How much would you pay for insulation?

I have been quoted €10,000 incl. VAT to insulate 54 sq.mts of a flat roof with Rockwool! Supplier proposes to strip the old felt and chipboard, install new joists, install 150mm rock wool, sheet the joists with 18mm water proof plywood, put an underlay and finish with a felt top. He will also replace old fascia and soffit, gutters (26x17 ft) and a downpipe. Personally, this sounds like a lot of money for Rockwool. I don't even think it meets building regulation standards. Has anyone put rockwool insulation in their flat roof? Does the house feel warmer and are you happy with it? Would appreciate your comments, suggestions and recommendations on what is the best insulation and method for flat roofs, and what I should expect to pay for 54 sq mts.
of insulation. Many thanks ....

what was your spec?
and how many quotes did you get?

lowCO2design - I'm not sure I understand your question about specs. I wanted a "warm" as opposed to a "cold flat roof, i.e. insulation above joists and not in-between joists, insulation boards (Kingspan) and not rockwool for a surface area of 54 sqmt. I am just puzzled by the differences in the quotes, 10,000, 2900, 7,500 and 4,000. They all seem "qualified", SEAI approved installers (if that means anything), FAS and Guild's certified. The only exception is the builder who quoted me 10,000. He was recommended by a friend. I know he is good at building but he subcontracts roof work to someone else and I don't know what qualifications he has. I am just surprised that he would install rockwool for that price!

polarbear said:

lowCO2design - I'm not sure I understand your question about specs. I wanted a "warm" as opposed to a "cold flat roof, i.e. insulation above joists and not in-between joists, insulation boards (Kingspan) and not rockwool for a surface area of 54 sqmt. I am just puzzled by the differences in the quotes, 10,000, 2900, 7,500 and 4,000. They all seem "qualified", SEAI approved installers (if that means anything), FAS and Guild's certified. The only exception is the builder who quoted me 10,000. He was recommended by a friend. I know he is good at building but he subcontracts roof work to someone else and I don't know what qualifications he has. I am just surprised that he would install rockwool for that price!

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'puzzled' - are you for real??? you will get different quotes and will find it impossible to compare unless you provide the builders with clear instruction ie a 'specification'

Sika-Trocal roof system on 200mm kingpsan on 18mm marine ply on joists sized to Engineers spec, Vapour barrier/air-tightness membrane fully taped & sealed plaster board & skim painted. uPVC gutters, fascia & soffit

this is only the briefest of spec's - this would normally be a page or more

dont get me started on 'qualified' none of them are 'qualified' to provide a specification - thats YOUR job

your talk of rockwool & kingspan scream a seroius lack of knowledge, may i suggest you involve a QS or Arch tech - a few hours of their time to spec and review quotes could save you time, stress and money