Hello,
I have an older house that has been additionally insulated on the outside so that the total thickness of the wall is about 18 cm. On the inside, I am going to remove the old tretex and replace it with drywall, which will then be wallpapered and painted.
My question is: today we don't have any vapor barrier in the house; should I install this inside the drywall or skip putting in the plastic? I will be screwing every 20 cm into the drywall, which means many holes in the plastic.
I should also mention that after additional insulation, we have installed a fresh air vent in each room, except in the kitchen & bathroom, where we have exhaust air.
What would you do?
Regards, // Y
I have an older house that has been additionally insulated on the outside so that the total thickness of the wall is about 18 cm. On the inside, I am going to remove the old tretex and replace it with drywall, which will then be wallpapered and painted.
My question is: today we don't have any vapor barrier in the house; should I install this inside the drywall or skip putting in the plastic? I will be screwing every 20 cm into the drywall, which means many holes in the plastic.
I should also mention that after additional insulation, we have installed a fresh air vent in each room, except in the kitchen & bathroom, where we have exhaust air.
What would you do?
Regards, // Y
You may consider installing windproof, diffusion-open fabric instead of plastic; it creates a slightly more forgiving construction than plastic when you can't make it 100% airtight at all joints (walls, floor structures, etc.). The largest moisture migration into the wall occurs via air leakage, while a smaller part occurs via diffusion, so focus on stopping air leakage with a fabric.
I don't see any reason why you couldn't use some diffusion plastic on your exterior walls.
An alternative might be to remove the tretex, apply the diffusion plastic directly on the wall, and screw 45*45 standing on c/c600,
(take the opportunity to straighten the wall if it's warped and crooked)
add 45 insulation, then apply OSB boards on which you attach the drywall, or alternatively, you can attach the drywall directly to the studs. That's an option I can imagine if you don't want 45 insulation on the inside and want to attach the drywall directly to the wall. I don't really know how you would avoid all the screw holes in the plastic.
The downside of the above idea is that you would have to move the electrical outlets if you have any on the wall. Also, the trim around windows and doors would need fixing.
//Anyone else have a better viewpoint/idea? :blushing:
By the way...
Can someone answer what you do with the electricity if you proceed with the above-mentioned method? Can the outlets be moved out in a convenient way, or how does it work?
//Regards
An alternative might be to remove the tretex, apply the diffusion plastic directly on the wall, and screw 45*45 standing on c/c600,
(take the opportunity to straighten the wall if it's warped and crooked)
add 45 insulation, then apply OSB boards on which you attach the drywall, or alternatively, you can attach the drywall directly to the studs. That's an option I can imagine if you don't want 45 insulation on the inside and want to attach the drywall directly to the wall. I don't really know how you would avoid all the screw holes in the plastic.
The downside of the above idea is that you would have to move the electrical outlets if you have any on the wall. Also, the trim around windows and doors would need fixing.
//Anyone else have a better viewpoint/idea? :blushing:
By the way...
Can someone answer what you do with the electricity if you proceed with the above-mentioned method? Can the outlets be moved out in a convenient way, or how does it work?
//Regards
We don't have space to add insulation from the inside . Windproof, is it the same material that is used on the outside?
It should also be mentioned that we have interior walls consisting of 17mm rough board. Shouldn't the rough board hinder diffusion somewhat?
Convection feels a bit easier to address through careful sealing between the floor/wall/ceiling/corner connections.
Regards, Y
. Windproof, is it the same material that is used on the outside?It should also be mentioned that we have interior walls consisting of 17mm rough board. Shouldn't the rough board hinder diffusion somewhat?
Convection feels a bit easier to address through careful sealing between the floor/wall/ceiling/corner connections.
Regards, Y
Here are some values of vapor diffusion resistance for some materials, given in [10^3 s/m] for different thicknesses.
Polyurethane film 0.2mm > 2000
Pine panel 25mm = 7-125
EPS 100mm = 71-111
Mineral wool 100mm = 8-12
Lightweight concrete 100mm = 21-48
Concrete 100mm = 50-81
Requirement for waterproofing in wet rooms =1000
(I believe this is the latest requirement for wet rooms, they do change from time to time...)
Raw plywood probably does not significantly impede diffusion, as long as you don't paint it with dense paint...
Polyurethane film 0.2mm > 2000
Pine panel 25mm = 7-125
EPS 100mm = 71-111
Mineral wool 100mm = 8-12
Lightweight concrete 100mm = 21-48
Concrete 100mm = 50-81
Requirement for waterproofing in wet rooms =1000
(I believe this is the latest requirement for wet rooms, they do change from time to time...)
Raw plywood probably does not significantly impede diffusion, as long as you don't paint it with dense paint...
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ok, interesting. We shall put plasterboard (and possibly OSB board) on the pine planks + wallpaper + paint. Do you know what the vapor resistance is on plasterboard?
I think I've read about a special paint specifically regarding diffusion, something you recognize?
best regards Y
I think I've read about a special paint specifically regarding diffusion, something you recognize?
best regards Y
The steam resistance is rather uninteresting, really. What causes problems with moisture is mainly convection and not diffusion. You can stop the convection just as well with a wind barrier or a well-plastered gypsum wall.
frhe; Ok, it feels a bit like two schools where it's easy to feel discouraged...
Just talked to Isolver and they said absolutely to put diffusion plastic. Even if, in my situation, I'm going to put it on a raw wooden wall and then screw wall gypsum (screw every 20 cm). Even if it doesn't become "completely" airtight, it cannot be worse than not having a diffusion barrier.
What do you mean when you say that the vapor resistance is irrelevant??
Is it only convection that creates moisture problems in constructions?
Best regards,
Y
Just talked to Isolver and they said absolutely to put diffusion plastic. Even if, in my situation, I'm going to put it on a raw wooden wall and then screw wall gypsum (screw every 20 cm). Even if it doesn't become "completely" airtight, it cannot be worse than not having a diffusion barrier.
What do you mean when you say that the vapor resistance is irrelevant??
Is it only convection that creates moisture problems in constructions?
Best regards,
Y
According to SP, tests have shown that the most important factor by far to prevent moisture in attics is convection, and it is believed that diffusion accounts for an insignificant part of moisture problems. Preventing the flow of warm air is therefore the most important, and this can be done just as well without plastic.
But what about moisture in walls then? In an exterior wall, you have a wind barrier on the cold side, which in my mind makes the wall denser, making it harder for moisture to dry out. In the attic, you have insulation and nothing more, thus it's airier and any moisture dries out more easily. I can add that I am extremely reluctant to install plastic because I don't think I can make it completely airtight (unfortunately, I haven't decided yet). I'm trying to create free paths for the air through vents and keep the indoor pressure down, considering installing a Pax fan that always runs, to create negative pressure.
Best regards, Y
Best regards, Y
I agree with frhe, focus above all on making walls & ceilings airtight from the inside.
You can do this just as well with membrane as with plastic...
-If you are building new in a climate where AC is not relevant in the summer;
then build with plastic, but above all be meticulous in making it properly tight.
You can do this just as well with membrane as with plastic...
-If you are building new in a climate where AC is not relevant in the summer;
then build with plastic, but above all be meticulous in making it properly tight.
I have been considering mounting an OSB board before the drywall to, among other things, even out any irregularities in the roof decking. If I then attach the drywall with staggered seams and am extremely careful to seal in the corners and at the ceiling/floor connections, this should resist convection, right?
Do you have any examples of wind barrier products??
Best regards, Y
Do you have any examples of wind barrier products??
Best regards, Y