Mandatory insulation upgrade of existing top storey ceilings
After 31st December 2015, ceilings of heated rooms to unheated attics (top storey ceilings) must be insulated in such a way that the heat transmission coefficient of the top storey ceiling does not exceed 0.24 W/m²K (§ 10 EnEV: “Retrofitting systems and buildings”). This does not apply if the roof above the top story ceiling is appropriately insulated instead of the ceiling or if the ceiling already complies with the minimum heat insulation according to DIN 4108-2: 2013-02.
A reference to Annex 3 means that the obligation is also fulfilled if the insulation is installed in spaces within the ceiling (e. g. between the beams) and the available space is filled with insulation material with a thermal conductivity not exceeding 0,035 W/m*K. If blow-in insulation is applied or renewable insulation material is used, the maximum thermal conductivity is set at 0,045 W/m*K.
There are exceptions to the retrofitting obligation for owners in owner-occupied single- or two-family homes where at least one apartment was used by the owner on 1st February 2002 (date of the first EnEV). In this case, the requirements apply after a change of ownership with a deadline of two years, or in case of measures concerning the ceiling or the roof.
The requirements of § 10 EnEV are covered by a special provision for exonerations in § 10 section 5, which does not foresee the involvement of authorities.