buildings_data<-readOGR("buildings.shp")
buildings<- spTransform(buildings_data, CRS("+proj=utm +zone=45 +a=6377299.151
                                        +b=6356098.145120132
                                        +towgs84=295,736,257,0,0,0,0 +units=m +no_defs "))

There were 19 warnings (use warnings() to see them)

In Polygon(coords = crds) : less than 4 coordinates in polygon