Inside St Michael's: Roof Timbers
The nave roof is of a common-rafter crown-post structure. The roof trusses comprise pairs of sloping rafters and a horizontal collar beam between them. The collars rest on the longitudinal collar purlin, which in turn is supported by the massive crown post above the central tie-beam across the nave. At the lower end of each rafter is a triangular arrangement of a vertical prop about a metre high — an ashlar piece — and a horizontal sole piece which rests on the wall.
The sole pieces can't be seen here, but outside the church the ends of the sole pieces and the rafters are visible below the north nave wall soffit.
Little doors between the rafters at each end of the nave on the north side provide access to an eaves void.
The same roof structure is used in the chancel.
Nave, door to eaves void
The roof timbers in the aisle are rather different from those in the nave and chancel.
The rafters disappear as they rise to the left. There’s a flat area about two feet wide between the disappearing rafters and the top of the arcade (effectively of the original wall of the nave) which echoes the wide soffit outside the north wall of the nave. The horizontal sole pieces of the nave trusses protrude into the aisle below the flat area, just as you would expect if the structure of the timbers here was essentially the same as the north timbers. So, we have the same structural characteristic as in the nave.
The structure of the roof timbers here, with vertical props, the ashlar pieces, resting on the wall rather than the rafters themselves resting on the walls, relates to the raising of the roof, essentially by the height of these props, without the external walls being raised.
Very unusually, the ends of the supporting braces rest on the capitals of the arcade pillars. This doesn't really look right. It looks rather like a temporary structure which ended up being permanent.
It is not clear whether the rafters in the nave extended all the way down to the aisle south wall, but given the total length, it looks more likely that at least some of the rafters consist of two pieces, with the join being hidden above the arcade. Though the aisle roof timbers look very old, you can see that many of them show evidence, such as mortises, indicating that they have been recycled.
In 1864, the ceiling was boarded, for warmth. However, the boarding was removed in 1964, exposing the rafters.
Supporting St Michael’s, Amberley
St Michael’s, like all medieval churches, requires regular maintenance. If you would like to help ensure that many further generations may enjoy our beautiful church click here to donate.