• Thanks - really helpful. I'm asking for more details of what is needed but think they were suggesting insulation under the concrete (which I have googled and is apparently a thing); maybe that is what makes it more expensive but not sure how much benefit it gives? Anyway I should probably stop spamming this thread as this isn't plant-based enough....

  • Presuming a void between the base and the building it sounds a little snake oil to me, find out what insulation they specify, it's normally inexpensive.

  • I think part of the point is to get around the void above the concrete as for a garden office, height is an issue - I think it will be a solid insulation layer under the concrete. But I am just repeating what I recall / have found on Google, until I speak to them later on.

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