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Ceiling Insulation

  • Ceiling Insulation

    Ceiling Insulation

    There are three ways of installing ceiling insulation:

    Segment format

    This is the more traditional way of installing ceiling insulation whereby segments are fitted between the ceiling joists (timber supports holding up your ceiling). Pieces are cut to size and fit snuggly into place. The end result is the top of the joists are left exposed.  In many cases, new segments can be installed over the top of existing insulation which means you cover all of the ceiling joists in a similar way to a blanket product.

    While this system will work well, two issues arise from installing in this way. The first is that heat escapes through the exposed ceiling joists because wood is a poor insulator (i.e. there is an incomplete thermal envelope of insulation across the roof space). Secondly, the spacing between joists tend to be inconsistent in older homes meaning pre-cut product does not necessarily fit and requires a lot of cutting and fitting. The net result of these two issues is that a higher grade of material needs to be used to achieve the same level of overall performance as a blanket system. On the plus side leaving the ceiling joists exposed makes walking across the ceiling and accessing wiring and services a lot easier. There is also no gap between the product and the ceiling meaning less chance of heat loss if the insulation is disturbed.

    Blanket format

    Installing ceiling insulation in blanket format is the more modern method. It creates a very complete thermal envelope in the ceiling as the insulation is rolled out over the top of the ceiling joists essentially ‘blanketing’ the whole ceiling. The insulation comes in roll form rather than a pre-cut segment. With the blanket system, it is very important that the cavity under the blanket is filled at each end before the blanket is laid. Whilst more insulation material is used to insulate the ceiling, the grade of material can be dropped to achieve the same level of performance as segment insulation. The major disadvantage of blanket insulation is that it can become hazardous to walk across the ceiling as the joists are no longer visible. Secondly, because the insulation sits on top of the joists, and not hard against the ceiling (i.e. Gib or plasterboard) there is a pocket of air trapped between the insulation and the ceiling. If this pocket is compromised, for example when one portion is moved, then thermal performance drops. What this means in real terms, is it becomes more important the insulation is fixed up by tradesmen or others working in the ceiling space when they have finished.

    There are two types of ceiling insulation material types we install – polyester and fiberglass.

    Loose-Fill format

    Installing loose-fill insulation into ceilings has been a common method in NZ for many years. There are several different materials used for loose-fill ceiling insulation including paper-based, glass fibre and mineral wool. Loose-fill ceiling insulation generally does not perform or last as well as segment or blanket solutions. Loose-fill ceiling insulation can move within the ceiling cavity and will generally flatten within a shorter space of time due to the way that it is manufactured.

    Our advice is to only use loose-fill ceiling insulation if you cannot fit segment or blanket product. This may be due to a low pitch roof causing space restrictions for installers.  

    Loose-fill ceiling insulation is installed using a machine that blows the material mixed with air using a hose that extends into the ceiling cavity of the home. Care must be taken to ensure safety aspects such as clearances around downlights are maintained per the manufacturer's instructions. 


    At The Insulation Warehouse, we will install ceiling insulation over the top of downlights that are rated appropriately.  There are many imported products on the market that suggest they can have insulation laid over them.  Our team are trained to identify the marks that show a downlight can have insulation laid over them. If the appropriate markings are not present, then there are specific rules about how the insulation needs to be laid around the downlights.

    Our Service

    Our knowledge of insulation and the materials available stems from extensive and continued market research and from years of installing the materials that we sell. To get the best result you need the right advice on the correct product for your home and the best way to install it.

    We have installed insulation into over 15,000 houses. That’s the experience you need.

    We offer the convenience of a full installation service, phone and online ordering as well as a prompt delivery service, we also have a warehouse where products can be viewed, demonstrated and purchased.  We know existing and older houses, we know what works and we are happy to share our knowledge!

    As with all our products and services, when it comes to ceiling insulation, where possible, we aim to sell NZ made products and ensure our high quality standards are continuously met. 

    We will work with you to understand your underfloor insulation requirements and offer you specialist advice on the ceiling insulation to warm up your home.

    Contact us to discuss your ceiling insulation requirements.