What Are Pre-Approved (Ready-Made) Home Plans?
You will see several terms used almost interchangeably — "pre-approved plans," "pre-designed plans," "ready-made plans," "stock plans." They overlap, but they do not all mean the same thing, and the differences matter before you buy. Here is a plain-language guide.
The core idea: design once, offer many times
Most architecture is drawn from scratch for one client on one lot. A ready-made plan set turns that around: a design is drawn, refined, and then offered as a finished package that many homeowners can purchase. Because the creative design work is already complete, a plan set can usually be sold for a clear, set price rather than a custom design fee. That is the whole appeal — a resolved design and a known cost, instead of a blank page and an open-ended one.
"Ready-made" and "pre-designed" — the design is done
When people say ready-made or pre-designed plans, they generally mean exactly that: the drawings describing the building already exist and you are buying them. This is the layer that shows the layout, the elevations, and how the building goes together. What it does not automatically include is everything your particular property and jurisdiction require — which brings us to the important distinction.
"Pre-approved" is a different claim
"Pre-approved" implies that someone with authority has already approved something. That word is best used carefully. A plan a designer sells is not automatically approved by your city. Separately, some California jurisdictions run their own pre-approved or pre-reviewed plan programs — most often for ADUs — in which a local agency has reviewed certain standard plans in advance. Those programs are real but they are specific to the jurisdiction, and whether one applies to your address and your chosen plan depends entirely on your city or county. If a plan is described to you as "pre-approved," it is fair to ask: pre-approved by whom, for what, and does it apply at my address?
What a plan set typically includes — and doesn't
Contents vary by seller and by category, so treat any general description as exactly that. In broad terms a plan set gives you the design of the building. Items that depend on your actual lot are usually handled separately: a foundation designed for your soil and slope, utility connections, structural and energy details to current code, and anything your jurisdiction specifically asks for. The share of a project that a plan set covers therefore varies — sometimes most of the design, sometimes just the starting point.
Where ready-made plans tend to fit
Ready-made plans fit best when your project is a common type on a relatively regular lot, when you like one of the available designs closely, and when you are comfortable adding the site-specific work your jurisdiction requires. They fit least well on steep, irregular, or heavily constrained lots, or when your requirements are particular — situations where a custom design usually earns its cost. We compare the two routes directly in stock plans versus custom design.
A plan set is the design layer of a project — a strong start, not a substitute for checking your own lot and rules.
Kevin Cohen Design is preparing a collection of ready-made plan sets for ADUs, additions, and standard-lot homes. You can read how it will work and join the early-access list on the plans page, and see our full design-build services for projects that call for a custom approach.
General information only, not legal, engineering or code advice. Rules differ by city and change over time, so confirm the details for your property with your local building and planning departments and with qualified professionals.