Got new HVAC and insulation, now I have cracked walls & ceiling.

[wingnutx]

Last spring I had my house rewired, then the rooftop heatpump replaced, and cellulose blown into the attic. Some ceiling cracks showed up fairly soon after, mostly in places where it had been patched some time in the past, and I figured it was probably just the additional weight, and possibly increas in temperature differential.

Since then I have had several areas crack in the interior walls as well. Some are a tiny gap, but some look like the are buckled under compression.

The house was built in 1947 on a slab, and has lathe & plaster on most of the interior. External walls are brick with plaster finish on the interior. I don't see any damage from the outside.

Some cracking seems to have appeared just in the past couple of weeks, since the temps started getting well over 100f, and I hear regular popping as the roof heats up or cools off, which I don't remember having before.

Doors do not seem to be affected, although several cracks start at the top corners of doorways.

Please take a look, and see if anything looks serious. Is it common to get cracks after having this sort of work done? Thanks.


This arch has cracks that I just noticed the other day, on each side. It looks like it was compressed and buckled a little. The white wall to the left is exterior.






On the other side of the house I have several cracks in my office.


There is this crack coming from a closet door to the ceiling.



And one from the door leading to the room.



There are a lot more, but I am limited to 4 pictures. There are quite a few where ceiling meets wall.

One more question: When repairing cracked plaster, should I drill the ends of the crack like I would for cracked metal? Thank you.

[pushkins]

Lathe and plaster is a whole different beast compared to drywall, your cracks seem to me to be from the interior drying out, how long was this property without HVAC or was the HVAC not working correctly for a period of time ?
What happens often (especially in unattended homes or foreclosures etc...) is that the HVAC gets turned off this allows moisture to build in the house an then when the home is bought and the HVAC is turned back on it dries the plaster out and wholla cracks appear.
Cracks emanating on a diagonal from doors often can mean some sort of structural issue, yours however straighten upm and head vertical to the ceiling. The one in your pictures that runs around a corner is another strange one, it appears to follow a line of the lathe.
What temperature are you keeping the thermostat set at right now ? Too cold a temp. will remove all the moisture from the air, basically sucking the plaster dry.

[wingnutx]

It has had AC for at least the last 20 years, probably a lot long than that judging by the age of the one I replaced, but didn't have much insulation. The new AC is just a much more efficient one, and it stays cooler with the added cellulose.

Temp inside is usually in the mid-to-low 70s, and it's been hitting 105-108 outside this week. The air is pretty dry outside (I'm in Phoenix) and even drier inside.

I didn't think about plaster drying out. Thanks.