Vol.1 No.4
20 March 2002

• Using Foam Core to Construct a Room Box, Part III--Questions & Answers
• Question of the Week: Could you please explain the difference between a jig and a fixture?

Using Foam Core to Construct a Room Box, Part III:
Questions and Answers

George Hoffman

Jim has the following questions.

Question #1:
The ceiling doesn't appear to have pine strapping, yet the side and back studding rise about 1" above the ceilings. Is this airspace, and if so how far can Foam Core cover with out support?

Answer: (See Part III drawing below.)

• Glue Foam Core ceiling to the top of room box walls.
  
• Next, glue square pine rafters to the top surface of ceiling of Foam Core and to the inside of studs. Construction at this point is very solid.
  
• Good question about air space. Yes this is airspace and it helps reduce heat build-up.
  
• In my experience 1/4" Foam Core for the room box needs support about every 3'
  
• The removable 1/4"exterior finished plywood top allows access later to wiring and for any maintenance.
  

Question #2:
Does plywood finished exterior screw into the ends of the pine studs? This seems like the weakest place to put a screw!

Answer:

• Yes the finished 1/4" exterior plywood top has screws that attach it to the tops of the vertical studs with cup washers to allow for removal for access to the interior ceiling and wiring.
  
• Actually this method is very strong and better looking when finished.
  

Question #3:
I think I understand the side and back exterior finish plywood glued to the studs and gator board base, but what if wiring pulls loose. How would you get to the wires feeding down through the sides and to the switch hub box?

Answer:

• Yes the side and back finished plywood panels are glued as shown in the drawing to the studs and base of the room box. You will note in drawing that there is space between the studs. Perhaps not large enough for your hand, but you can with a stiff wire guide a replacement lighting wire to the room.
  
• If you are replacing a new bulb with wire already attached, tape the new bulb and wire to the old wire and pull from outside wall and up between studs.
  
• The switch hub box is cut into finished plywood (see drawing) and held by screws to studs so it may be removed for greater access to wiring connections.
  

Question #4:
Does the bottom of the finished plywood sides glue or screw into the 1/4" Gator Board (or 1/4" plywood) base --- what would it screw into?

Answer:

• The outer finished plywood sides and back are glued to the outside of studs and outside of Gator Board (or Plywood) base. Using screws in Gator Board would not be advisable. Vinyl glue if applied properly will hold very well.