How to Build a Beautiful Boutique Greenhouse Cheaply From Reclaimed Materials

We moved house a few years ago and we have thought about buying a greenhouse for ages.
But, a new greenhouse is SO expensive to buy, and they all look the same. Anyhow, why buy a boring old standard one, when you can build a fabulous, bespoke and beautiful one for thousands less?!

Here's how I built our beautiful new greenhouse. I have broken the build down into the main stages, so you can see the order and dependencies of each stage and maybe build your own. It's really not hard to make something like this. It just takes a bit of planning and accepting that you may not get all the materials at once (alternatively, you can choose to buy some things that are hard to find for free if you need to save time more than you need to save money). It was definitely worth it for me. I love it!

The total cost was about £200/$280 - way cheaper than buying a standard greenhouse. I got almost all of the most expensive stuff for free, like the doors , all the glass for the roof/windows and all of the flooring. This was all sourced using reclaimed, scrounged and scavenged wood, glass and other stuff out of skips or off Freecycle.org (e.g. a very nice bench!). To be honest, I could have brought this down to about £80/$110 by waiting longer to find some of the wood. For example, I did buy some timber that I could have found for free, if I looked long enough and a few post-spikes that made it quicker to get the frame up, but they are not strictly required.

The best part is that you can make something that suits your space, large or small AND makes you happy because it looks just like you always wanted it to :)

Materials and Tools

Materials

Wood (i.e. timber/lumbar) for the frame carcass and roof beams
Apart from some very long rails, most wood was reclaimed out of skips
Door
Our old antique front door, c.1915 - lovely
Fancy windows
the leaded lights were also antique c.1915 from our house.
The curved front top windows and a few others are original Victorian sash windows, c1840-1860 - scrounged from a neighbour who was throwing them out.
Glass/acrylic for the glazing
All the glass was from old window frames, skylights, double glazing sealed units, etc from skips. One large pane is actually a glass conference table top, out of a skip.
I needed acrylic for any triangular windows, as cutting glass to odd shapes is very difficult.
Some of heavy-duty acrylic was from reclaimed from old museum exhibition cast-offs. I did buy a few long pieces of 3mm acryclic new. This is cheap, but much less sturdy.

Flooring
All the flooring is pallets. About ten in all. These are easy to find for free, are very sturdy and also come in regular standard sizes

Inner shelving and bench
The main workbench was a freebie off Freecycle.org. It is really heavy and strong. I made the drawer inside it from an adaptred drawer from discarded furniture. The shelving is all made from pallets. I did buy some cheap London style shelving brackets

Accessories
I bought the string lights, clock and barometer, as I wanted a specific look. They were pretty cheap online. The light switch and all cable was reclaimed from skips.
Screws
I used some reclaimed screws and bought the rest
Sealants, paint and GRP (glass reinforced plastic)
I used a lot of specialist clear exterior glazing sealant. This is not something you can find for free, so I had to buy that. I bought some green paint and used reclaimed old black paint to create a darker shade of green. The polyester resin and glass fibre matting was left over from a sculpture project, but it is quite cheap to buy. This was used to create a weatherproof cap on the complex apex joint

Tools (no specialist tools required)

For this, you will need to have common DIY tools, but nothing really specialist.
I used the following. You may not need all of these.

Protective eyewear and ear defenders
I've put this first - don't blind/deafen yourself!
Claw hammer
for general nailing and nail extraction
Lump hammer and cold chisel
for pulling nailed-on planks off pallets
Pincers
for pulling nails from old boards
Nail punch
- for punching out nail stumps from boards and punching in glazing nails
Hand saw
for general wood cutting
Reciprocating saw
for cutting off timber at a height and for cutting apart double glazing units
Table saw
- for ripping down pallet planks into filler strips when building the floor
(you could do this with a circular saw if you don't have a table saw)
Circular saw
for general cutting
Cordless drill
for drilling holes
Cordless driver
for driving/removing screws
Cramps
for holding wood in place temporarily while fixing frames together, etc.
Paint brushes
applying paint to the frame and polyseter resin when doing GRP on the roof
Spirit level
for checking that things are level
Metal builder squares
for checking corners are true

Aesthetic Design

I really love the look of our greenhouse. This is the best reason to make your own. It really can have any look you want. I wanted something that felt like it was from way back in the turn of the 19th century/ early 20th century - panelled and decorative and a lovely old fashioned dark green. It is a greenhouse after all.

This dark green is a classic British colour for things like cricket pavilions and recreation ground sheds. It is like British Racing Green, a colour historically used for British motorsport cars (although there is no agreed hue).

Another inspiration that was at the back of my mind was the London Cabbie huts, which are a distinctive feature in London, near where I used to work. They were built as refreshment places for London cabbies in 19th century Victorian London, when they were still horse-drawn. They still survive today and still serve cabbies today, albeit they are now taxis with engines, not horse-drawn. There is a picture of one that is still in use above*. You can also see one of my early sketches, heavily influenced by these huts, but also blending in the 135-degree angles of the other garden features and accommodating the salvaged antique leaded door and windows.

These leaded lights (windows with rectangular grid in them) and the lovely main door are antique from the early 20th century. They are original from our house, which was built around 1915 (although no-one knows the exact date). We had replaced the windows when they became too fragile to be practical anymore and the door, while lovely, was about as secure as a piece of hardboard.

Luckily, when we replaced these, I hadn't been able to bring myself to throw them out. A few years later, they turned out to be perfect for the greenhouse and it was lovely to keep the heritage of the house alive. It was great to give them new life. The beautiful hand-wrought iron window handles are also original to the house. I had to use those.

Another thing I couldn't resist was adding a finial. Where I live there are lots of spires and they always look great against the sky (see pics above). The finial is a modest 20" or so, but does recreate this atmosphere. It looks great at dusk, when the sun sets behind the greenhouse. An actual 3 metre spire would have been even more epic, but there are such things as planning laws!

*image used under cc licence from Oyxman, CC BY-SA 3.0 creativecommons.org/licenses/by-sa/3.0/, via Wikimedia Commons

Structural Design

The structural design for the greenhouse was driven by both aesthetic and practical needs.

Our garden uses 135-degree angles in features such as the summerhouse and the arbour for the swing seat (shown in a pic above). I wanted to continue these angles in the greenhouse shape. I also wanted the frontage to be angled to face right into the morning sun as it rose up.

As a result, the design is an irregular hexagon in plan. Building the wall frames was not so hard. They are just upright posts joined with rails. However, it is not so straightforward to build a roof that has many separate faces, which are both rectangular and triangular, and none of which is exactly identical.

To get my head round how to build this, I did what I always do when designing. I started drawing the structure as it would be when finished. This is a good way to figure out what will need to be done to make it work. After several reworks, it fixes a target design into your head. It also highlights any weird challenges that you may have to overcome later.

I made a lot of rough sketches and eventually made a 3D model to really see what would work. I made the model out of good old BBQ skewers along with masking tape. This helped me get a good visualisation how it needed to be built and also mimicked the structural design of the building, in that the frame is basically built from uprights and cross beams jointed together. The model had holes where the real thing would eventually have glazed panels.

The roof was also necessarily built from found panels such as two large Velux skylights and various panes from double glazing units, cut in half to form matching pairs. Using found panels with fixed sizes added a constraint to work around. As a result, some of the other roof panels needed to be quite unusually triangles.

One main challenge was working out how to span the 3.6 metres central area of the greenhouse without vertical props and also incorporating the varying roof angles. Eventually I worked out a design that was based on a combination of pre-built panels (found window frames) connected to various beams connecting up in angled triangles all meeting into one major apex. The weight of the various panels all push against each other holding up the central pinnacle of the roof. This is the point at which the finial was attached later.

Groundwork - Preparing the Area Ready for the Build

After extracting the design from my brain into a model, I then started building it for real at full scale. This started with the lowest base frame. You can see the irregular hexagon shape of the footprint of the building. This shape would later allow the rail for the rear wall to run tightly parallel to the border fence while rail for the main frontage face where the door would go was angled at 135 degree angle to face diagonally into the garden, as designed.

This involved lots of digging and raking. I used my son as slave labour for the hard earthworks to save my back. You can see pegs I used to mark out levels across the frame

The tarp is there to keep the soil off the grass, so it didn't get all muddy. I recycled all the top soil from the turf, by sun-drying it on the tarps and later beating it off the roots with a mallet. I then sifted the soil that was beaten off with a riddle. This went into my raised beds and into bags where I was growing potatoes - waste not, want not!

Building the Frame

Once the ground was cleared to the right shape for the irregular hexagonal footprint, it was time to start building the main carcass

Posts first

The structure is supported by six uprights, one at each corner. These are 70mm square fence posts, secured using fence post metal spikes. I had by chance obtained four of the posts, and three of these spikes for free. I bought the others. They made the build easy as each post is self-supporting. You could do this without using post spikes, but then you would have to find a way to keep the frame stable until it was all connected. If not using spikes, you would just rest the posts on paving slabs.to give them a solid base and avoid them sinking into the ground.

Major rails next

The next task was to connect all the posts together using strong rails (about 3"x2"). The lower rails act as supports to which the flooring pallets would later be attached at the perimeter of the greenhouse. These lower rails were attached inside the posts using heavy duty 6" screws. The top rails act as the tie beams that would eventually be used to attach the rafters of the roof. These top rails rested on the top of the posts. For these rails, cutting 135-degree angled joints was quite tricky.

Roof rafters and frames

The roof was constructed from a mixture of existing frames (e.g. from a wooden skylight which conveniently already had its own strong frame) combined with long-span rafters, which radiated in from the top of each post to a single central apex. Large areas of the front roof face and the rear roof face were made from rectangular frames. All the other areas of the roof were triangular.

The six radial rafters meeting together at the apex would eventually be extremely strong and once joined up completely supported the whole weight of the glazed roof.

Initially however before all the required rafters were in place and securely attached, I had to use a single central prop to prevent the whole frame collapsing (including when I was standing on top of it). I built this on my own, so had to use this support to keep everything in place as I popped up and down the ladders to screw the rafter joints together. These were jointed together with very big screws that act as pin joints. The angles of each rafter had to be individually mitred at very long tapering angles to form a six-pointed star joint at the apex. I used an angle square to mark these angles.

I particularly like the pattern of the irregularly angled roof. Because they meet in one joint, they support each other and spread the weight out to rails at the top of the wall frame and this is in turn supported by the six corner posts. The rafters are set at a low angle (about 15-20 degrees). This was an optimum angle chosen because I wanted a low pitch so the roof wouldn't be too high, so the heat would all end up at the top of the greenhouse. I couldn't take it much lower than 15 degrees or the rafters would not have enough vertical support and the roof would be at risk of collapsing by inverting (like an umbrella does in high wind). For example, if it snowed later, the roof needed to be strong enough to cope. Once completed, the roof was strong enough for me to stand on.

The pallets visible all round the frame at this stage were there to rest the ladders on, to protect the lawn during construction. Later they became the greenhouse floor. I used two ladders, to reduce the need to move them about too much.

Glazing the Roof and Windows

Glaze the roof first

It might seem obvious, but the roof needed to be glazed before the windows, so that it provided shelter from rain, making the greenhouse into a sheltered workshop area. The other reason not to glaze the windows first, was that I could walk in and out of the empty vertical frames easily as I worked, without having to keep coming through the door.

The first picture here shows the semi-glazed roof, looking down on the apex. This is a view from up a ladder, installing the panes. These rectangular roof panes are at the rear of the greenhouse. They are Velux skylights from a skip. They came already fitted into a nice wooden frame. You can also see the floor was still only pallets at this stage. I filled in the slatted holes later to make a solid floor.

The rest of the roof frames to be glazed were formed as spaces between the rafters, rather than as existing prefabricated frames. You can see this most clearly in the shot showing the temporary roof support post. All the triangular roof lights and the rectangular ones furthest away are not yet glazed. To glaze the open frames, I attached 3/4" baton rails all along the inside of each aperture.

The glass or plastic infills rested upon these baton rails. The rectangular glass panes were retrieved from discarded PVC double glazing units. I have included some pics to show how to extract these by popping the sealed double-glazed units out of their PVC frames, then cutting the frames to give a pair of matching panes. The great advantage of using these, is that the come with a remnant of the frame attached as an edge. This can be drilled to secure the panes in place.

The most difficult part was cutting the large acrylic triangular panels. The simplest way to mark these for cutting, was to just measure the three inner edges of the aperture and then to mark that on the acrylic. I cut these on the table saw. The roof panes actually vary from about 2mm (thinnest glass) through to 9mm(thickest acrylic), but you can't tell by looking up at them.

Then add the door frame, they key decorative windows and any opening windows

The vertical wall glazing was much easier than the complicated roof. For starters all the window panels were rectangular. I approached this by first building the door frame within the main frontage of the greenhouse. This was critical to get right first. I then used the most decorative window frames I had acquired and worked out the most pleasing arrangement of them that would fill in the gaps. I started with the larger curved Victorian sash windows frames, then the lovely rectangularly leaded windows. I next fitted frames for three opening windows needed to control ventilation. These were frames I had to build into the carcass, within which existing wooden window frames could be attached with hinges.

Then fill in the gaps

After the door and most important windows were fitted, I simply filled the rest with other existing frames. Once I'd used up all the pre-existing frames, I built frames in between the main carcass of posts and rails, and the already added windows. These formed new apertures, which I filled in with some plain glass panes. In one case, I had found a large (and really heavy) glass conference table top about 9mm thick and 1400mm by 1000mm. For the remaining apertures, I cut bespoke sized panes from acrylic.

For all windows made by fitting panes into newly made frames, I fixed them in with panel pins, then sealed them in with specialist clear glazing silicon sealant. This was one of the most significant costs in the project. You can't get this out of skips, so you have to buy it. This is quite a fiddly job. You can see my sketch of the various sizes of glass collected, that i used to draw up a rough plan of what would fit where, in the most efficient way.

Planning the sealing in of panes

To seal the complex panes in the roof required getting up onto the roof on a ladder inside the half-built roof. I had to plan the order of this carefully, so that I could reach all the panes from the ladder

Building the Floor

I am particularly pleased with the floor. I have used pallets before as a foundation layer for a wooden floor, but not as the actual main floor surface. Being prefabricated, they are very easy to use, and being regularly sized I could build the basic floor surface very quickly in a modular way.

The pallets are attached at the edges to the lower rails of the frame carcass. I used strong angle brackets, and in some cases wooden batons, to support the weight at those edges. Further into the middle of the greenhouse, the pallets are supported upon a mixture of bricks and broken paving slabs. I have added some pictures of how simple foundations can be built up under pallets. In this case, the images show support rails. For pallets, this may be the lower planks on the pallets.

Having multiple rails, pallets spread the weight out quite nicely. This is what they are designed for in bearing cargo. To keep the floor even, I used 2" thick baulks of wood under the top plank. As one pallet was butted up against the next, these 2" wooden baulks were placed under the top planks spanning across pallets. I screwed the top planks of the pallets down to each cross-joining piece to tie them securely together, locking the top faces of each pallet level with its adjacent neighbour.

Obviously, some edges of the floor were mor challenging as I had to cut either 45-degree or 135-degree angles into the pallets, to fit the irregular hexagonal shape of the frame. Some extra strengthening was needed here.

Finally, pallets have gaps which needed to be filled in. For this, I removed planks form other pallets using a crowbar and/o a cold chisel and then ripped them down into filler pieces using the table saw. You could do this with a circular saw if you don't have a table saw.

The finished floor has a nice diagonal pattern, like a rustic parquet.

Internal Shelves

At this point the building itself was more or less complete. I had a bit of panelling to do at ground level and the back wall was also partially panelled in a similar way to the floor had been built, using pallets and then infilling them.

The next job was to build the internal working space within which to potter about gardening!

To start this off I installed a large workbench I had got for free off Freecycle.org. This gave me a starting working area for potting. I then built two levels of shelving almost all the way around the inside of the greenhouse, upon which I would later support pots and grow bags etc to grow the plants in.

These were all made from sections cut from pallets and supported by a combination of rails and shelving brackets.

Decoration and Finishing Touches

I have already mentioned the green paint on the outside. This was a mixture of a colour called Buckingham Green, mixed 60:40 with black paint to create a darker shade of the green hue. This was done by trial and error. I had originally used the raw Buckingham green, but it was too light. You can see the before and after colour in the two pics of the front facade.

Inside I painted all the walls and frame white to reflect light. This makes it seem bigger inside than it would otherwise.

The front door has a beautiful brass boss for a pull handle and a brass letterbox. Brass and dark green go really well together. I continued this contrast on the wonderful finial. This was hand carved from reclaimed mahogany (from a specimen cupboard from a museum, in fact), before being painted green and capped with a brass sphere at the pinnacle. This was a small brass door knob I had reclaimed from an old cupboard about 10 years previously.

Inside I also bought a small barometer and an analogue clock, both with a brass finish, to match. The clock is actually a small alarm clock with the alarm bells removed, but it looks like a nice old ship's clock.

Finally, I added a long LED exterior tube strip light to add a subtle interior light that looks really lovely at night. It makes it into a lovely retreat. It is very relaxing to sit inside the greenery with the soft glow around you.

Summary

I am so please with the way this turned out. Hopefully, you can see how you could build your own to any shape you wanted. You don't have to reclaim the materials, but it is quite easy to get hold of really nice old windows that really make a difference and if you are lucky can be got free out of skips etc.