I recently had a company install new double walled class A stove pipe for our wood stove. It works fine inside. However, just a few weeks after installation we had some 40 mph winds and the section over the roof came flying off and landed on the ground. The installer said he can only twist the one pipe section into the roof section. he said they can't screw into double walled pipe. Is there a reason for this? The only other option he gave us was paying $250 for a roof brace, which he originally told us we didn't need. We get a lot of 40 MPH winds here. It seems like a properly installed Roof pipe section should be able to withstand that with whatever the normal installation.