Cavity wall insulation and solid floor insulation: before or after plastering?

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  • Chiara's Avatar
    Level 1
    I need to have my walls replastered and I also plan on having my cavity walls insulated (with polystyrene beads). Do these jobs need to happen in a particular order, or are they completely independent of each other?
    And what about insulating a solid floor with foamboards? Should it be done before or after replastering the walls? Or is the order irrelevant?
    Thanks in advance!
    Last edited by Chiara; 11-02-22 at 22:35.
  • 2 Replies

  • ToolTalk1's Avatar
    Level 20
    All the jobs youíve listed are independent Usually the cavity wall insulation is carried out from the exterior- Approved contractors drill holes through the bricks.
    i would organise the work as follows:

    1. Cavity Insulation
    2. Floor Insulation
    3. Plastering
  • ChelseaDave's Avatar
    Level 20
    Iíve always believed that cavity wall insulation is not a particularly good idea! After all the cavity is there for a reason, it is an air space between two walls and is effectively the insulation barrier and allows the building to breath. Think about it, bricks are porous and heat loss from a building is supposed to happen, this is what keeps the outer skin of the building dry and helps prevent the brickwork from crumbling! Iím sure we have all seen a wall that is generally darker and the brick faces have blown, this is because the wall is saturated and the frost has done its damage.
    Last edited by ChelseaDave; 11-03-22 at 07:21.