Fireplace too hot?

[bmwpower]

I have a typical fireplace setup, about 3 years old (newer home). I noticed today before getting the fire started that the back wall of the fireplace looked cracked in one area. The mortor was starting to crumble in the center of the cracked area. The crack ran straight up for about 6"-8" from the firebox floor. Upon tapping the back lower back wall with the poker, it sounded rather hollow, as if there was an airspace behind the lower back wall. As far as I know the firebox is made of firebrick and the appropriate mortor. The sides of the firebox appear unaffected and do not sound hollow when tapped with the poker. I don't use the fireplace a whole heck of a lot, except recently where I've been making fires almost daily. The fires usually last for 5-6 hours. I would think the fireplace should withstand this type of use.

Is there normally an airspace behind the the lower back wall?

Should the brick/mortor be cracking like this?

[Jacksnap]

It could sound hollow, but the cracks are something that should preclude you from using the fireplace at all. The cheapest way to see what condition it is in, is to call your local fire dept and ask if they will come and do an inspection. You can also check with your building dept. (Small town or large city, makes a difference :D ) Many will, a few won't. If you are lucky, they will give you an idea of what you should be repaired and needed to meet code. Then find yourself, a mason experienced in fire places (with references). Any chance of going back to the builder with warranty coverage? Also, if this is a development, check with your neighbors and see if they are having the same problem. If so, you can go back to the builder as a group.

[mdshunk]

I have always used my chimney sweep for fireplace repairs. They have seen just about everything that goes wrong with fireplaces and chimneys on a very regular basis. Masons (to me) don't seem intelligent enough to do the proper troubleshooting. Plus, chimney sweeps will often stop by and look it over for free. A mason could surely fix the crack, but they might not provide permanent corrective action.

[bmwpower]

It could sound hollow, but the cracks are something that should preclude you from using the fireplace at all. The cheapest way to see what condition it is in, is to call your local fire dept and ask if they will come and do an inspection. You can also check with your building dept. (Small town or large city, makes a difference :D ) Many will, a few won't. If you are lucky, they will give you an idea of what you should be repaired and needed to meet code. Then find yourself, a mason experienced in fire places (with references). Any chance of going back to the builder with warranty coverage? Also, if this is a development, check with your neighbors and see if they are having the same problem. If so, you can go back to the builder as a group.

My father and I built the home ourselves. We sub'd out the masonry work. I'm actually not suprised that this has happened since I've had some other issues with the mason we used. I'd go to the mason that did the work, but quite frankly I don't think he would do the proper fix. Maybe I'll just send him the bill?

Thanks, guys. I'll try contacting the people both of you have suggested. I guess tonight will be that last fire for a little while...