IZOTHERM COVER – Airtight Downlight Cover

IZOTHERM COVER is an airtight downlight cover which can reduce the amount of heat lost through the installation of downlights in ceilings by creating an air-tight seal around the lamp. Square and round versions are available.

Installing downlights can reduce the effectiveness of loft insulation by up to 30% so when trying to meet building regulations, or make a building as thermally efficient as possible, downlights can make all the difference.

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Ceiling down-lights present particular challenges for airtight design and continuity of the insulation layer.  An unprotected down-light within a ceiling represents a direct path for heated or conditioned air to pass from a habitable area into a cold attic space. Typically 25% of household energy wastage is lost through air leakage.

Down-lights are the source of a high proportion of air leakage in the home, each down-light can typically pass 20 cubic meters of conditioned air from the house into the attic space per hour at 50pa pressure and this air and energy are lost.

Our circular or square airtight downlight covers can offset this heat loss as they not only reduce air leakage, they also minimise condensation risk as draughts and air flow are blocked. Other benefits of downlight covers include acoustic insulation.


  • Reduce the risk of condensation, ensuring an effective moisture barrier
  • Reduce draughts
  • Improve air quality in living areas by reducing the air flow
  • Works in tandem with heat recovery systems (controlled air flow)
  • Can be fitted quickly and easily by anyone
  • Can help reduce noise entering and escaping through downlights
  • Meets the requirements for Building Regulations Approved Document E ‘Resistance to the Passage of Sound’

Solution and Application

The fitting of the Partel Downlight Cover dramatically reduces the volume of air leakage through each down-light and in fact at normal pressures totally negates it, therefore reducing draughts and energy loss.

The product is extremely easy to install and does not need to be installed by an insulation professional. Simply clear the area around the downlight after turning off the power. Making sure to clean the surface of dust and debris. After this affix, the downlight covers into place with the wires of the light fitting neatly through the gaps in the downlight cover. If preferred, water-based adhesive or airtight tapes to fix the downlight cover to the base. Loft insulation is then fitted over Partel Downlight Covers.

Gaps in ceiling insulation dramatically reduce its overall performance, typically insulation performance is reduced by 50% if only 5% of the ceiling area is not fully insulated.

The ‘Down-light Attic Seal’ restores ceiling performance to a similar level as a un-penetrated ceiling by allowing the insulation to be continuous and uninterrupted over the whole area of the ceiling saving energy and carbon emissions and COST!

IZOTHERM COVER 140 is the most popular solution as it can be easily fitted over most downlights. Squared sides allow for fitting close to the joist and there are four corner flanges for fixing in position.

Dimensions: 186 x 186 x 95 mm

IZOTHERM COVER 95 has been specially designed for use in sloped ceilings or fitting into a 100mm floor. The overall height of 95mm allows for fitting where height is restricted and maximum space for insulation is required.

Dimensions: 190 x 190 x 140mm