A CSA standard for certifying factory-built buildings. In Ontario, a Part 9 building certified to it is deemed to meet the Building Code for the work done in the certified factory.

What is the difference between CSA Z240 and Z241?

Z240 covers manufactured homes, which Ontario's Building Code accepts as homes when built in sections up to 4.88 m wide. Z241 covers park model trailers, which the Code accepts only as seasonal recreational buildings.

Can I get a mortgage on a CSA-certified tiny home?

It depends on the lender and on whether the home is on a permanent foundation on land you own. Certification helps, but ask lenders early which kinds of small homes they'll finance.

Is a CSA Z240 RV-certified tiny home legal to live in?

Certification alone doesn't make it legal. Your municipality's zoning decides whether a unit on wheels can be a home at that address, and most Ontario towns allow it only in mobile home parks or zones.

Home types and construction methods

CSA A277, Z240 and Z241: which certification does your tiny home need?

By Jonathan Kennedy, cabin owner and tiny home rental owner · Last reviewed October 28, 2026

Illustrative photo

In Ontario, a factory-built home certified to CSA A277, or built to CSA Z240.2.1 in sections no wider than 4.88 m, is deemed to meet the Building Code for its factory-built parts. A park model built to CSA Z241 meets the Code only as a seasonal recreational building, so the Province says not to buy one to live in year-round. Every one of them still needs a building permit for the foundation and installation.

What do CSA A277, Z240 and Z241 cover?

They're three different standards for homes built away from the lot, and the one on the label decides how your town and insurer treat the home.

Standard	What it covers	How Ontario's Building Code treats it
CSA A277	Certification of factory-built buildings: the plant, its process and its inspections	Deemed to comply for the parts built in the certified factory
CSA Z240.2.1 (Z240 MH series)	Manufactured homes, including mobile homes	Deemed to comply when built in sections no wider than 4.88 m
CSA Z241	Park model trailers	Deemed to comply only when used as a seasonal recreational building

Sources: 2024 Building Code, Division B, Article 9.1.1.9 and Section 9.39.

Does a modular home need CSA A277 in Ontario?

Not by law, but it's the simple route. A manufactured Part 9 building certified to CSA A277 is deemed to comply with the Building Code, so the building inspector reviews the site work instead of re-inspecting walls that were closed up in the factory (2024 Building Code). Without certification, the municipality has to be satisfied some other way that the hidden work meets the Code.

Our take: ask every modular or prefab builder for the certification label and the certifying body's name before you sign. A builder who says "it's built to code" but can't show A277 certification is the weak option; you may end up paying for an engineer to prove what a label would have shown.

Can I live year-round in a CSA Z241 park model?

Not as far as the Building Code is concerned. A Z241 unit is deemed to comply only when it's used, or intended to be used, as a seasonal recreational building, and provincial guidance says not to buy one to live in year-round (2024 Building Code). That's why park models sit mostly in seasonal resorts; see places to park.

What about a tiny home on wheels?

The certification doesn't settle where it can go. A unit on wheels that stays in one spot, is connected to water, sewage or power, or is anchored can count as a building that needs a permit and must meet the Code (Ontario guidance). Your municipality's zoning then decides whether it can be a home there at all: only 2 of the 326 Ontario municipalities we researched allow it outright.

Does a certified home still need a building permit?

Yes. Certification covers the factory-built parts; the Code still applies to everything built on site, such as the foundation, anchorage and service connections (2024 Building Code, Division C, Article 1.12.1.1). A house needs a building permit in Ontario (Building Code Act s. 8).

For small homes of 37 m² or less built partly in one municipality and installed in another, the Code sets up a two-permit process: the municipality where it's built reviews construction, and the one where it's installed covers the site (2024 Building Code).

How do I check a home's certification?

Look for the certification label on the home, and ask the builder in writing for the certifying organization and the plant's certification number. Then call your municipality's building department with those details before you buy; they'll tell you what they'll need at permit time.

Questions people ask

What is CSA A277?: A CSA standard for certifying factory-built buildings. In Ontario, a Part 9 building certified to it is deemed to meet the Building Code for the work done in the certified factory.
What is the difference between CSA Z240 and Z241?: Z240 covers manufactured homes, which Ontario's Building Code accepts as homes when built in sections up to 4.88 m wide. Z241 covers park model trailers, which the Code accepts only as seasonal recreational buildings.
Can I get a mortgage on a CSA-certified tiny home?: It depends on the lender and on whether the home is on a permanent foundation on land you own. Certification helps, but ask lenders early which kinds of small homes they'll finance.
Is a CSA Z240 RV-certified tiny home legal to live in?: Certification alone doesn't make it legal. Your municipality's zoning decides whether a unit on wheels can be a home at that address, and most Ontario towns allow it only in mobile home parks or zones.