Building Sustainability With The Right Materials

As a continuation of our series on Sustainable Home Making in the humid tropics, we are going to delve into the subject of materials. Picking up where we left off:
1. A local resource they we enjoy here in the Bay is pumice stone. Pumice (jal) mined in Tepic is used by local block makers to make ‘bloques de jal’. Very little cement is used as a binder, because pumice itself is a pozzolanic material, meaning it has a latent reactivity that extends the effectiveness of cement. As little as 3-5% cement is used in these pumicecrete blocks. Numerous production facilities exist near Sayulita, Ursulo Galvan and La Penita.
2. Integrally pigmenting white stuccos is a great way to add color to walls without supporting toxic paint industries. Conventional paints use petroleum derived binders that effectively “shrink wrap” the house in a plastic membrane. Just like hot food creates condensation on shrink wrap, condensation, salts and molds get trapped behind conventional paints, causing efflorescence, blistering and peeling. Pigmented stuccos allow for more breathability although you do see moisture patterns moving through the walls as “dark patches” before they evaporate. Our company, PHYTOSTONE, also specializes in breathable concrete-free plasters here to the north of the bay (www.phytostone.com) . If breathable plasters are not an option, eliminating stucco layers altogether is a better route to go, as in poured-in-place walls. The fewer zones for salts and molds to collect between unbreathable layers, the better.
3. Salts in mineral based building materials are fairly inevitable down here. Generally, pigmenting coatings in lighter shades makes efflorescence less visible. Additionally, light colors allow a building to reflect more light, which affects indoor comfort levels greatly.
4. Because of constant salt migration, use vapor barriers with abandon. Behind retaining walls, in conjunction with foundation work, under floors, vapor barriers are key to curtailing salts and moisture related problems. Vapor barrier can imply using pond liners or tarring building components where appropriate.
5. Palapas can be treated with clove oil based sprays or steeped parota woodchip teas teas. The organic store, Terrenal, outside Sayulita carries non-toxic palapa treatments.
6. Feel free to write me at phytostone@gmail.com if you have an inquiry about nontoxic, 0 VOC sealants for mineral surfacing (stone, concrete, plasters, marble and granite). Breathable sealants are key to respecting the natural vapor diffusion of all materials while nevertheless blocking pores against larger salt and mold molecules as much as possible.
7. Because acetylated and silicified wood products are not readily available in Mexico, cellulostic materials like bamboo and pine must be chosen with care. Currently, borate based insecticides are the most benign and available protection against termites. If you are using exotic tropical hardwoods or parota, make sure your wood has a certificate of origin that proves it was legally harvested. Legitimate ‘maderias’ or carpenter shops will be able to show this paperwork.
8. Living in the humid tropics means that you can consider air as an insulating thermal break between your materials! Air is an excellent insulator, so creating hollow wall systems is a viable option for our climate. Pink insulation and foam can’t beat the eco-credentials of air.
9. Did you know Rotoplast is making biodigestors these days, for more sustainable waste handling? See https://rotoplas.com.mx/catalogo/biodigestor-autolimpiable/
10. Always choose your materials with the 7th generation in mind. Acrylics, polystyrene and other artificial building materials should be foregone for biodegradable options based on plants, earth and minerals. High temperature kilning, like that of ceramics, is environmentally preferable to adding toxic or non-biodegradable ingredients, where performance is required.
Join us next article, as we continue our discussion on Construction Logistics and Best Practices for your tropical garden!

Emily Majewski
Emily Majewski is Co-Founder of PHYTOSTONE, a small firm based in Nayarit dedicated to creating advanced natural materials for home and garden.

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