The fire is pretty, but it should do more than just look nice. It should be tearing stuff up. Lets do some damage here. Make a new blank layer just below the fire layer. Hide the fire layer so that just the structure layers are showing. With the new blank layer still active, hold the "alt" key and select "merge visible" in the layer pallet menu. This will make a copy of all the visible layers and paste it into the blank layer. Why do this? So we can do some damage without damaging other layers we have worked hard on. Use the liquify tool on this new layer to distort the shingles. Don't worry about messing up anything else, we will fix that shortly.