EWI to New Manchester Window

Detail for a triple glazed replacement Manchester window and associated junction with EWI to wall above. Designed to help preserve the character of an existing Manchester window while reducing thermal bridging and improving air-tightness.

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EWI to Door Threshold

Detail for external insulation below ground, where an existing door with step access is to be retained. Used where the existing internal floor void is inaccessible by usual means, and it is not possible to lift the whole internal floor. Use of a granular insulating infill below an existing concrete stone step increases the thermal efficiency of the building envelope, and reduces cold bridging through the existing door threshold.

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EWI over large step in brickwork

Detail showing woodfibre external wall insulation carried around a large brick projection on an external wall. Designed to ensure a consistent depth of insulation over the whole external wall ensuring a continuous thermal envelope.

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EWI to clipped eaves with hidden gutter

A detail for external wall insulation to deal with potential cold bridging at eaves; where new or existing loft or roof insulation meets external wall insulation.

Where there is a limited overhang at the existing eaves, an integral hidden gutter is required to enable water run-off; to facilitate this the EWI is brought up to form a verge, which is then capped with a stainless steel gutter.

Target values: Psi Value: 0.0778 W/mK

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EWI to clipped eaves with room in roof (insulation to rafters)

A detail for external wall insulation to deal with a potential cold bridge at eaves where new insulation to rafters meets external wall insulation. To be used where there is an existing room-in-roof or loft/roof insulation to be applied to existing rafters.

Where there is a limited overhang at the existing eaves, an integral gutter is required to enable water run-off. The EWI is used to form a verge, which is then capped with a Stainless steel gutter.

Target values:

Target Roof U-Value: 0.18 W/m²K Target Wall U-Value: 0.18 W/m²K

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EWI to soffit eaves by room-in-roof

Detail for external wall insulation up to existing soffit eaves, including new loft insulation to an existing room-in-roof. This detail is designed to prevent a potential cold bridge at eaves where the loft or roof insulation meets external wall insulation at a soffit deep enough to accommodate new EWI beneath it. Loft and external wall insulation to be installed from outside.

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EWI- window to eaves with soffit

Detail for external wall insulation to an overhanging soffit above a window to be replaced. This detail shows new external wall insulation to meet new loft and roof insulation directly above the new window to prevent a potential cold bridge at the building eaves.

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EWI to eaves, flush with window head

Detail of external wall insulation to eaves; where existing overhanging eaves meet the head of an new replacement window fitted into depth of new EWI. Detail for insulation of space above the existing soffit, up to the underside of new phenolic eaves insulation. Designed to deal with potential cold bridge at eaves; where loft or roof insulation meets cavity or other wall insulation. New EWI to join to overhanging eaves insulation directly above window.

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EWI to Existing Parapet Eaves

A detail for external wall insulation, designed to deal with potential cold bridge at eaves; where new or existing loft or roof insulation meets external wall insulation. Where there is a limited overhang at the existing eaves, an integral gutter is required to enable water run-off. Here the EWI is brought up to form a verge, which is then capped with stainless steel flashing and associated gutter.

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EWI to Flush Flat Roof with Gutter

Detail for external wall insulation up an existing external wall, up to an existing flat roof where no additional insulation is to be added to the existing roof buildup. To finish the EWI and address water run-off: a single piece stainless steel gutter is provided to cap the new EWI; and a new membrane lapped from the existing roof over the top of the EWI beneath the rendered finish.

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EWI to new door- Threshold and Head

Section detail for external wall insulation fitted around a new replacement door with a new timber frame box surround. Door and surround installed as part of EWI installation works with insulation to reveal board and door frame.

The existing door threshold is reinforced with steel angle for structural support, with additional structural insulation over extruded polystyrene suitable for below ground insulation.

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EWI to New Door with Brick Nib- Retrofitted

Detail for external wall insulation to jamb of a new door, installed or retrofitted into an existing wall with a single brick nib; (detail presumes the new door fixed in place on the internal face of the brick). To prevent potential cold bridging at the existing opening, insulated external wall board is proposed over the existing wall to the door reveal.

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EWI to new door - Threshold and head with step

Detail for external wall insulation (woodfibre and below-ground), and the installation of a new insulated doorset and insulated reveal; to an existing opening; above an existing ground level with stepped access.

The new door is installed in a softwood timber frame; with the threshold reinforced with steel angles for structural support, with additional structural insulation over extruded polystyrene insulation board, suitable for below ground insulation.

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EWI to existing door with steps- threshold detail

Detail of External wall insulation installed below an existing threshold to ground, or minimum 300mm below internal floor level. XPS insulation used to reduce thermal bypass and mitigate heat loss through the existing wall beneath the door threshold.

Where there are existing steps to threshold, these should be carefully removed to allow installation of external wall insulation and/or perimeter floor insulation followed by re-instatement or replacement as required.

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EWI verge detail at flat roof

Detail for the junction of an external wall insulation system with an existing flat roof, where no additional insulation is applied to the existing roof buildup. To retain the existing parapet, the EWI system is carried up beyond the existing roof level to form a new parapet detail.

A new waterproof membrane is lapped under the existing mastic roof trim, and carried over the EWI to prevent water ingress into the woodfibre insulation system. New flashings are used to cap the top of the EWI parapet, and are glue fixed to the membrane beneath.

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EWI Perimeter insulation to footings

Perimeter insulation detail for external wall insulation down to below ground level. Detail for junction between EWI and XPS perimeter insulation for below ground use, providing 600mm maximum insulation below the depth of the internal floor level.

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EWI Plinth Insulation to below ground

Detail for an external wall insulation plinth detail to just below ground level. Intended to ensure water-tightness and prevent thermal bridging to zones under an existing floor by providing continuous insulation down to ground level.

Woodfibre EWI to stop a minimum of 300mm from the external ground level, with XPS insulation fixed using adhesive bond to carry down to below ground level, a minimum 300mm below the internal floor level of the building.

Target Values: 0.2 W/m2K for whole construction.

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EWI Recessed Plinth to just below ground

Detail for external wall insulation plinth to ground, where the internal floor of the building to be retrofitted is solid beneath the internal finished floor level. EWI is carried down to 300mm minimum below internal floor level to prevent cold bridging, but stopped short of external ground level.

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EWI to just below ground with plinth and ventilation detail

Detail for external wall insulation to below ground floor level, with a periscopic vent and air-brick installed through EWI to ventilate a basement or cellar. Required where existing air-bricks to a sub-floor space/void would be blocked by the installation of External or Internal wall insulation. Periscopic vents should ensure continued clear air-path to sub-floor, to ensure adequate ventilation.

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EWI with Recessed Plinth and Periscopic Ventilation

Variation on an external wall insulation detail for periscopic ventilation to a below ground cellar; where the building's internal floor can be insulated to reduce cold bridging through the external wall and below ground. For this reason the EWI to the external wall need not extend below ground level.

A recessed plinth is to be formed with 180mm perimeter insulation below where the 200mm thick woodfibre EWI stops with a minimum of 300mm above ground level; in order to protect the woodfibre insulation from damp and water ingress. A 20mm step provides a feature course as the EWI carries around the perimeter of the building.

A ventilation air brick and sleeve is required where existing air-bricks to sub-floor void will be blocked by floor insulation works. Periscopic vent should ensure continued clear air-path to sub-floor, to ensure adequate ventilation. Insulation to suspended timber floor.

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EWI perimeter+sub-floor insulation with controlled ventilation

Detail for insulation to a ground floor and sub-floor, where the existing internal ground floor void is inaccessible, or it is not possible to lift the whole floor.

To allow the existing ground floor finish to be retained: a granular insulation infill is proposed to prevent heat loss through the floor, with perimeter insulation to footings, used to to prevent cold bridging through the external wall, and the ingress of damp and mould.

The sub-floor ventilation is used to ensure a reduced risk of condensation and humidity build up within the void, using a small humidity controlled fan. (This system can also be modified with temperature and humidity monitoring systems below the floor; as well as additional personal controls for the ventilation fan.)

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EWI stop at ground for insulated timber floor

Detail for external wall insulation, with a stop a minimum of 300mm above external ground level. Designed to prevent thermal bridging to zones under an existing floor, in conjunction with an internal insulated suspended timber floor; accessible from above or below.

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EWI to lower pitched, or flat roof

Detail for external wall insulation to the top of an existing flat or gently sloping, lower roof, projecting from an external wall to be insulated. For use where the existing flashing to the projecting roof is to be retained, but with new flashing over the junction with EWI and existing roof.

Detail also indicates junction between woodfibre insulation system and insulation suitable for splash zone. EWI system is cut to slope of lower/projecting roof and flashed over to prevent any gaps in insulation.

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EWI to lower roof sloping along external wall.

Detail for external wall insulation to an existing roof, either pitched or sloping along the external wall to be insulated.For use where the existing roof tiling or other finish is to be retained, meaning perimeter junction of EWI needs to be sealed and flashed along the length of the junction with the roof.

Detail also indicates junction between woodfibre insulation system and insulation suitable for splash zone. EWI system is cut to slope of lower/projecting roof and flashed over to prevent any gaps in insulation.

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EWI to lower roof sloping away from external wall

Detail for external wall insulation to the top of an existing sloping lower roof, projecting from an external wall to be insulated. For use where the existing flashing to the projecting roof is to be retained, but with new flashing over the junction with EWI and existing roof.

Detail also indicates junction between woodfibre insulation system and insulation suitable for splash zone. EWI system is cut to slope of lower/projecting roof and flashed over to prevent any gaps in insulation.

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EWI corner detail - change of material around corner

Detail of junction between Woodfibre and EPS foam external wall insulation at an external corner; with an appropriate seal detail at junction. EPS external wall insulation to be used where reduced depth insulation required.

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EWI to external corner- standard corner detail

Standard detail for woodfibre external wall insulation carried around corner.

Target Values: Psi value: 0.05194 W/mk

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EWI carrying round internal corner

Standard detail for external woodfibre wall insulation system carrying round an internal corner.

Target Values: Psi Value: -0.1977 W/mK

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EWI corner detail to perpendicular wall, with opening for door

Detail for external wall insulation system to a perpendicular wall, with an opening for a new door/window. This detail applies where the opening size may be adjusted in order to accommodate the new EWI to the existing wall.

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EWI stopping at external corner

Detail for woodfibre external wall insulation system stopping at the external corner of a perpendicular wall. Capped by a single layer of woodfibre insulation with render over, and sealed at junction with existing wall.

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EWI stopping at internal corner

Detail for woodfibre external wall insulation stopping at an internal against a perpendicular wall. corner.

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EWI around meter box

Detail for external wall insulation to new/existing meter box. This detail presumes the application of internal wall insulation, on the interior side of the wall opposite the meter box at a future date to prevent cold bridging, but does not require the installation of both external and internal insulation at the same time.

Because of the the need to keep a required distance around gas meters and pipes as part of EWI works, it is recommended that Internal wall insulation be installed at a future date to the internal wall behind the existing meter. A 300mm overlap to the EWI on the external wall combined with insulation works to the existing ground floor is expected to mitigate cold bridging caused by carrying the EWI around the meter box.

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EWI around meter box with perimeter insulation

EWI detail around existing meter box, where perimeter insulation has to be provided around the base of an external wall, due to excavation work around new/existing gas pipes, in order to mitigate cold bridging.

Because of the the need to keep a required distance around gas meters and pipes as part of EWI works, it is recommended that Internal wall insulation be installed at a future date to the internal wall behind the existing meter. A 300mm overlap to the EWI on the external wall combined with insulation works to the existing ground floor is expected to mitigate cold bridging caused by carrying the EWI around the meter box.

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EWI stopping at party wall

Detail for external wall insulation up to, and stopping at, a party wall boundary. Designed for use where the external wall between properties is continuous without stepping.

Target values: Psi Value: 0.352 W/m2K

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EWI stop at step-in on wall or at boundary.

Detail for external wall insulation, to stop at a step-in on an existing external wall.

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EWI over small step in brickwork

Detail for external wall insulation carrying around a half-brick step-in on an external wall.

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EWI to pitched roof with extended verge

Detail for external wall insulation to the underside of a pitched slate roof with an extended verge. Used to retain the character of the existing pitched roof and verge after installing EWI system. Where the existing pitched roof does not cover the additional depth of the EWI the existing roof is subsequently extended over the new insulation.

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EWI to pitched roof, extended verge (existing roof supported)

Detail for external wall insulation to the underside of a pitched slate roof with an extended verge. Designed to retain the character of the existing verge. In this case,where a pitched roof needs to be extends beyond 200mm to provide enough shelter for insulation. New fascia board fixed to front face of EWI to match existing.

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EWI to slate roof verge with existing overhang

Detail for EWI up to an existing overhanging verge with sufficient overhang to take depth of EWI. Installation of a new timber fascia board over EWI at junction with roof. Mastic seal at all edges, existing membrane below eaves to be re-dressed over insulation.

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EWI to flashing at verge

Detail for external wall insulation up to a pitched roof verge without sufficient depth to cover depth of insulation. To be used where it is not possible to extend the existing roof verge over the insulation, and so a new cap flashing must be installed at the junction between roof verge and external wall insulation.

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EWI to pitched roof with flashing at verge over insulation.

Detail for EWI up to an existing verge on a pitched roof. Where it is not possible to extend the existing roof verge over the insulation, a new Stainless steel mini-gutter is installed, at the junction between the roof verge and the new external wall insulation.

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EWI to top of monopitch verge

EWI detail for insulation running up to the top of an existing monopitch verge and forming a new parapet with stainless steel cap flashing. New lead flashing to junction of roof with insulation and stainless steel cap flashing over insulation and render.

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EWI to top of monopitch, meeting verge

EWI detail for insulation running up to the top of an existing monopitch verge; forming a low parapet with stainless steel cap flashing. New lead flashing to junction of roof with insulation and stainless steel cap flashing over insulation and render. New EWI verge to side of parapet to aid water run-off.

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EWI insulation with new window.

This detail is designed to reduce thermal bridging and improve air-tightness whilst spreading the structural load of new window on EWI, and maximising glazed area.

The timber box also acts as self-finished internal reveal. (May be painted/ varnished as required). This detail is designed with the intention that the window and box be installed prior to the external wall insulation system.

Target values: Thermal Performance (overall u-value) : 0.79W/m2K. Cill Psi value: 0.066 W/mK Lintel Psi Value: 0.00023W/mK

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EWI insulation with new window (Plan)

Detail for a new window with a timber frame, to be mounted into external wall insulation, in place of an existing window. This detail is designed to reduce thermal bridging and improve air-tightness whilst spreading structural load of new window and maximising glazed area.

The timber box also acts as self-finished internal reveal. (May be painted/ varnished as required). This detail is designed with the intention that the window and box be installed prior to the external wall insulation system.

Target values: Thermal Performance (overall u-value) : 0.79W/m2K. Cill Psi value: 0.066 W/mK Lintel Psi Value: 0.00023W/mK

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New window to EWI, retrofit installation

Detail for a new window with a timber frame, to be mounted into external wall insulation, in place of an existing window. This detail is designed to reduce thermal bridging and improve air-tightness whilst spreading the structural load of new window on the EWI, and maximising glazed area.

The timber box also acts as self-finished internal reveal. (May be painted/ varnished as required). This detail is designed so that the window and box can be installed after the external wall insulation system is in place.

Target values: Cill Psi value: 0.045 W/mK. Lintel Psi value: 0.059 W/mK.

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New window to EWI, for single brick reveal (section)

Detail for a new window with a timber frame, to be mounted into external wall insulation, in place of an existing window. Used where a single brick reveal means the original window was originally sat behind, and larger than, a structural opening in the outer face of an existing masonry wall.

This detail is designed to reduce thermal bridging and improve air-tightness whilst spreading structural load of new window and maximising glazed area. The timber box also acts as self-finished internal reveal. (May be painted/ varnished as required).

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New window to EWI, for single brick reveal. (plan)

Detail for a new window with a timber frame, to be mounted into external wall insulation, in place of an existing window. Used where a single brick reveal means the original window was originally sat behind, and larger than, a structural opening in the outer face of an existing masonry wall.

This detail is designed to reduce thermal bridging and improve air-tightness whilst spreading structural load of new window and maximising glazed area. The timber box also acts as self-finished internal reveal. (May be painted/ varnished as required).

View in conjunction with Section detail: "New window to EWI, for single brick reveal (section)"

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New window to EWI, for single brick reveal, retrofitted

Detail for a new window with a timber frame, to be mounted into external wall insulation, in place of an existing window; in this case: retrofitted from the outside after the insulation is installed.

Used where a single brick reveal means the original window was originally sat behind, and larger than, a structural opening in the outer face of an existing masonry wall.

This detail is designed to reduce thermal bridging and improve air-tightness whilst spreading structural load of new window and maximising glazed area. The timber box also acts as self-finished internal reveal. (May be painted/ varnished as required).

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Options for new window to EWI, for single brick reveal, retrofit

To be read in conjunction with: "New window to EWI, for single brick reveal, retrofitted" (or EW01-W-RP-FR).Two alternative options for new window installation to a single brick reveal; with either no subframe or reveal; or with a timber studframe support and stainless steel reveal.

Used where a Victorian single brick reveal means the original window was originally sat behind, and larger than, a structural opening in the outer face of an existing masonry wall.

This detail is designed to reduce thermal bridging and improve air-tightness whilst spreading structural load of new window and maximising glazed area. The timber box also acts as self-finished internal reveal. (May be painted/ varnished as required).

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New window to EWI, reduced width due to corner (Plan)

Detail for new replacement window, fitted into external wall insulation, where the existing window is fitted to an external corner, and requires a reveal box with a reduced width .

A variation on the "New window to EWI, retrofit installation" detail where the new window is mounted onto a timber box and installed into a finished EWI installation. This detail modifies the box design to allow for the corner detail shown.

Target Values: Cill Psi value: 0.045 W/mK Lintel Psi value: 0.059 W/mK.

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Retained window to EWI, with sloping cill

Detail for external wall insulation to an existing window, to be retained, with an existing sloping cill.This detail allows for the profile of the sloping cill to be retained whilst improving the thermal efficiency of the building envelope by allowing insulation to be carried up to the window frame underneath the tiled cill. Used in instances where the original window jamb is reduced in depth.

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Retained window to EWI, thin jamb (section)

Detail for external wall insulation to an existing window to be retained, where the existing window sits up against the inside edge of existing window jamb. This detail proposes phenolic foam to be used where the existing window jamb and head is too narrow for standard 40mm woodfibre reveal boards.

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Retained window to EWI, thin jamb (Plan)

Detail for external wall insulation to an existing window to be retained, where the existing window sits up against the inside edge of existing window jamb. This detail proposes Aerogel insulation to be used where the existing window jamb and head is too narrow for standard 40mm woodfibre reveal boards.

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EWI to existing window, retained, with secondary glazing install

EWI detail to head and jamb of an existing window (single glazed or other) where a a secondary double glazed window unit is to be added to the inside face of the window for improved thermal performance.

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EWI Feature Course

Detail for a feature course within external wall insulation to an existing wall. Designed to preserve the character of an existing feature course detail that would otherwise be hidden by the application of EWI.

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EWI Service duct within Insulation - flush face

A detail demonstrating a recessed, insulated services run for an exterior wall, within an external wall insulation system. Used where service runs such as soil pipes or ventilation ducts are to be contained within the depth of the insulation, meaning an accessible service void should be created.

Prior to work carry out a visual inspection of the services to be enclosed within service void, to ensure in sound condition before constructing service void.

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New door - retrofit installation into EWI

Section detail for a new replacement door with a timber frame box to the existing door reveal installed into existing External wall insulation works; (or installed as part of EWI works: but with insulation installed before door.)

The new door is installed in a softwood box frame, glued or fixed to the new door frame; to the size of the existing opening, in order to replace the existing door. The new door and box frame means the door sits further into the EWI; bringing the door into the buildings thermal envelope, eliminating the need to insulate the existing opening, and therefore reduce thermal bridging around the existing opening.

The door threshold is reinforced with steel angle for structural support, with additional structural insulation over extruded polystyrene suitable for below ground insulation.

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EWI to Existing Conservatory

Detail for External Wall insulation fitted around the junction of an existing conservatory and an existing wall. Designed to help preserve an existing conservatory construction whilst installing EWI in order to mitigate heat loss through the building envelope.

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EWI Service duct within Insulation - Stepped face

A detail for an insulated services run within an external wall insulation system, stepped in from the finished face of the wall. Used where service runs such as soil pipes or ventilation ducts are to be contained within the depth of the insulation, meaning an accessible service void should be created.

Prior to work carry out a visual inspection of the services to be enclosed within service void, to ensure in sound condition before constructing service void.

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