First time working with wood/masonry. I just built a pad for

>>1074550
just push them as tight as you can together
the joints will just be more places for ash to get stuck

you could caulk it

>>1074554
grout is needed per fire code

>>1074557
i'll look for some high temp colored silicon sealant. good idea. thanks.

>>1074550
If it's close to a 1/4" you'll be alright, just slap some grout at the intersection and apply pressure along the crack. That sounds dirty for some reason, but it works, I've done it travertine that had about an 1/8" gap

>>1074566
Mix up your grout and then just putty knife it into the cracks. Keep a wet rag on hand and use it to clean the slate as you go.

Aside from that, you don't have many options. The sealant idea doesn't make much sense considering that they're mostly user as a method to slow down the spread of fire, not prevent it, and on top of that, most fire caulks are carcinogenic. Fire + carcinogens = lung cancer.

>>1074550
>Like a frosting bag or something?
do it and see if it works