- Check the firebox for cracks and loosening joints. In a masonry fireplace also check for damage to bricks and mortar. Make minor repairs to firebox joints and cracks using refractory cement; it’s designed to handle the extreme heat conditions in a fireplace and it’s readily available at fireplace stores.
- Open the damper completely. It should move freely and sit snugly against the throat. Make sure the metal is solid with no cracks, severe pitting, or rusted-through sections. Replacing a damper is not a do-it-yourself job; if the damper is in bad shape, hire a professional to replace it.
- Using a high-powered flashlight or work-light, look up the flue to check for damage. Metal flue liners should be clean and the joints well aligned. Tile or masonry flue liners should be solid and free of cracks. All repairs should be done by a certified professional.
- Make sure the chimney is unobstructed of leaves and other debris that may have fallen into the chimney. Chimneys are also favorite nesting places for birds and squirrels, even if it’s only been a few months since the fireplace was last used.
- If you can’t see the entire flue from below, you’ll have to check from the roof. If you’re at all uncomfortable doing this or have no experience working on a roof, hire a professional chimney sweep to inspect and clean the chimney.
Precautions you should take
- Excess creosote, over 1/8 inch or 3 mm, can ignite in the flue and send flames shooting out the top of the chimney, even causing the home itself to catch on fire.
- Cracks in a masonry chimney or corrosion in a metal one can cause house fires.
- If you use a fireplace for heat, have a carbon monoxide detector nearby. Fireplaces can use up the oxygen in a confined space, especially when there is very little ventilation.
- Find a professional to repair any problems you find that you do not feel competent doing yourself. The risk of a fire is not worth the cost.