King and Queen posts

This weekend we will see the coronation of King Charles III, but what is the relationship between the monarchy and roofs? Building Surveyors Adam Stimpson takes a timely look at what's holding up your roof.



Throughout history, your property and its size often determined your social status. Therefore the bigger your home, the larger the roof will need to be. 


In today’s standardised world, modern prefabricated timber trusses are used for roofs and act as an integral structural framework to the building. However, in the past, different design variations were required for differing spans and distributing loads of varying roof coverings.  


The King post truss was developed in the north of England, where heavy stone slate roof coverings required a structurally robust form.


The King post truss consisted of triangular frames which supported the ridge and purlins. The roof load was transmitted through the principal rafters to the walls below. 

A strut under the midpoint of the principal rafter prevented it from sagging. The vertical post, often known as the ‘King post’, reduced sagging and transferred the load to the supporting walls, stiffening and strengthening the truss. 


The original design consisted of large timber members bolted and strapped together at joints and spanned between 6 – 9m, and was mainly used in residential properties. 


Often the roof space would be required for accommodation or storage purposes. This could be achieved using an open truss known as a Queen post truss. 


Where a King post uses one central supporting post, the Queen post truss uses two.


A queen-post truss roof has two uprights, placed about one-third of the way from each end. They are connected across the top and bottom by a straining or tie beam. The Queen post can span far greater room widths of between 9m -12.75m

A Queen post truss carries all the load from its rafters and passes it to the vertical posts. These, in return, channel the load along the tie beams and transfer it to the supporting walls.


King post trusses are low-rise and support roof pitches between 30 – 45°. Queen post trusses are comparatively steep, and you can use them for greater 60° pitches too.

If you are concerned about the condition of a roof structure contact Woodward Chartered Surveyors in Herts, Middlesex and London to arrange for an inspection.

Woodward Chartered Surveyors cover an area from East of Oxford, Beaconsfield, Amersham, Berkhamsted, Watford, Rickmansworth, Ruislip and into London, Northwood, Uxbridge, Harrow, Ealing and Mayfair. 

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