DPC bridged by concrete slab

[tvrulesme]

We have a detached garage which we are looking to convert to living accommodation. Whilst trenching for utilities we noticed that the damp proof course has been bridged by the concrete slab. 

 

Just wondering, should I be concerned about this? What could I do to remediate? Do I need to dig out the slab, excavate and re-lay or is there a simpler/cheaper option?

 

 

Original plan was to follow this up to the screed layer. Is this still applicable or do I need to deal with the bridged DPC first?

 

[Brickie]

There are liquid membranes which can be applied to the slab,I believe. If you can get a grinder down the edge you could cut a groove so the slab above dpc isn’t in contact with the adjacent brickwork,that’s be a pig of a job though. 

[tvrulesme]

2 minutes ago, Brickie said:

There are liquid membranes which can be applied to the slab,I believe. If you can get a grinder down the edge you could cut a groove so the slab above dpc isn’t in contact with the adjacent brickwork,that’s be a pig of a job though. 

 

Thanks Brickie. Yeah does sound like a pain. By the looks of it it's half a lightweight block down so about 150mm which is too deep even for a 16" disc cutter 

[Brickie]

Given you have a breaker in there,you could just break out the whole slab & start afresh. Garage slabs normally laid to a fall so you’re going to have some work involved to counter that when converting to habitable space anyway. 
Especially if you want a pool table in there?

[tvrulesme]

1 hour ago, Brickie said:

Given you have a breaker in there,you could just break out the whole slab & start afresh. Garage slabs normally laid to a fall so you’re going to have some work involved to counter that when converting to habitable space anyway. 
Especially if you want a pool table in there?

 

 

I should have mentioned that this is the slab INSIDE the garage. Levels outside do not bridge the DPC. Does this make a difference? I ask because the walls are not at all damp in the middle of winter and breaking out the whole slab seems like a tonne of work and wastage.  

[Brickie]

How thick is the slab? I’d guess between 100mm to 150mm. The level should fall out to front (so the slab probably isn’t above DPC at the garage door.) You’re showing insulation & screed plus the blinding. You’re going to need to level the floor up so have measured up from the heighest point & transferred that height to the front to make sure you’ll have enough clearance to get a standard door frame under your existing garage lintol?