5, Higher Street, Dartmouth
A devastating fire in May 2010 damaged eight shops in Dartmouth’s historic town centre. Number five Higher Street (Grade II*) was a particularly well preserved example of a 17th C merchants house with carved and moulded decoration to the oak frame jettied and glazed frontage, internal spiral staircase and original plaster ceilings within. The entire roof collapsed bringing down parts of the medieval chimney stack which punched through the floors. The rear half of the building was completely lost.
TFCo were appointed initially to consult on the condition of the damaged timber structure and to survey the surviving oak frame elements of the floors, jettied frontage, and the softwood ground floor moulded plank and muntin passage screen and provide a condition report, costed repair, restoration and conservation methodology proposal. This was hugely challenging at first as the building was in a dangerous state. Much of the damaged historic material that had survived was still stressed under loads imposed due to the collapsing roof and masonry and supported by a forest of cantilevered scaffolding making working access limited.
Working closely with the appointed conservation architects Jonathan Rhind and the Heritage Consultant team our repair and restoration strategy and technical methodology was discussed and permissions were gained that allowed the repairable damaged material to be recorded and removed to be repaired in our workshops, with as much of the original material to be retained and their carved and moulded surfaces continued into the new timbers using age related tools and techniques.
On site we needed to release some of the strain that was implied on the delicate internal king post behind the jettied windows (it had bowed alarmingly), and reverse the racking movement in each storey wall frame that had distorted it due to the leverage the collapsing floors and masonry implied as if fell inward. We did this by carefully removing any surviving peg from their mortice and tenon joints and removed the old plaster internally and externally retaining the original lathes. This allowed the panels to articulate freely so that as we were able to support each wall frame level independently the loads reduced and we could bring the posts, studs, bressumer beams and rail mortice and tenon joints back into alignment.
We started by carefully jacking the moulded bressumer beams that lie over the jettied floor joists beneath, up on steel tubular needles, just enough to allow us to free off the original broken joist ends and slide the replacements into place before gently lowering the beam back onto them. Starting at the top we replaced each floor level’s lost internal floor beams replicating their section sizes and mouldings from the surviving fragments of the burnt originals. The beams were positioned in the original housings in the masonry walls. We replaced the missing floor joists replicating their section sizes, and managed to save many of those that support the jettied external wall frames by scarfing new material internally back to the floor beam, copying the external end shaping and positioning them on the exact locations as the originals had been. Once we had replaced the upper floor structure, lowered and pegged the beam, we had enough inherent restraint to employ a different support system below and remove most of the original scaffolding giving us much better access to the more seriously damaged frames below.
We replicated the process for the remaining floors from top to bottom. The first floor having suffered the most damage from the fire, as well as damage and scars from the remodelling of the ground floor shop front (we replaced a missing chunk of moulded bressumer presumably lost to house the top rail of the 20th C window frames). With the new Mabe support system in place we were able to use lots of small hydraulic jacks in specific locations in order to lift and even straighten the lower bressumers as we replaced and repaired the joists. As we carried out this operation we were observing key mortice and tenon joints within the wall frames as they returned to their original positions and closed up. This operation allowed us to significantly improve the level of each floor from side to side and front to back, realigning each storey of the new and original structure. We re-pegged each of the wall frame’s mortice and tenons with new hand draw oak pegs, the draw on the tenon’s peg holes still had enough offset left to pull the joints up tight helping to stiffen the entire structure and realign the wall frames elements.
