She needs a new Hip!
A big area for repair at Orleton has been the Hip end, joining the kitchen wing and hall range. Typically a hipped building is where the slope of the roof into the middle of a building like a tent or a pyramid with no gable ends. Usually, this makes for a structure where the roof's forces are resolved as they are self-bracing with the load going into the centre of a building.
Image courtesy of Modernize
To add to the complication at Orleton Manor, given the U shape plan of the building, you end up with valleys, which is the inverse of a hip, where the cross wing meets the hall range at both ends. So each corner or hip in this instance has two trusses, one hip rafter and one valley rafter.
Now, saying that Hip roofs are good and that they have resolved forces is all fine, but in the case of Orleton Manor, as it has evolved over time, many structural members had either been cut out, decayed, heavily notched or altered that gave a corner of a building with very little tying from corner to corner.
As you can see in the image above, most of the roof members were cantilevered and short of the apex, with many alterations over time to suit how the building was being used. The post down to the truss had been pushed back to give more space, and the purlin to the hip rafter had failed at some point, being replaced with a smaller section.
Again as per the hip side, the valley had a lot of cantilevered members, especially the large purlin to the left-hand middle that stopped short of the truss line, as well as the ridge at the top. As you can see in the photos above, the valley beam is suffering from decay, valleys are where the roof is working it's hardest as you have two roof plains of water converging along a joint, and a common area for failure.
So once the roof trusses had been craned back into place, works began on the truss in accordance with our engineer's drawings. The main issue to resolve as mentioned above was the lack of connection between the members that should have been tying the building together. Rather than add new scarfed pieces of timber to every short piece, a boss post was added to allow all the timbers to connect together.
The broken and replaced purlins were replaced as you can see above and below with new members. Unfortunately, in this area, they were too far gone to save and some missing, so they were faithfully recreated to match the right-hand piece, with a dovetailed end to hip. We were very pleased that with a bit of clever engineering the hip was saveable along with most of the purlins on the kitchen side of the hip.
Above is a close up of the hip, with its patch repair to the old notches and the scarf repair to the underside of the purlin, a principle rafter was reinstated into the empty mortice pocket of the floor beam creating a connection to the ridge and giving a location to land the purlins on.
Above you can see Jake, drilling the slip tenon between the new purlins ready for them to be securely pegged in place.
Here, you can see in detail the new valley rafter. This was increased in size and shifted slightly lower so that it sat in the correct position. This allowed collecting the previously cantilevered purlin which you can see here on the left, which had a new end scarfed into position. Two new large valley boards have been created that sits over the purlin, ready for the roof to go on. These are very much over-engineered, but will more than certainly outlast any new roof covering that goes on.
And there we have the main structural work to the hip and valley created. A real feat of craftsmanship and engineering that took much discussion from all parties to get to a conclusion that we were happy with. Certainly, some very complex geometry with 400-year-old timbers that twist and bow is a testament to the excellent carpenters we have on site. We will release another blog post in more detail looking at the Dragon Tie with its impressive steelwork and how the boss was constructed.