Roofs in Vila Real: frost, heat, PDM rules and the Alvão park

At the IPMA station in Vila Real (no. 567, 1991-2020; altitude 561.5 m) average rainfall is 951.2 mm a year, with peaks from October to January, and the mean temperature is 13.8 °C. There are 92.8 days a year with 1 mm of rain or more, 32.7 with 10 mm or more and 5.7 with 30 mm or more. The heaviest daily fall was 82.6 mm, on 11 December 2017. The note on the data sheet says only “hybrid series”.

Cold is the station’s mark: 16.7 days a year with a minimum below 0 °C (6.5 in January and 4.5 in December) and -5.7 °C on 1 March 2005. Summer weighs too: 40.2 days reach 30 °C and 6.6 reach 35 °C, and the maximum was 39.6 °C, on 3 August 2018. Your building may stand higher or lower than the station.

SCE climate zone. For the Douro region, at the reference altitude of 579 m, the SCE Manual gives 1,764 heating degree-days and a June–September mean of 22.7 °C: winter zone I2 and summer zone V3. The zone changes with the building’s altitude: I1 up to 247 m, I2 from 248 to 604 m, I3 above 604 m in winter; in summer, V3 up to 695 m and V2 above that. The limit for the thermal transmittance of horizontal elements of the opaque envelope, in new works or a renovated element, is 0.35 W/(m²·°C) in zone I2 and 0.30 in I3; conservation works are excluded. The Portaria does not say whether a pitched roof counts as a horizontal element: ask the SCE assessor. See the roof insulation aid guide.

The Vila Real PDM (Aviso 1447/2018, Official Gazette of 30 January 2018), article 77, no. 3, says that on buildings of the municipality’s cultural heritage and in their protection areas, works that alter alignments, building heights and, in general, the distribution of volumes and roofs or the exterior cladding of buildings are subject to council approval, without prejudice to the opinion of the heritage authority for listed buildings. For unlisted heritage, no. 2 sets safeguard areas of 50 metres.

In the Alvão Natural Park, article 24-B places works of reconstruction and alteration of buildings, whatever their use, under ICNF authorisation or a binding opinion. In the Alto Douro Vinhateiro, article 23 requires a binding opinion from the heritage authority to build, rebuild or alter buildings on rural land. Under article 26, new houses on forest land need a 50-metre protection strip within the plot and should use fire-resistant materials, with attention to the roof.

We read the 2018 text and did not confirm later amendments. We did not read the Código Regulamentar or the City Urbanisation Plan (Aviso 18469/2020), which may add rules.