Advice on knocking concrete block walls down - technique.

31 May 2005
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United Kingdom

I'm looking to merge the toilet and bathroom and move a bedroom door in order to reduce the size of the landing and gain space in the bathroom. Means knocking down one 3' * 3' L shape and one 3' * 3' * 3 U shape (reducing the size of a large airing cupboard). Walls are not load bearing - just plasterboard above them.

Had a exploratory bash today with my SRS drill on chisel and took the top layer out on the U (the base of the U). Wasn't too difficult as I stumbled upon a 2in mortar filled gap - once I'd knocked that out and the mortar fill along the top a couple of swift blows did the job and I had a way in. Next row is looking more stubbon, mortar in the is quite thin and seems harder that the blocks themselves (medium duty concrete as a guess). Couldn't seem to find an easy way in.

Any tips on technique etc for this? (One of the situations where "bigger hammer" is the right answer perhaps!)

N.B. House is an end terrance - so I'm aware of the impact of the noise on the neighbours - tempted to get someone in, just to ensure it's done and dusted on 1 day.

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Personally would just use a lump hammer, working on one block at a time just to loosen up then remove, no quick way without making a big mess and chance of damage
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Cant really comment on your scenario as it sounds a little more than I did and cant quite visualise without a picture.

I have however just knocked through most of a concrete block wall between bathroom and toilet. I stitch drilled vertically both sides of the area to be removed (many many holes but typically course by course so the whole lot didnt fall at once when hammered) and SDS chiseled to join the holes before knocking out the blocks with a lump hammer. I needed to take this approach to avoid damage to adjacent walls which appeared possibly keyed with the wall to be removed.

The blocks were very heavy and it was extremely dusty - everywhere !

Heres some pics of mine in a separate thread but take it all with a pinch of salt as im a DIY'er like you and similarly asking people more knowledgable on here as I go.


I'm typically cautious so would want to be very sure nothing is load bearing before removing - I was 99.99% sure but still had a mate who is a BCO check for me.
Work on the bed joints with a suitable cold chisel or crowbar, to break the bond, rather than trying to smash the wall to pieces. Starting at one end of the top course
Spent another hour on it this afternoon. Progress so far.

Drilling/chiselling the mortar and then a bash with a lump hammer seemed to work well - couldn't crowbar to much (need a better crowbar!) Plan is to remove the wall and return you can see and the wall behind to the doorway you can see at the back and then move the bedroom door across.

I was hoping to leave the bedroom door in place for as long as possible but the way the keying is turning out I'm going to have to take it out before I can get much further down.

Was just thinking about and SDS attachment for removing the mortar layers - google shows up one of these.

OR which I can pick up easily

Looks like it would make life easier than a normal chisel or drill bit? Take out the verticals then hit to break the bottom joint.
Just carry on with the way you're doing it.

The thing you really want to avoid is a big piece of wall falling down and hitting and damaging the floor. Also be careful not to damage any part of wall you want to keep.
Got a mortar chisel and had a go today - within the hour I was down to the floor on the side above - with the door still in place, so leaving a zig zag of blocks on the left. Took the door frame out and was able to remove the rest of the wall facing the camera in no time at all. In the process generated a big crack 2 blocks down in the wall to the other door way in the background - which is also coming down - so with both corners done the rest should be quite quick now.

This will reduce the size of the (double width) airing cupboard and allow the bedroom door to be move adjacent to the airing cupboard door in the background. Then later I have to knock down the wall between the existing bathroom and toilet - should be easier as I'll be starting on at a door, rather than on short wall with two keyed corners. Resulting bathroom/toilet will gain about 1m2 of space from the landing (wasted space before).

Thanks for all the tips - used elements of then all (except tony's!) - was beginning to think I'd bitten off to much when I had trouble getting started.

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