The Architect's Blog

Are there Square Footage Thresholds To Consider With a Room Addition?

There are so many things to consider when you’re thinking of adding onto your home; budget, design, budget, space requirements & budget, to name a few. Since budget ends up being the driving force behind most projects, it is important to find out ways to maximize value. When doing an addition, most clients understand that there are costs that vary based upon scope, but are difficult to eliminate altogether. Things like design, permits, and construction costs are difficult or almost impossible to avoid. There are however, other costs that can be minimized or avoided altogether. For example, the county assessor can increase your property tax when you add value to your home, but they are not particularly interested if you are “redecorating”. This distinction creates long term savings by merely limiting the scope of a project. If additional space is critical, there is a threshold that can impact the cost of your addition. This threshold is 500 s.f.

Local municipalities assume that a residential addition in excess of 500 s.f. translates into an additional member of a family – which translates into an additional load on the local school system. Keeping the addition under 500 s.f. avoids these fees and sometimes more. One simple way to shave up to a few thousand dollars off a small addition and avoid paying school fees is to keep your addition under 500 square feet (about the size of a master bedroom suite including: a master bedroom, master bath and walk-in closet, or a decent sized family room).

While the 500 s.f. threshold seems to be universal for most municipalities, some cities use exceeding 500 s.f. as a trigger for additional requirements. For example, the city of Long Beach currently charges $3.20 (going to $3.40 soon) per square foot for a 500 s.f. addition or $1,600 – but nothing for a 499 s.f. addition. Meanwhile, the city of Los Alamitos, charges school fees, but views an addition of greater than 500 s.f. as a significant enough expansion to also require a soils report. This soils report could add a couple thousand dollars to an addition.

Since every city has it’s own rules, it is important to ask specific questions if you are planning on exceeding 500 s.f. for your addition. While many of our projects exceed the 500 s.f. threshold, this is just one example of the kind of “out of the box” thinking we employ to give our clients the best possible value for their addition or remodel.


  1. Angelica says:

    We’re thinking about doing an add on & wondered about an increase of property taxes. I will look into our town to see if its the same 500 sq ft.

    Thank you for this information!

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