Say it loud, now: if it’s not an all-year-round garden room, it’s not a garden room.
It might be a summerhouse or a log cabin. It might even be something that looks a whole lot like a garden room. But with all these confusing names and classifications and specifications out there, it’s really difficult to know whether or not you’re buying a seasonal sitooterie or a year-round building.
So how are you supposed to know which one to choose?
How do you want to use your garden room?
Every garden room project is different, and your specific needs are unique. Your budget, your needs and your expectations will all influence the choices you make when you shop for a garden room.
In our no-obligation consultations, this is often the first question we ask. “What do you want to use the building for?”
Not everyone is looking for a year-round building. Plenty of people are quite happy with a seasonal space that they shut up over the colder months, and only use when it’s sunny and warm. If this is the case, maybe you don’t need a garden room – a summerhouse might well suit you just fine.
But if you want a home office, a craft room, a music room, or a social space you can use whenever you want, a single-skinned building just won’t cut it. These buildings should, with the addition of a power supply, be suitable for use whatever the weather.
What’s your priority?
Maybe your top priority is the appearance of the building. If you’ve fallen in love with a particular aesthetic, and you’re not particularly bothered about using the building all year round, this post may not be for you. There’s absolutely nothing wrong with prioritising how the building looks in your garden.
Similarly, if you’re on a tight budget you might have to compromise. If your top priority is saving some cash, you’re not likely to get a Building Control-compliant powerhouse of a garden room that you can use as a holiday home. But you can still find the best building that you can afford right now.
Another consideration is your definition of comfort. If you’re a walking human radiator who never feels the cold and is happy to work in a sleeping bag and cosy hat, you might have a different definition of a year-round garden room to a cauld tattie like me.
Our priority is making sure that you have accurate expectations of the building you choose.
But if you want to be certain that your garden room will always be comfortable whatever time of year you need it, here are the things you should look out for:
- Layered walls
- A cavity gap
- Appropriate insulation
Why do garden rooms have layered walls?
When it’s slightly chilly outside, you might put on a jumper. But if it’s really cold, you also put a coat on over your jumper. Buildings are the same. One layer of timber, even if it’s a thick layer, isn’t going to keep the heat in as well as two layers, or three, or even five!
Layered walls improve the thermal efficiency of a building.
The other major benefit of layered walls is that they limit the amount of moisture that the building is exposed to. The outer layer might get wet, but the inside layers won’t. This prevents water ingress and minimises timber movement.
Why do garden rooms have an air cavity?
First things first – not all garden rooms use an air cavity in their construction. But if you’re shopping for a garden room, this is an important detail to look for.
An air cavity allows two important things to happen: a capillary break and airflow.
What is a capillary break?
A capillary break is a fancy way of saying that something stops water from seeping from one material to another. Let’s say you have a layer of timber on the outside and one on the inside but no space between them. Any water that penetrates the outer layer will also get to the inner layer because both layers are porous. Putting an air gap between the two layers stops any moisture in its tracks and protects the inner layer from water damage.
Why is airflow important in buildings?
Airflow in buildings is a complicated affair. On the one hand, you’re trying to keep the cold out. On the other, you’re trying to make sure there’s enough air in the building. And letting air in without letting water in further complicates this situation.
Finding the balance between keeping excess air out and maintaining good air quality on the inside is a tricky business.
This post is part of our Radiata Garden Room Buyer's Guide
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Why is air quality important in a building?
If you build a garden room from SIPs and composite cladding you create an extremely airtight building which is very good at retaining heat. However, you’re basically in a big plastic box. These buildings can’t breathe, and may even need mechanical ventilation heat recovery systems (MVHR) to allow decent air quality inside the building.
MVHR systems are used in Passivhaus construction, where buildings are constructed to be as airtight as possible to save as much heat energy as possible. However, without correct design and installation, these ventilation systems can be the difference between a warm, well-insulated building and a damp, mouldy mess.
When MVHR systems work well, they improve the air quality of the building and help save energy. But they need expert design, appropriate installation and regular continued maintenance.
If you buy a cheap, relatively small garden room that’s not suitable for year-round use, most manufacturers won’t install a ventilation system. But this is a really good case of getting what you pay for.
If the construction of the building doesn’t allow for appropriate airflow, AND there’s no mechanical ventilation, BUT the manufacturer prioritises keeping costs down rather than addressing this fundamental problem, the consumer is the one who suffers.
The cheapest way to address a stuffy, airless, musty garden room with no airflow is to crack open the windows, but this brings us right back to the initial struggle of trying to keep the cold out while also allowing airflow in. If you can only endure being in your garden room when the windows and doors are wide open, it’s not appropriate for year-round use.
If you want to use your building all year round it must have appropriate airflow, which is why a cavity gap is so important.
What kind of insulation does a garden room need?
Oh, insulation! It’s a minefield, I tells ya! There’s U-values and R-values and complicated sums, not to mention Building Regulations and fifty thousand or so options!
When you Google anything to do with insulation you’re in for a world of rabbitholes (trust me – I’ve been there). This happens for several reasons:
How thick should insulation be?
Good question. Surprisingly complicated question. It depends on what type of insulation is used, how it’s being used, where and how it’s installed, and how the rest of the walls and roof are constructed.
One thing is certain, however: no insulation, no year-round use.
As a general rule of thumb, thicker insulation is better than thinner insulation. We use 50mm foilback insulation in our smaller Radiata Garden Rooms. Our larger Blackstone Garden Rooms use 100mm Knauff insulation. Both are year-round buildings, and our Blackstone Garden Rooms are Building Control-compliant.
But most insulation advice online refers to insulating homes. Building Regulations have all sorts of rules about how well-insulated homes must be.
Remember that the main concerns of these regulations are safety, efficiency and sustainability. If you want to live in a garden room, it must be constructed according to these regulations. You don’t need residential-quality insulation to build a year-round building, but you do have to have appropriate insulation.
Annoyingly, this comes back to looking at the overall structure of the building. It’s not as simple as using a single measurement like the thickness of insulation.
Will the U-value of insulation tell me how good it is?
Calculating U-values, which measure the rate of heat transfer through a single material, is a complicated business. You can’t just add together the U-values of each individual component in a wall or building to come up with an overall U-value. You have to consider the structure, size and components of the entire building.
If you’re not a physicist, a structural engineer, or an architect, you’re probably not up for this level of involvement.
It’s useful to know how efficient insulation materials are, and this is often expressed using a U-value. But by itself this is not enough information to determine whether or not the building will be warm inside.
See? Told you. Minefield.
How do you build an all-year-round garden room?
Buying a garden room is a big decision, and it’s easy to get swept up in your dreams of a perfect space. But before you commit to buying, make sure you ask your supplier or manufacturer about these all-important features. If you need an all-year-round garden room layered walls, an air cavity, and appropriate insulation are must-have features.
If you’d like to know more about the surprisingly complex world of garden buildings, head to our Learning Centre for everything you need to make the best decisions for your garden and your project. And if you can’t find what you’re looking for there, please let us know and we’ll do our very best to help.
