Building Efficiency installed insulation into my 1800 sf San Francisco house (which had no insulation prior) at the end of 2021. Insulation was installed both into the exterior facing walls (via holes in the interior drywall) and into the very low clearance attic crawlspace (maybe 1.5-2 feet of clearance). They were willing to crawl in the very small attic crawlspace to get the insulation installed – which was impressive b/c the clearance was so low.
Day-to-day life in the house is completely different. The temp is actually regulated. Heat no longer dissipates immediately after being run. The house also doesn’t get super hot when the sun shines on the walls. In the dead of winter we used to sleep with wool hats on – no longer! (We’ve never run the heat at night at still don’t.) I actually only use a light sheet when sleeping at night now – even when it’s cold. It really is the single best thing I’ve ever done to this house and I should have done it much sooner. It’s as life changing as anything you can do to a house can be lol.
I was concerned about having holes drilled in the drywall but they matched the texture of our drywall (skip trowel texture) and you absolutely cannot tell at all that there were ever holes in the drywall.
I also got my BayREN rebate timely to help offset some of the cost.