First identify the actual scenario
| Proposed location | Starting planning position | Main questions |
|---|---|---|
| Separate purchased site | Normal planning application is the starting point | Zoning, settlement policy, access, design, services and wastewater |
| Part of parents' or relatives' land | Normal application unless the precise rear-garden Class 3A conditions apply | Site boundary, principal house, subdivision, access and occupation |
| Rented or licensed land | Landowner consent does not replace planning permission | Planning, lease rights, services, removal obligations and title |
| Agricultural land | A dwelling is not authorised by agricultural use | Development-plan policy, rural housing need, access and wastewater |
| Rear garden of main home | Class 3A may apply if every condition passes | Owner occupation, size, existing structures, open space, placement and services |
| Temporary/mobile unit | Mobility does not create a residential exemption | Duration, placing, connections, use and material change of use |
Ownership is not planning permission
Property ownership and planning control answer different questions. A folio or lease may give you rights over land, but development and residential use remain subject to planning law, local policy and other controls.
Local development plans identify zoning, settlement strategy, landscape protections, infrastructure and rural-housing policies. These policies vary by authority and location. A design that may be supported on one site may conflict with policy on another.
What if the land belongs to your parents?
Family ownership does not create a general exemption. If a new plot is being created beside or behind a house, the proposal may still be a separate dwelling requiring permission and may be assessed under local rural-housing or settlement policy.
The current Class 3A rule is different. It allows a qualifying 32–45m² detached dwelling in the rear garden of a principal house without a planning application when every statutory condition is met. Among other matters, the principal house must be the property owner's sole or main residence when work begins; the new dwelling must be occupied in conjunction with it; and it cannot be sold or subdivided separately.
Use the Class 3A eligibility checker for that specific rear-garden scenario. Do not apply its 45m² headline to a field or separately divided site.
Agricultural land and local housing need
Agricultural land is not a blank category for cheap residential development. The local authority's development plan will determine where one-off rural housing may be supported and what criteria apply.
Some rural policies assess whether an applicant has a housing need or a connection to the area. National guidance and local policies have changed over time, so an old forum answer is not enough. Read the current plan for the authority and seek site-specific planning advice.
What if it has wheels or can be moved?
Mobility is relevant evidence but not a universal exemption. Planning can regulate the placing and use of structures and land. A unit used as a settled home, connected to services or kept on a site can raise planning issues even if a tow bar or chassis remains.
Claims such as “under six months is always allowed” or “no foundations means no permission” are unsafe without the exact statutory basis and facts. Ask the planning authority about the specific placement and use, or use the Section 5 declaration process where an exempt-development determination is needed.
Access, wastewater and services can decide the site
Road access
A safe entrance needs adequate sightlines and may require consent or works. A narrow lane may also prevent delivery or crane access even if planning is achievable.
Wastewater
Where mains sewer is unavailable, the site must be suitable for an on-site domestic wastewater system. The EPA states that planning applications for new houses must demonstrate site suitability under the applicable code and standards.
Water and utilities
Confirm water supply, electricity capacity, telecommunications and the legal right to bring services across any third-party land. Planning permission does not itself give those rights.
Flooding and environment
Flood risk, protected habitats, archaeology, landscape designations and nearby water bodies can materially change the application and professional reports needed.
A safe order before ordering the home
- Identify the exact land parcel, ownership and proposed residential use.
- Check zoning, settlement and rural-housing policies in the current local development plan.
- Retrieve the planning history of the site and adjoining property.
- Test access, delivery, water, electricity and wastewater feasibility.
- Arrange pre-planning advice where appropriate and decide whether a Section 5 request or planning application is needed.
- Only then coordinate the home specification, foundation and Building Control route.
Frequently asked questions
Can I rent a field and put a tiny home on it?
A lease or landowner agreement does not provide planning permission. Residential use, services and the placing of the unit still need to be assessed, alongside your contractual right to develop and occupy the land.
Can I live in a cabin while building my main house?
Temporary accommodation can still require planning permission or a specific planning condition. Include the proposed duration, location, services and later removal in discussions with the planning authority.
Can I use Class 3A on land next to my parents' house?
Only if the precise proposal falls within the statutory rear-garden class and every condition is met. A separate site or subdivided plot should not be assumed to qualify.
Will a pre-planning meeting guarantee permission?
No. It can identify policies and likely issues, but the formal application, submitted evidence and statutory assessment determine the decision.
Does planning exemption mean no Building Control?
No. Planning and Building Control are separate. Class 3A expressly preserves relevant Building Regulations and Building Control requirements.
Official sources
Legally reviewed: 6 August 2026. General information for the Republic of Ireland, not a planning determination, title opinion or site assessment. Local policy and site facts must be checked.