Converting a house into an adult family home

5 min read · 6 sections

The house decides most of your budget before you own it. A single-storey home with a wide hallway and two full bathrooms on the same floor converts for a fraction of what a handsome 1920s two-storey costs — and no amount of good intent changes that after closing.

Why I take this seriously#

I grew up in a house that did this. My parents converted the garage and the back yard, and the property now operates as a licensed adult family home north of Seattle.

So I have watched the property side of this from the inside rather than reading about it. The thing that struck me is how much of the outcome was fixed on the day the house was chosen, and how little of it could be argued with afterwards.

Everything below is the property question. Licensing is DSHS's business and I do not advise on it.

One floor, and why it is not a preference#

If you take one thing from this page: the house should be flat. Single level, no stairs to the entry, no stairs between a bedroom and a bathroom.

The people who live in these homes very often have limited mobility, and in my parents' experience a great many arrive after a fall that caused an injury. That fall is frequently the event that makes a family start looking. What they are shopping for, whether they say it out loud or not, is confidence it will not happen again.

So a single-storey layout is not a box you tick on the way to licensing. It is the thing the family is buying. Everything else about the house is negotiable next to it — and single-level homes are a narrower, more expensive slice of the Seattle-area stock than people expect, which is a fact to go in knowing rather than discover.

What actually drives the conversion budget#

Ranked by how much it moves the number, and by how hard it is to fix after you own the house.

1. Bathroom count and where they areRoughly one accessible bathroom per two or three residents is a sensible planning assumption, and they have to be reachable without stairs. Adding a bathroom to a floor that has none is the single most expensive thing on this list, and plumbing runs decide whether it is a five-figure or a low-five-figure job.
2. Door widths and turning spaceWheelchairs and walkers need clear width through doorways and room to turn in bathrooms and hallways. Widening a doorway is routine. Rebuilding a hallway that is fundamentally too narrow is not, and mid-century plans are frequently kinder here than older ones.
3. The entryA level or ramped entrance with a landing. A house with four steps to every door and a steep lot is a different project from one with a flat approach — and the lot is the part you cannot change.
4. Bedroom count and egressRooms used as bedrooms need conforming egress. A finished basement room with a small high window is not a bedroom for this purpose, however it has been described in the listing.
5. Floor surfaces and thresholdsContinuous, firm, level flooring without thresholds to trip on. Usually one of the cheaper items, and one of the most visible to a visiting family.
6. Fire and life safetyDetection, extinguishers, exit paths. Solvable in almost any house, but it is time and money and it belongs in the budget rather than as a surprise.
7. Parking and the approachStaff arrive on shifts and families visit. A house with one narrow shared driveway makes daily operation harder in a way that never shows up on a spreadsheet.

VERIFY BEFORE PUBLISHING — Requirements differ by jurisdiction and by the licence issued, and they change. This page describes what tends to drive cost, not what is currently required. Confirm specifics with the city and with DSHS before planning around any of it.

Buy the right house, or convert the wrong one cheaply?#

This is the actual decision, and it is a real trade rather than an obvious answer.

A purpose-suited house — single level, wide, two accessible bathrooms, flat approach — costs more up front and converts for very little. A cheaper two-storey with one full bathroom upstairs looks like a bargain and then absorbs the difference, plus months of permit review, plus the risk that something in the structure will not cooperate.

My instinct is that people underestimate the second path badly, because the purchase price is visible and the conversion cost is not. But there are genuinely good renovation buys, particularly ramblers that need cosmetic work rather than structural change.

What settles it is scoping the conversion before you write the offer, not after. That turns an unknown into a number you can compare against the better house's asking price.

The timeline is longer than the budget suggests#

Worth knowing before you start: from breaking ground on my parents' conversion to holding a licence took two years — construction, inspections, training and the state application, end to end.

Then they had their first resident within a month of opening.

Both halves matter. Demand, once you are licensed, was not the difficulty. The difficulty was carrying a property that produced nothing for two years while it was being converted and licensed. If you are converting rather than buying an operating home, that carrying period is the number that belongs at the top of your model.

Common questions#