20×12 Summer Houses at a Glance
Size: 20ft x 12ft (approx. 6.0m x 3.6m) · Construction: Quality redwood deal timber · Glazing: Toughened glass as standard · Floors: Solid wooden floors included · Roof styles: Apex and pent designs · Doors: Double door options available.
Uses: Garden office, hobby room, studio, entertaining space or garden retreat · Insulation: Insulation and fully insulated options available · Installation: Free installation included · Bases: Base building service available · Customisation: Bespoke designs and coloured paint finishes available · See before you buy: Summer houses on display at our Surrey show site near Guildford, Woking and Ripley.
Need advice? Our experienced team can help with your 20×12 summer house design, specification, insulation, base requirements, installation and bespoke options before you order.
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Why Choose a 20×12 Summerhouse?
A 20×12 summerhouse has a nominal footprint of around 240 square feet, or approximately 22.3 square metres. This is a genuinely substantial garden building, not just a place for a couple of chairs. Twenty feet gives you extensive usable wall space while the twelve-foot depth allows proper sofas, tables, desks, cupboards and hobby equipment. It can work as a spacious garden retreat, entertaining room, studio, substantial hobby room or large garden office.
I recommend marking out the complete 20ft x 12ft footprint before ordering. Stand inside the marked area, think about where your furniture will go and consider which direction you want the doors and windows to face. Remember that 20×12 is a nominal description, so always use the manufacturer’s precise dimensions, roof overhangs, and required base measurements when preparing the site.
What Can You Use a 20ft x 12ft Summer House For?
A 20ft x 12ft summer house gives you enough room to create genuinely separate areas inside one building. You might have sofas and chairs at one end with a desk, hobby table, workbench, or cupboards at the other, or use the whole room as an art studio, craft room, entertaining space, or substantial home office.
The twelve-foot depth gives you considerably more freedom with furniture than a shallow summerhouse, while twenty feet of length provides extensive wall space. If you already own large furniture, desks, or specialist equipment you intend to use, measure it before deciding where to position your doors and windows.
Is a 12 x 20 Summerhouse the Same Size?
A 12 x 20 summerhouse will normally describe the same nominal 240-square-foot footprint as a 20 x 12 summerhouse, with the measurements stated in the opposite order. Manufacturers do not always describe frontage and depth in the same sequence, however, so always check the individual product drawing before preparing your garden.
Establish exactly which elevation is twenty feet, which is twelve feet and how much additional clearance is required for roof overhangs, professional fitting and future maintenance. With a large building, leaving sensible working space around it can make both installation and ongoing maintenance considerably easier.
Which 20×12 Summerhouses Are Confirmed for This Size?
The products currently shown whose published size ranges genuinely include 20ft x 12ft are the Platinum Winchester Apex, Winchester Pent and Winchester Transverse together with the Royal Bletchley, Buckingham and Denham garden rooms. These are the six buildings I would concentrate on when comparing genuine 20×12 options.
The three Winchester designs are published in sizes up to 28×16 and currently offer full insulation as an option. The three Royal buildings are published up to 20×12 and are supplied fully insulated. All six currently include professional assembly, so I compare their construction, glazing, insulation and layouts rather than judging them solely by their dimensions.
Platinum or Royal 20×12 Summerhouse?
I would look towards the Platinum Winchester range if you want a substantial timber summerhouse with flexibility over roof style, layout and insulation. Winchester Apex, Pent and Transverse all accommodate 20×12 and let you decide whether full insulation is appropriate for how you intend to use the building.
I would compare the Royal Bletchley, Buckingham and Denham when regular use throughout more of the year is a greater priority. These are supplied as fully insulated garden rooms and are intended for customers wanting something much closer to a substantial extra room in the garden.
The right choice is not automatically the most expensive one. It is the specification that matches how you genuinely intend to use the building. You can also explore our complete summer houses range if you are still deciding which style or specification suits you.
Winchester Apex, Pent or Transverse?
The Winchester Apex gives you the familiar traditional pitched-roof appearance, while the Winchester Pent creates a cleaner single-slope profile. The Winchester Transverse changes the relationship between the roof ridge, frontage and entrance and may work particularly well in certain garden layouts.
I would choose according to more than appearance. Consider where the building will stand, which direction you want to face when sitting inside, the position of surrounding fences and buildings, and whether the doors and windows leave enough uninterrupted wall space for your furniture.
Royal 20ft by 12ft Summer Houses and Garden Rooms
The Royal Bletchley, Buckingham and Denham are fully insulated garden rooms whose published size ranges include 20ft x 12ft. I regard these differently from conventional seasonal summerhouses because they are built for customers who want more frequent use and a higher level of comfort.
If you are planning a substantial home office, studio, hobby room or regular garden retreat, compare their complete construction, insulation, glazing and layouts carefully. Don’t assume all fully insulated garden rooms are identical, or that the highest-priced model is automatically the best choice for your requirements.
Should a 20×12 Summerhouse Be Insulated?
Whether insulation is worthwhile depends mainly on when and how you intend to use the building. If it will mostly be somewhere to relax or entertain during warmer weather, you may decide that full insulation is unnecessary. If you expect to work, paint, craft or spend several hours inside during colder periods, insulation becomes considerably more valuable.
Insulation does not create heat; it reduces the rate at which heat passes through the building. Heating, glazing and ventilation matter as well. If colder-weather use is important, compare our insulated summer houses and examine the complete specification rather than relying simply on the word “insulated”.
Can a 20ft x 12ft Summer House Be Used as a Garden Office?
Yes. At around 240 square feet, it gives you a generous amount of office space. Depending on the layout, you can fit several desks, office chairs, shelving, and cupboards, plus a separate seating, meeting, or storage area.
If you intend to work inside regularly throughout the year, I would consider insulation, glazing, heating, ventilation, electricity, lighting and internet connectivity alongside the floor area. An occasional summer workspace and a regularly occupied garden office have very different requirements.
A 20×12 Summerhouse for Hobbies, Crafts or a Studio
This footprint can work particularly well for hobbies because twenty feet gives you extensive wall space for workbenches, desks, shelving and cupboards while the twelve-foot depth leaves generous working room in front. Artists may prioritise natural light, whereas crafters, model makers and collectors may value uninterrupted wall space and storage more highly.
I recommend planning the interior before deciding on the final glazing arrangement. More windows are not automatically better if they occupy the exact walls where you wanted shelving, tall cupboards, or specialist equipment.
Can You Create Separate Areas Inside a 20×12 Summerhouse?
Yes. At around 240 square feet, the building is large enough to create several distinct areas without necessarily installing permanent partitions. You could have a comfortable seating area, a home-working zone and a hobby or storage area within the same open room while still retaining generous circulation space.
Selected buildings can also accommodate internal partitions, additional doors and alternative layouts. If you already know how you want the room divided, discuss it before ordering so the design can be planned around how you intend to use it.
Why I Look Beyond the Photograph
After working with timber garden buildings since 1979, I know that two attractive photographs can hide considerable differences in construction. Photographs show design and style well, but they cannot tell you everything about the timber, framing, floors, roofs, doors, windows, glazing or joinery.
I look at the complete structure. Good cladding needs suitable framing behind it, substantial doors depend on proper joinery, and a solid floor needs adequate support. No single headline measurement should replace comparing how the complete building has actually been made.
Why Timber, Framing, Floors and Toughened Glass Matter
The applicable timber summerhouse ranges use quality redwood construction, solid wooden floors and toughened glazing. These fundamental details interest me more than many decorative extras because they are part of the building you will experience every time you use it.
I encourage customers to inspect the details that can be difficult to appreciate online. Stand on the floor, open and close the doors, examine the window joinery and look at the framing and roof construction where possible. Those practical details can reveal considerably more about quality than attractive photographs alone.
Can a 20 x 12 Summerhouse Be Made Bespoke?
Yes. Bespoke options are available on selected Platinum designs and can include changes to dimensions, doors, windows, partitions and layout. With approximately 240 square feet available, relatively small changes to a door, window or partition position can make a significant difference to how useful the finished room becomes.
If you already know where your sofas, desks, workbenches, cupboards or hobby equipment will go, plan those positions first. We can then explain which design and available alterations are best suited to the way you intend to use your building.
Can a 20ft x 12ft Summer House Include Storage?
A large summerhouse can lend itself particularly well to combining leisure or working space with a separate storage section. Depending on the design, one part of the building could provide space for garden tools, bicycles, furniture, or hobby equipment. At the same time, the main room remains available for relaxation, hobbies, or work.
If integrated storage matters to you, compare our summer houses with shed storage. Decide how much room you genuinely require for each purpose before settling on the final layout.
A Large 20×12 Summerhouse Needs the Right Base
One piece of advice I have repeated throughout my working life is that even the best garden building needs the right foundation. A 20×12 summerhouse is a substantial structure and should stand on a firm, flat and level base suitable for the exact model being installed.
Do not prepare the foundation simply by measuring twenty feet by twelve feet. First, obtain the manufacturer’s required dimensions. Our summer house base guide explains the main foundation options and why correct preparation is essential.
Professional Fitting Included
The confirmed Platinum Winchester and Royal 20×12 buildings currently include professional assembly, subject to the individual product, applicable delivery area, suitable site access and the correct prepared base. At this size, having experienced installers assemble the building removes a substantial part of the project.
Access becomes particularly important with a twenty-foot building. If your garden has narrow passageways, steps, high walls, restricted turns or anything else that may affect delivery, please contact us before ordering so the practical details can be discussed.
See a Summerhouse Before You Buy
When I started in garden buildings in 1979, there was no internet, so customers naturally inspected buildings before buying them. Online research makes comparison far easier today, but photographs still cannot show you how substantial a floor feels, how a door operates or what around 240 square feet actually feels like when you stand inside the room.
That is why I continue to recommend visiting our Surrey garden building display site if practical. We cannot display every model in every size, but representative buildings let you compare materials, construction, doors, glazing, and overall quality before deciding.
My Garden Building Experience Goes Back to 1979
I’m Robin Antill, founder of 1st Choice Leisure Buildings. I left school at 15 and started my own garden building business in 1979, trading as Marina Sheds. I learnt the trade hands-on by making and selling timber buildings, delivering them and dealing directly with customers, and that practical experience still influences the way I assess garden buildings today.
I sold Marina Sheds in 1990, although unfortunately I did not receive all the money that was due to me from the sale. It was a difficult business lesson, but I remained involved with garden buildings and continued building on the experience I had gained.
From Marina Sheds to Titan Garden Buildings
By 1992 we had expanded beyond traditional sheds and added summerhouses, garages, garden rooms and log cabins. Marina Sheds no longer properly described what we were doing, so this wider direction led to the name Titan Garden Buildings.
My son Craig joined me in 1992 after studying carpentry at Guildford College from 1990. His carpentry training brought additional practical woodworking and timber-construction knowledge to the business, alongside the experience I had already gained through manufacturing, retailing, and dealing directly with customers.
Why Craig and I Formed 1st Choice Leisure Buildings
We sold Titan Garden Buildings in 1998. In 2000, Craig and I decided to take a different approach. Rather than manufacture everything ourselves and naturally be restricted to our own products, we decided to retail carefully selected quality garden buildings from established manufacturers. That decision led to the formation of 1st Choice Leisure Buildings.
I still believe that independence matters because different customers genuinely need different specifications. Someone wanting an attractive summer retreat does not necessarily require the same building as somebody planning a regularly used insulated garden office or studio. Our job is to explain those differences rather than automatically sell the highest specification.
Craig now runs the day-to-day business, and I am there to support him and the team whenever required. You can read more about my background, Craig and how the business developed on our About 1st Choice Leisure Buildings page.
What More Than 45 Years Has Taught Me About Summerhouses
The first lesson is that dimensions alone do not define a garden building. Two 20ft x 12ft summer houses can occupy virtually the same amount of garden while differing considerably in timber, framing, floors, roofs, doors, glazing, insulation and overall construction.
The second lesson is to buy according to how you genuinely intend to use the building. There is no benefit in paying for features you will rarely use. Similarly, I would not choose a straightforward seasonal specification if I already knew the building would become a regularly occupied office, studio, or hobby room during colder weather.
Frequently Asked Questions About 20×12 Summerhouses
How big is a 20×12 summerhouse?
A nominal 20×12 summerhouse provides around 240 square feet of footprint, equivalent to approximately 22.3 square metres. Exact internal, external and required base dimensions vary between models, so always use the manufacturer’s detailed measurements when preparing your site.
Is a 20ft x 12ft summer house a good size?
For customers wanting a substantial garden room, it can be an excellent size. Twenty feet provides extensive wall space while the twelve-foot depth gives you considerable freedom with furniture and room layouts. It can work particularly well for entertaining, hobbies, a studio or a large garden office.
Is a 12 x 20 summerhouse different from a 20 x 12 summerhouse?
Usually the two descriptions refer to the same nominal 240-square-foot footprint with the measurements reversed. Manufacturers may describe frontage and depth differently, however, so always check the individual product plans and exact measurements before preparing the foundation.
What can I fit inside a 20ft by 12ft summer house?
The exact arrangement depends on the doors, windows and furniture, but this size can normally accommodate substantial seating, tables, several desks, shelving, cupboards and hobby equipment. Its proportions also make it practical to create several distinct areas within the same room.
Can I get a fully insulated 20×12 summerhouse?
Yes. The Royal Bletchley, Buckingham and Denham are fully insulated garden rooms whose published size ranges include 20×12. The Platinum Winchester Apex, Winchester Pent and Winchester Transverse also currently offer full insulation as an option.
Can I use a 20×12 summerhouse throughout the year?
That depends on its specification and how it is equipped. A suitably insulated building, combined with appropriate heating, glazing, and ventilation, can be considerably more comfortable during colder periods than a conventional seasonal summerhouse. Choose the specification based on how often and when you intend to use it.
Can I use a 20×12 summerhouse as a home office?
Yes. At about 240 square feet, you have plenty of room for several desks, office chairs, shelving, and storage, plus potential meeting or seating space. For regular year-round working, also consider insulation, heating, glazing, ventilation, electricity and internet connectivity.
Can a 20×12 summerhouse be made bespoke?
Selected Platinum designs offer bespoke options which can include changes to dimensions, doors, windows, partitions and layout. If the standard arrangement is nearly right but a door, window or partition conflicts with your intended room layout, ask what can be changed before ordering.
Can a 20ft x 12ft summer house include storage?
Summerhouse and storage combination buildings are available within our wider range. A twenty-foot-long footprint can work particularly well when you want a substantial leisure or working area, plus a separate storage section.
Does a 20×12 summerhouse need a proper base?
Yes. A firm, flat and level foundation suitable for the exact building is essential, particularly at this size. Do not assume that the required base should measure exactly twenty feet by twelve feet; confirm the manufacturer’s precise requirements before carrying out foundation work.
Do I need planning permission for a 20×12 summerhouse?
Many domestic summerhouses can fall within permitted development rights, but this depends on factors including the property, overall building height, position, proximity to boundaries, garden coverage and intended use. The 20×12 footprint alone does not determine whether permission is required. Read our summerhouse planning permission guide and check with your local planning authority where appropriate.
Is fitting included with these 20×12 summer houses?
The confirmed Platinum Winchester and Royal 20×12 buildings currently include professional assembly, subject to the individual product, applicable delivery area, suitable site access and the correct prepared foundation. Always check the individual product information for the precise installation conditions applying to your chosen building.
My Advice Before Buying Your 20×12 Summerhouse
After working with timber garden buildings since 1979, my advice is straightforward: decide how you genuinely intend to use the building, mark the 20ft x 12ft footprint out in your garden, plan your furniture and door positions, compare the actual construction and choose an insulation specification appropriate to your needs. A 20×12 summerhouse gives you a substantial amount of usable room, but good planning is still essential.
Craig, the team and I are here to explain the differences rather than automatically steer you towards the most expensive option. Tell us how you intend to use your summerhouse, and we can help you compare the Winchester and Royal choices, insulation, bespoke layouts, bases and professional fitting.
Robin Antill
Founder, 1st Choice Leisure Buildings
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