A butterfly plan is a nineteenth-century plan where two or four wings of a house are constructed at an angle to the core, usually at approximately 45 degrees to the wall of the core building. Used primarily during late Victorian and early Arts and Crafts movements. It is also known as a 'double suntrap'. Norfolk has several houses of this type.
Notable Arts and crafts examples:
- Happisburgh Manor, Happisburgh, Norfolk, by Detmar Blow to a concept by Ernest Gimson (1900) 
- Papillon Hall, Lubenham, Leicestershire (1902-4) by Edwin Lutyens. Demolished in 1950.
- Kelling Hall, Kelling, Norfolk, by Edward Maufe (1913).
- Yaffle Hill, Broadstone, Dorset, by Edward Maufe (1930).
- English Heritage Online thesaurus butterfly plan
- English Heritage Online thesaurus double suntrap
- Drury, Michael (2000), Wandering Architects: In Pursuit of the Arts and Crafts Ideal, Shaun Tyas. ISBN 190028913X
- Cantor, Leonard (1998), Historic Country Houses in Leicestershire and Rutland. Kairos Press. ISBN 1871344182