A garage conversion is the least expensive way to add a legal dwelling, because the slab, the walls and the roof already exist. What it needs is everything else: a raised and insulated floor, a vapour barrier, a kitchenette, a full bathroom, a separate entrance, and egress windows that actually open.
The work is less about carpentry than about sequencing — utilities, inspection and fire separation between the unit and the house. Done in the wrong order, the same job costs 30% more.
車庫改建是增加合法居住空間最便宜的方式，因為地坪、牆體與屋頂都已經在了。缺的是其他所有東西：架高隔熱地板、防潮層、簡易廚房、完整浴室、獨立出入口，以及真正能打開的逃生窗。
這種工程的重點不是木工，而是順序 —— 水電、勘驗、以及與主屋之間的防火分隔。順序錯了，同樣的活會貴三成。
What the work usually includes
Raised insulated floor over the existing slab, new framing where needed, insulation and vapour barrier, a kitchenette, a 3/4 or full bathroom, electrical panel capacity for the added load, heating, a separate entry door, egress windows and fire separation from the main house.
工程通常包含
在原有地坪上架高隔熱地板、必要處新增隔間、隔熱與防潮層、簡易廚房、四分之三或完整浴室、足以負擔新增負載的配電容量、暖氣、獨立出入門、逃生窗，以及與主屋的防火分隔。
What drives the cost
Whether the electrical panel can take the extra load or has to be upgraded, how far the new drain has to run to reach the sewer, and whether the garage shares a wall with the house (fire separation and acoustics). A conversion with a new bathroom far from the sewer line is a different project from one beside it.
費用由什麼決定
配電盤能不能負擔新增負載、新排水管要接到多遠的污水管、車庫是否與主屋共用牆面（防火與隔音）。浴室離污水管遠的改建，和就在旁邊的，是兩個不同的工程。
How long it takes
3–5 months on site for a garage conversion, plus permit review. If the panel has to be upgraded, add 2–4 weeks for the utility disconnect and reconnect — that is the item that most often moves the finish date.
工期
車庫改建現場約 3–5 個月，外加建照審查。若需升級配電盤，要多 2–4 週等電力公司斷電與復電 —— 這是最常讓完工日延後的一項。
Permits in Milpitas
An ADU or JADU needs a building permit from the City of Milpitas, and the state ADU rules set the timeline the city has to answer in. We submit a complete package the first time, which is what actually keeps the review short.
Milpitas 的建照
ADU 或 JADU 需向 Milpitas 市政府申請建照，州法對 ADU 也規定了市府必須回覆的期限。我們第一次就送出完整案件 —— 這才是讓審查變快的關鍵。
Questions we get asked
常見問題
Usually yes. The garage has to be replaced or waived as parking, which state law now makes straightforward in most cases, and the unit has to meet building, egress and fire-separation requirements. We check the specific property before promising anything.
Less than a new detached ADU, because the shell already exists. In 2026 Bay Area pricing, a conversion typically runs well under the $150,000+ that a new detached unit costs, and the range depends mostly on the bathroom location and the electrical upgrade.
Possibly, and it depends on the zoning and how the garage is replaced. We tell you what the city will require for your specific lot at the estimate stage.
That is a zoning and permit question for the city, not a construction one, and we flag it rather than advise on it. What we can do is build it so it passes inspection as a legal dwelling, which is the part that cannot be fixed later.
Yes — San Jose, Santa Clara, Sunnyvale, Cupertino, Campbell, Saratoga, Los Gatos, Mountain View, Palo Alto and Foster City.
