ᐅ Incorrect Construction Methods: Drywall and Insulation from Knauf?
Created on: 15 Jul 2020 12:10
I
Infuso00Hello fellow home builders,
We are currently building a townhouse with a developer and are facing an issue with the drywall partitions. According to the construction specifications, we are supposed to receive simply boarded metal stud walls with insulation. So far, so good!
Regarding the assembly (W111): Profiles from Knauf CW75 (75mm / 3 inches) are used, along with Knauf mineral wool insulation (40mm / 1.5 inches). According to Knauf, these must be installed securely to prevent slipping, as they do not fill 80% of the cavity and therefore require fastening. Our developer says that since this is friction-fit felt insulation, no securing is necessary. We are now at a loss because the rooms on both floors are adjacent to bathrooms and we are worried that if the insulation slips, we will hear everything. Knauf informed me again that they have had cases where the insulation slipped and therefore do not provide a warranty if anything happens.
Does the developer have to follow Knauf’s installation guidelines in this case?
We also find it odd that the drywall in the bathroom interiors has an 18mm (about 0.7 inches) gypsum board on the bathroom side and 12.5mm (0.5 inches) on the backside. I have not seen any approval from Knauf for this kind of construction— is this acceptable? Normally, I understand that bathrooms should have double-layer drywall.
Does anyone have more detailed information? I would be very grateful.
Best regards, Infuso00
We are currently building a townhouse with a developer and are facing an issue with the drywall partitions. According to the construction specifications, we are supposed to receive simply boarded metal stud walls with insulation. So far, so good!
Regarding the assembly (W111): Profiles from Knauf CW75 (75mm / 3 inches) are used, along with Knauf mineral wool insulation (40mm / 1.5 inches). According to Knauf, these must be installed securely to prevent slipping, as they do not fill 80% of the cavity and therefore require fastening. Our developer says that since this is friction-fit felt insulation, no securing is necessary. We are now at a loss because the rooms on both floors are adjacent to bathrooms and we are worried that if the insulation slips, we will hear everything. Knauf informed me again that they have had cases where the insulation slipped and therefore do not provide a warranty if anything happens.
Does the developer have to follow Knauf’s installation guidelines in this case?
We also find it odd that the drywall in the bathroom interiors has an 18mm (about 0.7 inches) gypsum board on the bathroom side and 12.5mm (0.5 inches) on the backside. I have not seen any approval from Knauf for this kind of construction— is this acceptable? Normally, I understand that bathrooms should have double-layer drywall.
Does anyone have more detailed information? I would be very grateful.
Best regards, Infuso00
K
knalltüte15 Jul 2020 15:05Infuso00 schrieb:
... that we simply got metal stud walls with drywall and insulation.
... Knauf CW75 (75mm) and mineral wool insulation from Knauf (40mm).
... and we’re worried that if the insulation slips, we will hear everything.
... Normally, I also understand that bathrooms need double drywall layers. In my opinion, single-layer drywall is completely inadequate. 12.5mm (0.5 inch) drywall won’t hold anything, neither screws for cabinets nor provide much sound insulation. Even 40mm (1.5 inch) mineral wool doesn’t help with that. I would prefer double layers on both sides (each consisting of OSB and drywall). However, I am not a drywall expert!
That said, I have had several rooms built this way and have been very satisfied with the results (apart from the cost).
For a wall between the bathroom and bedroom, I definitely would not include a cavity (a resonance chamber for sound, air volume affecting temperature differences), but an asymmetrical layering could explain that. Double-layering with thinner, hydrophobized (!) boards seems more sensible to me than a single layer of thicker boards.
A builder only has to comply with the aRdT (general technical building specifications); a general contractor must also follow their scope of work. Manufacturer installation guidelines are, in my opinion, legally only recommendations for both.
https://www.instagram.com/11antgmxde/
https://www.linkedin.com/company/bauen-jetzt/
Infuso00 schrieb:
Does the builder have to follow Knauf’s installation guidelines here?
A builder only has to comply with the aRdT (general technical building specifications); a general contractor must also follow their scope of work. Manufacturer installation guidelines are, in my opinion, legally only recommendations for both.
https://www.instagram.com/11antgmxde/
https://www.linkedin.com/company/bauen-jetzt/
I assume that a developer must also adhere to their construction specifications. Of course, these will usually be worded vaguely enough to allow them to excuse themselves in the end.
However, for my condominium unit, there was a specifications document, and the developer mostly followed it. Regarding the (pre-)wall installations in my bathrooms, this meant double drywall boards (2x12.5mm (0.5 inches)), but only gypsum plasterboard—no OSB.
However, for my condominium unit, there was a specifications document, and the developer mostly followed it. Regarding the (pre-)wall installations in my bathrooms, this meant double drywall boards (2x12.5mm (0.5 inches)), but only gypsum plasterboard—no OSB.
Tolentino schrieb:
I would expect a general contractor to follow their scope of work description. A general contractor, yes, but a property developer does not have to have one at all. You are essentially buying an existing property from them (even if its construction is ongoing or planned for the future), but they don’t actually build anything for you. A scope of work description can become part of the sales contract and guarantee product specifications, but it can also be completely absent. It might be included in brochures but not be part of the contract.
https://www.instagram.com/11antgmxde/
https://www.linkedin.com/company/bauen-jetzt/
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