Hi, please bear with me I'm not that good on plumbing.. Ok got an old house with a cast iron (I think, its metal anyway) soil pipe. This runs in an enclosed area of a pitched roof. From the bathroom and toilet adjacent to the pitched roof run metal pipes from bath sink and lav.
Ok what I was going to do was just connect pvc waste pipes up to the smaller waste pipes from the old bath and sink to the new items. Noticing the smaller metal waste pipe goes directly into the soil pipe I understand I need a normal U bend, the bath and sink wont be a problem but the shower may be as I'm using a compact one.
ANYHOW, would it be best to run a new large soil pipe into the old cast iron pipe and attach each of the other wastes accordingly. If so is there a suitable connector to attach the plastic pipe to the old cast iron one, the pipe runs up and down from the point that I would insert the pipe so I presume the connector will need to be a T junction.
Sorry for the long and complex rambling explanation but thought I should cover everything. Thanks John
You've covered everything alright, but I, for one, don't have the slightest clue what you're on about. We need sizes and lengths of the pipework. More info' on where and how the pipework is being changed inside and out.
Sorry i re- read it and I couldnt work out what I was on about,
The T junction was refering to the fact the soil stack is verticle, this is the plane Ive come up with, I was going to cut into the cast iron soil stack (Not sure on size, but its from about the 50's), would an angle grinder do? are the gases flamable?
So once that has been cut I need to insert the T junction and connect it somehow to the cast iron soil pipe, are there flexible joints?
Once this is done I was going to run a plastic soil pipe from this T junction all the way along one wall of the bathroom (Actually behind the wall but access is ok) To this long standard size soil pipe I was going to connect the WC then the sink then then bath then the shower At present thats alot of connection but the WC is in a sep room so will be directly connected, the sink is some distance from the bath/shower so again will be connected sep. Shower has a compact trap so would this need a deep trap if its going to be connected to th esoil pipe and the same with the bath?
Take a trip to your builders merchant (not a Buy and Queue!). They should have free booklets from whichever brand of soil and waste fittngs they sell.These booklets normally have pictures of each fitting and also typical applications. I would expect also to find details of conversion fittings for upgrade work such as you are doing.
The existing stack pipe, is it rain water or solid soil? You can't put a WC outlet to rain water stacks, as some, or most, rain water stacks don't actually connect to the main sewer system. Rain water stacks can just be, what is called, soak away systems. These are run into ground drainage systems and are used to keep things sweet and clean after a rainy day. They help wash down road drainage and other light water systems.
If the existing stack is actually being used for another WC somewhere else in the house, then you can do your plan of joining other appliances to it. This to needs to be checked that it will not over do the stack ventilation for the existing appliances connected to it. If another appliance is connected lower down on the same stack, it might need its waste outlet lowered to prevent flow back into the appliance from water coming down the pipe from your new installations above it.
The stack you need to use must at least 110 mm (4 inches) diameter for it to be a solid soil stack. Any narrower than this is most likely a grey water (rain water) system and can't be used for a WC outlet. Wrap a piece of string around the pipe, then use PI to work out what diameter it is.
Thanks for that it is a soil stack, currently used for a WC and will only have toilet shower sink and bath attached, is this ok or will it be over do the ventilation?
Your best to take the WC to a lower separate branch on the stack from the grey water system. You should try not to mix them together. The grey water is the bath, shower and sink Etc.
On the vertical stack, cut a large enough section out of the cast iron stack using an angle grinder with a 9'' wheel. The cut section should be low enough for a drop on the WC outlet and a separate grey water system. Try not to mix them for your own sake.
You'll need to buy:
1 of 110 mm (4 inch) Cast Iron "Equal TEE",
1 of 110 mm X 110 mm X 75 mm (3 inch) Cast Iron TEE the branch off is 3 inches diameter to take the separate grey water to the stack. You may also get away with using a WYE Branch TEE, which has a 45 degree angle instead of the 90 degree angle of a standard TEE. Looks more like a Y than a normal TEE.
4 of 110 mm (4 inch) Cast Iron Speed Clamps. These will allow you to join all your stack back together without the need for re-leading the spigot joints. When using the speed clamps, try to keep both bolt heads on the outside of the stack for easier access when fitting, and in the future for maintenance or repair.
Make sure the stack is properly secured back to the brickwork once everything is installed and checked for leaks.
You'll also need to buy access elbow bends to suit both the new 4 inch and 3 inch branches which take the cast iron inside the building. Always join the new internal plastic pipes to the cast iron pipes inside the building. Try not to use plastics outside the building, as most internal use plastic pipe isn't good in direct sunlight, especially the cheaper stuff, so you might also need some short lengths of cast iron pipe from the stack to where the pipes go through the wall.
You'll need safe access, up to the height of the cut section at least, if you're going to use an angle grinder to cut the stack. Safe access is a platform which you can comfortably stand on with both feet. Don't use a ladder, because the angle grinder may stick in the pipe and throw you, and the ladder, over next doors roof. You'll also need a cutting device for taking new holes through the wall for the new pipes.
Try a web search for things like "vent stack" or cast iron vent pipe" and you should get a lot of good hits to show your other means of branching into the system. Good luck with it, and remember, stay safe. We're always here if you need more.
Thanks for that description, that I think is how I'm going to design it, however not with cast iron but with plastic as the pipe is situated within an enclosed roof space.
However what I want to know is will I need to support the cast iron pipe as it runs vertical and I presume is pretty heavy, so when I cut a section out insert plastic pipe the plastic pipe wont be able to support the weight.
I don't know what weight you're dealing with above the section you need to remove, but the weight will need supported while you cut and fit the new branches into place. The horizontal sections are best fixed at 1 mtr spacing, so if the length isn't any where near that, then don't bother as the elbow going in through the wall will be enough to hold the weight of anything shorter than a metre. You'll will need to make sure you have ample fixings after the pipework is finished and set, so get all your main brackets and things ready before you start. Nothing worse than having bits of rope or string holding the pipes while you nip off to the merchants for more brackets.
If the existing stack is cast iron, then use cast iron for the new branch section as well. It's safer in the long run. Speed clamp joints are meant for cast iron really, and they don't take to kindly to plastics. Cast pipe isn't expensive, and it lasts a lot more years than new plastics anyway, honest.
There are new (well, fairly new) plug and screw brackets for cast iron pipework. These have a slot in the back plate which lets you screw beside the pipe and slide the back plate into position before you band the pipe to it. They're very handy for the type of job you're doing. The back plate gives a stand off from the wall of about 45 mm (nearly 2 inches) especially meant for the spacing of the spigot ends of cast pipe. Great for retro-fit on these alteration jobs.
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