[Pisto_Grih]

Hi Everyone,
I've just purchased a new TV and mount for the new front room, and I thought I would investigate the wall construction for mounting the TV by cutting into it for the cables. The wall is the "exterior" wall (brick-cavity-unknown internal construction).

Unfortunately, I don't seem to be able to tell what kind of wall it is, as it doesn't seem to match with any other type of wall I've seen discussed on the forums:

The wall sounds solid everywhere I knock. Not really solid, like it was made in the 60's solid, but not obviously hollow, like an internal partition. It starts off with about 5mm of plaster, as I can cut this out fairly easily with a stanley knife, but then there is something fairly hard after this, but when drilled (no hammer action required), this gives way after another 5-10mm to something soft with dark grey dust.

I initially thought this was plaster on plasterboard dot-n-dabbed onto thermalite, but the missing plasterboard and no gap between the middle unknown material and the thermalite makes me think it is something else.

The house was built about 5 years ago by Bovis, if this helps!

[Pisto_Grih]

Am I correct in thinking that this would be a cement render over the thermalite and then a plaster skim? It would explain the 10mm of hard material and lack of a gap.

If this was the case, then would I be able to use Rigifix mountings to mount my 40" LCD (only 17.5KG) with a flat Dekomount, or should I use something else? I was under the impression that using expanding anchors ran the risk of breaking the thermalite blocks behind the render, but resin fixings seem overkill for a light television like mine.

If I used Rigifix in addition to traditional heavy duty wall plugs and bolts (such as those supplied with the mount) I should be OK?