Over one of the doors is this saying:
Níl aon tinteán mar do thinteán féin
This is an Irish phrase meaning, "There's no place like home". Literally it translates to "There's no hearth like your own hearth". Sounds like it could be a nice house blessing!
Another blessing I found is the following; I wanted something that I could write on the subfloors of the houses we're building (everyone was invited to write down well-wishes for the families), but figuring out what to put proved to be a bit of a trick. The families are Christian, and I want to respect that, but I also wanted to be genuine about what I was writing. I think this (allegedly Celtic) blessing gets the best of both:
Bless this house and those within.
Bless our giving and receiving.
Bless our words and conversation.
Bless our hands and recreation.
Bless our sowing and our growing.
Bless our coming and our going.
Bless all who enter and depart.
Bless this house, your peace impart.