ᐅ Solid wood house / partial self-construction, wall structure / differences

Good morning Friedrich,

friedrich27 schrieb:
Time: Correct, what I wanted to express is that your concept might be fine for you, but the majority of home builders won’t be able to manage with it.

Yes, okay – the main point really wasn’t supposed to be the message of DIY. The trigger was your comment about it being best not to build (new) at all. In my opinion, with an existing house you don’t need to worry as much about the energy balance of the shell. If you get into ethical conflicts over every crumb of cement, that would avoid a lot of potential conflicts. That was the basic idea. Sorry if I didn’t communicate that clearly!

friedrich27 schrieb:
Money: When I read everything you do and assume that most home builders can’t do this themselves and have to hire contractors, I think it gets pretty expensive. That’s why new builds make more sense.

Renovation is probably more expensive than new construction in most cases. However, from my very subjective perspective, you don’t get a standard house with a design, size, and floor plan today that you couldn’t afford to build new. If I look at my "small villa" with 340 sqm (3,660 sq ft) of living space plus 60 sqm (650 sq ft) extension, a new build of this would probably cost millions. Nobody builds that anymore.
Whoever has the patience and money and wants to invest can also have everything done by companies. I don’t allow myself that doubtful luxury because I can barely afford my materials, which I don’t compromise on for quality, and building has been a fixture in my life for almost 20 years. I’m not driven by stinginess.

friedrich27 schrieb:
Risks: Where do these risks come from, from "stinginess is cool"? As long as people think building has to be mainly cheap, risks are wide open. It starts with trying to save on a proper architect and engineer, goes on to the craftsmen and materials, and of course expensive fixtures, etc.

Yes, you may be largely right about that. But, as always, you can’t generalize statements. There are many families ruined by construction companies, who didn’t "save cool," but just wanted to move into a new home.
In this forum, some "stinginess attitudes" do show up, trying to save on essentials. Those who end up with problems at least know why.

friedrich27 schrieb:
Insulation: Not a word about it.

Yes: keyword expanded clay. I mentioned it regarding the intermediate floor slabs. But, as I said above, the focus of my post was not to describe my current situation, but to look at renovation versus new build from an energy perspective. Unfortunately, that didn’t get through.

friedrich27 schrieb:
I am a convinced timber builder and we never insulate with petroleum-based products. We have excellent insulation materials from our own resources if it weren’t for the "stinginess is cool" again. Our insulation materials do cost a bit more. There are no uninsulated intermediate floors and the houses are built airtight, equipped with sensible heating systems, and the windows have excellent ratings.

I agree – in both new builds and renovations. Except for the difference in airtightness.

friedrich27 schrieb:
Energy consumption: I would call it a myth that older homes consume more energy just because the ceilings are higher. Surely you are right that it’s not only about the walls, but a comprehensive insulation concept including the airtightness of the building envelope. Highly insulated building envelopes use significantly less energy, that is an indisputable fact. Maybe you should have a blower door test done at the end. I really hope you don’t get a nasty surprise. Maybe I misunderstood you here; I only didn’t read anything about insulation.

Not only because of greater volume, but also for that reason. I had written that the higher energy consumption is also due to the fact that renovated older buildings can never be as airtight as new builds.
Even when calculated as conservatively as possible, the association of the mineral wool industry assumes only 25% of heat losses through the façade. Windows and roof/floor slabs already account for about 30% each. In many solid old buildings like mine with half-meter-thick (approx. 20 inches) exterior walls including an air gap, this 25% is likely overestimated. I have installed new insulated-glass windows and completely replastered the window walls with 25-30 mm (1-1.2 inches) of mineral-based insulating plaster (with pumice additives, etc., NO polystyrene). Together with 25 cm (10 inches) of perlite/clay loose fill insulation for the intermediate floors as interior insulation, that should be sufficient. I’m well aware that heating consumption is higher in such an old house. By the way, I have been collecting and drying wood for years because I plan to install additional fireplaces next.

friedrich27 schrieb:
Glue: Again, particleboard no longer plays a role in structural construction. If it is still found in DIY stores, that’s because many do-it-yourselfers think: "I live in a house and I have Mr. Google, so I’m a construction specialist, and besides it’s all so cheap." In structural building, PU-bonded OSB boards are generally used, and floors (laminate and engineered wood flooring) usually have MDF boards as carriers. That doesn’t mean there aren’t exceptions. Odor problems were and are less caused by building materials but by furniture, floors, and believe it or not, wool carpets. Not everything natural is ecological.

In my opinion, E1 should have been banned a long time ago because it represents decades-old knowledge that today has been disproven. The "stingy-is-cool" hobby builders you so vividly describe should never even have access to officially buy this stuff.
Why do you carefully distinguish OSB/particleboard and MDF? Regarding E1, the formaldehyde emission limits according to EN 120 are set for both materials in the same breath (0.1 ml/m³ (ppm) according to EN 717-1).
By the way, the "Blue Angel" label only states that the already too high E1 standard is undercut by at least 50%. Yet many institutes (I’ll spare you a list) still consider this to be hazardous to health.

friedrich27 schrieb:
PU: I must repeat myself. Modern wood products bonded with PU (OSB, glulam beams, laminated timber, cross-laminated timber) have no emissions from the PU glue. Of course, great care must be taken during processing in factories to protect workers. But once cured, and that’s the only thing you get as a customer, there are no measurable emissions, and the test methods are highly advanced.

Hmm, then I really don’t know why, for example, the Environmental Institute Munich explicitly lists the so highly praised "formaldehyde-free PU particleboard" as an indoor pollutant containing carcinogens. They must be mistaken, or the university…

friedrich27 schrieb:
Yes, and greetings from P.

Greetings from M

The text after my greeting belongs under the link, sorry.

Thank you for the text. I had been looking for this but couldn’t find it anymore. I think modern building materials have often been praised in the past, only to later turn out to be toxic and hazardous. Sometimes you only know for sure much later. That’s why I prefer to rely on old, proven, and safe materials. As a layperson, I wonder how people were able to build houses in the past without all the modern stuff, especially those that last for centuries and don’t become structurally unsound after 40 or 50 years. I don’t know. I need to make a decision soon and find a house we can actually afford. Dreams don’t help if you don’t have the necessary funds.

I will try to draw a floor plan. My dream house. Ideally, a simple bungalow around 120 to 130 sqm (1290 to 1400 sq ft), resembling a barn with a visible gable roof, large windows, and a covered terrace facing the garden. It absolutely must not look like a supermarket. I found a house on the moor online that I really like from the outside.

Wall construction either entirely wooden or insulated with natural materials (whether wood insulation, lava gravel, hemp, or cellulose), a concrete slab without Styrofoam (if that’s not possible, I could live with it), interior walls in the sleeping area and pantry made from clay, natural wood flooring in the living area, and natural stone in the wet rooms. Shower bathroom with a walk-in shower without a bathtub and a rain shower head; both the shower bathroom and guest toilet must have windows. Sleeping area and shower should be self-contained and separated from the rest of the house. Windows and doors sealed with natural materials. At least KfW 70 standard, preferably KfW 55. As much technology as necessary but as little as possible. Solar panels for hot water. Fireplace connection (stove to be installed later). Environmentally friendly heating system, but no pellet heating. I would prefer wall heating, but I don’t think that’s possible if we want more than 110 sqm (1184 sq ft) of living space. I still have to redraw the floor plan because so far, I have always tried to fit the rooms into the predetermined 108 sqm (1163 sq ft) building envelope. I always miss having a cozy corner for myself.

That sounds quite good. I would suggest planning the entire building structure using 10 cm (4 inch) cross-laminated timber panels. That should be sufficient for the walls and probably also for the roof panels. The ceilings will likely be 12 or 14 cm (5 or 6 inches). The entire envelope, including double beam girders, I estimate to be 20 cm (8 inches) or more. On top of that, as wind and impact protection, a 20 mm (0.8 inch) wood fiberboard, with counter battens or battens as support for the wooden façade and roof covering. For the façade, untreated larch or Douglas fir. The cavity would be filled with cellulose insulation. For the windows, wooden frames that you can simply screw on the exterior of the structure using an extended frame profile. Apply compressed foam tape as a sealing layer. Of course, this involves some chemicals in my opinion, but it is justifiable. I think this is a compromise because it ensures a reliable airtight seal. I would recommend zinc flashing with folded edges for the window sills. Another compromise, since it is durable and, due to being manufactured in one piece, provides secure protection against lateral water ingress. By the way, the entire roof covering is also a compromise. Other than thatch, I don’t know of any truly ecological materials that would realistically be an option.

You should consider whether to completely forgo a concrete slab for the base structure. If I were to build something like this, personally—and this is only my personal opinion (not even my wife would agree)—I would only consider a raised house. That means point foundations with a cross-laminated timber floor on top. High enough off the ground to allow air circulation under the house, and gravel laid beneath. Maybe make sure there is a larch layer facing downward. When planning, try to route utilities towards the center of the house and ensure you can manage drainage with a central technical room.

By the way, with cross-laminated timber, pay attention to airtight materials, meaning either 5-layer panels or panels glued with narrow joints.

If you design the building envelope as airtight and highly insulated as possible, and your floor plan is relatively open, you should be able to heat the house with your masonry heater (maybe soapstone?). Additional heating might only be necessary for the bathrooms.

Of course, have all of this calculated for building physics, and then consult a reputable timber builder for quotes.

For the interior finish, plan according to your preferences and budget, perhaps even as a DIY project (considering your family’s craftsmanship skills). You might then be able to avoid gas connections, ventilation systems, and similar installations.

Inside, I would mostly use exposed wood, so no additional cladding of surfaces. Where you want plaster, clay building boards are a good option—and you can apply those yourself.

It would be a shame if you couldn’t manage with your budget.

Best regards, Friedrich.

I don’t fully understand everything yet. I thought plywood panels were bonded with PUR adhesive, like KVH timber.

From the beginning, I wanted isolated footings without a concrete slab. I gave up on that because it seems we can’t afford it. My husband is fine with that as well. At first, I actually thought our budget wasn’t unrealistic. There are people who buy prefab houses including land for under 300,000 EUR. But those are masonry houses, so apparently, an eco-friendly wooden house without PUR adhesive is significantly more expensive.

For now, I’ll first draw our floor plan this weekend without restricting myself to a fixed grid and will get back to you.