Really useful stuff... Many of my tanks are on solid wood cabinets made for aquariums, so there's a large gap underneath the tank bottom. It's good for the UTH to "breathe" but sometimes the tape holding it onto the glass will eventually loosen & let go in time, & I wouldn't want the UTH to fall off unnoticed & park itself in the items stored below, so I've used pieces of hardware cloth under the UTH for this too- just for safety. It's unlikely that my Flexwatt would be hot enough to ever cause a fire, but hey. And besides, many here are running much hotter UTH than I am.
And for those of my tanks that are on solid wood-top cabinets, I definitely use ceramic tiles (+folded hardware cloth for some) to isolate the UTH from the wood, as the heat builds up more this way.
I've been keeping snakes a long time, & many years back when I was fairly 'new' I subscribed to a publication about snake-keeping from the U.K.- and in that there were 2 accounts of people who set their wood dressers on fire from the excessive heat of their apparently unregulated UTH that dried out the wood over time. So I've been more than careful.![]()