Stroke of genius or idiotic lashup

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After some advice here again.

Project House, Victorian, ground floor lath and plaster ceilings not in brilliant nick (quite flat but many cracks and a few holes where some big footed idiot had the floorboards up upstairs and dropped a hammer or something :) )

Anyway, rather than drop the old ceilings I was going to batten across the joists (with 2 x 1 roofing batten set to plasterboard centres to minimise cutting etc)- means I can retain the superior sound damping from the weight of all that plaster and a certain amount of joist stiffening from the laths (I'm putting 4 x 2 noggins between the joists anyway to stiffen them up a bit, there's a bit of bounce going on).

I also need to get heating (2 x 22mm) and hot and cold water (2 x 15mm) from the back of the house to the front. I wanted to run them under the landing but there are a couple of trimmers that have been hacked to bits already and I'm reluctant to put more notches in them so plan B was between the joists in the bedroom floors- which I didn't really want to do since there's the risk of circulation noise from the heating disturbing those in the bedrooms.

Plan C (which is where I would like your input) is to batten along the joists (well in the same direction as them) with 2 x 2 and I'll have to do some excess board cutting. Thinking here is add the 2 x 2 depth of the battens to the inch of lath and plaster and that's 3 inches clearance under the trimmers in the landing so I can run all the pipework under the landing and reduce any circulation noise problems in the bedrooms.

Is Plan C going to be worth the effort (and cost- 2 x 2 isn't free) or am I worrying about nothing, lagging all the pipework and making sure there's clearance round all the hot pipes will virtually silence them.

If there were any existing water services in the place at all I wouldn't be worrying but its a full clean install so I'd like to do it as well as possible.

Ta
 
From memory, 15mm will take 15 KBTHus with out excessive speed (or noise!) or 4.3 kW, so 22mm would take about 8.4 kW, so do you really need 22mm? Wrap two layers of plastic around anywhere the pipes are laying in slots/clamps. Long straight length of copper contract and expand by a significant amount so they should not be fixed rigidly at both end, i.e. by going into Ts right up against joists. This is the only place where I think plastic pipes could be advantageous.
Your noggins will only have a tiny effect on the bounce, certainly not worth the effort. What I don't get is that you are going to "underdraw" the ceiling to get your pipes in, I presume this is in the hall, so what about where your new lower ceiling bumps into the stair well? Are you going to cover the new skimming /old wall plaster with new coving?
Frank
 
Plan D would be to check whether the old Victorian floor joist would be capable of supporting the extra weight of plasterboard.
Deflection and bounce will only increase with the additional load and - as Franky - the 4x2s will add little to nothing to overall stiffness.
 
Thanks both and good point about the weight of plasterboard, 12.5mm isn't particularly easy to fling about. The existing joists are 8 x 3 in pretty good nick (no sign of worm or rot, ends all solid) except where 3 generations of electricians have notched and drilled in a fairly random fashion.

There's no coving in the place at all so my underdraw plan would extend from the hallway into the kitchen. I started doing the sums on 15mm vs 22mm as well- that leg will be driving 4 rads for definite,possibly 5 (depends if I hit snags on the other side of the house) total load of about 4kw (or 5.3 if the 5th goes on) so I'm erring towards 22mm for the main run from front to rear and then 15 to the rads. Good tip about leaving some expansion movement on that long run and elsewhere. I'm having to use copper- main heat source is solid fuel burner- though if I can solve the problem of where to put a heat store I should be able to relax that one.

Final one (with the noggins)- I'm surprised. Put new ceiling joists up in the 2 front bedrooms (6 x 2 on 3m span- there's 2 big trusses running across the house)- they were OK without noggins but became much stiffer with them.

Bottom line- you've talked me out of the 2 x 2 sketch so thanks for that.

Second edit- 'double layer of plastic round pipes in slots'- what sort of plastic? The grey lagging or something else? I'm going to be on thin ice for notching anyway- 8" joist = 1" max notch so not really room for lagged 15mm
 
Don't be too restricted to 1" notching - you can notch a little deeper if it is fairly near the end of the joist - say within a couple of feet or so.
 
Cheers both- yes notches can go in the approved areas (0.07-0.25 span) so may slip with the chisel :). Though lagging in hessian and/or thick polythene in the notches (and not clipping) should let me get away with the inch. All moving on now, many thanks all :)
 

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