Hello all, and thanks again for all the helpful advice on my other recent questions.

I’m preparing to insulate attic, stud bays, and joist bays between first and second floors on my ADU project (PDF wall section and floor plans attached). Two story, garage and office below, apartment above. Climate zone 5.

自许可证颁发以来，我已经进行了一些更改，并于去年夏天开始建设，这主要是由于材料成本和材料和承包商的可用性。在这一点上，我自己几乎做所有的工作。自去年秋天以来，该项目已经干燥，有4英寸的外部泡沫和WRB。我们正在包裹壁板，电气和管道粗糙，并开始将公寓天花板干燥。

最初，我计划将密集的包装纤维素用于螺柱和托梁，并在阁楼中散发出松散的纤维素吹散。当我很明显我不会找到一个绝缘承包商来做密集包，或者至少不能为我负担得起的东西，我开始看玻璃纤维棒，特别是新的道琼斯犬棒。矿物羊毛不再在预算中。

Then I read a couple article and comments on GBA suggesting dense pack was doable using rental equipment. Since I’m doing blown in cellulose in the attic, I ordered a little extra and some insulweb, figuring I’ll try a stud bay or two while I have the machine for the attic. If it works, great–if not, back to fiberglass.

However, reading recent comments on this blog post://m.etiketa4.com/article/insulating-a-wood-framed-floor-assembly#comment-231902
建议在一楼和二楼之间的托梁湾中吹入或致密的包装可能特别具有挑战性。

Additionally, because I’m locating the water heater and plumbing manifold in the garage, and some DWV and pex in the joist bay above the wet wall dividing office and garage, the inspector asked that I provide a heat source for the garage, with a 1000 W Cadet wall heater being an acceptable option.

I’ll be carefully airsealing the garage ceiling (5/8″ Type X drywall) and doing blower door testing.

Apologies for the long-winded intro, but the question is: if the garage and office are maintained at say, 45-50° minimum, what level of insulation in the floor below the apartment is necessary or desirable? And is using fiberglass batts likely to be less labor and more forgiving than attempting to blow in cellulose?

And should the interior wall (the wet wall) between office and garage get as much insulation as it will hold (which is not much, considering the space occupied by plumbing)?