Types of Insulation 

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Which material is best and what thickness do I need?

Insulation roll, insulation board, fiberglass insulation, Celotex, Kingspan! The topic of insulation materials and the types of insulation available, can sometimes leave a level of confusion, which material is best and what thickness do I need?

If you have every wandered down the insulation aisle at b&q or wicks, glaring at the 4 x 8 sheets and shrink-wrapped rolls, you will know what I mean.

Knowing about insulation is going to help you determine which garden room build specifications will require more heating to maintain a comfortable environment and ultimately which is going to have poor energy efficiency and higher ongoing energy costs. A usable space every day of the year is one of the ways you ensure you gain maximum value from your investment.

Brand or Material?

Often with insulation the distinction between an insulation material and its brand names gets confused.  A popular example of this would be Kingspan, most people will probably have heard of Kingspan as they are one of the most well-known insulation brands globally. Kingspan, to their credit, have become a bit like Sellotape and Hoover over the years in that their brand name has become generic to the product.  However, Kingspan is an insulation brand an they manufacture mostly polyurethane insulation, as do other brands such as Celotex and Xtratherm. 



For most insulation material there are also abbreviation associated with the material and in some cases more than one abbreviation to distinguish between two slightly different versions, that are close in chemical composition and thermal performance.  Sticking with the example of Kingspan, they manufacture polyurethane insulation, for which the abbreviations are PUR and PIR.

 Common Types In Garden Room Construction

Below we have some examples of commonly used materials in insulated garden room construction, you can see some associated brand names and also the industry abbreviations.  Essentially this will help you to determine the insulation material from the brand or abbreviation and untimely understand the pros and cos of that material for garden building construction.

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Glass & Mineral Wool Insulation

Abbreviations: None.

Brands: Rockwool, Knauf, Isover.

Appearance: Available in rolls or flexible slabs, this material is soft and spongy like the inside of a quilt.

Thicknesses: 25mm – 200mm typically.

Pros: + Lower cost insulation material + Some grades have excellent acoustic properties + Breathable + Easy to fit.

Cos: - Performs less well than other as an insulation material for the same thickness of material.

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Wool Fleece Insulation

Abbreviations: None.

Brands: Thermafleece.

Appearance: Available in rolls and also slabs, this material is denser than mineral wool, soft to touch and has the appearance of wool.

Thicknesses: 50mm – 140mm typically.

Pros: + Medium cost insulation material + Some grades have excellent acoustic properties + Breathable + Easy to fit + Natural product.

Cos: - Performs less well than other as an insulation material for the same thickness of material.

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Multi Foil Quilt Insulation

Abbreviations: None.

Brands: Ybs, Superfoil.

Appearance: Available in rolls with a silver reflective finish, thin quilt material on the inside.

Thicknesses: 10mm – 40mm typically.

Pros: + Medium cost insulation material + Easy to fit + Assists with vapour control.

Cos: - Normally used as an addition to other existing insulation materials and not as the only insulation layer in a building.

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Polystyrene Insulation

Abbreviations: XPS, EPS.

Brands: Jablite, Cellectra, Kay-Metzeler.

Appearance: Available in ridged boards in many colours, white, grey and blue. Light weight to hold and looks like it is constructed from thousands of small balls.

Thicknesses: 10mm – 200mm typically.

Pros: + Medium cost insulation material + Performs well as an insulation material when compared to other materials of the same thickness + Used in SIP panels.

Cos: - Needs cutting to fit which increases install times, poor comparable fire performance.

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Polyurethane Insulation

Abbreviations: PUR, PIR.

Brands: Kingspan, Celotex, Xtratherm.

Appearance: Available in ridged boards in an off white core colour. Sometimes with a foil face or felt face. Denser than polystyrene insulation.

Thicknesses: 50mm – 200mm typically.

Pros: + Performs very well as an insulation material when compared to other materials of the same thickness + Used in SIP panels.

Cos: - Medium to high cost insulation material - Needs cutting to fit which increases install times.

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Vacuum Insulation panel

Abbreviations: VIP.

Brands: Kingspan, Vacupor.

Appearance: Available thinner ridged boards with a silver foil exterior finish.

Thicknesses: 20mm – 60mm typically.

Pros: Performs exceptionally well as an insulation material when compared to other materials of the same thickness.

Cos: - Very high cost insulation material - Can not be cut to fit as this damages the vacuum integrity - difficult to install when following standard construction techniques.



Our insulated garden room build specification include the use of polyurethane insulation in the floor and roof construction and polyurethane SIPs in the wall constructions. The thicknesses that we use provide low U values and an excellent overall insulation envelope for any garden room, office or studio.

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More Information


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U values are how we measure and compare the insulation performance of materials. The U values are figures defined by laboratory tests carried out by the insulation manufacturers and then published. Knowing the U values of a range of insulation materials helps us to understand which materials will work best to keep our internal spaces warm in the winter and cooler in the summer. When it comes to garden rooms, knowing the U values of the insulation used and the overall u values of the floor, wall and roof constructions, which can be calculated, allows customers to compare different garden buildings to determine which will perform the best thermally.

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Insulated garden rooms

There are many insulated garden rooms available on the market, but it is the type of insulation and the thickness of the insulation used that matters. As we offer class leading levels of thermal insulation, we can comfortably discuss and disclose our insulated building specifications. Knowing this will provide you with the confidence needed that you new garden room will be usable 365 days a year.

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Energy efficiency

In most cases insulation type and thickness are key factors to consider when choosing a garden room supplier, as these factors contribute to the overall energy efficiency performance of the garden building. With many different material types, claims on energy efficiency performance and the possibly confusing world of u-values, we decided to return to one of our completed garden rooms, to find out how one of our previous builds performs in a real word environment.

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Build specification

We sometimes hear comments comparing a modern insulated garden room to no more than an insulated garden shed, for our insulated garden buildings that really isn’t the case. We don’t supply the cheap garden rooms that you can find made from shed like materials, instead we use residential specification materials that you would find in the build specification of any newly build home. This includes the insulation, main structure, windows and doors, roof weather proofing and external cladding among others. This results in quality buildings, that have a solid feel and will undoubtedly last the test of time. This approach does mean we are not the cheapest garden building supplier, however we do offer the most value.