"It is a house."
Interesting you say that. Not sure if you are correct. I have seen a couple of restaurants with the word uchi in it, implying the house of or home of the sushi etc. I did watch a girl in a show refer to her house as watashi no ie. That was the first time i ever heard the word ie so thats why i remember it!
the concept of うち is not the same as "house"
read more about it here:
で is the particle. It could possibly even be argued that there are, in a sense, two particles, に and て, by those who would refer to both of those as "particles", given that this で is a contracted form of に + て.
I often think it strange how other people assuming "です" to be a single word not made up of separate parts don't then question why the subject complement would appear to have no particle marking it. I'm glad to see someone wondering about it. ^^
It is not the particle because です is a copula verb. http://www.japaneseprofessor.com/lessons/beginning/the-copula-desu/#targetText=Forms%20of%20%22be%22%20English%20include,polite%20form%20%E3%81%A7%E3%81%99%20%22desu%22.
But へや means "a room", not a house... And いえ is actually a word for saying "a house".
部屋 (へや) = 部 (section, part, portion) + 屋 (roof, house, shop)
A room is just part (部) of a roofed building (屋).
家 (いえ) = house, home, residence, dwelling, household.
A house is a roof (宀) under which the pigs (豕) live. :P