Seam sealant for polycanvas

If it's worn canvas there are products available like dynaproof.

G'Day Krooznalong
I have used bee's wax on our camper seams and swag seams, have not had any issues with moisture or water entering. Bees wax comes in a stick form and you rub it on the seams. If your looking for sealing all of the roof Dyna Proof is a good option, we have used this product on the camper and swags works well even with heavy weather hasn't leaked, read the instructions first on what material you can use it on. Good luck.

Thanks - not looking to reproof. Just something to seal seams effectively. Might try the beeswax idea.

Is the material actually canvas or a poly material. If it's canvas and new, then you can help the sealing by going through a couple of cycles of wetting and drying. I did this on ours by setting it up in the sun, wetting down the roof and walls with a hose and then letting it bake dry. Did this a couple of times. It helps by going through a swelling and shrinking cycle. It's best to do this before applying any sealants. I use a wax candle for seam sealing on my canvas campertrailer.