With the sound dampening finished (except for the front cab area), we can now move on to the next layer in the insulation plan: 1/2 inch thick Pink Extruded Polystyrene Foam Board and Pink Fiberglass Batting.  We didn’t want to use foam board any thicker than 1/2 inch so that it was easily flexed to the rounding walls and ceiling.  If it’s too rigid, it would either break when bent, or overpower the glue used to adhere it (probably).  Speaking of adhering it the foam board, we used 3M Hi-Strength 90 spray glue.  Hopefully this glue will hold up well, there are many reports both good and bad about using it for this.


One quick note about using this spray glue with extruded foam: the glue has a solvent in it which is amazingly good at completely dissolving the foam!  Luckily this foam board has a plastic sheathing on both sides which the glue does not dissolve.  We were careful to not rip the plastic and keep the corners from peeling, which is easier said than done, especially when using utility knives to cut it.  So far we’ve used four 4-foot by 9-foot sheets of this foam board and probably 5 cans of the spray glue (I lost count) for the walls, ceiling, and floor.  After gluing all the foam board to the sound dampener, we taped all the edges with aluminum foil tape.


The ceiling was done first.  We used a couple boxes and wooden dowels lying around to keep pressure on each piece while the glue set.  Then we started on the walls.


It would be too difficult to fish a bunch of little foam pieces through the small openings in the doors and glue them all into place…three inch fiberglass batting to the rescue!


There are still a few small pockets in the doors there do not have much insulation so as to ensure the door locks would not have interference.  A small amount of spray glue holds the batting in place.


Finally, the floor was done a little different, and that will be covered in the next post.