Our contractor who will assemble our prefabricated house says that the house will not be able to be pressure tested as it will leak air at pipe connections and electrical outlets, etc.
The construction is as follows from the inside out:
drywall
plastic sheeting
170 standing studs with insulation
34x45 cross studs with insulation
wind barrier
nail battens
panel
Is there anything unusual about this construction? I understand that you break the plastic if you make a hole for a painting or similar, but is it that sensitive? Why should one pressure test???
The construction is as follows from the inside out:
drywall
plastic sheeting
170 standing studs with insulation
34x45 cross studs with insulation
wind barrier
nail battens
panel
Is there anything unusual about this construction? I understand that you break the plastic if you make a hole for a painting or similar, but is it that sensitive? Why should one pressure test???
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Sounds strange. I had thought that the purpose of the pressure test is precisely to reveal this type of leakage through the vapor barrier ...aggen said:
I think I would be cautious and investigate this more in your case...
But I'm not sure how it is ...
I have spoken with the house supplier, and they say that this is a common construction - are there new findings that suggest placing the transverse beam on the inside after the vapor barrier. The house supplier had what they called "additional insulation villa," an extra 45 beam on the inside, but we feel that's a bit overkill ???
It sounds like the company is saying, "Duh, dude! Don't spend money on that. The house is leaking like a sieve, don't you get it...".
When there is negative pressure indoors, cold and dry outdoor air is sucked in through leaks in the exterior structure. During the passage, it warms up, causing the relative humidity to drop, and the air can then dry out the materials it passes through. This moisture convection is normally counteracted by diffusion.
However, if there is positive pressure indoors, warm moist air is pushed out through leaks and even through all materials that are not absolutely airtight, causing moisture convection and diffusion to work together so that condensation can more easily occur.
To continue with the reasoning your supplier had, it can probably be said that neither drying out nor condensation is particularly good, especially in electrical contexts.
The airtightness of the building envelope has a significant impact on the indoor climate and energy consumption. Airtightness affects the ventilation of a building, thereby influencing energy losses.
In a building that is not airtight, the ventilation is greatly affected by outdoor temperature and wind speed. An airtight building is a prerequisite for heat recovery technology to be used effectively.
A non-airtight building affects energy needs as follows:
An excess of ventilation air has to be heated to room temperature.
Leaks can cause drafts that need to be compensated for by raising the room temperature, which in turn increases energy losses.
Air leakage can cool down parts of the interior sides of the building envelope. The room temperature must then be raised to compensate for radiation losses.
Leaks can also lead to through-blowing of, for example, mineral wool-insulated constructions, which can significantly reduce the thermal insulation capability.
According to the Swedish Building Regulations (BBR) 9:4, it is stated that the building's thermal envelope must be so tight that the average air leakage at ± 50 Pa pressure difference does not exceed 0.6 liters/second m2 for residences.
Start by looking in your contract to see which standards your house is built to. Probably AMA 98 and maybe BBR. I don't know (can't be bothered, to be honest) to find out what AMA 98 says about diffusion leakage, but you can always look it up.
Personally, I would humbly and kindly ask a salesperson who expresses himself in this way to jump up on xxxx and spin. When talking about the tightness of the building's envelope, there's no "but," either it leaks or it doesn't.
"Uh, you won't be able to pressurize the house because we haven't installed any windows...uh" -- Well, then maybe it's good to do so!!!
Especially remember that there is no "can't pressurize." You can, but if it leaks badly, the result is not going to be great. You can pressure test an umbrella if you want to.
Kindly ask the guy (after you check the contract) that, "Well, it's good I mentioned it now so you have time to fix it. There are xx days until the final inspection, so it should be fine because we'll do the pressure test then. Just state it and make sure it gets done. (excuse me, but there are such damn assholes in the prefab housing industry)...
When there is negative pressure indoors, cold and dry outdoor air is sucked in through leaks in the exterior structure. During the passage, it warms up, causing the relative humidity to drop, and the air can then dry out the materials it passes through. This moisture convection is normally counteracted by diffusion.
However, if there is positive pressure indoors, warm moist air is pushed out through leaks and even through all materials that are not absolutely airtight, causing moisture convection and diffusion to work together so that condensation can more easily occur.
To continue with the reasoning your supplier had, it can probably be said that neither drying out nor condensation is particularly good, especially in electrical contexts.
The airtightness of the building envelope has a significant impact on the indoor climate and energy consumption. Airtightness affects the ventilation of a building, thereby influencing energy losses.
In a building that is not airtight, the ventilation is greatly affected by outdoor temperature and wind speed. An airtight building is a prerequisite for heat recovery technology to be used effectively.
A non-airtight building affects energy needs as follows:
An excess of ventilation air has to be heated to room temperature.
Leaks can cause drafts that need to be compensated for by raising the room temperature, which in turn increases energy losses.
Air leakage can cool down parts of the interior sides of the building envelope. The room temperature must then be raised to compensate for radiation losses.
Leaks can also lead to through-blowing of, for example, mineral wool-insulated constructions, which can significantly reduce the thermal insulation capability.
According to the Swedish Building Regulations (BBR) 9:4, it is stated that the building's thermal envelope must be so tight that the average air leakage at ± 50 Pa pressure difference does not exceed 0.6 liters/second m2 for residences.
Start by looking in your contract to see which standards your house is built to. Probably AMA 98 and maybe BBR. I don't know (can't be bothered, to be honest) to find out what AMA 98 says about diffusion leakage, but you can always look it up.
Personally, I would humbly and kindly ask a salesperson who expresses himself in this way to jump up on xxxx and spin. When talking about the tightness of the building's envelope, there's no "but," either it leaks or it doesn't.
"Uh, you won't be able to pressurize the house because we haven't installed any windows...uh" -- Well, then maybe it's good to do so!!!
Especially remember that there is no "can't pressurize." You can, but if it leaks badly, the result is not going to be great. You can pressure test an umbrella if you want to.
Kindly ask the guy (after you check the contract) that, "Well, it's good I mentioned it now so you have time to fix it. There are xx days until the final inspection, so it should be fine because we'll do the pressure test then. Just state it and make sure it gets done. (excuse me, but there are such damn assholes in the prefab housing industry)...
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Yes, in terms of density you can do as you please, but don't buy any lame excuses for why you should have to settle for a house that leaks when no one needs that.
If I were you, and especially considering what your homeowner said, I would not accept a final inspection without an air pressure test done beforehand. Your contract probably states that the inspector is chosen by both of you (you and the builder) together, so call around to a few companies that can do a pressure test and get it done at the same time on inspection day.
If I were you, and especially considering what your homeowner said, I would not accept a final inspection without an air pressure test done beforehand. Your contract probably states that the inspector is chosen by both of you (you and the builder) together, so call around to a few companies that can do a pressure test and get it done at the same time on inspection day.
As Mikael says, the pressure test is meant to reveal holes and leaks in the vapor barrier. It's like if you were to buy a used car and the dealer says "no, you can't test drive the car because it doesn't start". The contractor has already said that the house won’t pass a pressure test. Naturally, this is not something you should accept. The house should be built airtight and this should be verified with a pressure test. There are threshold values, but we should ask someone who is knowledgeable in that area about them.aggen said:
The construction is not unusual, but far from optimal. Now there will be holes in the plastic at every wall socket and light switch. You are supposed to fix this by taping, but hardly anyone does that.
Doesn't sound like a well-constructed design with the plastic directly behind the gypsum. Feels like the wall is built the wrong way around. Shouldn't the 34x45 rule be inside the 170 rule? In any case, I think you should do a pressure test anyway. Where electricians and others break the plastic, you should tape it up to ensure it is sealed. The pressure test will show how meticulous the carpenters have been!
My wall does not look like yours but still has gypsum, plywood, and plastic (counted from the inside) and passed the pressure test gallantly as the electricians were very meticulous.
As mentioned, do not buy this argument from the company and make sure it is done before the final inspection.
As mentioned, do not buy this argument from the company and make sure it is done before the final inspection.