My 'hollow' wall is not actually hollow - what do I do next?

[martpol]

Hi there - I'd be grateful for any advice on the following.

I'm planning to fix a 3/4 inch thick piece of wood to the wall either side of the top of our staircase, which will enable me to install a child safety gate. (It's either that or take away the skirting board below.)

From tapping the wall I assumed it was plasterboard, and I managed to get self-drill plasterboard fixings in at two points. However, when I tried putting in the other fixings (two inches to the left) it seems that there is a thin layer of plasterboard, followed by a cavity, then a masonry wall.

I've now messed up the plasterboard by punching through it (I know, I should have tested it with something thinner first) and I don't know what to do next. Should I fill the holes and then drill through? Is there some sort of fixing that will go through (roughly) a quarter-inch of plasterboard and a a quarter-inch cavity followed by masonry?

Apologies if this sounds obvious, but I am a DIY novice!

 

[PrenticeBoyofDerry]

The type of wall you are likely to have is known as dot'n'dab in the trade (AKA drylyner system). This is were the boards are stuck to the wall using dry wall-adhesives.
The problem fixing to this wall is as you are experiencing, you hit a void between board and wall. Hollow wall anchors rarely allow for the gap, standard nylon raw plugs don't grip, self drive are pants!
I would go for the longer nylon (frame fixers) raw plugs and drill in to the masonry behind the board to get a good secure fit.