Sling braced frame


The design of this frame was inspired by the architects’ lack of attempt to show any oak detail in their drawings! Given it was the key element to the design criteria, they had done a marvellous job of hiding most of the oak away. See plan below:


As you can see, the corner posts (which dimension is 200mm sq) have only 10mm of face visible! It is quite typical to have this lack of detail as a starting point, but being given a blank canvas can be a blessing.

After some fairly major design revisions we managed to expose at least 50% of the oak in the exterior walls. Adding more detail with oak ceiling joists and a spine beam dividing the stairwell space. On the first floor we concluded with a ‘sling brace’ arrangement and tapered collars. This design allows for maximum usable space, whilst adding elegant detail.


This frame is annexed from the main house, this is due to it’s Grade II* listing classification. This makes assembly much easier as there is no direct contact with the existing house. Unfortunately access was terrible and all the timbers had to be carried through a garage by hand! Due to this access problem, there was no way a crane could be used to assemble the massive timbers. The only viable option was to use our hand operated mobile crane. This made for a very slow, but considered assembly process.


It took three days to complete the raising, which might sound quick, but typically something like this would be up in a day with a large crane. The following picture is from within the first floor (to be the master bedroom) overlooking the garden and paddock.


Picture taken from garden towards extension. Note the sling brace trusses are on the gable and internal dividing wall. A single open truss maintains space within the bedroom. The below picture shows the subtle difference between a tapered collar (horizontal beam in internal truss) and straight collar on gable.


We were asked to help with the softwood element too, which we typically do not get involved with. But given the oak roof was designed specifically to accommodate the softwood details we had to oblige (reluctantly!). Therefore the following pictures show the completed frame and softwood roof timbers. Actually, they set it off quite nicely. 🙂