Typically rectilinear. Therefore, for a 45° pitch and a roof resting on the inner wall head.
Internal surface area ≈ L X B (r =½B)
Surface area of hipped roof
≈ Area of lateral sides of pyramid + 2 rectangles
= ½(perimeter of base) X (slant height) + 2 ((L-B) X √2r) [(r = ½B)]
== ½ (8r) X √2 r + 2 ((L-B) X √2 r)
=4r X √2 r + 2 ((L-B) X √2 r)
≈5.66 r² + 2 ((L-B) X √2 r)
Maximum rafter length for both buildings
= √2 r², where r is radius or half the breadth
Airigh Muillin, South Uist (Symonds 1997).
Internal dimensions of up to 16 by 4m.
Internal area = 64
Roof surface area = 22.6 + 67.9 = 90.5
Rafter = 2.8
Crubisdale, Barra (Branigan and Merrony 1995, 193-95)
Average building size = 7.7 by 3.9m internal.
Internal area = 30
Roof surface area = 21.5 + 21 = 42.5
Rafter = 2.8
Gortein, Barra (Branigan and Merrony 1995, 193-95)
Average internal size = 9.5 by 5
Internal area = 47.5
Roof surface area = 35.4 + 31.8 = 67.2
Rafter = 3.5
Tangaval, Barra (Branigan and Foster 1995, 39-48)
Average of T26, T30, T35, T36, T46, T94, T98, T122 (excluding those at Gortein and Crubisdale).
Average = internal measurement of 7m by 3.4m
Internal area = 23.8
Roof surface area = 16.6 + 17.3 = 33.9
Rafter = 2.4
Garenin, Lewis (Burgess 1995)
Average internal dimension 15.6 by 4m
Internal area = 62.4
Roof surface area = 22.6 + 65.6 = 88.2
Rafter = 2.8
42 Arnol, Lewis (Walker and McGregor 1996)
Living area/byre is 18.5m by 3.5m and barn 13.5m by 2m
So internal area = 64.75 + 27 = 91.75 m²
Surface area of roof = 5.66 r² + 2 ((L - B) X √2 r)
Maximum rafter length = 2.5
39 Arnol, Lewis (Holden et al. 2002)
Dwelling byre is 19.5 by 3.5, barn is 8 by 1.5 and fosglan is 14 by 1.5.
So internal area = 68.25 + 12 + 21 = 101 m²
Surface area of roof = 5.66 r² + 2 ((L-B) X √2 r)
Max rafter = 2.5
Thomas (1890, 154)
Gives average size as 12.1 by 4.3m
Internal area = 52
Roof surface area = 26.2 + 47.4 = 73.6
Rafter = 3
Macpherson pers. comm. to Napier Commission 1883 (cited Walker 1989, 58)
Internal average of 11 by 4
Internal area = 44
Roof surface area = 22.6 + 31.9 = 54.5
Rafter = 2.8
Mitchell (1880, 117)
Max 20.8 by 5.8
Internal area = 120.6
Roof surface area = 47.6 + 123 = 170.6
Rafter = 4.1
Min 10.4 by 5.8
Internal area = 60.3
Roof surface area = 47.6 + 30.4 = 78
Rafter = 4.1
Ardveenish, Barra (Branigan and Foster 2000, 12-16)
Average of 42 'blackhouses' surveyed in the Ardveenish area
Dimensions = 8.8 by 5.3, 6.8 by 3.3m internal.
Area = 22.44
Roof surface area = 15.4 + 16.3 = 31.7
Rafter = 2.3
© Internet Archaeology/Author(s)
University of York legal statements | Terms and Conditions
| File last updated: Tues Feb 28 2006