DIY Garden Office – Cheapest way to build your own
If you are looking for information on how to build a garden office or garden room from scratch this post will detail my DIY process from a clear piece of land at the bottom of my garden to an insulated garden office with electrics. The room is actually going to be a garden studio for my daughter but the construction methods and end result are exactly the same if you are building an office for yourself.
Cheap Garden Office Ideas
Whilst there are many ways to create a cheap garden office ranging from converting your existing shed into a garden office shed, using your summer house to building your own garden office. If you want a room that you are going to be comfortable working in all year round you really need to build your own garden office. If you are looking for cheap garden office ideas a home build is a great idea!
You will need a bit of wood working / building ability but I had never built one before and have managed to do a reasonable job!
One thing to really consider is heating / cooling. As if you get this wrong it’s going to be cold in the winter and really hot in the summer!
How to build a garden room on a budget
This is a DIY garden office build with recycled materials.
The project has started with the acquisition of some double glazed windows and french doors from a conservatory that was being dismantled near me. I don’t have any garden office plans, just a vision in my head which I hope to bring to life over the next few weeks. Where possible all the materials will be sourced as cheaply as possible to keep the cost down but without affecting the quality of the build.
I must clarify that I am not a builder or have any experience in the construction of garden buildings. Everything I am learning is from research of garden office designs and building methods, youtube and a just do it attitude.
Hi, my name is Roger Perkin. I am actually a Network & Security Consultant, I am CCIE #50038 and if you want to read about Network Automation check out my pages on Network Automation
DIY Garden Office Build
This build started on 31st March 2017
Garden Office Construction – Day 1

Here you can see the piece of land I have at the bottom of my garden. A few of the windows can be seen against the fence. The building will be 12ft x 8ft. The first job is to dig some holes to put in the footings. Building a garden office by yourself is a big task, but the summer is coming and I am looking forward to some long evenings working in the garden. The spec of this building will be that of a professionally built building like one of these but at a fraction of the cost. I am not a builder just a keen DIYer – I have no plans at the moment just a size and some windows!
If you want to know how to build a garden room on a budget keep reading.
Garden Office Build Day 2 – Outside frame completed
I have now completed the frame showing the full size of the office, I have put down four concrete blocks sat on concrete foot plates to support the frame, I still need to add another five and then fill in the joists inside the frame.
The frame is constructed from 6×2 tanalised timber held together with 4″ screws. The concrete foot plates are 6″ deep and made from a 5:1 mix of ballast and cement. The concrete blocks sit just proud of the lawn allowing a few inches under the building to allow for good air flow.

Day 3 – Base nearly complete
I have made some good progress today and am 3/4 of the way to finishing the base. I have sunk 4 more concrete blocks in the ground and now have all the supporting points covered. I have also put a central 6×2 running the full length of the base, and am hanging all the joists from it. This will give the base more strength. I have also acquired some 100m Celotex insulation from a skip at my daughters school this is going to be put in the base.


Day 4 – I got some reclaimed wood for the walls.
The wall construction is going to be made with 3×1 softwood. Pricing this up it was coming in at around £3 per length of 2.4m – I am going to need about 60 lengths for the walls a total of £180. Onto my favourite site Gumtree and found a local builder not 5 miles from my house who was clearing some 3×1 timber! I picked up 60 various lengths all over 2.4M plus some 4×2 tanalised timber for roof joists (more on that in a few weeks) for a grand total of £70. The roof joists were going to cost me nearly £80 so today I have saved myself £190! Building a garden room is turning out to be more fun than I thought – saving money as well is also a bonus!
I am now on the hunt for some more insulation.

All the wood was dry and straight so a real bargain!
I took no time in constructing the first wall. Very simply I worked out the height of the building at the back needed to be 6′ 7″ so I made a square frame and then cut 5 more pieces to make the uprights. I screwed in 3 of these and then located the first window in the frame and added the remaining uprights to either side of the window giving it some strength. A simple cross beam with some supports underneath the window and one wall is finished.

The next task is to finish the base, get some more insulation in there and lay a floor. So I am now looking for some celotex insulation and 18mm OSB3 boards.
So back onto Gumtree and I have found 12 sheets of 25mm Celotex for £5 a sheet – which is a bargain so I bought the lot. I had to chop it in half to fit into my car!

I finished insulating the floor and used 2 sheets putting 50mm under the floor which I used 18mm OSB for. Then got straight into the walls. I am using some reclaimed 3×1/2″ timber and framing each wall. For the back I constructed 3 sections and clad it with 11mm OSB before screwing them into the floor. Started progress on the roof using 4×2 tanalised timber and also enlisted some help to paint the OSB boards before the were installed facing the fence, never to be seen again!

My daughter is painting the second back wall section and we soon had all the back walls up.

The next step is to finish the front. I had acquired another window from ebay as I was looking for a window that spanned the full width of the space. I found a mis-measure window on ebay that was exactly the right size for me. This was a brand new window that had never been installed and using K Glass. This window is better than what I have in my house!

So I now have the window installed as well, the next step is to finish the roof (or at least get a covering of OSB up there) and then get the doors on.
For the roof I have 4×2 tanalised timber at 16″ spacing this will be covered with 18mm OSB and then finally an EPDM roof.

With the roof on I can install the doors – this was very simple as the frame simply screws into the wood frame of the building. The two doors were lifted into place and the hinges screwed into the frame. The building is now semi-water tight and could withstand a light shower.

Self Build your own Garden Room – Phase #1 complete
It is starting to look the buildings in the brochures! Can’t believe it has come this far. The next step is to get an EPDM roof on and then I am going to be working on the insulation on the inside and starting the first fit on the electrics for lights and sockets.

Self Build Garden Room Cost
Total cost of the build so far is £547 which I don’t think is bad for a completely bespoke 12×8 garden office fully insulated and double glazed.
I will say that the Ryobi Drill is the best drill I have ever owned, and for only £129 it’s very good value. It has now helped me build 2 garden offices and is still going strong.
Shopping List
1 x UPVC French door plus 4 windows – (dismantled conservatory) £100
6×2 Floor Joists £99
Bullet Screws – £18
https://www.travisperkins.co.uk/Bullet-Gold-Wood-Screws-Pack-of-200—5-0-x-100mm/p/107803
Insulation – £50 (Gumtree)
Concrete Blocks, Cement, Ballast and some sharp sand – £18
60 lengths of 3×1 and 9 lengths of 4×2 tanalised roof joists (reclaimed from local builder) £70
The only tools I used to build this garden office
18mm OSB for Floor and Roof plus 11mm OSB for walls – £192
How much does it cost to build a garden office UK?
This depends on how much of the work you want to do yourself and how much DIY skills you have. You can, like I did build a fully insulated garden office with electrics, garden office for under £2000 or you can pay a company to come and do it for your from anything upwards of £20,000
Can you build an office in you garden?
As long as you keep to current building restrictions which are: an eaves height of 2.5m, an overall height of 3m (or 2.5m if within 2m of a boundary) then you can build any building in your garden for use as an office or for any other use.
hey Roger any updates on this project, looks really interesting and something i had looked into doing. would love to see how it turned out.
gaz
Yes it is still progressing, got the electrician in and have sockets and lights and the walls cladded, will update some more photos soon
Hi
a couple of questions. did you only used treated wood on the roof?
what did you put on the outside of your shed? we are thinking of putting the obs on the inside for walls and cladding the outside in plastic wood look cladding. Do you know if you need a breathable MEMBRANE for the that?
sorry about the caps don’t know why it’s doing them!
Hi, I am by no means an expert in this and am just making it up as I go along, but it’s the second one I have built and the first one is 8 years old and still standing!
Roof was tanalised joists and 18mm OBS board covered with an EPDM rubber sheet
So I used Tanalised timber for floor with 18mm ply on top, then standard CLS 2×4 timber for the wall studs with OSB on the outside and MDF on the inside with 50mm Celotex in the gaps
Then on the outside i have put tanalised battens with Shiplap boards with an air gap of about 3/4″
I have not used a breather membrane – I know you are supposed to but I have not, The Celotex was taped on all joints with Aluminium Tape
Will update with some more photos soon as it has progressed a bit
HI tHIs is a great guide. Did you clad the outside and if so with what? I am thinking of ATTACHING the cladding directly to the frame and then putting ply or OSB on the inside. I’m a diy’er like you and so I’m hoping that this would work. Don’t suppose you have any THOUGHTS on that?
Hi Al,
I need to update the post with some more pictures as it is fully cladded now. You need to attach the the OSB board some tanalised battens and then attach the cladding to that. This way if any rain gets through it drops down the gap and it also provides an air gap
Hi great post.
Posting from torquay australia.
-did You use a membrane anywhere on the walls and Roof prior to external cladding to stop moisture etc?
-with the floor insulation, how Did you stop it from falling through onto the Ground? Did i miss something about a sheet of of plywood On the underside of the floor frame?
I am just aBout to build an almost identical garden studio.
Also no idea why the UPper case is on!!!!
Thanks
Hi Mike in Australia!
I didn’t use any membrane, I know you are supposed to but I used 50mm Celotex in all walls and used the aluminium tape to seal all the gaps, so it was like a barrier, have had no problems with condensation in the last 2 years.
To stop the insulation falling through the gaps there is a batten on each side at the bottom of all the joists to support it, some people also put metal mesh under the entire frame to stop rats chewing the insulation, it just depends how much money you want to spend and how long you want the building to last, this is Mk2 for me I also have another office I built for myself which has lasted over 6 years and wasn’t built as well. But it’s just fun trying things out.
If you have the budget then the membrane can’t hurt, I also then put battens on the outside to attach the shiplap boards to leaving an air gap which also helps