“Portable,” “modular,” “manufactured,” and “temporary” describe different things. A unit can be built in a factory yet intended to remain permanently on a site. A portable garden suite can instead rely on a time-limited planning authorization. Neither the unit’s construction method nor its wheels determine whether it may be placed, connected, occupied, rented, or kept indefinitely on a particular lot.
Separate the product from the property approval
Identify the exact local unit type and the authority that regulates it. Check planning permission or zoning, temporary-use approval, site placement, foundation or anchoring, utility connections, building standards, fire requirements, inspection, and occupancy permission as distinct steps. Product certification addresses the factory-built unit within its scope; it does not itself approve the location, land use, servicing, or lawful occupancy.
The authorization may specify who can own or occupy the unit, whether it must remain ancillary to a principal home, whether it can be rented or transferred, and when it must be removed. Record the start date, end date, renewal process, conditions, and responsible authority. A unit that appears temporary may still be treated as a separate dwelling if its layout, independence, history, or actual use meets the local test.
Read the instrument that permits the unit
Perth County’s current Official Plan includes a Garden Suite policy for a portable, one-unit detached structure accessory to an existing residence. It treats a Garden Suite as an additional residential unit counted toward the lot’s overall limit. The Plan describes a Temporary Use Zoning By-law route with an initial authorization of up to 20 years and further renewals of up to three years. It also sets separate constraints for agricultural land, including servicing, farm-cluster location, MDS I, access, and transfer. These are County policies; the implementing township rules, approval and property records still matter. See the Perth County agricultural ARU and Garden Suite guide.
Fort Frances’s current Official Plan treats a Garden Suite as an additional residential unit and places it within the Town’s Temporary Use By-law framework. Its combination rule applies to specified dwelling forms and municipally serviced lots, and a Garden Suite does not gain approval merely because the Plan describes the use. Check the current zoning, capacity, and actual temporary-use instrument. The Fort Frances additional-unit and Garden Suite guide summarizes the Town’s conditions.
In Aberdeenshire, Scotland, the Council’s 2026 guidance uses a fact-and-degree assessment to distinguish ancillary accommodation from a separate dwellinghouse. For a caravan in a domestic curtilage, siting is assessed separately from works such as anchoring, service connections, or decking. Secondary short-term letting will most likely require a separate licence. Read the Aberdeenshire ancillary accommodation and caravan guide for the local scope and checks.
Rother District Council’s adopted Policy DHG10 expects an annexe to remain tied to the main dwelling and says a planning condition or, exceptionally, a legal agreement should prevent separate-dwelling use and separate sale. Belfast’s non-statutory guidance normally expects additional accommodation to be attached and internally accessible; a permitted annexe is conditioned to remain ancillary, while a separate self-contained curtilage building must qualify for permission as a dwelling in its own right. Read the Rother guide for its local criteria and check Belfast’s current planning framework and the actual decision notice. These examples concern ancillary planning use, not portable-unit removal or a UK-wide annexe rule.
Confirm the end-of-term plan
Before purchasing or installing a unit, ask what must happen when the authorization expires: removal, renewal, conversion to another planning status, or a new application. Confirm whether the permission attaches to the owner, the property, or the unit, and what notice or enforcement consequences apply if the term ends. Obtain the actual temporary-use bylaw, permit, agreement, and any written authority decision.
Finally, verify installation, service capacity, building and fire approval, and occupancy with the responsible offices. A planning classification or temporary-use approval is not a safety inspection, building permit, or certificate that a specific unit can lawfully be occupied. Do not rely on a manufacturer’s description or sales claim as proof of local approval.