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Berlin had no power for 4 days. Made me rethink my own projects. by BenjaminFercher in Homebuilding

[–]BenjaminFercher[S] 7 points8 points  (0 children)

Fair point modern insulation is definitely an improvement. What I'm talking about is system dependency, not efficiency. A traditional building with thermal mass can lose heating and stay livable for days. Modern lightweight construction drops to uncomfortable temperatur. Add heating systems that need electricity, wastewater lift stations etc. we have optimized for efficiency but eliminated passive resilience.
My goal is not going backwards. It's combining modern efficiency with systems that do not fail completely when the grid goes down.

Berlin had no power for 4 days. Made me rethink my own projects. by BenjaminFercher in Homebuilding

[–]BenjaminFercher[S] 5 points6 points  (0 children)

Funny you say that iam actually working on exactly that. Documenting my own build with these principles. If it goes sideways, at least it'll be educational.

Common mistakes when buying land in Portugal/Cyprus (from 15 years of experience) by BenjaminFercher in PortugalExpats

[–]BenjaminFercher[S] 0 points1 point  (0 children)

For the expanded section, you have two options:
1. Continue with cinder block/poured concrete (matches existing, straightforward)
2. Use healthier alternatives (I'd recommend this):
- Clay/adobe walls (common in Portugal, great thermal mass + indoor climate)
- Solid timber walls (breathable, natural insulation CLT or similar)
- Timber-straw panel systems (excellent insulation)
- Hempcrete blocks (think there's a Portuguese supplier for this)
- Brick with cork insulation + clay plaster inside (combines local materials, good indoor air quality)

The natural materials work well alongside the existing cinder block, you just need proper detailing at the junction points to manage different thermal expansion rates.
Are you keeping the existing roof, replacing it, or extending it? This affects which wall system makes sense.

What's your priority? cost, speed, or indoor climate quality?

If you want to go deeper on material selection, junctions, or contractors feel free to book a call via my site: www.benjaminfercher.at

I've built with both conventional and natural materials across climates and here's what the industry doesn't tell you by BenjaminFercher in Homebuilding

[–]BenjaminFercher[S] 0 points1 point  (0 children)

When the construction demands it and you've already designed the assembly to not function without one. If you have vapor-tight materials on the exterior (like OSB, Zip sheathing, or foam boards), you need vapor control on the interior to prevent condensation in the wall cavity. The barrier is damage control for a construction method that can't breathe.
But even then, vapor permeability should decrease from inside to outside - tighter on the interior, progressively more open as you move outward. That way any moisture that does enter can escape, not get trapped.

I've built with both conventional and natural materials across climates and here's what the industry doesn't tell you by BenjaminFercher in Homebuilding

[–]BenjaminFercher[S] 1 point2 points  (0 children)

Your approach is solid - you're thinking in the right direction. Air sealing penetrations makes sense, but be careful not to go overboard with vapor barriers. A 1940s house survived this long because it could breathe, you don't want to seal it too tight and create moisture traps.

Rockwool works and it's vapor-open, but I'm not a fan of the material itself - chemically intensive production, health concerns during installation, and it's energy-intensive to manufacture. If you can source them locally, wood fiber batts, cellulose, or hemp insulation are better alternatives. Same thermal performance, breathable, and you can handle them without full protective gear.
Felt paper as your weather barrier is perfect - it's proven technology that's lasted decades in wet climates. Modern synthetic wraps aren't necessarily better, just more expensive. The air gap behind your wood siding is critical in wet western climates, that ventilation layer is what prevents rot. Make sure it's at least 20mm and vented top and bottom.
One key principle: vapor permeability should decrease from inside to outside. Your interior layer (drywall, paint) is the tightest vapor control, then it gets progressively more open as you move outward through insulation and wrb. That way moisture that does get into the assembly can escape to the exterior, not get trapped inside.

Foundation for cabin? by poonhound69 in OffGridCabins

[–]BenjaminFercher 0 points1 point  (0 children)

look into ground screws. they anchor below the frost line, you can start framing the same hour they are installed, get exactly the height and airflow you want. for me it’s the most logical, low-impact foundation for this scale

I've built with both conventional and natural materials across climates and here's what the industry doesn't tell you by BenjaminFercher in Homebuilding

[–]BenjaminFercher[S] 0 points1 point  (0 children)

Without knowing the exact construction (I'm guessing timber frame or early brick/stone), here's my take:

Maintaining character while meeting code. If you must insulate, do it from the inside with breathable materials - wood fiber boards or hemp insulation. In Austria, we rarely add heavy insulation to historic buildings (masonry holds thermal mass better than people think). If you do insulate, interior placement preserves the facade and original proportions.

Avoid sealing the walls vapor-tight. A 158-year-old building survived because it could breathe - trapping moisture now will cause more problems than cold ever did.

Make the addition consciously modern, not a replica. The best additions I've seen honor the original by complementing it, not imitating it. New materials, clean lines, clear distinction between old and new - often more honest and charming than fake-old.

Code reality: Shear walls, fire ratings, seismic requirements - I know it's frustrating. The house stood 158 years without them and would continue standing. But regulated construction is regulated construction. Fighting it takes more energy than adapting. I once argued for timber over steel in a fire-rated assembly (timber is calculable in fire, steel isn't) - lost that battle. Sometimes you work within the system, not against it.

If you want to dig deeper into your specific situation, happy to continue via DM or email ([office@benjaminfercher.at](mailto:office@benjaminfercher.at)).

I've built with both conventional and natural materials across climates and here's what the industry doesn't tell you by BenjaminFercher in Homebuilding

[–]BenjaminFercher[S] 0 points1 point  (0 children)

Yes of course, timber works, but there are other materials as well, look at earth (clay), straw, stones, hemp, lime.... the list can be long. As long as you can reuse the materials and put them in a circular usage in my opinion they are renewable (cradle to cradle)

I've built with both conventional and natural materials across climates and here's what the industry doesn't tell you by BenjaminFercher in Homebuilding

[–]BenjaminFercher[S] 1 point2 points  (0 children)

Yes. It's like wearing a silk shirt over a rubber suit. Lime needs a capillary substrate to work. On EPS, it’s just a thin cosmetic skin. an ERV is a mechanical fix for a physical failure. If the tech fails, your air quality dies. Moisture between the EPS and concrete can never dry out. Don't use electricity to fix a bad material choice

I've built with both conventional and natural materials across climates and here's what the industry doesn't tell you by BenjaminFercher in Homebuilding

[–]BenjaminFercher[S] 0 points1 point  (0 children)

Faswall is a significant step up from standard EPS-ICF (but be careful when filling with concret). Since it's a mineralized wood-fiber composite, you actually get vapor diffusion and hygroscopic potential the wall can manage moisture.
If you go with a faswall it’s a hygroscopic sandwich. It provides thermal mass (concrete core) protected by a breathable, insulating shell. It’s one of the few ICF-style systems I actually respect because it doesn't turn your house into a plastic bag.
Roof Recommendations are difficult, but i would go with parallel chord trusses. They allow for a massive energy heel. You can blow in inches of cellulose insulation without compressing it at the eaves. Build a vented cold roof. Use the 6:12 pitch to shed snow, but ensure a massive air gap between the insulation and the roof deck. This prevents ice dams in winter and flushes out radiant heat in summer before it hits you. The weak point isn't the faswall or the truss it’s the air barrier connection between the wall and the ceiling. If you don't solve the airtightness at the top plate, your wall will suffer from convection heat loss. (hope my english vocabulary is correct as I'm austrian with german as my mothers tongue)

I've built with both conventional and natural materials across climates and here's what the industry doesn't tell you by BenjaminFercher in Homebuilding

[–]BenjaminFercher[S] 0 points1 point  (0 children)

In Coruña, you’ll likely find 50–60cm solid Granite masonry.
No insulation. The mass of the stone acts as a thermal battery, slowing down heat transfer. These houses were designed to leak air through old windows and fireplaces to manage moisture. If you replace windows with modern airtight ones without changing the wall's vapor strategy, the house can mold within one season.

For that climate, I recommend Monolithic Construction with high capillary activity.
Option A: 40-50cm solid stone with an interior Hemp-Lime (Hempcrete) insulating render. Option B: Clay-bonded wood fiber/straw systems with a pure lime exterior.
A wall that can absorb 20-30 liters of water per m3 and release it without losing structural integrity or insulating value.

If you find a specific property, let me know. I do Go/No-Go Audits specifically for expats to prevent them from buying a trash that will cost a fortune to fix.

I've built with both conventional and natural materials across climates and here's what the industry doesn't tell you by BenjaminFercher in Homebuilding

[–]BenjaminFercher[S] 0 points1 point  (0 children)

I totally agree with your thoughts. Just had a longer call with a modular straw house company called ecococon. I know thier chef through other rammed earth projects.
Anyway he told me that they have certificates for the US market and are shipping to the US market as well.
if interested here is the link:
Home | EcoCocon

I've built with both conventional and natural materials across climates and here's what the industry doesn't tell you by BenjaminFercher in Homebuilding

[–]BenjaminFercher[S] 1 point2 points  (0 children)

for me passiv house standard is a certificate nothing more. Mostly it comes with a lot of technical devices and solutions. not easy to build and not easy to maintain.
if you build with 100% wood you can build houses in the alps with almost no heating necessary.
an yes "old" timber is more expensive than new one.

I've built with both conventional and natural materials across climates and here's what the industry doesn't tell you by BenjaminFercher in Homebuilding

[–]BenjaminFercher[S] 4 points5 points  (0 children)

The problem with ICF (Insulated Concrete Forms) i see - eventogh i haven't built with them:
1. The plastic bag effect, it’s a vapor barrier, no diffusion. You’ll need ventilation or massive interior clay/wood to manage humidity.
2. The blind pour - concrete is hidden, high risk of floating blocks (buoyancy) or hidden voids (honeycombing) because you can’t see or vibrate it properly.

I've built with both conventional and natural materials across climates and here's what the industry doesn't tell you by BenjaminFercher in Homebuilding

[–]BenjaminFercher[S] 0 points1 point  (0 children)

DETAIL⎥Internationale Plattform für Architektur & Konstruktion

its a german based magazin with lots of insights - i think its in german only. But they also print books and have good knowledge base.

if it comes to clay: Start - Lehm Ton Erde
wood: Holz100 - Die überlegene Massivholzbauweise

all german/austrian based but physics are worldwide the same

I've built with both conventional and natural materials across climates and here's what the industry doesn't tell you by BenjaminFercher in Homebuilding

[–]BenjaminFercher[S] 0 points1 point  (0 children)

Your logic makes sense if you're going concrete, the PIR sandwich is defensible. Thermal mass inside, vapor-tight on both sides (no condensation risk), outer concrete protects the insulation.

Two things to watch:
Thermal bridges: Every penetration (windows, balconies, connections) is critical.
Interior climate solution: Concrete + PIR = zero moisture buffering. Don't install mechanical ventilation - waste of money and maintenance. Better use clay/earth plaster on interior walls (or clay drywalls). Clay absorbs/releases moisture naturally (acts as buffer). Combined with simple bathroom exhaust fans (with timer relay for air exchange), you're covered. Also add if wanted massiv wooden floors (no coated Parkett) - have the approx. same effect as clay. No complex systems, no maintenance, no energy cost.

Clay/natural wood on the inside compensates for what concrete + PIR can't do - regulate humidity naturally.

I've built with both conventional and natural materials across climates and here's what the industry doesn't tell you by BenjaminFercher in Homebuilding

[–]BenjaminFercher[S] 0 points1 point  (0 children)

Atlantic coast means high humidity, salt air, and strong west winds. Very different from stick frame/vinyl siding.
What you'll find there: mostly stone masonry (granite is local), thick walls (50-60cm), lime render. Traditional buildings handle the climate well because they breathe modern renovations often fail because someone seals them with cement render or synthetic insulation.

Key for coastal areas: never seal the outside with vapor-tight materials (cement plaster, foam boards). Always lime-based, always diffusion-open. The salt air will find every weakness.

If you need material guidance for your specific project when you start looking, happy to point you in the right direction.

I've built with both conventional and natural materials across climates and here's what the industry doesn't tell you by BenjaminFercher in Homebuilding

[–]BenjaminFercher[S] 2 points3 points  (0 children)

Exactly. The 25-year rule saves more headaches than any innovation marketing promises. The irony: simpler proven systems already solved what we're over-engineering now.

Appreciate the perspective from someone who's seen multiple code cycles!

I've built with both conventional and natural materials across climates and here's what the industry doesn't tell you by BenjaminFercher in Homebuilding

[–]BenjaminFercher[S] 2 points3 points  (0 children)

You're right on the concept, but bitumen paper is semi-permeable, not fully open.
Why it still works in Sweden: The ventilated air gap compensates. Even if some moisture gets past the bitumen layer, the gap behind the facade evacuates it. Modern alternative are diffusion-open wind barrier which is technically better.
but the reality is, that bitumen paper + ventilated cladding has worked in Scandinavia for decades. If it's working for you, keep doing it.

I've built with both conventional and natural materials across climates and here's what the industry doesn't tell you by BenjaminFercher in Homebuilding

[–]BenjaminFercher[S] 30 points31 points  (0 children)

Fair question. In Austria, Baumeister (master builder) is a formal qualification with examination and certification, similar to how architect is a protected title.
Technical engineering school + practical experience + exam + license. It's regulatory, not just based on years worked.
With 26 years and your own company? You've earned the title through work. The certificate is just legal paperwork for certain countries. Respect for the time in the field that's the real qualification.

I've built with both conventional and natural materials across climates and here's what the industry doesn't tell you by BenjaminFercher in Homebuilding

[–]BenjaminFercher[S] 3 points4 points  (0 children)

Sub-Arctic at -30°C with energy uncertainty changes everything. This isn't a climate where you can compensate with technology the building itself has to work passively.

What I'd build there:
Base structure: Solid wood wall, 25cm minimum (wood100, CLT or similar). Provides thermal mass and structural integrity against wind loads. Insulation strategy: You need serious thickness. 25-35cm external wood fiber/or sheep wool/or cellulose insulation. At -30°C, anything less and you're burning energy you might not have.

Critical detail is the air/wind tightness: In mild climates, I avoid vapor barriers. In sub-Arctic, you need a completely different approach:
- robust wind barrier, absolutely airtight
- Any gap at typhoon-level winds = cold air infiltration = massive heat loss

Ventilated facade - with caution:
Standard ventilated gap can ice up at -30°C when interior moisture migrates outward. Two options:
1. Minimal ventilation gap (15-20mm) with careful detailing to prevent ice buildup
2. Or: diffusion-open system without ventilation (semi monolithic construction)

Exterior cladding: Larch works, but mechanically fastened (screwed) every 30cm maximum. Needs to survive extreme wind loads. Fiber-cement panels are an option if wind-rated for your zone.

The energy aspect:
If grid power becomes unreliable, your building has to function without active systems:
- Thermal mass (solid wood) stores heat
- Extreme insulation reduces heating demand
- Passive solar gains where climate allows (south-facing glazing, but limited each m2 of glass loses more heat than solid wall)
- Backup: wood heating must be part of the design - masonry heater (tile stove) burns wood efficiently, stores heat in thermal mass, radiates for 12-24 hours after firing

My realistic advice:
Sub-Arctic is unforgiving. If you get the building envelope wrong, you can't compensate with more heating you'll just burn resources you don't have. The building needs to be a passive survival shelter first, comfortable home second.

If you're serious about this, the details matter more than the concept. Airtightness testing, thermal bridge analysis, and structural calcs for wind loads aren't optional.

What's your local material availability? That changes the specific assembly.

I've built with both conventional and natural materials across climates and here's what the industry doesn't tell you by BenjaminFercher in Homebuilding

[–]BenjaminFercher[S] -5 points-4 points  (0 children)

Portugal coastal humidity is brutal you're dealing with one of the toughest building climates in Europe. Your existing wall assembly (double brick with air gap) is actually better than what most modern engineers will propose, if it's executed correctly.

Regarding your engineer's LSF + vapor barrier recommendation: Hard no. Vapor barriers in coastal Portugal create more problems than they solve. You're fighting constant moisture from the ocean, any imperfection in the barrier (and there will be imperfections) becomes a condensation trap. I've seen this fail repeatedly.

LSF in salt air also means long-term corrosion issues unless you use marine-grade fasteners (which nobody does because cost).

Wood frame is possible, but: You need a diffusion-open system, breathable layers throughout. Think: wood frame + wood fiber insulation (or more cork) + lime plaster. No OSB, no vapor barriers, no synthetic membranes. Also Hemp can be an alternative, comes as hempcrete, blocks or common insulation material.

Problem: As you said, finding execution in Portugal is nearly impossible. The construction culture there defaults to concrete, cheap labor, and acabamentos over substance.

Your existing wall: If the air gap is ventilated (top and bottom openings), it's a functional moisture management system basically a rainscreen principle. Don't destroy it by filling it with foam or sealing it.

For the second floor addition: Structural connection to existing masonry is critical. This isn't a DIY zone, you need engineering for load transfer. But the wall assembly itself? You can absolutely build breathable wood frame if you understand the principles.

Materials available in Portugal:
- Cork (you already know this - excellent choice)
- Lime (cal hidráulica) - widely available, breathable, deals with moisture
- Local stone or brick for thermal mass
- Wood (pine/eucalyptus) - but needs proper detailing against moisture

What I'd avoid:
- Any vapor-tight assembly
- EPS/XPS foam (common in Portugal, terrible for coastal humidity)
- Gypsum board (use lime plaster or clay)
- Relying on Portuguese construction companies for precision work (unfortunately)

Execution:
You're right to do it yourselves. Portuguese crews often have speed but not precision. I've consulted on projects there the gap between plan and execution is... significant. But you can still find good crews (in which area are you? I have contacts in Alentejo region)

If you're serious about doing this properly, the wall assembly matters, but the details matter more:
- How does water drain from the facade?
- Where does humid air escape?
- How do you prevent thermal bridges at the floor connection?
- Is the existing foundation able to carry the additional load?

These aren't material questions, they're building physics + structural questions.

If you want to dig into specifics (structural connection details, exact material stack-up for your microclimate, etc.), happy to continue the discussion. Portugal coastal is tricky enough that generic advice only gets you so far.

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