Does my insurance extend to extensions?

My house insurance is currently up for renewal and I am trying to figure out the cost to rebuild. It is a Dublin semi-detached four-bed. The width of the house is 7.4 metres and the length is 13.80 metres (13.80 x 7.40 = 102.12m2). I have no idea what to do with this figure.

Presently the building is insured for €250,000 and I think it may be under insured. There is a small extension utility room at the back which I have included in the total length of the house (length: 275cm). I am not sure if I am correct in including it. I hope you may be able to shed some light on the subject.

A Firstly, the rebuilding value is the estimated cost of rebuilding the house in the event of a total loss situation such as a fire or similar event. The sum includes the structure and finishes: foundations, floor slab, external and internal walls, upper floors, roof, windows and doors (internal and external), plaster and paint to walls and ceilings, floor finishes, plumbing and electrics, sanitary ware, standard kitchen fittings, drainage connections and reinstatement works externally.

Rebuilding costs are based on the floor area of your property. This includes everything within the external wall of the property. Therefore, as long as the extension is a building onto the main house, the area should be included in the floor area of the property.

We don't do house insurance but we can recommend someone who does.

Source: Does my insurance extend to extensions?