Water Underfloor Heating Install / Options Advice - 1908 house

Discussion in 'Builders' Talk' started by TGull, Jan 12, 2018.

  1. TGull

    TGull Member

    Afternoon all,

    Just wondering if you could help with any or all of the questions below. All thoughts welcome, and would love to hear your personal experiences.

    Current situation in a nutshell:

    • My Background - I'm I DIYer looking to do a fair bit myself, hopefully with a hand at end of job with technical side (electrics, connections of manifolds etc, I will just lay down insulation / pipes and leave the setting up / testing / final install of system to professional).
    • House Background - 1908 house with radiators and pipes getting to end of days (boiler still doing quite good). Looking for new heating system. So far, underfloor heating may be less expensive than buying new radiators + putting in more radiators, as current ones are small and pretty sparse.

      Currently all heating pipes run under the original wooden floor but none of them are insulated. Under the ground floor there is a 1 foot void. We live on top of a hill, so the winds really whirl around down there. Great for open fires, not so good for heat loss / insulation.

      Ceiling heights are ~2.9m high.
    • Underfloor Heating Cost (water based) - Roughly 92square meters downstairs that needs doing. Estimate parts (without insulation cost) being around £2500. This includes 7 circuits and 5 zones and all gear needed to set up.
    • Installation Method - Currently I'm thinking of keeping the original pine floor boards, pulling them up and installing the pipes in between the joists. I may use 50mm of insulation, and then an aluminium plate to hold the pipe itself. Or I may use this 50mm insulation that has the pipework 'network' already in it.

      This installation will be sealed to stop drafts getting through. Wooden floor will then go back down as per usual and sanded for finish.

      This will hopefully stop the drafts, add insulation and allow the void below to breath still. In addition to this, we will hopefully have a much larger area for our heatsource, rather than our current small radiator system.

    • Given that I'm very much exposed to the wind, I'm worried about the amount of insulation to put under the joists. Do you think 50mm would be enough. Or would you go for the full 100mm more if possible? This as you can imagine could be quite costly. With 150mm Celotex that could be ~£2300 on its own.
    • From experience, would old pine planks over top be ok working with underfloor system? We could start we new materials, but like the idea of keeping as much original as possible. This also greatly reduces overall project cost only investing in the system + insulation, without worrying too much about floor except sanding + stain.
    • ‎Prowarm vs Polypipe - has anyone seen the difference in product quality, as Polypipe tends to be more expensive.
    • Energy savings - I have the issue with insulation + heating, so I would like to think there would be some savings just from the insulation alone. But just wondering if anyone has seen any benefits from this side?
    • Any other thoughts people might have or contributions I may have not thought about?

    Any thoughts welcome.


  2. leesparkykent

    leesparkykent Well-Known Member

    Most I've seen done use 150mm insulation.
  3. TGull

    TGull Member

    Ok interesting to hear. I'm half tempted to push the boat out when it comes to insulation. It must get close to 0c down there, so I guess anything that cold should be insulated!
  4. leesparkykent

    leesparkykent Well-Known Member

    Probably best to contact someone like Uheat. If 150mm was required then that would be at least a couple of grand on insulation. https://www.uheat.co.uk/quotation-request/
  5. TGull

    TGull Member

    Yes this is one of my worries as the insulation could be the most expensive part of it all.

    But it could also be the most essential part of it.

    Crazy how expensive it is really.
    leesparkykent likes this.
  6. leesparkykent

    leesparkykent Well-Known Member

    Yeah you don't want to scrimp on the insulation for sure.
  7. TGull

    TGull Member

    What insulation would you recommend just out of interest? Celotex / Kingspan / ecotherm?
  8. leesparkykent

    leesparkykent Well-Known Member

    Whatever's the cheapest :D
  9. TGull

    TGull Member

    I think I might need to start 'selling my body' at this rate.

    Anyone got any tips on buying 150 / 100mm joist insulation in bulk e.g. 92 square meters worth?
    leesparkykent likes this.
  10. TGull

    TGull Member

  11. leesparkykent

    leesparkykent Well-Known Member

    When I done a newbuild, I went up to a timber frame manufacturer near me and collected all their off cuts. It didn't look the prettiest before it was boarded but didn't cost me a penny. I estimate it saved me about 8K
  12. TGull

    TGull Member

    £8k isn't a bad sum of money for anyone!
    leesparkykent likes this.

Share This Page