fireplace crack repair

[richard_s]

Hi,
I'm really glad I just recently found this site. Although I sweep the chimney each year, I've just recently gave the firebox a good cleaning with masonry cleaner so I could fill a crack in the back of the firebox prior to installing a wood fireplace insert (I haven't yet decided which one as I'm still in the research mode). As it turns out the crack is a bit deeper than I had originally suspected and there are some other hairline cracks. For the most part, the crack is less than 1/4" but there is one small part of the crack which is a bit wider & deeper. Also, the feet of the grate has gouged out 4 small spots on the firebox floor. I used Sacrete concrete crack filler on the crack and the gouged spots. In reading some of the posts, it appears that I should have used refractory cement. It's not completely dry & I could scrap it out. I would really appreciate it someone could provide guidance on this.

I'll also try to post some pictures of the firebox to ask for opinions on whether the firebox is worth saving or if a rebuild is necessary.

Thanks in advance for any advice offered.

 

[granpajohn]

I have made similar repairs. You don't say too much about your FP, but if it is a traditional masonry/brick FP, it should be OK. If it is one of those modern, zero clearance, framed in wood, things,...well I'm not sure, but still should be fixable.

Anyway, I used Rutland mortar, which comes in tubes like the Sakrete brand, (which I have also used elsewhere). This is it: (broken link removed to http://www.rutland.com/productinfo.php?product_id=19)
(I'd attach a photo, but I can't.)

After several years of monitoring, the cracks have held, thus indicating that the foundation and other structure is not moving and making matters worse.

I did this back when it was and open FP. Added different doors, etc., then ultimately installed the QF4100 insert.

I'm not certain, but I believe that the Sakcrete product would be fine for the insert installation...the heat is not bad. However, for the open FP, I recommend the fire-tested Rutland product.

OK Bottom Line: I repaired mortar and cracks using Rutland mortar. Have since installed a full insert. One cracked brick is visible even with the insert. Everything is fine.

 

[richard_s]

Thanks so much for the reply. It makes me feel much better about my repair. It is an open masonry FP. But for safety's sake it sounds like I shouldn't use the FP until I install an insert.