hello,
building a house with high walls, 1.5 stories.
how do I install a vapor barrier against the exterior wall when there is a floor joist blocking the plastic? should I cut and tape around each beam in the floor joist?
is a vapor barrier needed in the floor joist if we plan to start living on the ground floor and later finish the upper floor?
is it a good time to install a vapor barrier in the wall when I'm not heating the house until we move in next August? the risk is that it will be colder indoors on some days.
should I skip plastic in the bathroom walls since I have another form of vapor barrier in the form of wall mat behind tiles?
should there always be a vapor barrier above the bathroom (on the ground floor) in the floor joist?
thankful for answers
building a house with high walls, 1.5 stories.
how do I install a vapor barrier against the exterior wall when there is a floor joist blocking the plastic? should I cut and tape around each beam in the floor joist?
is a vapor barrier needed in the floor joist if we plan to start living on the ground floor and later finish the upper floor?
is it a good time to install a vapor barrier in the wall when I'm not heating the house until we move in next August? the risk is that it will be colder indoors on some days.
should I skip plastic in the bathroom walls since I have another form of vapor barrier in the form of wall mat behind tiles?
should there always be a vapor barrier above the bathroom (on the ground floor) in the floor joist?
thankful for answers
Question 1: Yes, tape does not hold. Cut the plastic in the middle of the beam, so that there is some overlap (about 2 cm if you have 4.5 cm joists), clamp the plastic with screws along with a board piece corresponding to the height of the joists. The board presses the plastic against the beam.
Question 2: Yes, in this case, it will be a cold attic and then there must be a vapor barrier in between. Then I think you should have at least 35-40 cm of insulation to avoid wasting energy. Then it depends on how long the upper floor will be idle. I was in the same situation last year and I fixed the insulation as quickly as I could on the upper floor, then the rest of the upper floor had to wait. I placed the plastic and then a company came and sprayed insulation. It took them about 3 hours and then the insulation was finished.
Question 3: If you're not going to have heating, it might be best to wait with the plastic.
Question 4: There should not be double vapor barriers. That's not good.
Question 5: Don't know.
Question 2: Yes, in this case, it will be a cold attic and then there must be a vapor barrier in between. Then I think you should have at least 35-40 cm of insulation to avoid wasting energy. Then it depends on how long the upper floor will be idle. I was in the same situation last year and I fixed the insulation as quickly as I could on the upper floor, then the rest of the upper floor had to wait. I placed the plastic and then a company came and sprayed insulation. It took them about 3 hours and then the insulation was finished.
Question 3: If you're not going to have heating, it might be best to wait with the plastic.
Question 4: There should not be double vapor barriers. That's not good.
Question 5: Don't know.
We bought a prefab house with a finished ground floor. There was plastic between the different levels. It is a type of protective cover to prevent the carpenters from falling through, and it also works as a vapor barrier, I think it's called combiweave. Normally this isn't needed, according to my KA guy, since it's warm on both sides of the vapor barrier.
However, I don't have any plastic that goes from the upper floor down and connects to the ground floor's vapor barrier. I was a bit quick to lay the floor. This won't be a problem, according to experts from the municipality and my KA guy, since warm air rises. I do have a vapor barrier between the two floors. You could say it looks like two upside-down U's with a gap of about 220 mm around the whole house.
If you can connect with the vapor barrier on the lower floor, that's the best option, but if you have a vapor barrier between the two floors, you can fasten it with a piece of wood against the furring strip in the ceiling of the lower floor just like you did on the sides of the rafters. I hope you understand what I mean.
However, I don't have any plastic that goes from the upper floor down and connects to the ground floor's vapor barrier. I was a bit quick to lay the floor. This won't be a problem, according to experts from the municipality and my KA guy, since warm air rises. I do have a vapor barrier between the two floors. You could say it looks like two upside-down U's with a gap of about 220 mm around the whole house.
If you can connect with the vapor barrier on the lower floor, that's the best option, but if you have a vapor barrier between the two floors, you can fasten it with a piece of wood against the furring strip in the ceiling of the lower floor just like you did on the sides of the rafters. I hope you understand what I mean.
maybe not a dumb investment to insulate both floors for example if in the future you choose to only live on the first floor when the children have moved out or when the knees can no longer handle the stairs due to frailty.
then you can let the attic be a few degrees colder and thereby save a lot of energy
then you can let the attic be a few degrees colder and thereby save a lot of energy