ᐅ Prefabricated House – Wall Construction

Are you looking for ecological materials? Even with timber frame construction, you might not be completely satisfied once you consider how these materials are produced.

For us, high-quality materials were important, but we also had to set some limits:

From the outside to the inside:
- Silicone resin plaster
- Wood fiber insulation board
- Timber frame with cellulose insulation
- OSB board with a vapor retarder
- Installation cavity with mineral wool insulation: This could have been done with cellulose insulation as well, but for DIY work close to the installation layer, it’s tricky because the cellulose must be blown in.
- Fermacell board

I personally think this approach is very good and it was already standard for us with a 31cm (12 inch) thick wall. Most others simply add another layer at the installation level if desired, but you then lose living space.

In the end, the deciding factor is the budget. A quality timber frame construction starts at around 1500 per square meter (approximately $140 per square foot), so contrary to common belief, it is not cheaper than solid construction. However, the difference in energy efficiency is significant. Point one: use your brain—someone offering 1100 per square meter (about $103 per square foot) simply can’t provide the same quality as one at 1500, no matter how tempting it sounds. Even professionals find such comparisons difficult. Years ago, there was a manufacturer who only mentioned in the fine print that VAT (then 15%) was added on top of all prices.

Regarding the wall structure next to the service layer: I always prefer a ventilated facade (also with plaster). If that’s not possible, then a wood fiber insulation layer is acceptable. Never use Styrofoam insulation.

Choose heavy insulation materials; they are good for protection against summer heat.

The list is already quite long. Don’t rush things. Take your time to review everything carefully and think it through. If necessary, ask questions again.

About the service layer: if you want to go eco-friendly, do it here too, whether with hemp or wood fiber, and for the really determined, flax.

And adding a service layer doesn’t cost you any living space—that’s what separates the good from the truly good.

Rübe1 schrieb:
An installation level is now standard practice in quality timber frame construction, with no additional cost.

So far, except for the one we used in our current build, I haven't found any manufacturer (not even the major ones) that offers this as a standard feature. It’s always available only with the next wall thickness up.

Uwe82 schrieb:
So far, I haven’t found any manufacturer (not even the big ones) that offers this as standard, except for the one we are currently building with. They always offer it with the next higher wall thickness.

There are quite a few of them. The problem is that until a few years ago, this market was dominated by prefabricated house manufacturers (the big players). However, many of them have remained stuck in the 1970s in terms of development. Nowadays, they just add a bit more polystyrene. To be frank: every good Scandinavian builder has been working with installation levels for well over 10 years—back when this concept wasn’t even known here yet....

In our timber house (not a "prefabricated house"), the layers from inside to outside are as follows: glued laminated timber board as interior cladding (instead of drywall), battens, installation layer filled with soft wood fiber insulation boards, OSB board serving as a vapor retarder, timber stud frame with cellulose insulation (Isofloc), rigid wood fiber insulation boards, battens/ventilation gap, wooden facade.

Uwe82 schrieb:
Are you looking for ecological materials? You won’t be very happy even with timber frame construction if you consider how these materials are produced.

For us, high-quality materials were also important, but we had to set priorities somewhere:

From outside to inside:
- Silicone resin plaster
- Wood fiber insulation board
- Timber frame construction with cellulose insulation
- OSB board with vapor retarder
- Installation cavity with rock wool insulation: this could also have been done with cellulose insulation, but for do-it-yourself work close to the installation level it’s difficult since cellulose has to be blown in.
- Fermacell board

I think this approach is very good personally and was already standard in our case with a 31cm (12 inches) thick wall. Most others simply add another layer at the installation level if requested, but then you lose living space again.

Thank you for your answer. No, ecological aspects are not my primary concern. Rather, I want high quality so that in 20 years there will still be good insulation and indoor climate. Many thanks also for the construction layers! Is there a building diary of your house as well? Or how could I find out who you built with?