We would like to use our wood burning fire pit on our wood patio deck. What can we make to put underneath it that will protect the deck from heat and sparks?
Do check with your fire department; if they are OK with the distance from the house, you could get concrete pavers to put on the deck first, then put the fire pit over the pavers. A metal oil drip pan could go under the pavers first as an additional layer of insulation. If you fire pit has legs on it so it isn't sitting right down on the surface, it will be better for your deck.
Our local fire department recommends that people keep things like that so many feet or yards away from the house. It wouldn't hurt to call your fire department or fire inspector and ask about that. Here this was done after a couple really bad house fires from the pits being too close to the house.
I would think the best way to have a fire pit on your pation would be to make a circle of bricks and let the fire pit rest on them suspended above the wood. But redhatterb makes a good point. It may not be safe. But then again grills can be dangerous too.
I've seen a few of these that were sunken down into the wood patio with a cement foundation and then decorative bricks along the top edge. And also check with your local regulations for open fires and see if they have any policies you must follow as well.