Drilling through exterior brick wall - Feels like half the brick is missing

[Spetznaaz]

I noticed while drilling into the exterior house wall the other day that on a few bricks i would drill about 3-4cm and the drill would suddenly go all the way in, like half the brick was missing.

Does anyone know what could be causing this and if it is something i should be concerned about?

I was thinking maybe some seriously spalled bricks have been taken out, turned around and put back in but it really doesn't look like they have ever been taken out.

 

[RandomGrinch]

on a few bricks i would drill about 3-4cm and the drill would suddenly go all the way in, like half the brick was missing.

You found a (core) hole perhaps?

 

[Mike13]

Some have an even bigger central hole than that, look up "Dorking Multi" bricks, there are two types, one with three larger oval holes than that one, others with 5 or 6 skinny slots.

 

[Spetznaaz]

I guess this could be a possibility, just i know the bricks used were solid all the way through, unless some of them with holes were used in random places. Judging by the length of the drill bit, i'm pretty sure it was going in further than the full width of the brick as well.

 

[Mike13]

when they come in different cuts and batches there might only be a few of that type in use