international lawyer ireland

I am an artist (resident in SPAIN with VAT Number registered as an autonomous company) and I won a competition to build a monument in Dublin. I am hiring a steel company to build the sculpture for me. They are charging me 23% of VAT. Is this correct? I need advice on that. Some companies are charging me 13,5 % and this others 23%.
I need an international lawyer to tell me what is the correct amount of VAT I should pay to the company I am hiring.
Thanks,
Ana