External wall...What is it? Not block as expected....

Postby Ravnut » Mon Oct 20, 2008 10:24 am


Recently doing a bit of DIY in a corner of the room. It's a 3 storey townhouse about 4 years old.

The first wall I drilled into (between us and our neighbours) was plasterboard dabbed onto breeze block, This is what I expected so no problem there.

The external wall is also a plasterboard finish and I assumed behind that and the external brick face would also be a block construction. This doesn't seem to be the case though.

I drilled through the plasterboard the drill moved across the air gap and hit the next surface. I was surprised that I was then also able to drill this material using a standard HSS drill bit.

I thought maybe both drill holes had hit mortar between the blocks but this doesn't appear to be the case as I moved a few inches up n' over on both holes and hit the same material.

So what am I drilling into here...Any suggestions?

Thanks in advance!!!
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Simply Build It

Postby plumbbob » Mon Oct 20, 2008 11:22 pm

Maybe the blocks are Thermalite which is a very soft breeze block (can be cut with a wood saw). Possibly the hose is a framed construction with only plaserboard, frame and insulation between inside and the external brickwork.
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Postby Ravnut » Wed Oct 22, 2008 2:17 pm

Hi Plumbbob,

Thanks for the reply!

I can rule out framed construction. I bought the house new, so saw it during the build. (yeah OK! clearly should of paid more attention......tut).

Thermalite? that's the first time of heard of it. wouldn't that be a bit strange if the partition walls are regular breeze block?

If it helps, Whatever I'm drilling into comes out creamy in colour.

Beginning to wonder if there may be thick insulation between the breeze block and plasterboard?

Whatever it is, it's quite hard. It appears to be holding a rawplug into the wall quite firmly at the moment. It's the long term durability that concerns me though.

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Postby plumbbob » Wed Oct 22, 2008 8:07 pm

Maybe it's not surprising the party walls are made of a different material. It is probably load bearing, and needs a denser construction to be soundproof. Stronger as well to prevent active DIY neigbours from knocking holes in each other's walls.

Thermalite is a light powdery dust made from power station ash. Can be scratched with your nail, and has a strength and weight one up from polystyrene.

Rawlplugs will hold to a point, but as the blocks are so soft, will pull out if under excessive loads.
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