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Solutions for heating/insulation with solid concrete floors in multi-period solid wall cottage

AliW68
edited April 2015 in General
Hi
We have a multi-period cottage - one section timber framed brick and flint 17th century; one section Victorian solid brick; another section 1960s solid brick to walll base with timber cladding externally and brick internally thereafter.
The floors throughout are solid concrete, uninsulated, and probably date to the mid-1960s extension.
We want to do the right thing with the building and insulate with breathable materials, install double or triple glaziong and MVHR etc etc.
We were keen on the idea of taking up the concrete floors (only digging down to 45 degrees from the external walls) and installing Limecrete with UFH, however the architect and an eco building retrofit specialist, among others, have firmly advised against this because of the cost and potential for subsidence in the oldest part, which is unlikely to have any foundations of note.
If we follow the advice and keep the solid, uninsulated concrete floors, how best to go about insulating the floor so that moisture isn't driven up into the newly insulated walls; and how best to go about heating the space?
We don't have a great deal of head height in the Victorian part but as this will be the entrance hall it may not be too critical to lose a bit of height here.
We will have lots of insulation, an opportunity for passive solar gain through south facing glazing, and a couple of wood burners, but obviously they can't be set to come on in the morning and would like to have the reassurance of some reliable background heat even if the overall aim is to use as little energy to heat the building as possible.
Is it sensible to go for wet or electric underfloor heating on top of the existing concrete with insulation between? What do we do about the wall-floor join?
Any advice gratefully received.

Comments

  • Mike George
    Sounds like your Architect and Builder know what they are talking about. I think you should take their advice to be honest.. underfloor heating of any type will either mean going against their advice and digging up the floors or putting on insulation and new surface on top of the floor and losing headroom.... The thinnest wet system I have seen utilises Gypsum screed at around 40mm but that's on top of probably around 120mm insulation to comply with regs..
  • Peter_in_Hungary
    I would suspect that any moisture to be driven up the walls will be as a result of the concrete floor rather than what goes on the concrete. However what about engineered wood over 5cm of EPS (or more if you have the height) as a loose layed floor with matching battens at the wall/floor join. EPS is a bit breathable - not sure about the engineered wood. For space heating probably standard rads. are the easiest - if you don't mind looking at them!
  • CWatters
    If the concrete isn't breathable does it matter what goes on top? Are there any damp issues in the walls or floor anywhere? That has to be sorted as part of any solution.

    Is it sensible to go for wet or electric underfloor heating on top of the existing concrete with insulation between?

    Direct Electric heating of any kind is expensive to run compared to other fuels. Comparison site here..

    See the column "pence per KWH (after boiler efficiency)"...

    http://www.nottenergy.com/energy_cost_comparison/
  • SteamyTeaSteamyTea
    Posted By: CWattersDirect Electric heating of any kind is expensive to run compared to other fuels
    The installation costs are low though and it is very controllable.

    This is from another thread:
    Posted By: SteamyTea
    Posted By: MikelMy question is this: Any idea how good re-carpeting with a good insulating underlay would be for the existing solid floors?
    How about this:
    http://www.thermablok.co.uk/wp/wp-content/uploads/2013/05/InstallGuideThermablokSPAerogelMagnesiumInsulationFloorBoard.pdf
  • renewablejohn
    How is direct electric expensive to run if your using PV surely the cost is whatever the alternative export rate is.
  • CWatters
    edited April 2015
    The OP doesn't mention PV but yes it would reduce the cost. Still better to use a heat pump though.
  • gravelld
    The trouble is the PV isn't as performant when you need the heat.

    Better to reduce heat demand as much as possible and use those solid walls and the solar gain as a passive solar contribution to the heating demand?
  • renewablejohn
    edited April 2015
    Posted By: gravelldThe trouble is the PV isn't as performant when you need the heat.

    Better to reduce heat demand as much as possible and use those solid walls and the solar gain as a passive solar contribution to the heating demand?
    Was looking to use the PV for the UFH as a heat sink with 2 ft thick walls once the heat is in it does take a long while to cool down.
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