Temporary Garden Suites in Ontario: The 20-Year Granny Flat
In a lot of rural townships, “garden suite” doesn’t mean a permanent backyard house. It means a portable unit allowed by a temporary use by-law under the Planning Act, for up to 20 years, with a signed agreement to take it away when it is no longer needed. It is a good tool for an aging parent on a rural lot, and a poor one if you want to build equity.
At a glance
Each township writes its own rules on top of the Act: lot size, floor area, who may live there, and the security deposit.
A temporary garden suite is a one-unit, portable detached home with its own kitchen and bathroom, allowed beside an existing house by a site-specific temporary use by-law under the Planning Act. Council can approve it for up to 20 years and extend it by up to 3 years at a time. You usually sign an agreement covering removal, who lives there and a security deposit.
Same Name, Different Animal
In Toronto a garden suite is a permanent second home in the back yard, allowed as of right. In much of rural Ontario the same two words mean something narrower and older: a temporary, portable unit that council approves one property at a time.
The Planning Act describes a garden suite as a one-unit detached residential structure containing bathroom and kitchen facilities that is ancillary to an existing residential structure and is designed to be portable. Section 39.1 lets council pass a temporary use by-law for one, and section 39 is the general temporary use power it sits beside.
The key word is portable. Townships picture a modular or mobile unit that can be trucked off the lot when Mom moves on. Tiny Township’s page says it outright: garden suites are usually mobile homes.
Before you go further: many townships now also allow a permanent additional residential unit on rural lots through ordinary zoning. If yours does, the permanent route is usually better value: no removal agreement, no expiry date, and something a lender and an appraiser understand. Ask the planning office which routes exist on your lot. Our names guide sorts out ARU, ADU, coach house and garden suite.
What the Planning Act Sets and What the Township Adds
The Act sets the outside limits. Every township then writes its own policy in the official plan and zoning by-law.
| Item | Planning Act | What townships typically add |
|---|---|---|
| Approval | Site-specific temporary use by-law passed by council | Pre-consultation, application fee, public notice and meeting |
| Term | Up to 20 years | Some township policies still say 10 years (Essa’s checklist does). Ask. |
| Extensions | Further periods of up to 3 years each | New application before expiry; Morris-Turnberry says renewal is a public process that can take up to 2 months |
| Agreement | Council may require one covering installation, maintenance, removal, period of occupancy and security | Often registered on title at the owner’s cost; can name the occupant |
| Security | Monetary or other security for costs to the municipality | Morris-Turnberry: currently $1,500. Others: security required, no amount published |
| Structure | One unit, detached, kitchen and bathroom, designed to be portable | CSA-certified mobile or modular units (Morris-Turnberry); Essa wants the internal construction portable |
| Size | Not set | Selwyn: max 65% of the main house floor area, 4.5 m high. Cavan Monaghan: 50 m² minimum, max 100 m² or 40% of the house. Essa: smaller than the house |
| Lot | Must have an existing house | Essa: minimum 1 hectare. Selwyn: rear yard, one per lot, no extra driveway |
| Who can live there | Not set | Essa: seniors or farm help. Selwyn: the person or couple it was installed for, then removed |
Last checked October 2026 · Sources: Selwyn garden suite guideline, Cavan Monaghan, Essa checklist, Morris-Turnberry guideline, Tiny Township, Planning Act
Good Fit, Bad Fit (Be Honest With Yourself)
It works well when
- A parent or relative needs to live close, for a few years to maybe 15
- Your rural or agricultural zoning doesn’t allow a permanent second unit
- You need a farm hand on site and the township lists farm help as an approved occupant
- You are fine with a factory-built unit on piers or blocks
- You can live with signing an agreement and posting a deposit
It’s the wrong tool when
- You want a permanent rental that adds value to the property
- You want a full basement or an ICF foundation under it
- You want to sever it off and sell it some day (you can’t)
- You plan to rent to strangers; some agreements name the occupant
- You need a mortgage on it; ask your lender first, most prefer permanent units
We build permanent ICF homes, so we’ll admit our bias. When a client could go either way, we usually push for the permanent unit if the township allows it. A temporary suite is money spent on a unit you’ve promised to take away. Our granny pods page covers the prefab end of this.
The Process, Start to Keys
Timelines vary by township. A temporary use by-law needs a council decision, so plan on months, not weeks.
Phone the planning office
Ask three questions: is a garden suite by temporary use allowed in my zone, is a permanent additional unit allowed instead, and what does pre-consultation cost? Write down the answers and the name of the department, not the person.
Check septic and water first
Before you pay an application fee, find out whether your existing septic can take a second unit and whether your well can supply it. This is where most rural projects live or die.
Pick the unit and site it
Choose a CSA-certified modular or mobile unit sized to the township’s limits. Site it to meet yard setbacks, stay off the septic bed and reserve area, and share the driveway if the township requires it.
Apply for the temporary use by-law
Application form, site plan, fees from the township’s fee by-law, sometimes a planning justification letter. Public notice goes out and council decides at a meeting.
Sign the agreement and post security
Removal, maintenance, occupancy and security, often registered on title. Read it as carefully as you’d read a mortgage.
Building permit and septic permit
The by-law is permission to use the land. You still need a building permit for the unit, its foundation and its connections, plus a sewage system permit if the septic changes.
Set a calendar reminder for the expiry
Apply to extend well before the by-law runs out. If you miss it, the use has to stop.
Rural lot, septic and a council application?
Our Rural Garden Suite Pack (from $2,499.99 + HST) bundles the site plan, heat loss and septic design through our partners, so the building and sewage permits go in together. Send what you have and we reply with a fixed quote.
The Septic Decides Before Council Does
Nearly every temporary garden suite we see is on a rural lot with a private well and a septic system. The Building Code sizes a septic system on the total daily design flow of every dwelling unit it serves. A second unit, even a small one, adds a full unit’s worth of flow on top of the house.
Some townships want the suite to share the main house’s services; Essa’s checklist says the suite shall not be serviced separately unless council agrees otherwise. Others will accept a separate system. Either way, an existing bed sized for a three-bedroom house is often too small for the house plus a suite, and the fix can be anything from a tank change to a new bed.
Cavan Monaghan asks for a permit or a letter of compliance for the existing system from the health unit. Tiny Township calls checking septic capacity “imperative.” Get the answer early from a septic designer. SepticReplacement.ca does septic design and capacity checks for rural lots, and our rural and septic hub walks through the basics.
Water matters too. Essa requires an adequate water supply for the suite. If the well is marginal for one house in August, it won’t get better with two.
Rules of Thumb for a Temporary Suite
- Don’t pour a full foundation under a “portable” unit. If the township expects removal, a basement or an ICF frost wall is money you’ll be asked to dig back out. Piers, helical piles or a pad are the norm. Our foundation options page compares them.
- Read the occupancy clause twice. Some agreements name the person who may live there. When that person leaves, a new agreement is needed before anyone else moves in, or the unit comes out.
- Price the removal on day one. Trucking out a modular unit, capping services and restoring the site costs real money. The security deposit is not a refund you can count on.
- Tell your buyer. If you sell, the agreement on title goes with the land. Buyers and their lawyers will ask.
- Keep the septic and well paperwork. You’ll need it again for the extension, the lender and the next owner.
- Ask about a permanent unit first. Township rules have changed fast since 2023. The answer you got five years ago may not be the answer now.
Already have an old garden suite by-law on your property? Find the by-law number and the agreement, check the expiry date, and ask the township whether the unit can now be made permanent under current zoning. Some can, if the building and septic meet today’s code.
Find out which route your rural lot actually has
Temporary or permanent, shared septic or new, how much floor area, where it can sit. Our $399 + HST Garden Suite Feasibility Report answers it in 48 hours, credited toward permit plans or the build. In Simcoe County and Georgian Bay we can build it too, through ICFhome.ca.
Temporary Garden Suite Questions
What is a temporary use by-law for a garden suite?
It is a site-specific zoning by-law, passed by council under the Planning Act, that permits a garden suite on one property for a set period. For garden suites the Act allows up to 20 years, with further extensions of up to 3 years each. It usually comes with an agreement covering removal, occupancy and security.
How long can a temporary garden suite stay?
Up to 20 years under the Planning Act, then council can extend it by up to 3 years at a time. Some township policies still use a shorter term, such as 10 years, so check your township’s official plan. Apply for any extension before the by-law expires.
Does a temporary garden suite have to be a mobile home?
It has to be designed to be portable. In practice that usually means a CSA-certified mobile or modular unit on piers or blocks. Tiny Township notes that garden suites are usually mobile homes. A site-built house on a full foundation generally does not fit the idea of portable.
Who can live in a temporary garden suite?
The Planning Act lets the township’s agreement set the period of occupancy and, in many cases, name the occupant. Essa describes garden suites for seniors or farm help. Selwyn says the suite is for the person or couple it was installed for and is removed when they no longer live there.
Can my garden suite share my septic system?
Often yes, if the system is big enough for both units. Some townships require sharing the main house’s services. The Building Code sizes septic flow for every dwelling unit served, so many existing beds need an upgrade. Have a septic designer such as SepticReplacement.ca check capacity before you apply.
How much security deposit does the township hold?
It varies. Morris-Turnberry lists $1,500. Many townships only say security may be required and set the amount in the agreement. Ask before you apply, and budget for removal costs separately.
Can I sever a garden suite or sell it separately?
No. A garden suite is ancillary to the main house on the same lot. It cannot be severed into its own lot, and the agreement and by-law stay with the land if you sell.
Is a temporary garden suite better than a permanent additional unit?
Usually not, if your township allows a permanent unit. A permanent unit has no expiry, no removal agreement and is easier to finance and value. A temporary suite makes sense where zoning only allows the temporary route, or where the need really is short-term.