Making a trench in concrete floor

[SUNRAY]

Hi All

I am fitting a new downstairs toilet.

The plans show a soil pipe under the garage extension, supplied by an internal rainwater pipe (used to be external before the garage was built. The plan was to remove the trap and install an elbow and branch above floor level for the toilet then a new trap above it. I spent 3 hours today digging a hole about 500x400mm only to find there's no trap and it feeds a soakaway, not to the sewer as shown on the drawings.

My question is: what is the best way to cut through the concrete floor the full length of the garage to make the trench for the new pipe I need to fit?
The concrete is about 200mm thick and very hard, takes about 2 mins to drill a 10mm hole with a Hilti 220!

Planning are all over this.

 

[freddiemercurystwin]

Why can't you make the two external?

 

[SUNRAY]

Why can't you make the two external?

I'd have to go out the front wall of the house and through the whole length of the garage, adding several metres of pipe and a couple of extra bends.

 

[Nige F]

Hire a diamond floor saw - or use a company that will do the job, and save you getting covered in dust and muck. I've looked around on the net and it seems like c£500 hire or more if you get the contractor. There isn't much pricing info

 

[bernardgreen]

Be sure that cutting the floor of the garage into two halves does not compromise the foundations that support the garage. It is not unkown for a garage to be built on a very shallow raft foundation. The two halves of a cut raft with a gap between them could move ( slowly ) apart if they are not securely "glued" together when the trench is re-filled and the floor ( raft ) made good. If they move apart they will take the walls with them.

 

[SUNRAY]

Be sure that cutting the floor of the garage into two halves does not compromise the foundations that support the garage. It is not unkown for a garage to be built on a very shallow raft foundation. The two halves of a cut raft with a gap between them could move ( slowly ) apart if they are not securely "glued" together when the trench is re-filled and the floor ( raft ) made good. If they move apart they will take the walls with them.

Thanks for the thought, its an extension on the house and built on foundations with a slab laid after.

Hire a diamond floor saw - or use a company that will do the job, and save you getting covered in dust and muck. I've looked around on the net and it seems like c£500 hire or more if you get the contractor. There isn't much pricing info

I saw one being used on a road since i posted and had a chat with the operator, it certainly looks like the way to go as all the cutting was done inside the machines casing and the dust seemed minimal, lot of water though

At the moment we're considering a macerator as we may just about get away with a 40mm pipe if 1:20 for the first 2000mm followed by 1:100 for 2500mm then a swept elbow to the stack. BUT my personal experiences of macerators is not good when they break down!!