Typical Construction
A pitched roof of timber trussed rafters with tiles or slates on batten and sarking felt underlay, on sarking board. This incorporates a ventilated roof space and plasterboard ceiling below.
Multi Roll is installed in two layers, the first layer between and the second layer across the joists. This method minimises thermal bridging through the ceiling joists.

Installation
The first layer of Multi Roll is laid between the joists to the same depth.

1. The insulation should be taken over the wall plate to link up with the wall insulation. This should complete before the eaves ventilator is fixed, during installation of the roofing underlay.
2. The second layer of Multi Roll is laid at right angles to the ceiling joists, with all edges butt jointed. The insulation should be pushed up tight against the eaves ventilator, taking care not to block the ventilation airpath.

The table below gives U-values for typical constructions insulated with Multi Roll.

Product Information

• Multi Roll 44 & Multi Roll 40 have a thermal conductivity of 0.044 or 0.040 W/mK respectively

Fire Performance

• Multi Roll is classified as Euroclass A1 BS EN ISO 13501-1

Typical Construction

It is possible to install insulation between rafters where either traditional impermeable sarking membranes or modern breathable membranes are being used as the roofing underlay. The U-values quoted on the table opposite are valid for both types of construction.

A pitched roof of timber rafters with tiles or slates on battens and counter battens on underlay. The space between the rafters is fully insulated with glass mineral wool.

Note: Where an impermeable sarking is specified, such as type F1 bitumen felt, a minimum 50mm wide ventilation path must be maintained between the insulation and the sarking felt.

Installation

1. Breather membrane underlay is pulled taut and laid directly over the rafters. 50 x 32mm counter battens are nailed into the rafters with minimum penetration and 38mm into the rafter. Tiling battens are nailed into the counter battens. Finally, the roofing tiles or slates are fixed, to the manufacturer’s recommendations.
2. Superglass Timber & Rafter Batt 32 is simply friction fitted (in layers if necessary) to fully fill the space between the rafters.
3. All layers should be closely butt jointed. The Timber & Rafter Batt 32 is normally fitted from below, once the roof is weather tight.
4. If installed in layers, ensure joints are staggered.

Product Information

• Timber & Rafter Batt 32 has a thermal conductivity of 0.032 W/mK

Fire Performance

• Timber & Rafter Batt 32 is classified as Euroclass A1 BS EN ISO 13501-1.

Typical Construction

A pitched roof with existing loft insulation. Earlier Building Regulation requirements were achieved with various thickness of loft insulation that ranged from 25 to 150mm thickness. This insulationc can still be found in existing properties.

An overall insulation thickness of at least between 270 –300 mm is now recommended when upgrading the thermal insulation of an existing roof.

The table opposite gives the U-values achieved by adding Multi Roll to existing ceiling insulation

Installation

1. In most pitched roofs, any existing insulation is likely to be between the ceiling joists. Where the existing insulation reaches the top of the joists, Multi Roll can simply be laid over the existing joists and insulation. Where the existing insulation is below the joist height, top-up the insulation so it reaches the top of the joists, and then add a further 170mm thickness over the joists.
2. Take care not to block the eaves ventilation. If the new insulation covers the top of the eaves ventilators, install new extended ventilators before installing the insulation
3. Seal any gaps or holes in the ceiling to the loft to limit air leakage into the loft from the dwelling. This is particularly important to the ceiling above the bathroom.

Thermal Information

• Multi Roll 44 & Multi Roll 40 have a thermal conductivity of 0.044 or 0.040 W/mK respectively

Fire Performance

• Multi Roll 44 & Multi Roll 40 Roll are classified as Euroclass A1 to BS EN ISO 13501-1