A time slot has opened (August/September) to rip out the existing Victorian flooring and move to the 21st. century.
Various aspects have been covered in earlier threads but uncertainties remain:-)
Can this sort of work be covered by a simple building notice or does it require BR consent?
Where necessary excavation depth to install hardcore, concrete sub base, insulation, flooring screed and engineered timber floor might endanger existing wall foundations are concessions available? There are unlikely to be putrescible materials under a floor constructed around 1900 so could the hardcore be reduced?
ISTR TNP mentioning securing plastic piping to steel reinforcing mesh. What size?
Is *R* value the reciprocal of *U* value and do I really need 100mm of Celotex?
Does anyone want some pitch pine flooring blocks carefully indented with stiletto heel marks from my 21st. birthday party?
BCO approved 50mm and a 50mm screed ( with added fibres) for our office refurb. I just pushed plastic clips into the celotex for the polypipe, depth wasn't a problem as the pre existing concrete floor was still well below the original 1860 suspended floor level.
Hmm.. I'm restricted in needing to match finished levels to other later construction. There is a 4" step between two of the three rooms and I wonder if they have also stepped the foundations.
How do you organise spiral pipe layouts or is it a grid? I have used the plastic *egg shell* sheets supplied by Polypipe and think they are worth avoiding.
Yes.
OK but is corroded aluminium a hugely bad thing?
Yes.
The middle room has a suspended floor so I can look under there. The original construction is mixed; mostly 4" pine studwork on dwarf walls, gable wall 9" red brick but there are later bits of 9" brick infill.
Don't see why you can't do it on a Building Notice - you can do most things. It's best to go and have a word with your local friendly BCO before you get very far. That way, you'll find out what issues they're likely to be interested in.
Discuss with your BCO.
The plumber who in stalled our UFH used some strips with slots to hook the pipes into - like this:
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Is *R* value the reciprocal of *U* value and do I really need 100mm of > Celotex?
It's very desirable to use 100mm - especially if you use engineered wood flooring above the screed. Anything which conducts heat less well than screed and ceramic tiles will mean that the water will have to be warmer than otherwise in order to get sufficient heat into the room - thus increasing the heat loss *downwards* into the ground.
Look all the pipe retainers do is to hold the pipe steady so you can pressurise the loops and lay the screed without them shifting. My floors were large enough to make rebar mesh advisable so I tie wrapped to that. It was very cheap!
If you dont need rebar almost anything will work.
The proprietary systems make the work go fast for commercial layers of screed, but in a DIY context yuu could make staples out of bits of coat hanger and use that just as well.
One thing is worth saying - I went for 4" spacing. It works, but its very slow to get the room warm. Where I have pipes at 2" or less spacing in corridors its far greater heating effect.
So don't skimp on pipe.
IIRC its about 100W/sq meter at 4" 150W at 3" and 200W/sq m at 2" spacing. with sane water temperatures.
Since you probably have a separate circulation pump, feed that from a separate master stat for the UFH, and if that's not a smart stat, time the UFH several hours ahead of the main CH.
What constitutes a floor large enough for rebar? Mine are roughly
4.5x5m. Will rebar help with using the minimum screed thickness?
In the bit we did last year, I opted for 8" spacing. We are never going to run from ground source or attempt to change the room temperature very quickly. Burying pipe joints seemed worth avoiding.
Can you buy pipe in more than 100m continuous lengths? The layout is open plan-ish with a log burner in the middle. I had thought to use 3 circuits with individual thermostats.
Hall, bedrooms and kitchen will remain on wall hung radiators so should respond fairly quickly. There is a separate circulator.
Am I going to have problems running a temperature control valve and the under floor circuit in parallel with the remaining conventional radiators?
you know I'd do rebar. Mine were 6x5.5 meters mostly
It certainly does no harm and its not very expensive from memory
No and you shouldn't use runs longer than that. I have about 8 loops off the manifold - two per room in the big rooms.
you need a relay to isolate the UFH pump from operating whenever the main CH pump is..unless you have double pole motorised valves,...
essentially the timer/stat drives the motorised valve for the UFH zone, and the motorised valve drives the UFH pump and a relay. The relay contacts are in parallel with all the other motorised valve switches to start the boiler in a wired OR sort of way.
You don't need to! Just wire the UFH pump in parallel with the zone valve - with both being directly switched by the stat. That's how mine works - you don't need any relays.
That may work but I was recommended not to as the stat and timer were not rated to handle pump inductive loads, and it is rather bad practice to run the pump with the valve potentially faulty and staying closed
Although less so in a circulation mode where there should always be some sort of 'loop'
If you are putting down celotex (or similar), you can simply clip pipes to insulation. System I used had little plastic bards .. which pushed into insulation and pipes clipped into bars.
Vital - repeat Vital ... you need at least 75mm cover of screed, and it needs to be fibre reinforced screed ... order it as such, or order fibrin to add if mixing yourself.
Also fit 25-30mm thick insulation vertically at all perimeter .. gives an expansion point, plus stops heat leakage at edge.
I wrote a large piece on UFH for SelfBuld FAQ .. PM me if you want any details.
I would never build another house without UFH .... it really is very good.
Make sure you do your homework about coverings ... (again in FAQ) you need to spec the right materials to make sure you don't end up blocking heat transfer.
German research in particular focused on pentane migrating out over time. To some that meant if the end performance of PIR foam is no better than extruded polystyrene at 25 years in the future, then the price premium is not justified. The reality was that a) sheets are foil faced front and rear and b) whilst the edges are not foil faced they are usually tight fitting or even foil taped at least on one side.
It is not as severe as DG economics, where argon filling has a benefit of finite life (leaks out), where frames have a lifespan over under
12yrs in the UK (*), and where economic (and carbon) payback is simply never achieved.
(*) That is I think the figure, but it includes early DG systems which lacked stainless steel, lack of steel supports, poor quality installs, colour change re brown, white, dark brown, white (4 changes in 15yrs to neighbours, still on the original wood here, what is 4 changes to an entire house from 1995-2012 in cost?).
Aside, I would be wary of putting staples that might corrode in concrete with less than 50mm concrete cover. Although it might help find leaks in the future (!) where unprotected steel staple corrosion coincides with the leak. I am sure barbed plastic clips are probably the cheapest solution in terms of quantity required - the custom moulded insulation is a bit pricey though? Going for as much insulation as you can with underfloor heating is obvious - no point in paying to heat the underlying structure, which if saturated clay is going to rob heat blind compared to nice free draining clay. Underfloor wet heating is the best heating bar none compared to wall radiators, storage heaters, heat pumps etc. A long term cost saving on rusty radiators, lost wall space, pipework, and if you insulate the upstairs I suspect nothing much needed upstairs (save for bathroom perhaps).
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