The big thing to remember is that water in the ground is the enemy... If your insulation soaks up water, it turns into a thermal conductor and becomes WORTHLESS! There are two basic types of foam, open cell and closed cell. Open cell is like a sponge, it absorbs water readily, and has minimal insulation value when wet. Closed cell is essentially waterproof - it doesn't absorb water to any significant degree.
Open cell foam is good insulation, but ONLY in places where it is essentially kept dry, or where it is important to have a moisture permeable material - it is great in INTERIOR house walls, but it is not going to work properly underground! Don't attempt any sort of "waterproofing layer" on the outside of an open cell block, as any leak will eventually compromise the entire installation.
Closed cell foam is what you want for underground "foam in place" type installs, as it is inherently waterproof, and thus both keeps the PEX from losing heat, and keeps the ground water out.
I am not an expert on their products, but my recollection is that the Tiger Foam stuff is open cell, or not suitable for underground applications (If I'm wrong, feel free to correct me :coolhmm: )
I would suggest going with the foam contractor, and be sure to specify a CLOSED CELL foam! That will solve the volume problem as he just sprays as needed, (and charges accordingly) Rather than spending a lot of money on foam board, I'd consider just partially filling the trench (Maybe after dropping in your data and power conduits in the part you'd fill (Remember, you can't put power and control wiring in the same conduit, and you should keep the two types of conduit as far apart as you comfortably can... The other option might be to see if anyone has a narrower bucket for your digger that you could borrow or possibly rent....
Gooserider
Open cell foam is good insulation, but ONLY in places where it is essentially kept dry, or where it is important to have a moisture permeable material - it is great in INTERIOR house walls, but it is not going to work properly underground! Don't attempt any sort of "waterproofing layer" on the outside of an open cell block, as any leak will eventually compromise the entire installation.
Closed cell foam is what you want for underground "foam in place" type installs, as it is inherently waterproof, and thus both keeps the PEX from losing heat, and keeps the ground water out.
I am not an expert on their products, but my recollection is that the Tiger Foam stuff is open cell, or not suitable for underground applications (If I'm wrong, feel free to correct me :coolhmm: )
I would suggest going with the foam contractor, and be sure to specify a CLOSED CELL foam! That will solve the volume problem as he just sprays as needed, (and charges accordingly) Rather than spending a lot of money on foam board, I'd consider just partially filling the trench (Maybe after dropping in your data and power conduits in the part you'd fill (Remember, you can't put power and control wiring in the same conduit, and you should keep the two types of conduit as far apart as you comfortably can... The other option might be to see if anyone has a narrower bucket for your digger that you could borrow or possibly rent....
Gooserider