Design
A toolbox of design information for fascia, soffit, guttering and cladding. Animated sequences, NBS specification, CPD and Building Regulation information for architects, clients and contractors.
Fascia and soffit assembler
The Swish Visual Assembler is an animated representation of the major fascia and soffit components. It shows their relationship to each other and how they fit together.
Notes
- Fascia boards are available in a large number of colours, styles and sizes to suit most applications.
- Ventilation may be provided over the fascia or through the soffit (alternatives not shown).
- For 16mm to 25mm fascias a backing board is not required.
- Guttering fixes directly to these fascias.
- Fascia & soffit joints are made between rafters.
- 8mm expansion gaps required at joints in long runs.
- A4 marine grade stainless steel fixings required.
Design Guides
A series of A4 leaflets setting out the important design and installation considerations for all the major fascia, soffit, gutter and cladding components.
| 1. Jumbo & 16mm Fascias.pdf | 129.15 kB | ![]() |
| 2. Capping Fascias 9mm.pdf | 125.49 kB | ![]() |
| 3. Bargeboards.pdf | 140.26 kB | ![]() |
Ventilation at the Eaves
Roof voids must be ventilated in order to stop warm air condensing on cold surfaces. Condensation encourages rot and mould growth. The air gap dimensions shown on the drawings are the minimum widths required for clear continuous ventilation air paths at the eaves.

*Duo pitch roofs greater than 200 pitch or greater than 10m span should have additional ventilation at the ridge to assist airflow through the roof void, equivalent to at least a 3 mm wide continuous gap. Additionally, if the span is greater than 10m the overall ventilation area should be increased to at least 0.6% of the total roof area.
**Air paths should not be obstructed. A minimum 50mm free air path should be maintained between the top of the insulation and the underside of the roof decking.
Ventilators
Swish ventilators for roof voids are covered by British Board of Agrément Certificate No.91/2620. When used in accordance with the Certificate, Swish ventilators will satisfy the following statutory requirements.
England and Wales
The Building Regulations 2000 (as amended) (England and Wales):
Requirement C2 (a) (b) (c): Resistance to Moisture
Regulation 7: Materials and workmanship.
Scotland
The Building (Scotland) Regulations 2004: (as amended)
Regulation 8: (1) (2) Fitness and durability of materials and workmanship
Regulation 9: Building Standards – Construction; Standard 3.10 – Precipitation and Standard 3.15 - Condensation
Northern Ireland
The Building Regulations (Northern Ireland) 2000, Regulation B2; (as amended)
Fitness of materials and workmanship, C4: (b) Resistance to ground moisture and weather and C5: Condensation.
Swish ventilators also meet the recommendations BS 5250: 2002 which deals comprehensively with the subject of condensation in dwellings.
Swish CPD
Swish provides RIBA approved CPD seminars dealing with fascia, soffit and rainwater technical and environmental information. The latest Swish CPD is now available to view below.
The document is best viewed by selecting the Fullscreen mode (in blue below). At the bottom left of the document ensure that the SLIDE option is selected, and move through the presentation using the arrows at the bottom centre of the document.
RIBA Approved CPD presentation concerning Cellular PVC, including the technical aspects of fascia and soffit installation, and the environmental advantages of PVC specification.
- PVC materials
- The material challenge at the roofline
- Installing PVC roofline
- The Code for Sustainable homes
- Sustainability of cellular PVC
Roofline CPD presentation lasting approximately 30-40 minutes
NBS Clauses
Swish has developed a number of NBS clauses for the specification of cellular PVC fascias, soffits and cladding profiles.
The National Building Specification system helps to standardise and improve the specification process for specifiers and manufacturers.
The contractor also benefits with less need for checking the specification which should ultimately be easier to price accurately.
NBS roofline and cladding clauses are available here in Word and Pdf formats. Examples of completed forms may also be viewed in Pdf format.
Swish provides an advice service for the completion of relevant clauses. Click here to email details of your requirements.
To contact the NBS:
Telephone: 0845 456 9594
Email: info@theNBS.com
Web: www.theNBS.com
Files
Open the file you require from the list below. If you need any help please call 01827 317200
| 1- G20 Carpentry - Blank1.pdf | 29.03 kB | ![]() |
| 2- H20 Rigid Sheet Cladding - Blank.pdf | 19.67 kB | ![]() |
| 3- G20 Carpentry - Blank -Word.doc | 41.47 kB | ![]() |
| 4- H20 Rigid Sheet Cladding - Blank - Word.doc | 30.21 kB | ![]() |
| 5- G20 Carpentry - Completed.pdf | 32.05 kB | ![]() |
| 6- H20 Rigid Sheet Cladding - Completed.pdf | 41.4 kB | ![]() |

