Spray foam insulation questions

[acanthophippium]

We just bought our home and discovered and fixed a massive rat infestation.

Were looking at installing our insulation, and I really want to avoid blown insulation or fiber rolls as they made amazing homes for the rats.

I've been researching the closed spray foam and want to spray the top of the under roof. My air ducts are in the attic, and Southern California is pretty hot.

My house is 1800sqft. How many inches does the foam need to be to reach r40? Should I mix closed foam with open foam?

The internet said about $800 for, 600sqft at 1 inch. Is that correct?

1inch is r6, so I would need about 6.5 inches?

My math: 600x3= 1800(1inch), at $2,400. So 2,400*6.5= 15k to insulate my home with foam? No way.

What am I doing wrong here?

[acanthophippium]

On 08/03/2023 at 04:17, acanthophippium said:

We just bought our home and discovered and fixed a massive rat infestation.

Were looking at installing our insulation, and I really want to avoid blown insulation or fiber rolls as they made amazing homes for the rats.

I've been researching the closed spray foam and want to spray the top of the under roof. My air ducts are in the attic, and Southern California is pretty hot.

My house is 1800sqft. How many inches does the foam need to be to reach r40? Should I mix closed foam with open foam?

The internet said about $800 for, 600sqft at 1 inch. Is that correct?

1inch is r6, so I would need about 6.5 inches?

My math: 600x3= 1800(1inch), at $2,400. So 2,400*6.5= 15k to insulate my home with foam attic insulation northern va? No way.

What am I doing wrong here?

thanks in advance for all your suggestions

Edited March 10 by acanthophippium