Broken clay gully/trap - What to replace it with?

[IgamOgam]

OP,
No they have not - you misunderstand what I asked for.

Yes, sorry for that. I don't have any other photos of the complete patio area, and I think I have it sorted now, so thanks for your suggestions.

 

[Ivor Windybottom]

That looks about 10x better than the prototype!

It will be fine. Not ideal, but fine.

Stand the gully on a brick, then pack up with tiles, packers or whatever to get just the right height and level. Then put a couple of bricks on top to hold it down.

You need concrete under the gully. For the pipe, 10mm gravel is the norm. You need 100mm cover around the sides and above.

Or all concrete is another option, which probably makes more sense given the small volume. But use some board or polystyrene sheet to keep it away from the rubber joint and clay pipe, otherwise any slight relative movement will crack the end off the clay pipe.

 

[Ivor Windybottom]

.

 

[IgamOgam]

That looks about 10x better than the prototype!
It will be fine. Not ideal, but fine.
Stand the gully on a brick, then pack up with tiles, packers or whatever to get just the right height and level. Then put a couple of bricks on top to hold it down.
You need concrete under the gully. For the pipe, 10mm gravel is the norm. You need 100mm cover around the sides and above.
Or all concrete is another option, which probably makes more sense given the small volume. But use some board or polystyrene sheet to keep it away from the rubber joint and clay pipe, otherwise any slight relative movement will crack the end off the clay pipe.

Thanks for the vote of confidence (eventually!). I tried using 3 x 45 degree bends but my simple brain couldn't make it work, hence the final arrangement. The bottle gully is sat on a concrete pad that was built to set the top grille at 5mm below finished surface level. It is now embedded in a raft/doughnut of mortar on top of that concrete pad and is set level and 10mm off from the kitchen wall.

The clay pipe has been covered with 10mm pea gravel to just above the Fernco adapter, which seems to be as per Building Regs (Wales) Approved Document H, Diagram 10 b).

Once the mortar has set, the plan is to use the material dug out from the hole to back fill it, sifting out any large lumps/stones beforehand, and compacting it as best we can.

As a long time DIYer, I take a fair amount of pride in the quality of the work I do. After all, I don't have time or profit constraints. I kinda knew that my original plan was sub par, but I was very, vey reluctant to touch underground clay pipes, as it's way off my beat. Your comments were just the push I needed to get me over that hesitancy, so thanks for that.

Next problem to deal with is a broken collar on a clay swept bend where it meets the cast iron soil pipe. More fun.

 

[Ivor Windybottom]

Your plastic pipes will be fine. The clay pipe is the weak link, the 70 year old ones I took out here were about as strong as a biscuit. Make sure it has at least 100mm of 10mm gravel over it.

 

[Hugh Jaleak]

Next problem to deal with is a broken collar on a clay swept bend where it meets the cast iron soil pipe. More fun.

Again, not too difficult if you dont overthink it, however it is vital to check the Cast is adequately supported above before removing the existing drain from underneath it. Cast is extremely heavy, if it's relying on the drain underneath for support then it could fall without warning if you remove that support.

Assuming all is well, then excavate and expose the clay pipe leading away from the Stack, cut at a suitable point. Use a Flexseal or other suitable coupling to change to 110mm plastic. Long radius bend ideally at base of the Stack, couple back to the cast using another Flexseal. Peagravel around pipe, backfill as required.

 

[IgamOgam]

Again, not too difficult if you dont overthink it, however it is vital to check the Cast is adequately supported above before removing the existing drain from underneath it. Cast is extremely heavy, if it's relying on the drain underneath for support then it could fall without warning if you remove that support.

Assuming all is well, then excavate and expose the clay pipe leading away from the Stack, cut at a suitable point. Use a Flexseal or other suitable coupling to change to 110mm plastic. Long radius bend ideally at base of the Stack, couple back to the cast using another Flexseal. Peagravel around pipe, backfill as required.

Very aware of the dangers of how heavy cast iron is. The bottom end of the cast iron downpipe was approx 10mm above the start of the clay pipe, so it looks like it wasn't properly supported for some time. The short term fix to stop waste spilling into garden was to cut out a section of the bottom cast iron pipe and fix a straight drain coupler, length of 110mm pipe and Fernco adapter with the cast iron conveniently fitting inside the 110mm pipe. Everything now quite solid and watertight. As the original round wooden blocks used to space the cast iron about 25mm off the wall are not in good shape, the medium term plan is to (carefully) completely replace all the cast iron.