Los Altos makes the ADU decision easier in one way and trickier in another. The city offers free permit-ready plans in several styles and sizes, designed to move quickly through plan check. For the right property, that is a genuine head start. For the wrong one, choosing it without thinking can buy a faster permit for a building that does not fit the site.
This is worth understanding from either chair. If you are hiring a builder, it frames the first real choice: speed or fit. If you are building it yourself, it is the decision that quietly determines whether the project goes smoothly or hits engineering surprises you did not plan for.
The program changes. Treat the description here as the shape of the choice, and confirm the current permit-ready offerings and process with the city. We weigh the two paths against the actual lot before recommending one.
What permit-ready actually saves
The free pre-approved plans streamline the design and plan-check stage. Because the city has already vetted the building design, that part of the approval moves faster, which saves time and some design cost up front. If one of the standard plans genuinely suits your lot, your sun, and your main house, it is a sensible way to go.
The key word is suits. A permit-ready plan is a fixed building. It does not know your topography, where the sun falls on your yard, or how it will look next to your home's architecture. When those line up with a standard plan, you win. When they do not, you have bought a shortcut to the wrong destination.
What custom buys, and what it costs
A custom ADU is designed to your site and your house. It can follow the grade, catch the right light, match the main residence, and put the rooms where your property actually wants them. The cost is time: a custom design goes through the full plan-check path rather than the expedited one, so approval takes longer.
Neither path is better in the abstract. A flat, simple lot with a standard-style home may be perfectly served by a permit-ready plan. A sloped lot, a tricky drainage situation, or a distinctive house often justifies the custom route. The right answer comes from the property, not from a preference.
The trap inside the word ready
The dangerous assumption is that permit-ready means planning-free. It does not. Even with a pre-approved building, your project still needs site-specific engineering: grading, drainage, utility connections, and a foundation designed for your soil and slope. Those do not come with the free plan. An owner who picks a permit-ready design and skips the site work can hit the same expensive surprises a custom build would have caught, just later and with less room to adapt.
The building can be standard. The ground it sits on never is. Whichever path you choose, the site engineering is real work that has to be done well.
Sorting out which path fits, and handling the site engineering either way, is the part of our process we walk owners through first. You can see both standard and custom work on our portfolio.
If you are weighing an ADU in Los Altos and are not sure whether permit-ready or custom is right for your lot, we are glad to walk the property and help you choose before you commit.