The answer is yes, but drywall needs to be removed before you can install the foam. Spray foam expands rapidly when it is applied to the inside of walls. If you try to add the insulation without removing drywall, the expanding foam may overfill the panel and exert pressure against the inside of the plasterboard.

That being said, if you are interested in insulating your attic with spray foam roofing, you must first remove old insulation solution. You might think that leaving it there is a good idea, that it will pair well with the spray foam solution. However, this isn't the case.

However, one area where we would not advise to use expanding spray foam insulation is in spaces too close to electrical mechanisms, such as outlets or boxes. If foam were to get inside the box or outlet, the components could jam up.