Cost of two story extension

We're thinking of extending our house, adding in a two storey extension - sunroom and utility downstairs with bedroom, ensuite and walk in wardrobe upstairs. So it'd be coming out approx 5m x 4.5m from our house. We also want to put a downstairs loo under the stairs and knock our hall and porch into one.
Has anyone an idea of how much that'd cost in Dublin? Obviously not exact science, but even a ballpark figure would be great - we're wondering would we be better to sell or extend. Thanks...

you should allow about €180 (hopefully less) a sqft to build that,
your extension of 4.5m x 5m=22.5m2 or 242sqft per floor or
484sqft in total and that comes out at 87K, now a load of factors
may change this cost ie roof type and construction, wall construction
etc so let this cost only be considered a very rough guide.

Push that a bit closer to the 100k mark and I'd say you'd be closer to the mark.

there is really only one way to find out. get quotes from builders. Also before you agree anything make sure you get a detailed written quote from the builder, NEVER pay the final amount before you are completly satisfied the work has been carried out as specified. Might be worthwhile getting your architect / draughtsman to oversee the main points of the build. A few euros extra spent would look after your interests.

another thing looking for your builder try [broken link removed] let meknow how you get on

Thanks for that, it's dearer than I thought, but looks like it still might be worth looking into. So we'll try the architect/builders now. I appreciate the advice...