I am going to be laying a floor slab (probably about 125mm thick) that will be more or less bisected twice (trisected?) by two 50mm diameter floor drain pipes. Because of elevation constraints the pipes will need to run horizontally through the actual slab at a gentle gradient, I can't run them underneath the slab. This will introduce lines of weakness in the slab, but..

 

1.) Is it worth worrying about as long as the slab is properly supported in all sections? This floor slab doesn't have any structural purpose beyond people and furniture but it will need to support wall hung toilets and a bath. Underneath the slab there is a layer of EPS insulation with a compressive strength of 150 kPa. Intuitively this support is either fit for purpose or it isn't, the slab weaknesses introduced by the drain pipes is neither here nor there as far as the underlayer is concerned. But please correct me otherwise.

 

2.) What would be the best way to add reinforcements? Something like single layer horizontal grids, maybe each 2 feet wide, running beneath the pipes?

Edited February 28, 20242 yr by JohnMartin68

Not ideal but no big issue either, get your pipe runs in a sensible place - parallel to any crack inducers or joints etc. strip of mesh over and under (if possible) and you will be fine.

You ideally want to run 110mm PVC pipes under the slab, then up where the drains will connect. 

 

You don't want (can't?) to run 50mm standard PVC pipes underground. 

 

I recall your other post about the shallow 110mm pipe. This will be the same situation. 

Edited February 28, 20242 yr by Conor

2 hours ago, markc said:

Not ideal but no big issue either, get your pipe runs in a sensible place - parallel to any crack inducers or joints etc. strip of mesh over and under (if possible) and you will be fine.

Cheers, what type of mesh would you use? Apologies for ignorance next to no experience using reinforcement.

2 hours ago, Conor said:

You ideally want to run 110mm PVC pipes under the slab, then up where the drains will connect. 

 

You don't want (can't?) to run 50mm standard PVC pipes underground. 

 

I recall your other post about the shallow 110mm pipe. This will be the same situation. 

The 110mm pipes from the other post can go underneath the slab, but the 50mm ones can't. Long story but they aren't going to the same place.

Edited February 28, 20242 yr by JohnMartin68

58 minutes ago, JohnMartin68 said:

Cheers, what type of mesh would you use? Apologies for ignorance next to no experience using reinforcement.

For your application it doesn’t need to be specific reinforcing mesh, if you can get some off cuts or strips then great, A142 (6mm wire) or above will be more than sufficient to stop the pipe creating a crack line