Other Weak Links!
2. USING A CHEAP DOOR SEAL - There are a lot of different seals on the market today. There are some that expand and fill in the door gap, but when temperatures reach 1000 degrees or more those seals break down and fall apart. Once a seal breaks down, it allows heat and smoke to enter in through the door gap.
3. NOT ENOUGH DOOR BOLTS - When temperatures reach 1200-1400 degrees, one-sided door bolts do not hold the door in place as well, allowing distortion and warping to occur and gaps for heat to enter in.