How can I provide enough insulation with the minimal depth for my laundry room area?

Question

I am remodeling my laundry room. As you can see from the elevation drawing, I am building out a custom cabinetry for the washer/dryer so they are elevated. There will be drawers below which can be fully removed to reach the cleanout access. But, just in case there is a cleanout access under the stairs as well.

The cabinetry sticks out quite a bit farther than my other cabinets because the depth of the washer/dryer alone are 33" deep. Normal cabinetry is 24", the washer/dryer cabinetry will be roughly 40" deep to accommodate the units and space behind the units for cable/pipes and also about 2-3 inches in front so the washer/dryer are not literally at the edge of the cabinets.

I had an idea to save a few inches as well as make the back area look cleaner and easier for hookups. Currently I had a normal 2x4 framing to put insulation/drywall back there to handle hot/cold/moisture. The pipes and outlets, etc. will be recessed to save space. This gets a bit complicated trying to perfectly recess the dryer vent pipe so it aligns as close to possible with the dryer vent connection. Additionally, the recessed nature still means hot/cold water pipes and electrical means the units still need a few inches away from the wall. My idea is to make the entire area behind the washer/dryer recessed instead. But, I still want to protect against hot/cold/moisture, so I know I can't simply stick drywall directly against the concrete wall.

Is there a safe way to do what I want and protect against heat/cold/moisture? The recessed area does not have to be the entirety of the 4" of the 2x4, maybe I build the recessed portion as 3" and use 1" of insulation? Is that enough? Is there thin but super effective insulation that can handle this scenario?

I'm not sure if I am explaining this correctly, but hopefully I did, and if not hopefully the images convey what I am trying to go for here. Thank you.

Answer 1

The short answer is that insulation is always an average, and it's not critical that you have full R over every square inch. Consider all the windows and doors already in your home at much lower R-value than the thicker wall insulation provides. It's also less critical below grade, where exterior temps are less severe and conduction tends to be slower.

It's alway challenging in utility areas. Fit what you have space for, and for the severely limited areas look to high-performance options like isocyanurate sheets with foil facing, or just sheet foam as is available.

Also note that plumbing should remain within the conditioned space. Sometimes folks think that making it cozy with insulation helps prevent freezing. It doesn't. You need to let heat access the pipe where possible and insulate to the exterior.

If you have at least something everywhere, and if you do well with the vapor barrier, you'll be just fine.