Case Study:

Shepherdswell - Dover


Our customer is an experienced property developer with a background in architecture and planning.

With a passion for sustainable buildings, she wanted to achieve an airtight thermal seal of the property envelope to ensure that the family home would operate in a cost efficient manner with minimal carbon footprint. Offsetting airtight insulation with a whole house ventilation strategy, the aim was to transform this bungalow into a two-floor dormer home for an expanding family.


Vectis Insulation Solutions


Dover, Kent

Project Type

Residential Renovation

Product Used

Sucraseal Open Cell Foam

Install Date

October 2023

Install Size


Install Duration

3 Days

The Project


Our client initially approached us because she needed to achieve a 0.18 U-Value in roof and wanted to know if spray foam insulation could achieve better thermal results than other types of insulation. Airtightness and thermal performance was a vital requirement from our client who wanted her family to enjoy low running costs with minimal heating. A big believer in MVHR Heat Recovery Ventilation, the performance of the insulation was integral to how effectively the ventilation system would perform.


With a brand new roof being fitted, our client was reliant on our expertise to guide her on the building assembly thicknesses required to reach the U-Value targets. After discussing the thermal requirements with the appointed Building Control Officer, we specified 225mm of our Sucraseal Open Cell spray foam insulation to reach the SAP targets of a 0.18 U-Value. Our client constructed a cut roof using 225mm rafters and we proposed to fully fill the rafters in the sloping ceilings of the dormer, trimming back flush ready for plasterboard. We calculated the condensation risk to the property using Build Desk Hygrothermal software and due to the low resistance, breathable materials proposed, a vapour control layer was not required, particularly as the MVHR system would also help to control humidity and moisture.


Our specialist Sucraseal install partner, Vectis Insulation Solutions, worked with us on the project to fulfil the brief and specification. Spray-applying the Sucraseal gently to the low resistance roof membrane, Vectis reached the required insulation depths by spraying in layers of 115mm. Overfilling the rafters by around 10mm, the team trimmed the foam back flush with the roof rafter faces to ensure that the client could fit the plasterboard with ease. Although the project was several months in the making whilst we agreed the specification with the client, the installation was fully completed inside three days. The speed of installation helped our client to remain on track with her tight building schedule and with Christmas just around the corner, the insulation was a major step in the building programme. The end result was one happy client in her new airtight, hermetically sealed, thermally efficient home. Traditionally, dormer roofs are notorious for heat loss and excessive solar gain. Based on the performance of BBA Certified Sucraseal in these types of project, we are confident that our client will enjoy year round comfort.

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