My cover came with an extra piece of material for patching. I have not made that mistake but did melt the back of an ice maker that was on a table in front of that same exhaust. Still makes ice luckly. Before I put my cover on I cut holes in tennis balls and tape them over each eaves trough downspout. Third Canadian winter with the same Adco tarp now.
First time I was putting it on though I stepped backwards onto the washroom/shower skylight. My right leg went right through & almost made it to the toilet before my hips got jammed. Whenever I go up there now I stay ON MY KNEES.