I wouldn't put any grill or smoker " against the house" I've had mine at least 6" away from my wall but you can be sure the safety police ( manual) will say more.
Deck, get a fireproof pad or some pavers. On my 18 I use a large galvanized wash tub to set it in. Haven't found one large enough for the 22.
Tim
Actually, I meant the deck is up against the house. I would have it about 9 Ft away from the side of my house, but on a wood deck with wood railings. It is Cedar and a bit old and dry.
Should I be concerned about and flames perhaps igniting it?