesh stands a few mms off surface of bricks? I'm thinking that something that gives mechanical grip would be a big help.

When I say mesh, I mean just the flat mesh, not the reinforced corner part.

 

[noseall]

Ok, thanks for the tips. I now understand the problem. Would it help to screw some of that metal mesh that reinforces render edges to the brickwork to help with grip? Use some washers so that the mesh stands a few mms off surface of bricks? I'm thinking that something that gives mechanical grip would be a big help.

When I say mesh, I mean just the flat mesh, not the reinforced corner part.

Yes, as long as you can get decent coverage.