Foam Retrofit?

[fritz1255]

In an existing uninsulated home, would it be even possible/adviseable to spray in foam between the sheetrock and outer wall? Since most foam expands, wouldn't it be likely to bulge the walls if they filled the cavity with foam? I can't see how you could get an even layer of a couple of inches or so inside the wall without drilling multiple holes in either the interior or exterior wall, and even then there would likely be some slipups.

[RTF]

Why not blow insulation into each cavity? Foam expands and you would have issues.

[fritz1255]

Blowing in cellulose is the "default" treatment. However, foam would likely be more efficient, so there is some "carrot" there. But is it even possible to retrofit with foam without tearing the walls out? Is it even worth consdiering for a retrofit, or only new construction?