Architectural Designs

On house plans, are the footage figures from wall to wall supposed to be the accurate room sizes?

We had a home built and the rooms are not the sizes on the floor plans as we expected. The builder says these are not the room sizes, and it is normal to have inches (as much as 6 inches) missing from each room. Is he right?

Public Comments

1. Only the sizes in metres or some fraction thereof have to be accurate (generally ±5mm. or ±10mm., but it will give the actual tolerance on the drawing). Conversions to other units are *never* guaranteed.
2. It depends who drew the plans and for what purpose. The house builder wants to know where the center of the walls are when settting out the foundations etc, so the builder's plan will usually show that. The thickness of internal non-load-bearing walls doesn't matter at that stage, and it might not even be known because it depends if you decided to have extra thermal insulaton, soundproofing, thick wood panelling, etc. On the other hand if you were buying a house finished and ready to move in, the sales information would probably give the internal dimensions of the rooms because that is what you are interested in for carpets,. furniture, etc. Don't be too surprised if you find the rooms are not perfectly rectangular and the walls are not perfectly vertical. (A common time to discover that is when you decide to tile the walls or the floor). House building isn't precision engineering. Of course if you paid somebody to design your particular house (i.e. it wasn't a building company's "standard" design) and they didn't understand your requirements correctly, that's a different problem - you left it rather late to get the house fixed, but you might get some cash compensation.