Knowing what size shed do I need is crucial before investing in a custom steel shed in Northern Ireland. The right shed size depends on its intended use—storage, workshop, garage or garden office—as well as planning rules, base dimensions and future needs. This guide covers all you need to consider to get the correct shed size for your garden.
Common Shed Sizes and Their Uses
Sheds come in a range of sizes tailored to different purposes. Understanding typical dimensions helps you decide what fits your needs and garden space. Here are some common uses and the shed sizes that suit them:
- Storage Sheds: Usually smaller, around 2m x 2m to 3m x 3m, to keep garden tools, lawnmowers, bikes or seasonal items safe and dry.
- Workshop Sheds: Larger, often 3m x 4m to 4.5m x 6m, with space for workbenches, power tools, and ventilation for DIY or hobby projects.
- Garages: For one car, a shed about 6m x 3m or 6m x 4m is typical. Double garages are bigger. Roller doors are common for easy vehicle access.
- Garden Office Sheds: Usually 3m x 4m to 4.8m x 6m, designed for comfortable working space with insulation, electricity and internet connections.
At NMG Outdoor Living, we tailor every shed size to your exact requirements, so these ranges are a starting point. The right size depends on how you use it and your garden layout.
Planning Permission and Height Limits for Sheds in Northern Ireland
Before deciding size, check planning permission rules. In Northern Ireland, a garden building needs no planning application if it meets all these conditions:
- Maximum height 4 metres overall.
- Where within 2 metres of a boundary, eaves height no more than 2.5 metres.
- Buildings other than the house cover no more than half of the garden.
- Not in front of a wall facing a road that forms the front or side of the house.
- Not within 3.5 metres of the boundary where a road runs opposite the back of the house.
- No deck, balcony, veranda or raised platform attached.
- Not used as a separate dwelling.
- Not within the grounds of a listed building.
If you want a veranda or glass pergola attached, it could need planning permission. Also, sheds in Areas of Outstanding Natural Beauty or National Parks have stricter limits for outbuildings far from the house. Always confirm your site with your local council; see our planning permission guide for details.
Base Size and Preparation for Your Shed
The shed base is critical for a good fit and long-lasting building. NMG requires a concrete base that matches the shed size plus a 60mm allowance on both length and width. For example, a 6m x 4m shed needs a base of 6.06m x 4.06m. The base must be square, level and crack-free. We check this by measuring diagonals before manufacturing your shed.
If you choose a roller door, the base needs a recessed tray 25mm deep, set 180mm from the front edge, and 100mm wider than the door opening on each side. This allows the door to roll smoothly and sit flush.
We do not start building until you send photos confirming the base meets these specs. A poor base can cause problems fitting the shed and damage over time.
Door Options and Internal Layout Considerations
Choosing shed doors affects your shed size needs. Personnel doors need space to open inward or outward; roller doors require enough front clearance and a properly prepared base.
Consider internal layout early: where will shelves, workbenches or desks go? For workshop sheds, allow at least 600mm depth for workbenches and 800-900mm for comfortable standing space in front. For garden offices, plan desk and chair space plus room to move.
Headroom is also important. Think about the height of stored items or equipment and the space you’ll need to work comfortably inside. Discuss these details with your installer to ensure the shed suits your needs.
Future Use and Flexibility
Think beyond immediate needs. Will your shed need to accommodate growing hobbies, more storage or even conversion to a garden office later? Planning a slightly larger shed now can avoid costly moves later.
Consider how your needs might change, such as adding electrical wiring, insulation or ventilation. While these features may not come standard, planning the space to allow installing them later can save time and expense.
Checklist Before Requesting a Quote
Before contacting NMG for a quote, check the following to help us design the right shed size for you:
- Measure your garden space and mark boundaries.
- Decide shed purpose: storage, workshop, garage or office.
- Consider door types and access space needed.
- Check planning permission rules for your site (planning guide).
- Prepare or plan for a concrete base to the correct size and quality.
- Think about future uses or expansion.
- Note any specific requirements like insulation or electrical fittings.
NMG Outdoor Living builds every shed bespoke from our workshop in Maghera, delivering and installing professionally across Northern Ireland and County Donegal. Our sheds are steel-framed and clad in Tata Steel Colorcoat® LG, built tough for our climate. We answer enquiries within 24 hours and provide free quotes. See examples of our work in the gallery.
Comparing Shed Sizes: Quick Reference Table
| Use | Typical Size (m) | Door Type | Base Size Allowance | Planning Notes |
|---|---|---|---|---|
| Storage | 2 x 2 to 3 x 3 | Personnel door | +60mm both directions | Usually permitted, max height 4m |
| Workshop | 3 x 4 to 4.5 x 6 | Personnel or roller door | +60mm; roller door needs recessed tray | Check eaves height near boundaries |
| Garage (single) | 6 x 3 to 6 x 4 | Roller door | +60mm; recessed tray essential | Max 4m height; near boundary limits apply |
| Garden office | 3 x 4 to 4.8 x 6 | Personnel door | +60mm | Check planning limits; insulation needed |
Additional Advice on Shed Size Decisions
When choosing your shed size, also consider practical issues that often arise:
- Access and manoeuvring space: Make sure you have enough room to move around the shed and access doors comfortably.
- Storage height: Think about how tall your stored items are and whether you need shelving or tall cabinets.
- Ventilation: Proper airflow is important, especially for workshops or storing sensitive items.
- Lighting and power: If you plan electrical fittings, ensure the shed size allows space for wiring and fixtures without clutter.
- Security: Larger sheds may need stronger locks or alarms depending on their contents.
- Maintenance access: Leave clearance around the shed for cleaning and repairs.
Discuss these points with NMG when planning your shed to avoid common pitfalls and get a building that truly fits your needs.
For more on planning and custom sheds in Northern Ireland, visit our pages on planning permission, steel sheds and garden rooms. If you want a shed designed as a workshop or office, these pages offer useful info.
Next steps
Every shed NMG builds is made to measure, so the quickest way to a real number is a free quote. Have a look at our sheds, finished projects in the gallery, then send us the details or ring 07438 676043. We answer enquiries within 24 hours and cover all of Northern Ireland and County Donegal from our workshop in Maghera.