Keeping a warehouse roof

When we first walked through the warehouse that became River Works, the brief assumed a new roof. The building had been empty for six years, the sheeting leaked and pigeons had moved in. The timber trusses above all of it were the best thing in the building.

We had each truss surveyed and graded by a structural engineer. Most needed nothing more than cleaning. Eleven had split or rotted at the bearings, and those ends were repaired with new timber and steel plates rather than replaced. Every repair is visible, which the makers in the building seem to like.

Keeping the trusses meant designing everything else around them. The new roof of insulated, galvanized corrugated metal panels sits on top of the old structure, so the timber stays inside, dry and in view. Daylight comes in through tall steel windows along the brick walls, which means the workshops rarely need lights on during the day.

It was not the cheapest option on paper. Repairing a roof takes longer to price and to build than replacing it. But the trusses carried decades of carbon already spent, and they give the workshops a height and a rhythm no new roof on our budget would have matched.

We would keep them again. The one thing we would do differently is survey earlier: we found the damaged bearings after the cost plan was agreed, and the repairs used most of the contingency.