would downstairs kitchen extension have to use plumbing from upstairs bathroom?

[CurlyhairedAssassin]

Have no idea about this stuff.

we would like to put in a new bathroom upstairs next year. However, we also want to extend downstairs maybe the year after which would include the kitchen and so plumbing and drainage implications. Would they have to mess up any plumbing/pipes in the bathroom upstairs while doing plumbing stuff downstairs in the kitchen? Don't want to put a nice new bathroom in next year only for us to have to mess it up a bit to get to pipes etc for downstairs extension the following year.

I think the problem will be the downpipes to get waste water from the bathroom. Do you know where they are? If the downpipe goes down a wall that you intend to knock down in the future then you'll need to find another way of getting the waste water out, which might involve changing the pipework under the bathroom floor.

When we did our extension we left the 'old' downpipe which served the bathroom in place, but hidden behind plasterboard (with an access point in case it gets blocked). Then we created a new drain point for the kitchen waste water.

Your architect ought to consider the pipewater as part of his drawings.

Is the ground floor concrete or wood with a space under?

Have you got a combi boiler or a hot water cylinder and a cold water tank? Where is (whichever you have got)?

Where does the incoming water main appear?

How far is the kitchen from this downstairs room?

Is the upstairs bathroom directly above the downstairs room?

You aren't going to fit any floor coverings like laminate or tile that "can't possibly come up" are you?

thereinmadnesslies: Hmmmmm......at the moment we have the crappiest diy job ever of a small side extension to our kitchen. It is just basically a lean-to added on to the side of the original kitchen. They left the outside downpipe and external drain wotsit in its original position so that it is now basically INSIDE the extension part whereas on the original house it would be outside on one corner of an external wall. It's disgusting what they did. It's full of damp as a result. We also have water pouring down the internal walls of the lean-to extension when it rains very very heavily and the gutters on the roof are a bit blocked with leaves, because of the way they have done the roof guttering.

It basically needs knocking down and doing properly to the side, and we want to add all across the back of the house too. So an L-shape extension really. I wish those people who did that bad side extension had just left it alone really and we would have done it properly ourselves - going to cost more money to knock it down and have it done properly than it would to have done it properly in the first place.

PigletJohn: The kitchen floor is concrete, the rest of the downstairs (i.e. back living room where we would also want to extend out towards the back garden) is flooboards with space under.

We have currently got a conventional boiler in kitchen with hot water cylinder in upstairs bedroom. Cold water tank in loft. Possibly as part of the extension costs we would upgrade the boiler to a combi.

The incoming water main is in the kitchen, kind of set into the side external wall which is shared with the crappy lean-to! It goes straight up into the bathroom to the sink. (The bathroom is directly above our kitchen.)

As far as your question about flooring goes: Well, that's just it really. We would have liked to have some nice flooring in the bathroom when it's done, possibly tiles (which we currently have), but really don't know much about flooring (I grew up in a house with parents obsessed by the "luxury" of having a carpeted bathroom. ) - all I know is that once tiles are down they are down!

And finally, wow, thanks! Didn't expect anyone to ask questions as indepth as you two have done, it's much appreciated! This is going to be a bit of a steep learning curve for me, I can tell!

Just plan the two out together, and make sure that when they do the plumbing for the bathroom they leave reservations as needed for the kitchen - should be easy enough to do.

"The kitchen floor is concrete"
then it will be easiest to run the pipes down the wall from above. Perhaps you can do it in a corner, or conceal with a cupboard, or at teh side of a shower cubicle. Remember to insulate them well

"hot water cylinder in upstairs bedroom"
The cylinder can be located anywhere, higher or lower than the boiler. You might consider putting it in an airing cupboard in the new bathroom. They are typically 100 to 120 litres, which is a bathfull. They are available tall and thin, or short and fat, like people.

"Possibly as part of the extension costs we would upgrade the boiler to a combi."
A combi can give a good shower, but if you try to run a bath, you will need a book to read while you wait for it to fill. Run the cold kitchen tap into a bucket, time it, work out how many litres per minute your water main delivers. This will be the maximum you can get, from all taps combined, hot and cold, at any one time, if you have a combi. So they are OK for a small household, but disappointing if anyone runs a tap, flushes a WC or turns on a washing machine at the same time, since the water flow in all other outlets will drop. If you are having a lot of work done, and can afford a big combi, you can dig out a trench and lay a new, plastic, incoming water main out to the street, in a larger size, which will give you better flow. A cold water tank and cylinder may seem old-fashioned, but can delivere water (using 22mm pipes and big British taps) at a far higher rate (but lower pressure, so not so good for showers). It is technically perfectly possible to have a combi which also heats a cylinder, so you can have a high-pressure shower from the mains, and a high-volume bath from the tank, at the same time, but this is seldom done as it is more work for the plumber.

"The incoming water main is in the kitchen"
So that is where the supply must come from, for your tank (if any), combi (if any) and kitchen cold tap. You can also use it to run an electric shower, provided you like a weedy jet of water, which will not be very hot in winter.

A plumber will not charge you to come and talk to you about what you are planning. You will get far better advice from someone who can see where you pipes, soil, wastes, drainage are in real life. Just get a couple of recommendations and ask them for quotes for the work you are thinking of.

Definitely worth planning both out on paper at the same time. Forward thinking costs nothing.

These days you can have a European-style pressurised unvented hot water system, It has system (not combi) boiler to heat up a well insulated sealed cylinder, as well as run the central heating. You don't need the tank in the loft any more but otherwise it should basically be an upgrade of your existing set up. This is what we are proposing to put in as our combi boiler couldn't support two bathrooms. Hopefully we will get fast-filling baths and high pressure showers, both.

You just need to be sure your water supply pipework is sound enough to cope with the higher pressure but sounds like you will be replacing most of it anyway.

"Weedy jet of water". We struggled on for years with a weedy dribble of an electric shower, and when it packed up, our plumber replaced it with a Mira he'd taken out on another job. I could not believe the difference - clearly not all showers are created equal!

Thank you all for your very comprehensive replies!

After thinking about all the advice, and doing a lot of research online, I think we could just go all out and do the whole lot at the same time - extension and bathroom, and just be done with it. Just need to convince DH that we can afford it. And the more cautious part of me!

We have only about 58 grand left to pay on our mortgage with 17 years left, so am sure it would be affordable. It's just biting the bullet and thinking about the 250 quid extra we would have to pay each month. We can certainly afford it now, but then the cautious part of me thinks "Well, if I lost my part-time job we could probably just about cover the extra payment on DH's wages, but there would be no spare money for luxuries like holidays etc and what if I didn't manage to get another job and we would have to scrimp away for the next few years just to pay the basic bills and food shopping? And the interests rates are well low at the moment, what if they shot up" etc etc

How do people get past that way of thinking? There's not much leeway for anything going wrong with our current situation but my mum said yesterday "If everyone thought like that about everything, then no-one would do anything." Is she right? We always said we'd extend this house when we bought it 8 years ago and the time hasn't really been right financially. Now that it IS, it just seems like such a massive thing to do.

From experience, extensions always end up costing a bit more than planned, so I would be very cautious going ahead if you will be totally stretched. That said, I don't regret the money we spent or the extra mortgage payments, the house is fab now and works for us

"Run the cold kitchen tap into a bucket, time it, work out how many litres per minute your water main delivers. This will be the maximum you can get, from all taps combined, hot and cold, at any one time, if you have a combi"

this also applies if you have a Megaflow or other pressurised system. They are very good, but you do need to have a good big watermain coming right into the house from the street and all the way up to the vessel, to give you plenty of flow with good pressure.