Jadnashua
Retired Defense Industry Engineer xxx
It's a tough call deciding when to stop. You need to keep going until you find solid pipe. That might be much further than you really want to deal with, but there's no time like the present! A rusted through, leaking pipe is a magnet for termites, carpenter ants, tree roots, that can generate all sorts of new problems.
Once you find solid pipe, there are couplers that work fine connecting between the CI and ABS or PVC (whichever is more common in your area). If you end up going all the way back to the stack, there are gaskets (donuts) that seal the plastic pipe into a hub.
Some people find cutting CI easier with a grinder and a cutoff wheel verses trying to saw it. You probably don't have enough room to use a snap cutter, and while those work great on new pipe, it may not make a clean snap on older, partially corroded pipe where it might just end up crushing it verses snapping it. I don't think the blade you mentioned would work well on CI, but I have not cut much...I was able to snap it.
When working with deckmud, it's much more like working with wet beach sand than concrete. You do need to pack it in place, but it will remain sandy on top. It should end up with great compressive strength, but not fantastic surface hardness. The reason you use deck mud verses concrete is that you can shape it easier plus, it is porous so that any moisture that gets beneath the tile can percolate to the weep holes of the drain.
As was noted earlier, should you choose to use a surface membrane like Kerdi or one of its competitors, you'd need a different drain assembly, but only need to make one layer rather than two of deckmud. I, personally, really prefer to make the whole shower waterproof verses just the pan. A conventional shower's walls are only water resistant, relying on gravity to keep moisture out of the walls and penetrating the structure. Cement board is not waterproof, but it is not damaged by becoming wet. Waterproof is critical on the horizontal pan, but not so much on the walls, which is why a conventional shower construction works. A surface applied membrane means no moisture gets beneath, and the whole thing dries out much faster. Minimize trapped moisture, much harder for any mildew to take hold.
Once you find solid pipe, there are couplers that work fine connecting between the CI and ABS or PVC (whichever is more common in your area). If you end up going all the way back to the stack, there are gaskets (donuts) that seal the plastic pipe into a hub.
Some people find cutting CI easier with a grinder and a cutoff wheel verses trying to saw it. You probably don't have enough room to use a snap cutter, and while those work great on new pipe, it may not make a clean snap on older, partially corroded pipe where it might just end up crushing it verses snapping it. I don't think the blade you mentioned would work well on CI, but I have not cut much...I was able to snap it.
When working with deckmud, it's much more like working with wet beach sand than concrete. You do need to pack it in place, but it will remain sandy on top. It should end up with great compressive strength, but not fantastic surface hardness. The reason you use deck mud verses concrete is that you can shape it easier plus, it is porous so that any moisture that gets beneath the tile can percolate to the weep holes of the drain.
As was noted earlier, should you choose to use a surface membrane like Kerdi or one of its competitors, you'd need a different drain assembly, but only need to make one layer rather than two of deckmud. I, personally, really prefer to make the whole shower waterproof verses just the pan. A conventional shower's walls are only water resistant, relying on gravity to keep moisture out of the walls and penetrating the structure. Cement board is not waterproof, but it is not damaged by becoming wet. Waterproof is critical on the horizontal pan, but not so much on the walls, which is why a conventional shower construction works. A surface applied membrane means no moisture gets beneath, and the whole thing dries out much faster. Minimize trapped moisture, much harder for any mildew to take hold.
