Hello! I am planning to convert a storage room into a guest room/TV room that is adjacent to a detached garage. The garage building is currently insulated about 90mm. I was thinking of installing new interior walls and adding extra insulation. Since the space will be heated year-round, I've been advised to have a vapor barrier on the warm side of the insulation or a maximum of 1/3 in.
I have some surface-mounted electrical wiring on the current storage wall that I plan to have the electrician reroute or install junction boxes so that the connections can be accessed later. I was advised not to place the vapor barrier directly against the current chipboard wall. However, I'm not sure about the order in which to do this. How would you proceed?
1. Install 25 mm battens for an air gap, ask the electrician to remove all electricity, and then place the vapor barrier against it. Then frame 45 mm on the battens (total 70 mm) and run the new wiring with junction boxes in the new interior walls, insulate + surface layer (probably plasterboard). Perhaps an expensive and complicated solution but where the vapor barrier is more protected.
2. Frame 70 mm studs directly and notch for the current wiring, allowing the electrician access to run new wiring. Then add insulation and vapor barrier closest to the plasterboard. The simplest solution for me. But each drywall screw will perforate the construction plastic even if I do hit the studs. The advantage is that I can start immediately and possibly avoid removing every wire that already has reasonable protection without the flex.
And finally, two dummy questions.
One of the walls (the one straight ahead in one picture) is free of electrical wiring, relatively straight, and has the garage section behind it. I had hoped not to have to frame it at all and leave it as is. But I assume I need to wrap it too for the room to be done correctly? Will moisture otherwise risk penetrating that wall? And if I need to wrap it, do I need an air gap, or can I press it directly against the existing wall?
I had a carpenter here who said that a vapor barrier might not even be needed in this 12-square-meter room with the intended use. Of course, it would solve all my problems if I didn't need the plastic. But I assume it's unwise to take a chance?
I have some surface-mounted electrical wiring on the current storage wall that I plan to have the electrician reroute or install junction boxes so that the connections can be accessed later. I was advised not to place the vapor barrier directly against the current chipboard wall. However, I'm not sure about the order in which to do this. How would you proceed?
1. Install 25 mm battens for an air gap, ask the electrician to remove all electricity, and then place the vapor barrier against it. Then frame 45 mm on the battens (total 70 mm) and run the new wiring with junction boxes in the new interior walls, insulate + surface layer (probably plasterboard). Perhaps an expensive and complicated solution but where the vapor barrier is more protected.
2. Frame 70 mm studs directly and notch for the current wiring, allowing the electrician access to run new wiring. Then add insulation and vapor barrier closest to the plasterboard. The simplest solution for me. But each drywall screw will perforate the construction plastic even if I do hit the studs. The advantage is that I can start immediately and possibly avoid removing every wire that already has reasonable protection without the flex.
And finally, two dummy questions.
One of the walls (the one straight ahead in one picture) is free of electrical wiring, relatively straight, and has the garage section behind it. I had hoped not to have to frame it at all and leave it as is. But I assume I need to wrap it too for the room to be done correctly? Will moisture otherwise risk penetrating that wall? And if I need to wrap it, do I need an air gap, or can I press it directly against the existing wall?
I had a carpenter here who said that a vapor barrier might not even be needed in this 12-square-meter room with the intended use. Of course, it would solve all my problems if I didn't need the plastic. But I assume it's unwise to take a chance?
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Skip the plastic entirely, it's of no use, it will only be a hassle to fix. In new houses with different heating & ventilation systems, tight plastic is more important, especially in bathrooms where there is a lot of moisture, for you, not at all! Good luck with the construction.
Janathan79 I hope you're right. It would be very nice not to have to think about it. Considering the garage is wall-to-wall, maybe I can also have a ventilation opening there (besides the ventilation in the outer wall) to expel any moisture from the heat.
The room will be heated with an oil-filled electric radiator at 1000w.
The room will be heated with an oil-filled electric radiator at 1000w.
The valve in between does not have a direct effect, and it is not certain that there will be an exhaust effect depending on the rest of the house's ventilation system. In the worst case, you might get the smell from the garage into the new room 
Ok.. Yes, maybe 1-2 fresh air vents in the outer wall will be enough. I'm planning to start with one with a 120 mm pipe.Jonatan79 said:
A valve between won't have a direct effect and it's not certain that there will be an exhaust effect depending on how the rest of the house's ventilation system looks. In the worst case, you might get garage smells in the new room