My loft has old insulation bags installed between the rafters. Can't be more than 100mm thick. I see that the general recommendation is for minimum 300mm.

Does anyone have any experience of a cost effective source for insulation? Are their cheaper options than Bau-Hobby/Jumbo. I guess that the soft fibreglass insulation would be far easier to install than the hard foam that seems to be prevalent in new builds. Anything else to consider?

Thanks in advance for sharing any experience

Cheers
Jekyll

Bau Haus or Hornbach are probably a bit cheaper than Obi/Jumbo ect but the problem you will have is choice. There are better products available but only through specialized timber or building supply stores but unless you are have a company account the prices are not cheap. Replacing insulation is physically hard but simple but you need to consider damp/waterproofing barriers here to stop mould growth and how the building will "breathe" without creating draughts. I used Steico flex http://www.steico.com/en/products/wo.../overview.html on this barn Big Thanks and recommendation of EF member for the very reason that it needed to breathe, could be installed without extra damp barriers and was a more natural product. Either way with any insulation it should be covered underneath to stop fibres floating loose and dust collecting creating a health hazzard for the future. I hope this helps.