Is it normal for a new build to have this much heat bleed in the corners?

R30 is actualy the bare minimum code requirement for central California, and in 105-degree heat, it's going to struggle. Those 84-degree readings in the corners are classic examples of **thermal bridging**. Since wood studs and top plates have a much lower R-value than insulation, they act as a bridge that pulls heat directly from the hot attic and exterior siding into your drywall. Unless your builder installed continuous exterior foam board before the stucco went on, those framing members are basicly radiators. It’s also very common for blown-in insulation to be thin at the eaves. Because of the roof pitch, there’s often not enought vertical clearance for the full 11 inches of material unless the builder used 'raised heel' trusses. If the insulation is tapering down to three or four inches near the wall plates, that's exactly where your heat spikes are coming from. You shoud climb up there and check if the material is consistent all the way to the edges or if it's being compressed by baffles. Another thing to consider is that the 'standard roll' insulation in your walls often has gaps at the top and bottom of the stud bays. If the fiberglass wasn't cut perfectly around electrical boxes or if it's sagging slightly, you get convection loops inside the wall cavity. That heat soak you're feeling trough the frame is a mix of that and the sun hitting the stucco all day. Stucco has high thermal mass, so it holds onto that 100-degree heat long after the sun goes down. You might want to ask the builder for the **blower door test** results. New builds are required to hit certain air leakage targets. If your ACH (air changes per hour) is high, you aren't just dealing with heat transfer; you're losing your conditioned air through top plates and recessed lights. If the numbers look bad, that’s your leverage to get the supervisor back out to properly seal the attic floor.

R30 is honestly a joke for the Central Valley. If you want to stop that 84-degree soak, you need to be looking at R-49 or even R-60. I’d bet money they used a basic Owens Corning or Knauf fiberglass blow that’s settling alredy. Get some Rockwool 80 or similar mineral wool batts and stuff them into those edge gaps where the blower couldn't reach. Also, check your recessed cans. If they aren't IC-rated and sealed with somthing like a Tenmat cover, they’re basially chimneys sucking the AC right out. I’d also verify if they used a radiant barrier like TechShield on the roof decking; if not, your attic is prolly 140+ degrees right now.

I had the same hot spots in my new build and what acutally worked for me was grabbing a few cans of Great Stuff foam and a cheap headlamp. I climbed into the attic and realized the builder completely ignored the top plates where the drywall meets the wood. I spent an afternoon sealing every single wire hole and gap I coud find. It was a miserable, sweaty job, but my corner temps dropped about 6 degrees immediatly. If you're seeing those spikes, don't trust thier 'second pass'—get up there yourself and see if you can see daylight or feel a draft near those corners.

Don't forget the windows. Even if the walls are okay, if you've got standard dual-pane glass without a decent Low-E coating, that Central CA sun's just gonna bake your interior. I'd grab an IR thermometer and check the glass temp vs the frame. If the glass is scorching, it's radiating heat right onto those corners you're worried about. Might be worth looking into some ceramic window film if you don't wanna bug the builder again.

While the previous points regarding thermal bridging and air sealing are certainly valid, you must also scrutinize the potential for convective looping within the wall cavities if the fiberglass batts weren't split properly around the electrical wiring. If the installer simply compressed the insulation behind the Romex rather than incising it, you've essentially created a chimney effect where air circulates behind the material, rendering the R-value negligible in those specific localized zones. I whould highly suggest verifying if the builder utilized a 'Grade I' installation per RESNET standards, as even minor gaps or compressions at the top plates can facilitate significant bypasses that manifest as those frustrating 84-degree hotspots you're observing.

Quick update—I spent yesterday sealing the top plates with foam like you guys suggested, and it's definately made a difference in the drafts. However, those corners are still radiating heat. It sounds like thermal bridging is the culprit. If I add more insulation to get up to R-49, will that actualy help with the heat transfer thru the wood studs, or is that just a wall issue?