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The Material Guide for Building a Garden Room

Garden rooms have really taken a spike in popularity in recent years. Homeowners and DIYers have become increasingly inventive when it comes to designing and building stunning and functional outdoor garden rooms that complement the garden space.

If you’re thinking about building a garden room from scratch, we’re here to give you some tips and ideas, in addition to a shopping list of materials you’ll need to achieve a quality, long-lasting finish.

garden room with cladding

Why build a garden room?

The great thing about these dynamic, on-trend outbuildings is that they are incredibly versatile. They can be used for a vast range of purposes and functions and built to a custom size and shape.

Some build office garden rooms in the pursuit of creating a quiet workspace to run a business or work from home, whilst others have used their garden room to create a stay-at-home recreational space such as a mini bar, games room, gym or relaxation room.

Compared to a house extension, a garden room is often a cheaper way to create more space. And, generally speaking, garden rooms are classed as outbuildings, which often don’t require planning permission. However, we’d always advise you check the requirements of your local authority before you begin your project, particularly if your garden will be used for business purposes, and especially if you intend on installing a bathroom as these will often require you to seek planning permission.

How much does a garden room cost to build?

garden room with bike shed
There’s no set price – naturally, the size and specifications of your garden room will influence the types of materials and labour you’ll need, and subsequently the cost.

Building your own garden room is a superb way to reduce the cost of installation. Whilst there may be some aspects of the project that require help from a professional, such as electrical installation or plumbing, much of the structural work can be done by any budding DIYer.

You’ll need to budget for structural materials, such as the foundations, timber frame, roof and any windows and doors, as well as decorative features such as exterior cladding, decking, internal features, flooring and furniture.

Materials needed to build a garden room

There really are so many different ways to build a garden room and plenty of personal features and additional touches you can add along the way. However, the foundations and structural composition of a garden room remain pretty similar, regardless of the size and shape of your building.

Some opt for the flat pack route, but here at Equestrian Fencing, we’re here for those who want to get stuck into the self-build approach, designing their own garden building and putting their DIY skills to the test along the way.

And, actually, with a little know-how, some handy tips and patience along the way, anyone who fancies giving a DIY garden room a go, really can achieve something great.

Think of this as your shopping list. We’ll outline the types of materials you’ll need for different aspects of the build project.

The garden room foundations; what do you need?

garden room foundation base
The best foundation you can build for a garden room is a concrete slab foundation. When done right, this will ensure you have a flat, smooth and raised surface to build on.

Of course, you’ll need to measure and mark out the area to find out what quantities of materials you’ll need first. This can be done with string or old decking boards.

Once you’ve done this, you can dig out around 150-200mm of ground. Next lay around 75-150mm of type 1 scalpings, using a wacker plate or roller to compress.

Before laying your concrete, you’ll need to lay a damp-proof course (DPC) to stop ground moisture from rising through the base. Some also choose to lay steel reinforcement mesh sheets at this point.

Then it’s time to mix up your concrete. You’ll need 1 part cement to 6 parts ballast, mixed together with a cement mixer. Some choose to buy their own mixers whilst others rent or borrow one from a friend or neighbour (you’d be surprised to find out how many people have a cement mixer lurking in their shed!).

You’ll then need to add your floor insulation. Recticel Eurothan GP Rigid Insulation Board is the ideal material for this. Cut to the size and shape of your garden room floor space before laying it on top of the concrete and then cover it with 5mm hardwood ply to protect it.

Materials for the walls

frame structure
Once you have a flat foundation to build from, you can start to assemble your garden room structure.

Start with the walls, using 4×2 C24 graded timber. Again, the size of your build will determine how much timber you need.

Create a frame, cut some centres and place them around 400mm apart. Use a nail gun or hex pro screws with a screwdriver to fix them to the wall frame.

Next, you’ll need some OSB boards. Cut them to size where necessary using a saw, square them with the corners of the wall frame and fix them with screws. Ensure the OSB is firmly fitted, screwing into each centre joist as well as the frame joints. Work your way down the wall frame, fixing the OSB to the wall joists.

Repeat this process for all walls.

When it comes to erecting the first two walls, lay down DPC, place your wall frames on top and create a 45-degree support using a piece of timber to create an anchor point.

Once they’re up, use your spirit level to make sure the walls are square and then use 100mm screws to screw the two walls together at a 90-degree angle. You can also use the 3,4,5 rule to check both walls are at a precise 90-degree angle.

Anchor the walls into the base using 100mm screws. Drill through the bottom of the timber frame into the concrete.

You’ll also need 6×2 C24 timber for any door frames or stud work lintels needed for bifold doors.

When it comes to door choices, many opt for bi-fold doors, which are a superb, contemporary option.

You’ll also need to insulate the inside of your garden room. This can be done with sheets of Recticel Eurothan GP Rigid Insulation Board placed between the stud work and covered with softwood ply.

Materials for building the roof deck

garden room with patio doors
You’ll need 6×2 C24 timber for the roof joists, placed 400mm apart.

Use a string line to ensure that any overhang is the same size, and it’s also handy to have a spare piece of timber cut to a length of 400mm to ensure that each joist is equally spaced. Screw or use a nail gun to attach the joists to the frame.

You’ll then need some more 6×2 to cover the end of the joists on the overhanging joists and for any noggins in between the roof joists. Steel joist hangers are also a great way of further securing the joists to the rafters.

To board the roof, opt for OSB tongue and groove. Fix the board to the rafters with screws or a nail gun and get yourself some liquid wood adhesive to secure the tongue and groove.

When it comes to the rooftop, you have a few options. You could opt for a fibreglass roof, which is pretty low maintenance and offers a contemporary style, an EPDM covering which is particularly environmentally friendly and has a great life span, or metal sheeting. Alternatively, you could install a living roof, which offers additional noise and heat insulation, however, it does require more maintenance.

These are all great options for flat roofs, but if you go down the pitched roof route, tiles, slates and wooden tiles are also options you could consider.

To keep your garden room warm, use insulation boards between the roof struts, and cover with plyboard.

Internal features

Once you’re happy with the shell of your garden room and you’ve installed any doors, windows or bi-folds, you can start to consider the interior decorations. This is a bit like decorating the inside of your house; the functionality of the room will depend on the fit-out features you include.

If you’re planning on building a bar, built-in desk or shelving display, use CLS , available in a range of sizes. Sheet materials such as softwood and hardwood ply, as well as MDF, are excellent for boxing in and creating solid structures and furniture pieces. For any joinery work, timber treatments such as Osmo top oil will help to ensure a quality finish.

When it comes to the floor, luxury vinyl tiles and wood-effect laminate are popular choices as they are easy to keep clean. But if you’re aiming for something a little cosier, then a fluffy carpet or rug is a great choice.

For the walls, to ensure you have a smooth finish, you may wish to plaster. You can then paint or wallpaper the walls.

Completing the exterior

garden room
To get your garden room looking slick and smart from the outside, you’ve got lots of cladding options to choose from. If it’s a more traditional look you’re going for, European Oak feather edge or Douglas Fir waney edge cladding are great options.

If it’s a classic Nordic, log cabin style you’re going for, you can’t go wrong with traditional log lap cladding. Or for a smooth and contemporary finish, treated shadow gap or shiplap are both options to consider.

For a luxury look and feel, consider Western Red Cedar or Siberian Larch cladding. And for something bold and beautiful, opt for pre-painted black feather edge cladding.

Don’t forget that cladding can be painted. Sage green, striking grey, quaint white and even pretty pastel pinks, blues and lilacs are all great options.

To complete the look, match your cladded garden room with a complementary deck. If your garden room is slightly raised, raised decking with steps will ensure easy access to your garden room whilst creating a sunspot to relax in the summer. Again, there is a great range of decking options available to choose from, all of which can be painted or stained to match your garden room.

Alternatively, you could use 10mm grey pea shingle to create a pathway and surround for your garden room. This is a great way to ensure you’re not treading mud from the garden and grass areas into your indoor space.

To give the garden room a natural inside-outside blend, you could fit a trellis to the exterior walls. Grow climbing plants such as wisteria, ivy or even runner beans in the summer.

Other materials you’ll need to consider

Typically, most homeowners building a garden room require a power supply. With this in mind, you’ll need to factor in additional materials and professional labour required to safely install power sockets and lighting on the interior and exterior of your garden room that comply with relevant building regulations. This could include wall or pendant lighting as well as motion sensor outdoor lighting or even sunken deck lights.

Considering plumbing in a sink, toilet or shower? You’ll also need to ensure you have the correct pipework and drainage. Again, it’s always a good idea to seek professional assistance with these aspects of a garden room project, in addition to the correct planning permissions.

During your garden build, the weather may be unpredictable so ensure that you can quickly cover any areas with tarpaulin to keep the build dry. For any timber components exposed to the elements, be sure to use cut end preserve on freshly cut ends.

Find everything you need to build a garden room at Equestrian Fencing
Shop online for a range of timber materials including structural timber, sheet materials, fixtures and fittings as well as decking, cladding and aggregates.

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