How to Choose an ADU Builder in the Hudson Valley
By Spenser McCoy
If you searched "ADU builder near me," you probably already have a person in mind. A parent who is getting harder to leave alone in a house three hours away. An adult child who needs a few years of breathing room. Maybe, down the road, a rental that helps carry the property.
The results will give you builders, prefab manufacturers, and design firms. Almost none of them will tell you the first thing you need to know: whether your lot can take an ADU at all.
Here is how we would approach the search, in order.
Start with the lot, not the builder
In the Hudson Valley, the project is usually decided by the property before anyone picks up a pencil. Four things do most of the deciding:
Setbacks. How far a second structure has to sit from each lot line, and from your house. Rules differ by town, and sometimes by the type of structure.
Lot coverage. A lot that looks like it has plenty of room can still be at its limit once the driveway, house, and sheds are counted.
Septic and water. If you are on a septic system, the health department's view on adding a second dwelling can decide the project before zoning does. Wells and slopes add their own questions.
The approval path. Some towns handle an ADU through site plan review. Others route it through a different board. The path changes the timeline and the cost.
Wetlands, steep grades, and easements can matter too. None of this is glamorous. All of it is cheaper to learn before you commit to design or construction spend than after.
Know what kind of company you are calling
"ADU builder" covers three different businesses:
Builders construct the structure and pull the trades together on site.
Prefab manufacturers build the unit in a factory and deliver it.
Design firms draw the plans.
Each is paid for their own step. None is paid to hold the whole project together. That gap is where homeowners get stuck: the drawings assume a septic design nobody has priced, the unit arrives for a foundation nobody has scheduled, and the town asks for something none of the three expected.
None of that makes any of them bad at their job. It means someone has to own the sequence. If that someone is you, plan on a second full-time job for a year.
Seven questions to ask any builder before you sign
Have you built in my town? Not in the county. In the town. Ask which board approved it and how long it took.
Who applies for the permit, and who answers the town's comments?
What is included in the price and what is not? Site work, utility connections, septic, foundation, and landscaping are common places for a quote to go quiet.
Who do I contract with? You should know exactly who holds each contract and who gets each payment.
How are changes handled? Ask for the change-order process in writing, with an example.
What controls the schedule? The town, the manufacturer, the weather, and the builder each control a piece. Ask them to name theirs.
What would make you tell me not to build here? If the answer is "nothing," keep looking.
The last question is the most useful one. A company that can say "this lot should not take an ADU" is working for you, not for the job.
What a feasibility study is for
A feasibility study answers the lot question on paper before you spend on drawings or a deposit. We confirm what your town allows and what the site will take: setbacks, septic, and coverage. You come out with a clear answer on whether to move forward, adjust the plan, or stop.
Our feasibility study is credited toward your build package if you proceed. Sometimes the answer is no. We have closed out a study with the advice that a site should not be built on, and the client was better served by hearing it then.
Where OneBuild fits
We are not the builder. We coordinate. You contract directly with the builder or the manufacturer, and you pay them directly. We don't mark up construction or pass-through costs.
Our fees are flat, defined by scope, and agreed in writing before work begins. We take no commission from manufacturers or contractors, so nothing we earn changes with which builder or model you choose. That is what lets us say "this one fits your lot better" or "this lot is not the right place."
From the first question to the Certificate of Occupancy, we read the code, run down the agencies, and keep the sequence straight, project by project and town by town. OneBuild is designer-led, founded by Spenser McCoy, B.Arch, Syracuse University.
We work in the Hudson Valley, and we would rather have an honest conversation with you about your property than run a long sales cycle.
Next step
Book a free Discovery Call. We will talk through your property, who the ADU is for, and what is most likely to get in the way. If it makes sense, the next step is the feasibility study. If it does not, you will know that too.
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