SR211 Installed performance of ceiling insulation (2018)

This report presents a summary of a research project that compared the performance of ceiling insulation installed in the more traditional layout of friction fitting between ceiling framing with the performance of the same insulation installed over the top of framing (without insulation between the framing).

The project sought to determine the in situ performance of insulation installed using these two methods and to verify the results using laboratory measurements. The project was based on in situ measurements of thermal resistance in three ceilings using heat flux transducers.

One conclusion was that it is very difficult to avoid air exchange thermal bridging of insulation installed over the top of framing (without insulation between the framing). Another conclusion was that, when insulation is of a suitable thickness and is cut to a suitable width, it can be installed friction fitted so that the top of the insulation expands over the top of the framing, adding insulation to the frame and thereby reducing the extent to which it thermally bridges the rest of the insulation.