Having a wood-burning heater in your shed can be a nice touch in a location that's usually cold and unwelcoming. That being said, a wood heater can be very dangerous without proper ventilation. Technically, this is the type of job that should be done by a professional, but you can install the wood heater yourself. After this project is completed, you may want to contact a professional so they can inspect your work and make sure it was installed safely.
Determine the desired location for your heater, making sure that it's centred between two rafters. Planning the project is probably the most important step.
Attach two 5 by 10 cm (2 by 4)s between the rafters on the ceiling as close to directly over the heater as possible. Attach the support box to the 5 by 10 cm (2 by 4)s. Screw it in place, making sure that it's level, and leave at least 5 cm (2 inches) of the box hanging below the rafters.
Drill a hole all the way through the centre of the support box.
Using a plumb line, drill a hole through the roof directly lined up with the hole in the support box.
Take your metal flashing to the roof and scribe the hole from the inside of the flashing. Cut a square hole using a skill saw.
Use a putty knife to slide the flashing under the shingles where only the top of the flashing is not covered by the shingles.
Run a class A pipe down through the flashing and seal it to the support box. Use a high-heat silicone to seal the pipe around the flashing. The pipe should stick up a minimum of two feet out of the top of the roof with a 3 m (10 foot) clearing radius.
Attach a P connector to the support box, which will you'll attach and seal to the class A pipe coming in from the roof.
Run the class A inside pipe from the heater to the support box. Use 45-degree elbow-pipe pieces at the support box P connector and/or the stove if necessary for connection.
It is your responsibility to prevent smoke nuisance to neighbours. Be sure that your wood heater is in accordance with all safety and regulation laws.
Smoke from wood heaters contains numerous pollutants and chemicals that can be extremely toxic if inhaled.