Eventually what “kills” canvas tents is the harmful UV. Our average end user who uses the tent a couple weeks out of the year has no problem. If you plan on setting the tent up for extended periods of time we recommend a “rain fly”. A rain fly is a plastic tarp that has a UV inhibitor built into it to prevent the UV damage. It also protects the tent top from burn holes, slides the snow, and is another barrier in the rain. To allow your tent top to breathe, the rain fly must be set up correctly.
It is O.K. to have the rain fly touch the tent at the top. But out at the sides of the tent you should use a longer pole to lift the fly up off the tent top. A couple of poles on each side is sufficient just enough to get a pocket of dead air to a large portion of the tent top.