Honestly, mild steel isn't a terrible choice—it's affordable and easy to work with, so I wouldn't beat yourself up over it. Sure, corten steel is trendy and has that cool rusted look, but mild steel can last plenty long if you take care of it. A little warping is pretty normal after some intense fires; mine did the same thing and it's still going strong after four years.
About the lining though...I'm skeptical about refractory cement. I've seen it crack pretty quickly under regular use, especially if you're dealing with big temperature swings or moisture. Fire bricks can loosen up if they're not installed right (your neighbor might've rushed it?), but in my experience, they're still the safer bet long-term. Just make sure you use a good high-temp mortar and give them room to expand a bit.
As for drainage, drilling a few small holes won't hurt your airflow much at all—trust me, I've done it. Moisture buildup can cause more corrosion than you'd think, so better safe than sorry. Just keep the holes small enough that you're not losing too much heat.
Sounds like you've got a solid setup overall though...just needs a couple tweaks before winter hits hard.
"Fire bricks can loosen up if they're not installed right (your neighbor might've rushed it?), but in my experience, they're still the safer bet long-term."
Gotta disagree slightly here—I went with refractory cement and it's held up surprisingly well. Key is applying thin layers and letting each cure properly. Mine's two winters in, no cracks yet...just sayin'.
I've gotta side with refractory cement here too—did mine on a tight budget, and honestly, it's been rock solid. The trick is patience (which I admittedly struggle with, lol). Just take your time layering it up, let each coat cure fully, and you'll be golden. Mine survived marshmallow roasting marathons and some pretty harsh storms...still no cracks or shifting. Fire bricks might be great, but don't underestimate a well-done DIY cement job.
Gotta be honest, refractory cement can work fine, but I'd still lean toward fire bricks if safety and longevity are your top priorities. Cement can hold up great initially, sure, but over time—especially with frequent high-heat use—it can degrade or crack internally without obvious signs. Fire bricks are designed specifically to withstand those extreme temps consistently. If you're investing in a quality home setup, might as well go the extra mile for peace of mind...just my two cents.
Good points there—I agree fire bricks are definitely the safer bet long-term. Plus, from a sustainability angle, bricks can often be reused or repurposed down the line, which is a nice bonus if you're into eco-friendly building. Cement usually ends up as waste once it cracks or wears out...not ideal. Curious though, has anyone tried combining both materials? Like using fire bricks for the main heat zone and refractory cement as a filler or sealant in less critical areas? Wonder how that'd hold up over time.
