Insulation for a better tomorrow
Loft Insulation

Loft Insulation

Pitched roofs

URSA 10 DIVERSO Loft Roll is for use as loft insulation in ventilated and unventilated cold roof spaces.

When used in new buildings or upgrading existing buildings URSA 10 DIVERSO loft insulation is the most cost effective way to reduce heat loss through the roof.

URSA 10 DIVERSO Loft Roll - thermal conductivity 0.044 W/mK.


URSA 10 DIVERSO Loft Roll is suitable for both ventilated and unventilated roof spaces and may be used in multiple layers to achieve very low U-values.

 To minimise the condensation risk a vapour control layer is required when insulating between the rafters at ceiling level, this can either be a polythene sheet (minimum 500g) or a foil-backed plasterboard. The use of the vapour control layer also creates an air barrier that helps to improve the air tightness of the building and so limit air infiltration. The type of roofing underlay should be carefully considered. Breathable membranes (Type LR) may not require roof space ventilation provided they are covered by BBA certification. More traditional bitumen or polythene based membranes (Type HR) require provision for eaves and ridge ventilation.

The plasterboard ceiling should be sealed at the junction with walls with plaster, adhesive or flexible sealant and around service penetrations using a flexible sealant.

As the loft space remains cold any water services, tanks, pipes and cisterns must be insulated to avoid freezing or condensation problems. Omit insulation underneath water tanks at ceiing level as heat from inside the building will help to prevent the tanks from freezing.

Recessed lighting should be in a sufficienctly large enclosure to ensure continuity of the insulation whilst still allowing heat to dissipate from the lamp. The fixture should be sealed to maintain a vapour tight ceiling and prevent unwanted air leakage.


URSA 10 DIVERSO Loft Roll is designed to fit between and over the roof timbers at joist (horizontal ceiling) level. The usual procedure for construction is;

  1. The roof trusses, sarking membrane (Type LR or Type HR), sarking boards (if applicable), tiling battens and tiles are all installed in the normal way in accordance with good practice and BS 5534.
  2. When using Type HR membranes there must be provision for roof space ventilation at the eaves and, if required, at the ridge also. Proprietary eaves ventilators should be used to maintain a clear path from the eaves vents into the roof void. Type LR menbranes may not require ventilation of the roof space provided they are covered by BBA certification.
  3. The plasterboard ceiling, incorporating a vapour control layer (500g polythene or foil backed plasterboard) is installed in the normal manner ensuring the VCL is correctly detailed and sealed.
  4. The first layer of URSA 10 DIVERSO Loft Roll, same depth as the joists, is laid between the joists.
  5. The second layer of URSA 10 DIVERSO Loft Roll is laid at right angles to the joists with all edges closely butt jointed.
  6. Ensure that the loft insulation continues over the wall plate to maintain continuity with the wall insulation and is tight against any eaves ventilator units.
  7. Ensure that any penetrations through the ceiling, especially if formed by following trades, are correctly sealed to ensure an air and vapour tight ceiling.

URSA 10 DIVERSO U-values


U-Value (W/m²K)

(600mm c/c)

U-value (W/m²K)

(400mm c/c)

2 x 200 0.12 0.12
3 x 150 0.10 0.10
3 x 200 0.08 0.08

For further information and more U-values see our technical brochure in the Documents section. Alternatively please contact URSA Technical Department.

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