I was following a YouTube channel which answered almost all my questions in good detail, but when it came to this part they skipped over it in the video and then later on briefly said “mud them in” and didn’t elaborate. I know they’re referring to concrete, but didn’t give any suggestion as to how much a gap I should leave etc. you often see pavers go right up to the side of a house as well whereas in the video it looked like they’d left a good 4 inches. I’ve done some further research but haven’t had much luck finding a clear answer.

I’m leaning more towards leaving a 10-15mm gap, inserting some gap filler rod and then using a brick and mortar gap filler to seal it properly. Is that acceptable? The space has no protection from rain so it’ll need a decent seal. Also, if I do this method should I fill some of the gap with sand or something and then push the rod in? The pavers will be 40mm thick. Any advice appreciated!