The Director of Public Prosecutions (DPP) has decided not to lay criminal charges against contractors accused of incorrectly installing ceiling insulation in Canberra homes.

Between November last year and January this year, insulation batts were installed in the Macarthur, Fadden and Lyneham homes under the Federal Government's failed home insulation scheme.

Soon after, fire damaged the homes - in one instance, a blaze broke out on the same day.

During a coronial inquiry, a statement tendered to the court said each fire started as a result of incorrect installation.

It said batts were placed directly over down lights, leading to a build up of heat in the roof space.

No covers were used in the Lyneham or Fadden installations, and a cardboard guard was used in the Macarthur home.

Coroner Grant Lalor said in each of the cases there had been serious non compliance with Government safety advice.

He described one of the jobs as hurried and unprofessional.

In March the coroner referred the matter to the DPP saying he believed there may be enough evidence to charge the three installers.

Now the DPP has decided that no criminal charges will be laid on the material currently available.

It is expected the coroner will now complete his inquiry.