I'm not certain if you mean a model of an Indian longhouse or an *actual* longhouse, but I'm in the process of building a model right now and I am 90% complete - I got the plans from the internet.
I believe you could build an actual longhouse from these plans as well, but with a modification or two. I am also making changes to my model. I have cut the lower cross-poles short because otherwise they are shown sticking across the aisles, and in the full-size models I've seen in the NYS museum, the lower cross-poles do not interfere in the aisle, or else you'd bang your shins on them.
These plans are also light on detail for the rounded end (giving floor plan but not rafter plans) but I am going to make my own ends in the same style as the rest of the longhouse.
See related links below for website
the kootenai indians sheltered in sweat lodges,tipis and longhouses
They made houses such as longhouses, houses that were long enough for more than one family in the Iriquois tribe.
woodland indians lived in longhouses and olmecs in tepees
longhousesthey lived in longhouses they made it out of young trees and bark
Pretty much the same as everyone else.