Insulation Question

Discussion in 'Building' started by peweuk, 5 Jan 2021.

  1. peweuk

    peweuk

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    At the back of our garage we have a large area which is not really used apart from storing junk.
    I thought of clearing it out, then partitioning of the area to use as an office/work space - which would not be used constantly, maybe just for a few hours every few days.

    The walls are block/render and I thought of insulation them with Recticel GP (or equivalent) and plaster boarding over.

    The floor is concrete and I was thinking, as a background form of heating, of laying some electric underfloor heating, which would require an insulation mat below.

    So, my questions:
    - with the walls, I was looking at 70mm insulation board. Would it be best to I leave an air gap between the insulation/blockwork or insulation/plasterboard or not bother
    - with the floor, which would be the better thermal barrier, the XPS 6mm insulation sold with under floor heating kits, or 25mm of Recticel, or both.

    Thanks
     
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  3. Harry Bloomfield

    Harry Bloomfield

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    Underfloor heating has a long lag from on to the place being warm, not a problem if the place is often in use, but you are suggesting just a few hours, every few days. Some more direct heating system might be more sensible.
     
  4. peweuk

    peweuk

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    Thanks for the input.
    I take your point, and for short visits we would use a fan heater of some sort, for longer visits we would start the heating off with the fan heater and have the electric u/f on to maintain a comfort level.

    What about the question re insulation - anyone?
     
  5. ^woody^

    ^woody^

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    No air gap for wall insulation.

    For the floor, the thickest amount of the best type (most efficient) is to be aimed for. Silver or foil faced insulation is always best for underfloor heating.

    What about roof insulation?

    Is the heating mat of a suitable output to keep the room warm? It will need to be on a timer to warm the place up well before the room is used, and preferably on a wall thermostat too. But consider if it will be worth the effort, expense and running cost for just a few hours use per day.
    If you have wet CH, can't a radiator be piped in? Or a slim wall mount electric oil or convector.
     
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  7. peweuk

    peweuk

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    Thanks.
    So Recticel for the floor is the way forward. As thick as I make it practically.
    I plan to use Recticel between the roof trusses (which are re-inforced for floored storage), with plasterboard under.
    The heating mat will cover the entire 10sq metres of floor and comes with a wall mounted timer/thermostat.
    It would not be practicable to extend the house wet system to the garage.
    The only issue with using a wall mounted heater is the localisation of the heat source, whereas u/f spreads the heat, and if additional heat is required we could add a mobile heater for backup.

    Thanks again for the input - you've confirmed my thoughts regarding the insulation.
     
  8. ^woody^

    ^woody^

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    When a room is well wrapped with insulation, especially foil insulation, you tend to find that the whole room stays at an even warmth and a localised heat emitter is not an issue.
     
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  9. IT Minion

    IT Minion

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    There usually is a lag on UFH because of the thermal mass of the screed it's laid in. With one that's presumably just going under some laminate would it be that bad?

    An additional heater to warm things up faster would make sense for an office.
     
  10. peweuk

    peweuk

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    I accept that, and the area would be well insulated.

    We have the same underfloor heating laid under laminate in the conservatory, and that floor heats up well enough within half an hour or so.
     
  11. DIYnot Local

    DIYnot Local

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