Hi all
I decided to finish part of my basement and I am planning to use 3" EPS boards to insulate the foundation walls and then have a 2x4 frame in front of the foamboards to screw in the drywall.
The insulation sheets are covered with foil on one side (interior) so there should be no need for a vapour barrier. I am in Ottawa Ontario where the winters are brutal regardless of what Greta thinks. The foundation wall has 3 sections, the bottom concrete part, the top part between the wood joists and there is a wood section in the middle. The bottom part will be covered by foam boards and for the top section between the joist which is 2" deep I will cut squares of foam board and secure them between the wood then fill with spray foam.
What I don't know how to deal with is the middle section, from where the concrete wall ends and the joists start. This section is 3.5 " deep. I was thinking of 3 options.
1. Leave it empty and use foamboards that extend from the floor all the way to the joists. This way I would be only using one sheet of insulation that will cover both the concrete and the mid section, leaving a 3.5" pocket of air behind the mid section.
2. Do the same thing but on top of that also cut pieces of foamboard and stuff / spray foam them in the mid section slots and then cover it again with the sheet that goes all the way to the floor. There would be half an inch space in between the 2 insulation boards in the mid section.
3. Fill the mid section with individual pieces of foamboard, and have the concrete wall covered with the insulation boards that do not extend up to the joists.
For option 2 I am a bit concerned about leaving a pocket of air between 2 vapor barriers. And also for option 1 I am concerned that hot air from inside can somehow make it in the 3.5 inch deep pockets.
I really don't care much about R values and heating bill, what I want to avoid is moisture / mold problems and if possible minimize the risk or mice nesting in the walls.
What would be my best design in this case?
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I decided to finish part of my basement and I am planning to use 3" EPS boards to insulate the foundation walls and then have a 2x4 frame in front of the foamboards to screw in the drywall.
The insulation sheets are covered with foil on one side (interior) so there should be no need for a vapour barrier. I am in Ottawa Ontario where the winters are brutal regardless of what Greta thinks. The foundation wall has 3 sections, the bottom concrete part, the top part between the wood joists and there is a wood section in the middle. The bottom part will be covered by foam boards and for the top section between the joist which is 2" deep I will cut squares of foam board and secure them between the wood then fill with spray foam.
What I don't know how to deal with is the middle section, from where the concrete wall ends and the joists start. This section is 3.5 " deep. I was thinking of 3 options.
1. Leave it empty and use foamboards that extend from the floor all the way to the joists. This way I would be only using one sheet of insulation that will cover both the concrete and the mid section, leaving a 3.5" pocket of air behind the mid section.
2. Do the same thing but on top of that also cut pieces of foamboard and stuff / spray foam them in the mid section slots and then cover it again with the sheet that goes all the way to the floor. There would be half an inch space in between the 2 insulation boards in the mid section.
3. Fill the mid section with individual pieces of foamboard, and have the concrete wall covered with the insulation boards that do not extend up to the joists.
For option 2 I am a bit concerned about leaving a pocket of air between 2 vapor barriers. And also for option 1 I am concerned that hot air from inside can somehow make it in the 3.5 inch deep pockets.
I really don't care much about R values and heating bill, what I want to avoid is moisture / mold problems and if possible minimize the risk or mice nesting in the walls.
What would be my best design in this case?
