Tiny House Garage Conversion Insulation Dilemma
Garage retro fit best insulation solution for budget and the environment?
Have you ever felt the frustration of wanting to do the right thing for the environment and then, try as you might, not being able to find the definitive answer for your diy project?
Well hopefully this will cut out some of the agonising time I went through to understand how to gain the best U-Value while not compromising on my eco values. I was stuck on using the most natural materials with all the options, it was really making my head spin - internal v external insulation, labour time cost, material ingredients and all the carbon impacts, transportation costs on top of that…
In an ideal world I would be starting from scratch but as always, ideal world is a rare luxury. My reality is a small retro fit space, constructed of painted concrete rendered block circa 1970s (basically not breathable and therefore my hope to use hemp plaster and natural layers within were not going to perform as effectively as they should with that synthetic existing outer barrier).
So retro fitting restrictions taken into account, in this instance, unfortunately, standard, good quality insulated Celatex (not Polystryrene) plaster board for wall, Dot and Dab and 50 mm insulation board on floor is my best bet. This would double the UV ability over wood fibre board and still allow me to use a healthy plaster option, such as clay, on the inside..
Exterior preliminary sketch
I won’t go on about all the ins and outs it took to get to that decision as it gets way complicated. I will say go to the link below by Superhome who lay out all the environmental options and simply explain the priorities.
My motivation for adding this blog post was to highlight what led me to a solution and the tactic I will use again when weighing the complexity of eco choices between carbon reduction and environmental impact.
Rich at PYC Group, a passive house builder, helped me realise I needed to step back and see the bigger picture to make that decision.
No 1 priorities - energy saving, budget restriction (non negotiable) and longevity (do it right and make it last).
Cost wise, 50mm of Celatex is the same price as 50 mm of wood fibre board (my preferred material) but Celatex would provide double the insulation value which would lower carbon output down the road. Rich advised that of all the effort I could take to conserve energy, making it air tight would make the most impact, preventing the most heat loss. Sealing all those air gaps where wall, ceiling and floor and corner meet.
Rich convinced me that although Celatex had a high carbon footprint in its manufacture, the process could be seriously offset by the long term saving of carbon output over its lifetime. In this instance, it confirmed my choice, however if you have the choice to increase thickness, do so and use the natural wood fibre board. Now, I can justify clay plaster as a healthier choice in my immediate environment over conventional plaster because of the savings I made.
Of course you might disagree? There are many variables so please feel free to add your opinion.
I have to say I spent a good week trolling for as many independent comparative solutions as possible. For all of that, I recommend these go-to sources for information. These people were willing to talk at length and go the extra mile to help me with my particular challenges.
http://www.superhomes.org.uk/resources/whats-best-insulation-material/ for all the environmental considerations broken down into digestible chunks comparative information.
https://www.backtoearth.co.uk/products/external-wall-insulation/ Chris Brookman’s very useful Youtube direction on pros of natural insulation and natural finishes.
https://pycgroup.co.uk/ Rich helped me make the final pragmatic decision and weigh up pros and cons.