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H1 Ceiling Insulation Solutions

H1 Ceiling Insulation requirements for new housing 

H1/AS1 applies to housing, and other buildings that are under 300 m². The schedule method of compliance requires roof construction R-values of at least R6.6 in all six climate zones. If using the calculation method, a minimum of R3.3 can be used. 

Exceeding the minimum R-value in ceilings can pay dividends elsewhere!

By using a construction R-value which is higher than that provided in the H1/AS1 table (i.e. in the case of ceilings insulation R6.6), it provides the ability to use a lower R-value on other elements or to adapt the home elsewhere such as using lower cost windows or using a higher glazing percentage to increase the amount of natural light provided to the home.

H1 solutions designed to help optimise your build


Our new glasswool insulation range includes a selection of R-values to provide builders, designers, and installers the opportunity to choose the best thermal performance for their project.

New R7.0 and R8.0 single layer ceiling insulation batts are designed to reduce heat transfer through the ceiling, improve comfort and enhance energy efficiency. Insulation batts are specifically tailored to fit the most common ceiling joist spacings for quick and easy single layer installation.

Our new R7.0 single layer insulation solution will provide a construction R-value of circa R7.05. The R8.0 ceiling insulation product is designed to provide an even higher level of performance where further optimisation across the build is either required or desired.

Our Ceiling batts are designed for use in cold roof applications where pitched roofs are insulated at ceiling level

Our glasswool insulation solutions play a major role in providing thermal, fire safety, acoustic performance and comfort with the built environment.

Ceiling Batt R7.0

330mm x 460mm x 1200mm


Ceiling Batt R8.0

330mm x 460mm x 1200mm

*only available in Earthwool Glasswool




If using a double layer ceiling insulation solution, the top layer of insulation must cover the truss chords to reduce thermal bridging. If using a single layer insulation solution, some insulation may need to be notched. The Knauf Insulation R7.0 and R8.0 Ceiling batts are designed specifically so that they do not require notching.

Significant savings in labour
Less complexity to demonstrate compliance
Increased thermal performance above and around timbers
Less material wastage


If using the schedule method of compliance, H1 provides an allowance to reduce the construction R-value to R3.3 for the first 500mm from the inside of the top plate. The following tables  illustrate how this can be achieved using the R7.0 and R8.0 ceiling batts compressed into the eaves in conjunction with the use of a barrier to maintain the required 25 mm air gap between insulation and roof underlay and achieve R3.3 compliance.

Heel Height (mm)  R-Value Roof Pitch Material Performance
90 R7.0 20 R4.1
90 R8.0 20 R4.7
105 R7.0 20 R4.5
105 R8.0 20 R5.0

The above values have been calculated using the BRANZ home insulation guide 6th edition.

Heel Height (mm)  R-Value Roof Pitch Material Performance
90 R7.0 25 R4.5
90 R8.0 25 R5.1
105 R7.0 25 R4.8
105 R8.0 25 R5.4

The heel depth has been calculated based on the table above. Greater heel depth will increase the thermal calculation.

Ceiling insulation for your project