Strap boss for 3.5" cast iron pipe

[Mr Uncalled-For]

I have a 3 1/2 inch drainpipe that I need to T into, but cant find a strap on boss designed to fit such a diameter. Does anyone know if such a thing is sold? Thanks.

[fred]

In article , Mr Uncalled-For writes

Try part no 16148, 82 mm, black, strap boss, 2/3 down this page:

adaptors here, top of the page: a local plumbers' merchant or drainage supplies place should do the same. It is 3" nominal so that is what you should be asking for.

[The Natural Philosopher]

Normally you cut the pipe and insert a branch, or a hopper.

[Mr Uncalled-For]

page:

Boss adaptors here, top of the page:> But a local plumbers' merchant or drainage supplies place should do the

Thanks. It's exactly 3.5 inches external though - I'm not sure if that's the same as 3 inches nominal.

[Mr Uncalled-For]

I was hoping that the strap-on-boss route might be easier! The pipe is also crammed into a corner, partially submerged in render (harling) on one side, which I'll need to chip off to do anything. If I need to do it properly I think I'd get a plumber in to do it. I am a bit concerned that the pipe would drop if a section were removed, although it already does have a branch coming into it that's rendered into the wall as well, so maybe that'd act as enough of a support. Hmm.

[fred]

page:

ltd.uk/products/130a.asp>> Boss adaptors here, top of the page:>>> But a local plumbers' merchant or drainage supplies place should do the

The one at BES is 82mm so 3.25" which is plenty close enough for a strap on boss but buy a longer bolt for the back fixing which I'd guess will be M6.

Last one I fitted needed a 57mm hole saw for the pipe, cut slow and use lube.

[Mr Uncalled-For]

page:

Thanks fred. Yes, a longer bolt should do the trick.

Presumably I should use an appropriate grade of waterproof sealant to ensure a watertight connection between boss and pipe.

[Mr Uncalled-For]

Fred, could you tell me would you'd use as a lubricant, when drilling cast iron?

[Mr Uncalled-For]

Well, I checked with a plumber and apparently I would:

• Not be permitted by 'building control' to use the strap-on-boss solution.

• Would have to do it all in cast iron (externally, that is).

• Have to get a building warrant, covering the entire job, including routing of the pipe internally.

So, from previous rough quotes I've had in the past for putting together building warrant applications, I bet it would probably all cost in the region of =A3600 if I'm lucky.

For installing a kitchen sink!

But at least I'll now have various speedfit fittings and plastic pipe that I can take out admire of an evening.

[John Rumm]

I would not take that as gospel....

The pipe you want to attach to, what is it a soil pipe or a rainwater pipe?

If the latter then you would not be able to tee into it unless you also have a combined surface and foul water sewer.

There is nothing to stop you mixing plastic with CI in this way as far as I am aware either.

[Mr Uncalled-For]

Hi John. I spoke to a guy at the council building control department, and he said that the new branch would need to be cast iron, but the drain pipe that feeds into this branch could be 50mm plastic. So no strap-on-bossage allowed.

Also I discovered that because I'm not installing the kitchen in a room that already had a kitchen in it, all the work would need a building warrant - and I've already started the work, including putting in some sockets. I hate the world! :)

[John Rumm]

Why do you need a new branch in the first place? (assuming you are only connecting a small (ish) bore sink style waste pipe.

Did you tell him who you were? ;-)

[Mr Uncalled-For]

The new sink is quite a bit further away from the stack and the fall over the distance means that the existing branches are too high up - the existing drain exits the building at just below the height of the floorboards.

Nope! But I think he kept me on the line long enough to trace the call. I'm going to phone architectural technician to see how to proceed with regards to the (bleeding) building warrant.

[Colin Murphy]

You could cut into the pipe and fit a cast iron branch. There are various manufactures, but you can find a .pdf catalogue of the one I know most about at

- you'ld be looking for a Timesaver Soil catalogue where you'll find details of GT12 90x100mm stepped couplings designed for 3.5" LCC pipe and GT06 100mm branches. If the stepped couplings were frowned upon by the council then you'ld have to get a 3.5" LCC branch, they are still available.

You did say that space is tight but maybe you can get a disc cutter to do most of the work. Do you have control over the whole stack or is someone above you. If the former, then you have the luxury of time for the installation at least.

[Colin Murphy]

Err,

, is a much better link.

[fred]

I suspect the o/p's pipe is the grey water pipe for his part of the block (if it is a tenement) in which rain and non-foul waste is mixed (around here at least).

[Mr Uncalled-For]

Yeah. I've been having a whinge elsewhere in this group about how the equivalent website in Scotland only publishes a high level platitudinous version of the building regs.

Yep that's the case.

[Mr Uncalled-For]

Actually, I've been drawing layouts using the data from the saint gobain site. It looks doable, apart from the fact that the timesaver couplings stick out quite far from the pipe and would probably neccessitate hacking into the brickwork on the close side at least. The LLC stuff is more compact, but longer so there is less space vertically. Unfortunately there's a flat upstairs that shares the same stack, but it is just the rainwater/grey water stack at least.

[Mr Uncalled-For]

I had a go at using google documents to publish some pictures of the situation:

's a fair bit of hacking to be done just to expose the existing pipe.