We refinanced our home from a 30-year to a 15-year this past December to take advantage of low rates — we managed to drop our payment and shave off ~12 years from our original mortgage (we originally purchased this home in 2017 and the area has appreciated considerably since them), so we have a fairly recent appraisal.

On top of this add rigid foam insulation also with the seams taped.

The buyers rebuilt the wall with cement block jacked up the floor joists & its still OK 12 years later, (we still hold the note).However, it appears that foam spray is NOT a good solution !!!

I did all the work on the rehab except for the new heating system, spray foam, and roofing.

Overall, I was able to shave off $700/month.I'm assuming this would reduce my DTI ratio. 

@Sean SloopYou can get foam or felt pads for the weight bearing ends of furniture legs.

Olee Sleep 13 inch Galaxy Hybrid Gel Infused Memory Foam and Pocket Spring Mattress (Full) https://www.amazon.com/dp/B010GO33LW/ref=cm_sw_r_cp_api_glc_fabc_o37.FbWGGS3BVInsuranceYou will need short term rental insurance and for liability a lot of mortgages won’t let you transfer the property to an LLC so if that’s the case study you can get an umbrella insurance policy to cover yourself.

(If you have a spray foam attic decking you might think about replacing as you won’t know about a leak till it’s late)

With shaving my living expenses to a minimum, I could, in theory almost be FI with just this one property.

.- The FIRE crowd (generally) seems so preoccupied with the stock market and hitting a single "number" that they can't possibly consider diversifying into real estate or the fact that some passive monthly income (through rent) now could shave a decade or more off how long they have to work that job they hate - but are apparently willing to keep trudging away at it anyway.