Very cold house- can anyone identify problem?

rev229

we have lived in this house from new now 7 yrs and like all our neighbours we have had cold spots in vary places due to the builders not doing the job properly in the first place. We have found gaps under window sills and by the front and back doors. One neighbour had no insulation at all in one room!! As for our study, the draught is just below the radiator and despite having new flooring and the area being sealed my feet get very cold!!