How Are Garden Rooms Insulated?

How Are Garden Rooms Insulated?

Posted by Rubicon Garden Rooms on 11th Apr 2022

One of the questions we often receive here at Rubicon, is ‘how are garden rooms insulated?’ It’s an important question, as we know that most people will want to use their garden room all-year-round, and to do so comfortably. So, keep reading and we’ll tell you exactly how our garden rooms are insulated…

Why is it important that your garden room is insulated?

Is insulation really that important for a garden room?

Our answer is an emphatic yes.

If you want to use your garden room all-year-round, then ensuring that your garden room is properly insulated will ensure that it is warm, easy to heat and keep heated, and is energy efficient.

As energy prices continue to rise, insulation will go a long way towards making your garden room cheap to heat.

Conversely, a well-insulated garden room will also stay cool and comfortable during the warmer months of the year.

In short, it’s important that you buy a garden room which is properly insulated.

How well insulated are garden rooms?

Another one of our most commonly received questions is, ‘how well insulated are garden rooms?’

The simple answer is that garden rooms are as well insulated as modern homes.

Here at Rubicon, our garden rooms are designed and built using the same materials and techniques that are used in modern house building.

That’s why we refer to our garden rooms as being a genuine extension to your home.

What types of insulation do garden rooms use?

Whilst there are a number of different types of insulation that are used in garden rooms, some are far superior to others. At the cheapest end are the fibreglass and polystyrene types and at the upper end are the foiled PIR foams and layered Multi-Foil/Honeycombs.

Recognising the excellent thermal qualities of the PIR Foams made by Celotex, Kingspan and a number of others, this material has remained the mainstay of our insulated buildings for the past 15 years.

However, new innovations have recently arrived on the market which not only offer excellent insulation qualities, but also improved acoustic and wind resistance performance such as Actis Hybris

At Rubicon we also recognise that it’s not simply enough to ensure a garden room is well insulated. It has to be breathable too.

To do this, we construct our insulated garden rooms using timber frames that are made in factory controlled conditions, from a minimum of 96mm x 47mm C24 and C16 structural-grade regulated timber for the walls, and 175mm for the roof joists.

Our timber frames are then sheathed on the exterior side using structural-grade sheets of Oriented Strand Board (OSB). This helps to reduce wind penetration through the exterior walls.

We also add a waterproof, breathable membrane to the outside face of our garden rooms. This is complemented by an integral vapour barrier on the internal wall and ceiling panels. This prevents condensation from building up in the wall and roof cavities of your garden room.

Once this stage of construction has been reached, we then add the insulation.

Garden room insulation used by Rubicon Garden Rooms

At Rubicon we ensure that our garden rooms and garden offices are fitted with only the best insulation, offering warmth and comfort along with a high degree of acoustic performance

Previously we would only have used PIR foiled foams but have recently changed our specifications to adopt the latest technology from Actis.

Actis Hybris is a reflective insulation product for timber frame walls, pitched roofs or ceiling applications. We now install 100mm of this new material to all floors, walls and roof cavities.

Based on a honeycomb structure made of shaped polyethylene foams glued to aluminium coated polyethylene foils.

The high thermal performance of Hybris Actis is provided by a special structure composed of a large number of low emissivity cavities, protected from dust and excessive air movement. Moreover, the low emissivity external films provide additional thermal resistance, when associated with air cavities.

Hybris Actis has many benefits over other types of garden room insulation, including:

  • A unique composite layered honeycomb structure - which is both strong and durable.
  • It does not compact over time unlike some other insulations.
  • It doesn’t contain any irritating fibres.
  • Exceptional thermal performance.
  • High-acoustic performance, helping to keep your garden room peaceful and quiet.
  • Wind and moisture resistant, and therefore long lasting.
  • Lightweight - it’s easy to carry, transport and store, making the construction of your garden room quicker and more efficient.
  • High-degree of air tightness, which will result in a warmer, more comfortable garden room.

However, if you really want to kick your insulation up another notch, you can upgrade ) the specifications to include an extra layer of 25mm PIR foil-foam insulation across the wall frames and ceiling joists, which offers even better thermal performance.

The importance of garden room breathability

As we mentioned above, it’s important when thinking about insulation, to also consider breathability.

Failure to consider breathability in the design of your garden room can result in problems with condensation and damp further down the line.

Here at Rubicon we construct our garden rooms and offices along TRADA and NHBC guidelines on ventilation. We ensure that our garden rooms have proper cross ventilation from the front to the rear of the building.

We also include eave overhangs with a ventilation grill (giving a 25mm continuous gap along two opposite sides of the building). You’ll also find a minimum 50mm clear void for airflow inside the roof cavities.

In short, we make sure that our garden rooms are not only well insulated, but well ventilated too, meaning you’ll have a trouble-free, comfortable garden room that’s a pleasure to spend time in.

How is garden room insulation performance measured?

Not all types of insulation are created equal. The type of insulation you have in your garden room will determine how well it retains heat and its overall performance.

The performance of insulation is measured in something called a ‘U-value’.

U-values allow you to assess how well a type of insulation will perform in your garden room.

The lower the U-value, the more thermally efficient the insulation is.

Bear in mind that the U-value doesn’t just take into account the insulation, but will also consider wall thickness, material and any renders used in the construction of the wall.

U-values also apply to floors and roofs. To give you an idea of how well insulated our garden rooms are, we’ve provided some comparison tables below:



Type of wallU-value
Victorian solid wall2.1
Cavity wall (brick/cavity/block)1.6
Timber frame (brick/cavity/wood)0.46
Rubicon wall0.35

As you can see, a Rubicon wall offers exceptional insulation performance, especially compared to older construction methods such as Victorian solid walls and cavity walls.

How about the different types of roof construction? How well are they insulated? Take a look at the table below:



Type of roofU-value
Uninsulated roof2.3
Rubicon roof0.35

Of course, you’ll want some windows in your garden room so that you can take in the view. But what types of windows offer the best insulation performance? Let’s take a look:



Type of windowU-value
Single glazed window5.6
Double glazed window2.8
Rubicon window1.6

So, when you’re looking at how well insulated a particular garden room is, be sure to check the U-value of its insulation.

This is an easy, at-a-glance way of comparing garden rooms and assessing which has the best thermal performance.

Tip - remember, the lower the U-value, the better the thermal performance of a construction method.

Do windows affect the insulation of a garden room?

As you would expect, the answer to this question is yes.

When it comes to installing windows in a garden room, you have to think of the trade off you’ll be making.

More windows will give you a brilliant view of your garden and create a light and airy atmosphere in your garden room. But, more windows will inevitably reduce the thermal performance of your garden room.

So, if thermal performance is particularly important to you (for example if you live in a colder part of the country), then you’ll want to select a garden room like our Cabin style model, which has less glazing.

On the other hand, if you’re going to be placing your garden room in a sheltered location, and you’re more concerned about seeing the view and having a light and airy atmosphere in your room, then select one of our Canopy style panoramic or Vista style garden rooms.

Garden room insulation and the Building Regulations

In general, garden rooms do not have to adhere to the Building Regulations and do not require planning permission.

This applies if they are no higher than 2.5m from the bottom of the building to the top of the roof, do not take up more than 50% of your garden area, and are not used as sleeping accommodation.

However, just because you don’t need to adhere to the Building Regulations doesn’t mean you should ignore all of the stipulations in the regulations. There’s some good stuff in there - particularly around insulation!

Because the Building Regulations don’t always apply to garden rooms, it’s important to check if your garden room does include insulation, as this may not necessarily be the case with some suppliers.

Here at Rubicon we are always monitoring the building regulations and ensure that our garden rooms are properly insulated to provide excellent thermal performance.

How do you heat a garden room?

So far we’ve talked a great deal about how to ensure your garden room stays nice and warm, retaining heat on even the coldest of days.

But, how do you actually heat a garden room up in the first place?

Here at Rubicon as standard we install wall-mounted heaters. Running on electricity, these heaters are more than adequate to keep our garden rooms well heated and comfortable.

What’s more, our electric heaters are very economical to run, with a year’s worth of heating being only a few hundred pounds (actual rates will depend on your particular energy provider).

Alternatively, you could also specify a wall-mounted AC unit that includes both heating and cooling functionality. However, these must be installed by qualified F-Gas fitters to comply with building regs.

What are the best insulated garden rooms?

Having read this far, we hope you’ve gained an understanding of how important garden room insulation is, and the intricacies involved in selecting the right type.

So, if you want the best insulated garden room for your home, what are your options?

Below, we’ve set out the best insulated garden rooms that are currently available.

Cabin Style Garden Room

Find out more - Cabin Style Garden Room

Featuring a rustic, traditional appearance, the Cabin style garden room makes an ideal office, hobby space, man cave or hang out spot for the kids.

But, whilst it may have traditional looks, it has incredibly modern insulation. In fact, you’ll find that it’s as warm as a modern house!

With our new Actis Hybris insulation, a fully-plastered interior, and a zero maintenance exterior, this is a garden room that can be used all-year-round. On even those coldest of winter mornings, you’ll be able to get comfortable in your Cabin style garden room.

If you wish, you can also upgrade the insulation further. This is particularly handy if you’re going to be spending a lot of time in your garden room and want to reduce your energy bills.

Canopy Classic Garden Room

Find out more - Canopy Classic Garden Room

The Canopy is a beautiful, contemporary looking garden room that features twin (or sliding doors) which provide maximum light and wall space in the interior of the room.

Available with either a full or half-canopy, the Canopy classic garden room offers not only a light and airy space, but also a warm and comfortable one.

That’s because the Canopy features a fully-insulated floor, a fully-insulated and cross-ventilated roof, and fully-insulated and ventilated cavity walls.

Combi Style Garden Room

Find out more - Combi Style Garden Room

Are you looking for an insulated garden room that is highly versatile and suitable for multiple purposes?

Then you’ll want to check out the Combi. This is a garden room which can double as both a storage space and a home office/man cave/chill out space.

Being as warm as a modern house, the Combi’s insulation makes it ideal for storing things that you need to keep safe and dry.

Whether you want to store collections, tools or anything else for that matter, the Combi’s well insulated storage area means it offers a far superior storage solution compared to other structures such as garages and sheds.

The office/living space next to the storage area is also well insulated and ventilated, making it the perfect place to spend long periods of time. Whether you want to run a small business from it or simply spend your leisure time in it, the Combi is perfect even on the coldest of winter days.

Like many of our other garden rooms, the Combi features fully-insulated and ventilated walls, floor and roof.

Find your perfect garden room with Rubicon

Are you in the market for a quality, well-insulated garden room? Then you’re in the right place.

Here at Rubicon we’ve been designing, building and installing the highest-quality garden rooms since 2006.

Our approach, which includes a 20 year guarantee, has won us many awards, and as you can probably tell from the level of detail and information provided on our website, we are passionate about what we do.

So, if you want to invest in the very best garden room for your home, speak to us today!

Speak to Rubicon about your garden room project today

For more garden room information, inspiration and advice, read the Rubicon blog

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