The Brew Cabin

I have had a massive extension/conversion on my house that has pretty much become a self build in the latter stages due to both cost overrun and disattisfaction with the quality of work performed by the builders/plumbers.
I have two separate drainage runs, one up each side of the house. I completed the first OK thanks to your site! The second run involves a couple of new challenges.
One challenge is dropping a new internal S&V from upstairs accomodation down through floorboards at ground level and through a brick built cavity wall to connect to the new drainage I/C. I am confident I can do all this apart from installing a couple of 450x70x100 lintels above the S&V outlet.
Will I need to provide support for the wall while before removing the bricks for such a small hole? If so, how should I support the wall while doing this?
My other question is that part on the new drainage needs to pass under my front door step. I plan to encase this step area in concrete about 1100 long x 450 wide x 350 deep. Would you recommend pouring the concrete directly next to the brickwork footings, or should I line the brickwork with a sheet of plastic or a compressible liner of some sort to allow for expansion and to stop the concrete sticking directly to the brickwork?
Later I will be laying paving areas and will face a similar question of laying concrete directly next to the house wall brickwork.

I'm not sure why you need to install the lintels, and, without being familiar with the site, the proposed point of entry/exit, the access etc., it's yet another of these problems where it would be unwise for me to recommend any particular modus operandi. It's sometimes possible to create a small-ish opening in a brick wall without having to resort to Acrow props or other forms of carrying the upper brickwork. In my experience, cutting a roughly 150x150mm hole to evacuate a soil pipe is straightforward enough, and does not normally require lintels or support structures, but then, your situation may be different.

Your second question brings a similar response, I'm afraid. Unless I can see the job, I can't really say what would be my plan of attack. Can you provide me with an annotated sketch of your plan?

Sorry I'm not much use on these questions, but they are so individual and site-specific, it would be unprofessional, and possibly dangerous, for me to suggest solutions when I'm not familiar with the layout.

Tony,
Thanks for your comments.

Here's a bit of extra info about what I am up to.
My property was a 1950's bungalow which has been extended both outwards and upwards (Dormer windows etc). It's in a rural location with long drain runs to a septic tank. I also built 4 soakaways using your excellent advice.

Re: Why I need a lintel?
Obviously I have plans for my extension have been granted planning + building regs approval. The plans are a little lacking in detail regarding how the SVP from the new upstairs exits through the original bungalow walls. I have 2 other SVPs which exit the newly built part of the property both of which have small lintels but obviously it is easy to to put these in a new build.
I asked my architect/building consultant if I needed to put lintels in for this SVP (having seen them in the newbuild part) and he verbally advised me it would be best, so I guess I had better put them in even if it is probably an overengineered solution.
I also need to make sure the building inspector is happy, although I guess could ask him what he would be happy with.
To be honest, it is probably unfair of me to ask you how you would put lintels in - after all you are not buildingexpert.com!
So anway, no worries and thanks for your advice on that.

Regarding the concrete, I suppose my question is not really a drainage question at all - more of a genaral question about laying concrete.
If you are laying concrete right up to a house wall would you:
(a) Always put a liner (e.g. plastic sheeting) between the new concrete and the existing wall?
(b) Never put a liner between the concrete and the wall?
© Sometimes put a liner between the concrete and the wall, depending on circumstances?
If you answer (a) or ©, what materials would you use as a liner and what purpose would the liner typically serve.
(e.g. maybe one purpose of a liner to act as an expansion buffer?,
another purpose may be to stop the concrete sticking to and damaging the wall the wall in case it ever needs to be broken up and removed at a later date)
Sorry if this question seems a bit vague, but I will be laying quite a lot of concrete around my house when the drainage is finished. If I understand the factors to be considered in deciding if a liner should be used then I will be able to make my own mind up in the various situautions.
Also, sorry if this question seems a bit daft.
As you can probably tell I dont know very much about laying concrete.

Somehow, the fact that an architect specc'ed the lintel comes as no great surprise. If you ever want to do things the hard way, get an architect! ;)

I think you;re right - ask the BCO what they would accept and go with that. The trouble with many of these types of jobs is that you can't see what you;re up against until your get the ground opened up, and you could get yourself all geared up for a lintel installation only to find some prescient builder has left a 150mm dia hole in the foundations just for this sort of eventuality. Well, maybe not, but you know what I mean! :)

So, on to the concrete - usually, we'd use a membrane between the existing brickwork and the new concrete, unless there was good reason not to, and nothing you've mentioned so far suggests such a good reason. The standard 'membrane' is a PIFA 1200 micron impermeable membrane, but we call it 'visqueen' for short. It's the blue-tinged plastic you've seen a million times on building sites and in Builder's Merchants.

You'll not need a full roll (100m2) so see if you can cadge some from a local builder in exchange for a small donation to their favourite pocket.