Is a 6-degree indoor swing normal after sealing the attic?

A 6-degree drift over a 34-degree outdoor swing is a solid result for a house with empty wall cavities. Most of the thermal pressure in a ranch-style home happens at the ceiling and the floor. By sealing the attic and crawlspace, you’ve effectively shut down the **stack effect**, which is what usally sucks conditioned air out of the top while pulling raw air in through the bottom.

The reason for those results is that the attic is the biggest surface area exposed to the sun's radiant heat during the day. Since you air sealed it properly—presumably with canned foam or acoustic sealant on the top plates and light fixtures—you aren't losing your indoor air mass to the outdoors. The air inside the house is essentially sitting still now, which is exactly what you want.

As for the walls, they definitly still represent a significant thermal bridge. On a 1965 build, those empty cavities are likely drafty too, even if you sealed the top and bottom plates. You’ll realy feel the lack of wall insulation when the outdoor temps drop below freezing or stay above 90 for several days in a row. That’s when the thermal mass of the house finally gives up and the walls start radiating heat or cold directly toward you.

If you decide to do the walls next, look into **dense-pack cellulose**. They can blow it in from the exterior by popping off a row of siding. It’s a bit of a process but it adds both R-value and an extra layer of air sealing. Did you use spray foam to seal the attic or just the standard canned foam and board? Also, what was the total cost for the crawl and attic work? Having a baseline for what your temperature swing looked like before the project woud help tell if the walls are still a major leak or if you're alredy at the point of diminishing returns.

I'm curious if you noticed the house getting quieter after the blown-in went in? I've got a similar ranch and the street noise is driving me nuts. Also, with your walls being empty, do you feel any drafts coming from the electrical outlets? I’ve heard you can get these little foam gaskets to put behind the covers, but I wonder if that’s just a band-aid if the whole wall is empty. I'm trying to decide if I shold follow your lead and do the attic first or just try to get the walls done at the same time.

That 6-degree drift is actually pretty impressive for a ranch with empty walls. One thing people forget is solar gain through the windows. If you kept the blinds closed, that likely helped keep those numbers stable.

You should grab a cheap IR thermometer and check your interior wall surface temps compared to the ceiling. If the drywall stays within a couple of degrees of the room air, your walls aren't the emergency you think they are. Also, keep an eye on your indoor humidity now. Since you've tightened up the envelope, you might notice it creeping up becuase the house isn't "breathing" out all that moisture anymore.

The real test is gonna be how often your HVAC cycles now. Even if the temp drift stays low, the actual run time on your compressor is where the savings show up. One thing I'd check is your attic access. If it's just a piece of plywood in a closet, that's basially a hole in your thermal envelope. I built a tent out of rigid foam for mine and it killed the last drafty spot in the house. Since your walls are empty, you might also want to check where the plumbing comes up trough the floor under the sinks—those gaps are ussually huge and let crawlspace air bypass all your hard work.