How to convert a standard roof truss ceiling to a vaulted ceiling

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Converting a conventional flat roof with trusses to a vaulted ceiling will create an open, spacious-looking living space. A vaulted ceiling angles up from the top plates of the wall sections. This design element makes a room appear larger and provides more natural light. Trusses consist of triangular-shaped components that hold up the roof and keep the wall sections in alignment.


Consult with a structural engineer about the project and have drawings completed. The likely design option may involve removal of the existing trusses and replacing them with a scissors truss system, which uses about 50 per cent of the pitch of the existing roof. The engineer must compute the roof load, such as snow accumulation, roofing materials and other factors. This computation ensures the new trusses have the proper dimensions.

Verify that the engineer outlines the correct spacing for the new trusses and the method for securing them to the top of the wall sections. These elements make for a safe roof and keep the structure from sagging, warping or collapsing under a heavy load.

Submit the engineer's drawings to the local planning department for approval. The drawings may require the structural engineer's stamp. Apply for a planning permission before starting the project.

Locate a truss fabricator and order the scissors trusses. Allow time in the project for the manufacture and delivery of the new components.

Ceiling material removal

Inspect the attic for electrical connections, telephone wires, pipes, heating ducts and other systems. Disconnect these components in the area where the vaulted ceiling will go. Refer to the engineer's drawings when rerouting these items.

Set up a work platform in the room where you will begin removing the ceiling. Construct a work platform by placing planks between two stepladders. Some tool rental shops have rolling platforms, which make manoeuvring and working over large areas and overhead easier.

Open the windows to allow dust to escape and bring in fresh air. Apply masking tape around the doors to prevent dust from entering adjacent rooms. In addition, cover vents, wall fixtures and other ceiling elements.

Start in a corner of the room. Make a hole in the plaster or plasterboard with a hammer. Rip out all the materials, such as plasterboard or plaster and lath, with a pry bar. Have a helper move the debris to a corner of the room or outside to a container. Do not remove the trusses at this point.

Scissors truss system installation

Cut out and remove the existing trusses one at a time with a reciprocal saw. Secure the replacement scissors truss in place in accordance with the engineer's instructions. This ensures the proper structural support remains in place until completion of the modification.

Refer to the drawings to meet the ceiling's ventilation requirements. Most rules require 1 square metre of venting for each 150 square metres of space( or 1 square foot for each 150 square feet of space). Install rafter vents if necessary. The vents create a minimum 2.5 to 5 cm (1 to 2 inch) cavity between the insulation and the roof sheathing, which allows the space to breathe.

Install the insulation. Buy insulation with a vapour barrier facing already attached if needed. Reroute cables, electrical wires and duct work. Finish the new ceiling by adding plasterboard or put a decorative finish on the wood for an exposed look.

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