We just bought a 10x12 and I see the instructions recommend sealing the seams from the underside, which I just completed.
Question:
Is there any reason to not flip it over (after curing) and seal the top side of the seams?
Thanks for the input.
Tom

Don't know that you would gain anything but it wouldn't hurt either.

I am not familiar with the waterproof coating or coatings used on the CCS Tundra tarps but it is common practice for manufactures to use ripstop nylon fabric that has a silicone based waterproofing on one side and a polyurethane based waterproofing on the other. Using polyurethane based waterproofing allows you to increase the hydrostatic head rating beyond that of using silicone based waterproofing alone. There are advantages and disadvantages to both silicone and polyurethane waterproofing but the increased strength and durability of silicone over polyurethane make advertising as silnylon attractive for marketing.

For proper adhesion it is important to use a silicone based seam sealer on silicone and a polyurethane based seam sealer on polyurethane. IMHO, as long as you use the appropriate seam sealer you should be able to apply it to whichever side or sides you desire.

I did one side on both of mine 10+ years ago. They both held up great and were leak free during last weeks continuous downpours.

It won’t do any harm, but I don’t think it’s necessary.

Tomcat: "I am not familiar with the waterproof coating or coatings used on the CCS Tundra tarps but it is common practice for manufactures to use ripstop nylon fabric that has a silicone based waterproofing on one side and a polyurethane based waterproofing on the other. Using polyurethane based waterproofing allows you to increase the hydrostatic head rating beyond that of using silicone based waterproofing alone. There are advantages and disadvantages to both silicone and polyurethane waterproofing but the increased strength and durability of silicone over polyurethane make advertising as silnylon attractive for marketing.


For proper adhesion it is important to use a silicone based seam sealer on silicone and a polyurethane based seam sealer on polyurethane. IMHO, as long as you use the appropriate seam sealer you should be able to apply it to whichever side or sides you desire."

Adhesion is the reason for my question.
CCS recommends sealing the underside but it sound like they basically say that because it's easier, not necessarily because of the sealant not sticking.
I am using the sealant that they supplied with the tarp so I assume it should be compatible with both sides of the tarp but we all know assumptions can sometimes cause unintended consequences.
Appearance may also be a reason they recommend sealing the underside. Sloppy application of sealant can detract from a nice, clean look which is more noticeable from the outside IMO.
It just seems to make logical sense to seal from the top side and I do have enough sealant to do both sides so I figured "why not?" but I thought I'd ask first.
What I really need to do is contact CCS and ask them. It's a beautiful tarp and it wasn't inexpensive. I just want to treat it properly.

Seam Sealing the Cooke Custom Sewing Tundra Tarp.

Starting on the bottom side, the side opposite the side the of open loops on the seams. Skin coat the exposed seam and the hidden one as well. The pole patch seal the four exposed seams and the one corner to corner. Do not seal on the edges.

I'll add that CCS tarps are not polyurethane coated, they are all silicone impregnated nylon which is superior, so you only need the sil-nylon seam sealer no matter how you do it. I did it the way Dan said and have had no problems in 10+ years and many trips.