ᐅ Insulation for Wooden Beam Ceilings

I want to insulate the wooden beam ceiling (cold floor) in my new build, between the upper floor and the attic.

First, I would install a vapor barrier from below in the living space and fix it to the wall using metal C-channels. (This step, of course, after plastering.) The joints should be properly sealed. Then, I plan to cover the ceiling from below with drywall, attaching it using direct hangers.

Now for my main question: I want to add insulation from above (from the attic side). The rafter spacing is about 660mm (26 inches), and the beam height is 200mm (8 inches). Which insulation would you recommend? Rockwool compression fleece with a thermal conductivity of 0.035 W/mK (WLG 035) at 200mm (8 inches) thickness, or something else? I’m reluctant to use blown-in insulation, though I’m not sure why—maybe I’m not familiar enough with the technique.

After that, should I simply install an OSB board on top, or is it better to put something between the insulation and the OSB?

Hello mirk909,

we decided on loose-fill cellulose insulation between the rafters. You pour the cellulose from above between the rafters, fluff it up a bit, and then, for example, install OSB panels on top. You need about 3 bags of 12 kg (26.5 lbs) per cubic meter.

Good luck

RFR

Hello,

mirk909 schrieb:
I want to insulate the wooden beam ceiling (cold floor) between the upper floor and the attic in my new build.

It’s not really about wanting to do this; it’s more or less mandatory.

mirk909 schrieb:
.....Which insulation do you recommend? The Rockwool compressed fleece with a thermal conductivity of 0.035 W/(m·K) in 200mm (8 inches) thickness, or something else?

The requirements for this should actually be provided to you! => Energy Saving Ordinance/planning permission or KfW certification and heat load calculation!

Best regards.

I have these. They just don’t specify which version to use. Whether something is allowed, required, or optional—let’s not get hung up on wording here. That’s not the point. Otherwise, I would have signed up for a teacher forum.

mirk909 schrieb:
I have these. But the variant is not specified.

Then that is a defect! Of course, self-proclaimed hobby experts always think they know everything much better than trained professionals.

Best regards

Is it possible to have a factual discussion? For example, I have a requirement for WLG 040 insulation but am using WLG 032. So it’s not as simple as that. However, there’s no need to get hung up on specific wording. After all, this is not a fetish forum.

Okay, whoever wants can provide factual comments.