Adding to insulation done in 5 separate steps.

1. Add to lid and top insulation.

My icebox had an old maple cutting block top which fit poorly and which was coming apart. I replaced the top with a close fitting heart pine top insulated on the bottom with 1/2 of foil backed insulation. Probably 1 could also be fitted to the bottom of the lid. In addition, 1 of rigid insulation can be fitted to the top outboard of the lid. In this area of the box, the top is just the plywood of the cabinet bottom and on my boat had leaked enough heat over the years to condense water on the teak trim, discoloring it.

2. Add batt fiberglass insulation to the back

The photo shows the cavity with the stove removed. I cut out two hand access holes as shown. these holes allowed the introduction of ordinary R11 fiberglass house insulation (with the vapor barrier removed) to completely fill the area behind the box. I had originally thought to inject expanding foam in this area, but it is such a huge volume, that the batt fiberglass turned out to be more practical. It helps to cut the fiberglass into strips, as big as can be poked through the holes and work it with a stick across the back being careful to try and leave no cavities without insulation.

Partion Aft of icebox

3. Adding batt insulation to bottom, forward side, and aft inboard sides of icebox

This photo shows the exposed inboard side of the icebox. Access is obtained by removing outboard sink cabinet partition. Partition is fastened with silicon bronze screws. Theyre soft and strip very very easily. Best way to get them out is to use the biggest phillips head screwdriver that will fit them, and tap the screwdriver down into the screw to seat before attempting to remove. Insulation is added to bottom, forward side, and aft portion of inboard side as was done previously except here insulation may have to be torn into thinner strips before inserting with a push stick. Before starting, a flashlight underneath the icebox and in the crack aft of the icebox should show solid insulation at the back from the previous step.

Icebox with inboard partition removed

Photo shows how bottom and aft sides are filled with insulation.

4. Insulate inboard side of icebox
A piece of R11 insulation cut to fit can be placed over inboard side and then the sink cabinet partition screwed back in place.

Inboard side with edge insulation

5. Adding Insulation to AFt Side

This side is not accessible for the batt insulation and so I drilled a set of injection holes in the partition aft of the icebox, and injected a common expanding foam aersol insulation. Photo shows the operation after expansion has ceased which may take several hours. Notice the support struts in place to make sure that the expanding foam did not warp the partion. As it turned out, the handholes evidently acted fairly efficiently to relieve any pressure and there was never any evidence of significant deforming force on the partition. After the foam hardens, it can be cleaned up easily.

Insulating Aft side of icebox