We will be building a one-and-a-half-story house with a knee wall height of 1.30 meters (4 feet 3 inches) using solid construction.
The building site is subject to some noise from the nearby railway, which we do not find overly disturbing, especially since the open space in between is partly going to be developed.
We have been advised externally to consider using double drywall boarding on the sloped ceilings of the upper floor for sound insulation purposes. The attic already has a thicker roof structure with 200mm (8 inches) of mineral wool insulation due to the KfW 70 standard.
Now we face the choice between single or double 12.5mm (1/2 inch) drywall boarding in the upper floor. Since we already have a relatively high knee wall and additional insulation in the roof, we are wondering whether the extra investment in double boarding is really worthwhile.
Does double boarding significantly improve soundproofing? Is the additional cost of around 1000 euros (about 1100 USD) a good investment?
The building site is subject to some noise from the nearby railway, which we do not find overly disturbing, especially since the open space in between is partly going to be developed.
We have been advised externally to consider using double drywall boarding on the sloped ceilings of the upper floor for sound insulation purposes. The attic already has a thicker roof structure with 200mm (8 inches) of mineral wool insulation due to the KfW 70 standard.
Now we face the choice between single or double 12.5mm (1/2 inch) drywall boarding in the upper floor. Since we already have a relatively high knee wall and additional insulation in the roof, we are wondering whether the extra investment in double boarding is really worthwhile.
Does double boarding significantly improve soundproofing? Is the additional cost of around 1000 euros (about 1100 USD) a good investment?
In theory, according to U-value calculators, this already makes a significant difference, but they only consider the roof as a single component. In a solidly built house that already has a high internal mass (concrete ceilings, etc.) as a heat reservoir, this probably does not result in much additional improvement in the end, that is correct.
A
Andreas Teich17 Feb 2015 23:52I would recommend using thicker rafters—at least 24 cm (9.5 inches)—and filling the cavity with cellulose insulation at a higher density (about 60 kg/m3 (3.7 lb/ft3)).
If you then add 40 or 60 mm (1.6 or 2.4 inches) thick wood fiber boards between the battens on the interior side, this will provide even better insulation, as well as significantly improved soundproofing and protection against summer heat.
After that, you can first check whether a simple cladding is sufficient.
Andreas Teich Building Energy Consultant/Construction Advisor
If you then add 40 or 60 mm (1.6 or 2.4 inches) thick wood fiber boards between the battens on the interior side, this will provide even better insulation, as well as significantly improved soundproofing and protection against summer heat.
After that, you can first check whether a simple cladding is sufficient.
Andreas Teich Building Energy Consultant/Construction Advisor
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Bauexperte18 Feb 2015 11:26Hello Andreas,
Regards, Bauexperte
Andreas Teich schrieb:I agree regarding sound insulation; however, speaking from personal experience, there is absolutely nothing—except for an air conditioner—that makes a finished attic bearable on a hot summer day.
and overall it offers much better sound insulation as well as summer heat protection.
Regards, Bauexperte
Bauexperte schrieb:
Hello Andreas,
I agree on soundproofing; from my own experience regarding summer heat protection, there is absolutely nothing—except for air conditioning—that makes a converted attic bearable on hot summer days.
Best regards, Bauexperte I think the focus should be on the word "better" summer heat protection...
Most heat comes through windows facing the sun that either lack external shutters or when those shutters are not used.
In our new build, we also experienced unbearable heat in the upper floor during summer, even worse than in our previous older house... Since we installed shutters, including ones on the lower floors that are timer-controlled, it’s sometimes almost too cool upstairs. The difference is really significant.
Of course, if you plan to use air conditioning, you might leave the shutters out. Ideally, windows with integrated power generation in the glass, like those used on large glass buildings, would be great =) Basically generating electricity through the glass facade to operate the necessary air conditioning.
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