Build a greenhouse — step by step
Extend the growing season with a small wood-and-glass greenhouse — for tomatoes, cucumbers and seedlings.
This is a complete guide to build a greenhouse yourself — step by step, with a material list, tools, a timeline and what it costs. It's written for anyone building at home without professional experience: count on 3–5 weekends and a material cost of around 10,000–30,000 kr.
Showing method: Build it yourself in wood & polycarbonateRecommended
The price is an estimate based on typical material prices and can vary depending on size, material choice, location and store.
Which method suits you best?
Best for: Anyone who wants to build it themselves, tailor the size to the plot and get a good greenhouse for half the price of a kit.
Please note: Material quantities, prices and building methods are guidelines. Always check current prices, local regulations and product instructions before starting a project.
How a greenhouse comes together
A small greenhouse of 4–6 m² goes a long way for a family — you can start growing in March and pick tomatoes into October. Here we build a simple free-standing greenhouse with a timber frame and polycarbonate (or glass) that provides light, warmth and wind protection.
Materials for a greenhouse — full list
Check items off while you shop — the list stays with you on the page.
Build a greenhouse step by step
- 01
Plan the size and location
Choose a sunny spot — at least 6 hours of sun a day. A standard size of 2×3 m is enough for a family. Mark out the corners with pegs.
Tip: Place the entrance in a sheltered spot — you'll want to be able to open the door even when it's windy. - 02
Build a stable foundation
Set concrete piers 70 cm deep or ground screws at the corners and along each post. Check that the foundation is completely level and at 90-degree angles.
- 03
Build the floor frame
Screw together a rectangular frame of 45×95 mm studs on the piers. This is the base the whole greenhouse stands on.
- 04
Raise the posts and roof trusses
Set vertical posts at the corners and along the sides at roughly 60–80 cm spacing. Build roof trusses with about 30° pitch so snow slides off.
Tip: Pre-assemble the roof trusses on the ground — much easier than up in the air. - 05
Fit glazing bars and prepare for panels/glass
Between the posts, fit glazing bars (45×45 mm) that frame each polycarbonate or glass panel. The dimensions should match the standard sizes of the panel or glass.
- 06
Fit the polycarbonate (or glass)
Cut the polycarbonate with a sharp knife or fine-toothed saw. Fit U-profile along the edges and fasten to the frame with screws through the sheeting (with sealing washers).
Tip: Always face the UV-protected side outward — otherwise the sheeting will only last a few years. - 07
Fit ventilation flaps
Build at least one vent flap in the roof and preferably another in the gable. In summer, temperatures can otherwise climb past 50°C and kill the plants. An automatic wax-cylinder opener (~400 kr) handles this on its own when it gets warm.
Tip: The roof vent should be at least 15% of the floor area for good airflow. - 08
Build and hang the door
Make a simple frame with a piece of polycarbonate in the middle. Hang it on two sturdy hinges. Secure it with a simple hook.
- 09
Treat the timber
Apply two coats of wood oil or stain. The timber sits outdoors year-round and needs maintenance every 2–3 years.
Help specific to build a greenhouse
How the time breaks down
A 2×3 m greenhouse is built over 3–5 weekends. The frame and roof go fastest; fitting the polycarbonate or glass neatly takes the most time.
- Planning, measuring & marking out3–4 h
- Piers & floor frameWeekend 1 (8 h)
- Posts, roof trusses & glazing barsWeekend 2 (8–10 h)
- Cutting & fitting the polycarbonateWeekend 3 (8–10 h)
- Door, vents & adjustment4–5 h
- Oiling or staining (2 coats)3 h + drying time
How to save time
- Buy a greenhouse kit (~12,000 kr) instead if you want to save time — you'll save a weekend and get proper aluminium profiles.
- Cut all the timber parts before you start assembling — otherwise you'll be running back and forth to the saw.
- Get help for a weekend when the roof trusses and panels go up — much easier with two pairs of hands.
Questions and answers about build a greenhouse
How do you build a greenhouse?
A small greenhouse of 4–6 m² goes a long way for a family — you can start growing in March and pick tomatoes into October. Here we build a simple free-standing greenhouse with a timber frame and polycarbonate (or glass) that provides light, warmth and wind protection. The guide breaks the work into 9 steps — you start with plan the size and location, build a stable foundation and build the floor frame and work your way forward at your own pace.
How much does it cost to build a greenhouse?
Material cost is typically 10,000–30,000 kr. Total cost 10,000–30,000 kr for a 6 m² greenhouse. Polycarbonate is cheaper than glass but lasts a shorter time. The biggest items are studs 45×95 mm ntr (~50 m) 3,000–4,500 kr, studs 45×45 mm ntr (~30 m) 900–1,500 kr and polycarbonate sheeting 10 mm (~12 m²) 2,500–5,000 kr. The price varies with size, material choice, location and store.
What materials do you need for a greenhouse?
You'll need things like studs 45 × 95 mm pressure-treated, studs 45 × 45 mm pressure-treated, polycarbonate sheeting 10 mm (or tempered glass), u-profiles & h-profiles for polycarbonate and concrete piers or ground screws — the full material list with quantities is in the guide and can be checked off while you shop. Tools you'll need at home: power drill & batteries, circular saw or mitre saw, long spirit level and tape measure & square.
How long does it take and how hard is it?
Count on 3–5 weekends for a greenhouse. A 2×3 m greenhouse is built over 3–5 weekends. The frame and roof go fastest; fitting the polycarbonate or glass neatly takes the most time. The difficulty level is moderate, so you can manage it without professional experience if you follow the steps in order.
Which method should I choose for a greenhouse?
There are 2 common ways to build it: build it yourself in wood & polycarbonate and aluminium greenhouse (ready-made kit). Choose a method at the top of the page — the guide, material list and cost then adapt to that solution. We recommend build it yourself in wood & polycarbonate for most homes.
What's the most common mistake?
The mistakes we see most often: placing it in shade — the plants will never do very well, skipping the foundation — the greenhouse gets lifted by wind or damaged by frost heave and fitting the polycarbonate the wrong way round (uv side inward) — the sheeting becomes brittle and cracks within a year. Read through the whole guide once before you start — that way you'll avoid most of them.
And that's it, done.
Take a step back, pour a cup of coffee and enjoy. You built it yourself.
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