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Low expansion foam turns sticky and brown after 1 year

Kevin_Edmund's picture


We had an air jet bath tub installed and to stop the floor of the bath tub from flexing, the installer used (window and door) low expansion foam to fill the gap between the subfloor and the bottom of the tub. After more than a year of complaining of the drastic cooling affect of the jet, we decided to remove the removable section of the skirt of the tub and just check things out for ourselves.

The subfloor around the perimeter of the tub/foam appeared wet to the touch at first, but now seems to have dried to a slightly sticky oily substance. The foam under the tub has turned brown in many places and is now sticky to the touch. In several places the foam pooled or mounded into a brown blob. Originally, the foam had cured to the typical bright yellow color that I'm used to seeing. The foam product came from a can (not a two part application).

What would cause the foam to turn brown and sticky?

Although maybe unrelated, the vapor barrier is not installed properly where the jet air blower is located. At first i thought that the wet surface might be related to condensation, but now I'm not certain. However, I now know why the jets cool the tub water quickly.

I know that my question doesn't quite line up with Energy & Heating,  but any insight or help on this would be great?