I agree, I cannot see how it would be less than 400 either. I get 468 sq ft. Only other possibility if if they count only floor space which would mean you would need to measure each part or room individually.
Only reason I ask is over 400 square ft. they are to be built to certain specifications and I can't get anyone to give me a straight answer. If they measure just the inside rooms it would be the only measured that way. I've tried to ask the manufactures and none will answer. Over 400 ft. they should be built to HUD standards. Thank you for the anwer.
My guess is that it would be more expensive to build to HUD standards, therefore they are going to measure the Park Models so that they fall below 400sq ft. Sounds reasonable to me. I know that in most RV Parks that sell/rent lots for Park models, if you want added rooms (utility/enclosed porch/office) they hire carpenters to add the rooms after you purchase the smaller Park model from them.