Loft Insulation and Preventing Condensation Problems

[Lesley14]

we are wanting to insulate our loft as occasional room/storage we have had the floor strengthened ladder and hatch and window professionally put in but wanted to economise by doing the insulation on rafters ourselves. we think we have unbreathable roof felt so left a breathing space then covered over rafters with foil and then 50mm thick poly boards we obviously got this drastically wrong as within weeks water was coming through poly and when we removed a board water was pouring down foil behind so have had to rip everything out. how can we insulate the loft just to keep dry and warm we are not too bothered cosmetically just want to be able to use and keep reasonable warm and dry without any condensation problem. can anyone help with advise please? don't understand what we did wrong or what to do. Lesley

[welsh brickie]

you will need to ventilate the soffit boards with vents and also install ventilated ridge tiles to have a constant airflow through the roof

[Lesley14]

Thank you for your answer.