Taking 75mm from the top of a dense concrete block

Dynamite

 

9" Grinder,maybe Stihl disc cutter, or knock it down & redo.
In fairness the BCO should have pick up on this sooner.

 

SDS drill and then chisel, I guess.

Look to go deeper - to around 100mm - and then you can lay a bed of mortar to level the bumpy surface off.

If access is only from the top, I think I'd drill a series of holes vertically down to 100mm, and that will both give you a depth guide and I think make sections more easy to break away. Then fit a chisel in the SD drill and fire away. Make a V first to the required depth, and then start chiselling away. I'm not sure if it would be more successful to try and work by 'widening' that V - ie taking sloping 'cuts' down in one inch steps - or to try and work more horizontally along the bottom of the slot.

See what works best. Take it steady and slow, tho' - you don't want to split any blocks...

 

That's the risk with sds, also dislodging blocks is possible.

 

Tell the BCO it's not possible and to come up with another way around what they're are asking you to do, as said above this should have been sorted before any brickwork was laid.

 

Have I missed something. The entire wall has been built and you have to remove the inner bricks ? PIR insulation board isn't structural and can't replace blocks. Thermal blocks can but these have to have structural loading

Because if it is below the DPM then you would have to break the floor all the way round peel back the DPM and remove blocks one by one ?

I think he means that you have to cut out a channel in the slab and insert a 25mm piece of insulation ?

 

sounds like sospan is on the right track - where floor meets wall - thermal barrier

 

might be a stupid idea but what about a core drill-
drill to correct depth all along then knock out what's left ?

 

SDS as before - I can't think of an easier way.

Drill drill drill a series of holes almost 100mm deep and then chisel. Take it steady - you will get there.

The reason I say to aim deeper - ~100mm - is that in practice you'll end up with a bumpy finish which will have peaks and troughs. If you aim for roughly 100mm deep, then you should find that all of the level will - even the high bits - be at least 70mm when you finish.

If, instead, you aimed for 70mm depth, then you'll find you'll spend ages trying to smooth-off and level the bottom to get it all to at least 70mm. It'll be easier and quicker to go slightly deeper and then spread a layer of mortar over it to bring it back up

 

Ooh - that's clever.

 

Ah I see,

Whilst it is going to be a pain, I would take out the frames - one to give access and secondly to prevent the odd tools hitting it.

With the frame out you will probably have to the cavity. I would be tempted to use a 4.5 inch angle grinder with a diamond disk and cut along the top edge of the block where it joins the floor and then go in horizontally across the cavity.

If you don't want to take the frame out - put a thin strip of ply alongside the frame to protect it. Then cut parallel lines with the angle grinder through the top of the block. A cold chisel and hammer will remove the bulk.

 

Ooh, that's a good idea too - and I'm sure I've seen it done.

Basically, use any of the ideas above except mine...

 

I thought you would have advised him to cover with insulate PB? lol

 

and given a few coats of PVA