Challenge of Converting a 17 th Century Stone Barn into a Liveable Home: Old Headington, Oxford
Ian G Heggie
The speaker started by noting the importance of the word “challenge” in the title of his presentation. Had he and his wife realised what they were letting themselves in for, they would probably not have bought the barn.
They purchased The Barn from Lady Berlin in 1972. She was the wife of the famous Oxford philosopher, Sir Isaiah Berlin, Fellow of All Soul’s College. The Barn had previously formed part of Mather’s Farm which had been owned by Magdalen College.
The Barn was a handsome building constructed of oolitic limestone with a slate roof. It was 112 ft long and 23 ft wide overall. The walls were nearly 2 ft wide and 15ft high. The plot size was about half an acre overlooking open grass fields owned by the Oxford Preservation Trust. The roof trusses were made of heavy pieces of Baltic pine. Some still had the names of the ships on which they had been imported cut into their sides.
The initial problems identified with the barn included: (i) the prevailing fire regulations did not permit the installation of exposed structural timbers; (ii) when constructed, the roof trusses had not been properly braced and had leaned over about 6 ½ ins out of plumb; (iii) those building the roof had hurriedly propped the trusses against the end wall of the barn which had cracked and was also now leaning over 2 ½ ins out of plumb; (iv) the distance between the walls (19ft 4 ½ ins)meant any upstairs partition walls would need support from below; (v) there was no city sewer in the vicinity and the next door farm had a working well; and (vi) new building materials do not usually sit well with old “historic” buildings.
The initial architectural advice they received was devastating. First, the leaning roof trusses meant there could be no exposed roof timbers --- they would all be visibly leaning over. They would have to be covered in plaster board painted white (i.e., a wholly modern ceiling). Second, the large floor span meant the planned open span kitchen on the ground floor would have to have a column in the middle to hold up the upstairs bedroom partition wall. Third, the lack of sewage access, plus a working well next door, meant the barn would need to have a sewage holding tank which would be emptied every 4-6 weeks by a sewage lorry. Not an attractive prospect.
But there were some advantages: (i) the owner was a qualified and experienced civil/structural engineer; (ii) Dutch Elm disease meant there was plenty of good quality elm wood available; (iii) a nearby business specialised in recycling second-hand building materials; and (iv) the owner found two local builders (Fred and Reg) who were accustomed to refurbishing old buildings.
In the context of the above problems and advantages, the owners adopted the following overall refurbishment strategy. First, they would discuss the issue of exposed structural timbers with the Fire Research Station to see if there was any way in which floor beams, etc., could be left exposed in the proposed barn conversion. The FRS were extremely helpful and advised that, provided all exposed structural timbers were pressure impregnated with fire retardant, they would issue a certificate confirming that they satisfied the current fire regulations. This was a major breakthrough. Second, the owners decided to try and straighten the roof trusses – everyone thought they were mad to try this and they had a point!! Third, it was decided to build the gable wall on the broken end wall eccentrically to use the weight of the new wall to help pull the broken wall back in (a typical structural engineering trick). Fourth, the problem of the large floor span supporting the bedroom partition wall above the open span kitchen was solved by hanging the wall from the heavily over-designed roof trusses above (again a typical structural engineering solution). Finally, it was decided to lay a private sewer across the Oxford Preservation Trust fields to join the city sewer lower down the hill where a new housing development had been built a few years earlier.
The presentation then sequentially presented images of the above strategy being put into place. A tree winch was borrowed from the City Parks Department and used to pull the roof trusses straight, using steel safety cables to ensure the roof did not collapse. A diagram was presented showing how the gable wall was built .eccentrically to help pull the broken end wall back in. One of the working drawings was then shown illustrating how the upstairs partition wall was held up by the roof rafters. The presenter noted that people converting old buildings could not simply apply such trickery themselves. They had to demonstrate to the Building Regulation staff that the solution would stand up. The presenter’s diagrams and calculations were made available for inspection by anyone interested. Finally, the sewer was laid using 4 in PVC flexible jointed sewer pipes laid in a bed of gravel, before the trench was back-filled.
With all the major problems solved, building work then began and various images were shown illustrating the roof being slated, the windows being cut into the 2 ft thick stone walls, and the interior partition walls being built. The barn soon started to look like a house.
The presenter then showed various images of the design details in the barn conversion. The beautiful oak front door, the handsome elm staircase, the traditional joinery that Fred insisted on using and the handsome stained glass Saggitarius built into the leaded window over the front door (the presenter’s birth symbol).
A number of images were then presented illustrating the usable space created inside the converted barn. The spacious living room, the minstrel gallery which the owner used as an office (one must have a minstrel gallery in an historical barn conversion!), the spacious open span kitchen (without any pillar supporting the upstairs partition wall) and the spacious master bedroom overlooking the green fields outside. Images were then shown of the completed barn conversion. It was a snowy winter and the images were quite spectacular.
Finally, the presenter showed the award they received from the Oxford Preservation Trust, “for the tasteful conversion of The Barn.”