2. LVL STRUCTURES IN FLOORS, WALLS, ROOFS AND IN SPECIAL APPLICATIONS Figure 2.54. Large LVL I-beams as main beams of a warehouse roof structure at Herttoniemi, Helsinki, Finland. Metsä Wood 2.3.8 Roof renovation applications In the renovation of residential buildings, nail plate truss roof structures can be converted to room-in-the-roof attics by reinforcing or replacing the top and bottom cords with LVL-P beams and removing the truss diagonals. LVL-C or plywood connection plates are nailed or screwed to the corners to build a new rigid frame structure. The economical span range for the solution is 8-10 m depending on snow loads and thermal insulation requirements. It is recommended to leave at least a 100 mm ventilation gap between the thermal insulation and roof covering. The building physics design must, however, be done project-specifically based on national requirements. Figure 2.55. Conversion of nail plate truss structure to room-in-roof attic. Top and bottom cords have been reinforced with LVL-P beams and truss diagonals removed. LVL-C or plywood is used for the frame corner connections. Metsä Wood LVL Handbook Europe 83
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