Floor Insulation Repair

[lkt1954]

First off I am a newbie to this site and like what I have found for information. I have a repair that I could use some advise on.

I have an older 70's model 14 x 70 mobile home that is a rent trailer and I need to repair the insulation and sheathing under the floor. There are several large spots where the sheathing has been either torn up and/or ruined by water leaks. I solved the leaks by using pepex lines (sp). The main problem we are having is poor cooling by the HAVC (central heat and air). The system is big enough and in good shape, yet it does not keep the mobile home cool and in Texas it can get hot. I have come to the conclusion that it is due to the ducts being exposed and the cold air loosing efficiency due to the ducts exposed to the heat. While the home is skirted it is still hot under there.

This home has the older sheathing that looks like roof felt draped between the frames and the insulation on top of it. The question I am working up to is how do you repair and/or replace all the sheathing and insulate the home to improve cooling and heating?

Thanks
Larry