Read all about it .... The benefits of timber buildings
And… breathe. Timber Buildings help us achieve both energy-efficient airtightness and natural breathability
At Garden Affairs, our customers often ask about maximising insulation levels in our log cabins, reducing heat loss and helping to create a warm, comfortable environment all year round.
It sounds simple enough, but there is a dilemma at the heart of this question. It seems to make sense to ensure any building has airtight windows and doors and high levels of insulation. This helps reduce energy consumption and CO2 emissions, but it can also prevent moisture escaping and creates internal humidity.
High internal humidity can cause a number of issues, affecting both the health of a building and its occupants. Trapped water vapour within an airtight building is linked to condensation, reduced thermal performance and structural damage through mould and rot.
With greater quantities of dust mites and mould spores, we can be sitting in a nice warm building but one which smells bad and can even make respiratory conditions like asthma worse.
Of course, what buildings need is effective ventilation. We can use the trickle vents on the doors and windows, or simply open them. The trouble is, this also lets warm air escape undermining all your careful measures to insulate. At worst you can end up sitting in cold draughts. That’s the dilemma.
Happily for timber garden building owners, there is help at hand. The natural breathability of a wooden construction, providing it isn’t enclosed in non-porous renders or paints, combats humidity with the minimum mechanical ventilation. It may seem counter-intuitive, but a timber building can be both airtight (keeping heat energy in) and breathable (letting moisture out).
Natural building expert Neil May explains: “Breathability in buildings is not really about air. It is about water: water as a gas and water as a liquid; water inside the building, water outside the building, and water in the walls, floors and roofs themselves. It is not only about how water moves through structures (water vapour permeability), but also about the ability of materials to absorb and release water as vapour (hygroscopicity) and about the ability of materials to absorb and release water as liquid (capillarity).”*
Breathable building materials like timber do not trap moisture, but absorb it in their porous structure and allow it to dry out and evaporate. As internal and external temperatures and humidity levels rise and fall, wood takes up vapour and later releases it, helping to maintain a comfortable equilibrium. We can enjoy a natural clean air environment without the need for open windows and cold draughts.
Perhaps the worst materials to use are UPVC doors and windows with PVC lined plastic wall finishes. These form a cheap and quick internal
lining, but they trap moisture which can often be seen clinging to the internal walls, ceilings and window panes at the end of the day.
A timber building with a high specification roof and floor insulation and good quality double-glazed timber doors and windows creates a natural, breathable work environment with good airtightness but also good breathability. There are other natural building materials like strawbales, wool, clay, cob and lime mortar, but you’d have to agree timber is the easiest on the list to source and build!
We manufacture our log cabins with solid timber walls in 45mm, 58mm, 70mm and greater thicknesses. Importantly, you can finish them with microporous breathable paints to maintain this natural breathability advantage. Breathe easy!
* Neil May: ‘Breathability: The Key to Building Performance’.