Best wall insulation for summer houses & garden offices

Best Wall Insulation For Summer Houses

See the best insulation to keep your summerhouse or garden office cool in the summer and warm in the winter….

Best wall insulation for summer houses & garden offices

Summerhouses, garden offices and gardens pods are now very popular as more people work from home as they offer additional space away from the main living area for work and relaxing.

People also use them all year round which means not only do they need to be kept cool in the summer but more importantly warm in the winter months.

So if you are looking to build your own summerhouse and are in the process of researching the topic then you may be wondering what is the best wall insulation for a summerhouse?

The best wall insulation for summerhouses and garden offices is loose-filled cellulose, hemp, cork and sheep’s wool insulation as they are all made from environmentally friendly sources and have fire, mould and insect resistant properties which make them durable.

The cost, durability and R-Value (the level of insulation from heat and cold) do differ slightly between products which we will go into in more detail along with the pros and cons of each type of insulation.


  1. Best way to insulate a summer house
  2. Loose filled cellulose insulation
  3. Hemp insulation
  4. Cork insulation
  5. Sheep’s wool insulation
  6. Rock wool insulation

Best way to insulate a summer house

There are a number of things to look out for when choosing the right insulation for your needs – how sustainable the product is, the overall cost, how durable it is and the thermal rating (known as the “R-Value or rating).


The best insulation for any accommodation whether it’s a permanent home, summerhouse or garden office should be made from a sustainable source which means its composed of recycled or natural non-toxic materials.

And is getting easier to buy eco-friendly insulation as more companies produce sustainable products in response to consumer demand and government policies


When starting any project it’s good to have a budget in mind so you can keep costs down and find the cheapest way to insulate your summerhouse or garden office.

As you would expect Some insulation products are cheaper than others due to the materials it’s made from and how abundant the source is.


If you are building a summerhouse you want insulation to keep it cool in the winter and if you are using it all year round warm in the winter.

This means choosing insulation that is durable and is resistant to things like mould, insects fire and even sounds if you want to keep the noise levels from outside to a minimum.


The R-Value, also known as R-Rating is a measure of how well a layer of insulation (usually per 1 inch of thickness) resists the conductive flow of heat. The higher the R-value, the greater insulation performance.

The R-value is usually provided by the manufacturer which should be on the product labelling.

You can find out more about insulation ratings here.

1. Loose filled cellulose insulation

Best wall insulation for summer houses & garden offices - loose filled cellulose

Cellulose insulation for commercial purposes is made from recycled paper such as newspapers, cardboard and other types of waste material. It’s then treated with boric acid to make it fire, mould and insect resistant.

As it’s loose as opposed to hardboard it can then be blown through drill holes in the plaster or drywall to densely pack the cavity between the inner and outer wall.

The fact that loose filled cellulose insulation is made from plant-based material and recycled paper makes it not only one of the most eco-friendly insulation materials on the market but it’s also comparatively the cheapest way to insulate your garden office or summer house.

R-Value – R 3.5 per inch of thickness.


  • Eco-friendly (made from recycled materials)
  • Durably (treated with Boric acid)
  • Cheaper than other types of insulation
  • Can settle around awkward shapes


  • Creates a lot of dust when installed (mask is needed)
  • Can get a little messy
  • Can produce air pockets over time trapping both cold and hot air, passing it into the structure.

You can buy loose-fill cellulose insulation from Amazon at the latest price here.

2. Hemp insulation

Best wall insulation for summer houses & garden offices - Hemp insulation

Hemp insulation for garden and summer houses is another good alternative to cellulose. Its made from hemp wool which is derived from the strong woody fibre produced by hemp plants.

It comes in either insulation batts (also known as slabs) which are rectangular sheets or insulation boards which come in larger square sections, measuring around 3.5-5.5 inches.

Hemp insulation is completely compostable, renewal and non-toxic and is also a very durable product. It also has a slightly higher R-value than cellulose making it a more heat efficient insulation.

However, it is slightly more expensive per square metre than loose-filled cellulose.

R-Value – R-3.69 per inch of thickness

Price – £15-20 per square metre


  • Eco-friendly (reusable, recyclable, non-toxic)
  • High R-Value
  • Resistant against moulds and bacteria


  • Can be prone to damp
  • More expensive than cellulose

3. Cork insulation

Best wall insulation for summer houses & garden offices - Cork insulation

Cork insulation is manufactured using bark from the Cork oak tree (Quercus Suber) and made into sheet boards or loose-filled granules which is used for insulating around awkward objects.

As it’s made from an organic material it’s a 100% natural material making it environmentally friendly and compostable. It also has natural soundproofing properties and is very resistant to both mould and damp making it durable and a good choice of insulation for walls, floors and ceilings.

However, it is slightly most expensive than other eco-friendly alternatives, such as cellulose and hemp.

R-Value – R 3.6 – 4.2 per inch of thickness


  • Good sound insulation
  • Eco-friendly
  • Durable
  • Cork granules good for insulating around akward objects


  • More costly than other eco alternatives

You can buy cork insulation from Amazon at the latest price here.

Related articles:

4. Sheep’s wool insulation

Best wall insulation for summer houses & garden offices - sheep's wool insulation

Sheep’s wool insulation is manufactured from, you guessed it, sheared sheep’s wool. It’s probably the most environmentally friendly type of material on the market as it doesn’t take energy resources to produce, and is recyclable and compostable.

Sheep’s wool has very high insulation properties and has the highest R ratings of all the products on the list. It is also very durable as its resistant to fire, mould and tearing and has a natural elasticity making it easy to install.

However, sheep wool insulation is one of the most expensive types of insulation on market.

R-Value – R 13-19 per inch of thickness


  • High R rating
  • Durable
  • Easy to install


  • More costly
  • Has to be treated with chemicals to ensure resistance

You can buy sheep’s wool insulation from Amazon at the latest price here.

5. Rockwool insulation

Best wall insulation for summer houses & garden offices - Rock wool insulation

Rockwall insulation is made from basalt volcanic rock and recycled slag, which is a by-product of steel and copper production. These materials are then melted together to form rock will fibre (an almost candy-floss like material) and pressed into rolls and sheets for insulating walls, floors and roofs.

It’s naturally moisture resistant when means it retains its insulation properties when wet, has sound-proofing qualities, reducing the outside noise and will not burn until its reaches over 1800F.

However, protective clothing and gear must be worn when installing this type of insulation as the microparticles it produces can be harmful to humans when inhaled.

R-Value – R 2.2 – 4.5 per inch of thickness


  • Heat-resistant
  • Moisture resistant
  • Sound-proof


  • Protection equipment is needed
  • Not as environmentally friendly

You can buy Rock wool insulation from Amazon at the latest price here