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wofati and earth berm

Underground/berm in humid climates?

K Eilander

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posted 2 years ago

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I like the summer cooling benefits of underground or earth-berm structures, but is there also a condensation (and accompanying mold) problem in humid climates?

And if so, what are some possible workarounds for that?

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Alice Fast

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posted 2 years ago

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I've seen a few underground homes built in the Southeast where it's very humid - these are good for tornado areas.
I think the issues of moisture/condensation are solved by adding roof vents, passive and even ones with electrical fan if passive venting doesn't solve the problem.
If the moisture source is external, from surrounding soil, the solutions can range from french drains and proper grading to waterproofing the walls (in standard underground build that meets codes the walls are waterproofed at build time), but the water table and flood zones better be well away in any case.

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Condensation/Humidity is from:
Showers/Bathroom
Boiling Water on the Stove/Kitchen
Laundry
So I would vent those area before the humidity spreads to the entire house.

You can also pre-condense the extra humidity in the incoming make-up air with:
an underground air-tube,
AC/de-humidifier (it would be low power because it is only taking out the extra humidity not cooling the entire house)

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Alice Fast

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S Bengi wrote:Condensation/Humidity is from:
Showers/Bathroom
Boiling Water on the Stove/Kitchen
Laundry
So I would vent those area before the humidity spreads to the entire house.

You can also pre-condense the extra humidity in the incoming make-up air with:
an underground air-tube,
AC/de-humidifier (it would be low power because it is only taking out the extra humidity not cooling the entire house)

Dehumidifier is definitely an option, but I'd say if the house/basement needs a dehumidifer there's a bigger problem that needs to be addressed. The exception is when the place is sitting vacant and doesn't get air flow, dehumidifiers sometimes are left on in above-ground homes too. (when I said roof vents above I of course meant venting directly from the living space and through the roof, I've seen underground homes with tons of vents literally all over the roof, I guess they have extra humidity problems justifying the need for so many vents, but normally several vents is sufficient)

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In addition to sufficient venting, I plan to use lots of lime in my finishes and very little wood, zero particleboard or drywall.

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John F Dean

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posted 2 years ago

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A friend of mine put in a pricey underground home. It was well vented. He also had a carefully designed system to remove humidity. His goal was to have a tornado proof home.

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Aaron Yarbrough

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R Scott wrote:In addition to sufficient venting, I plan to use lots of lime in my finishes and very little wood, zero particleboard or drywall.

Would lime plaster be better at controlling indoor humidity than an earthen plaster?

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I am not sure if lime or earth plaster is better at regulating humidity but lime is a great anti mold finish.

Kimi Iszikala

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posted 1 year ago

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R Scott wrote:I am not sure if lime or earth plaster is better at regulating humidity but lime is a great anti mold finish.

I wouldn't know myself, but Athena Steen of Canelo project says clay is a much better humidity regulator than lime. At a workshop she mentioned that many people use lime in the bathroom but (on walls not directly hit by water) clay is much better at regulating humidity.

At Canelo they use lime (or possibly limecrete) for shower walls but clay for, e.g., above the sink or other areas iin the bathroom.

For our house and needs (we said we didn't want to resurface regularly, and the south-facing wall has a 2' overhang) she suggested 1:3 cement:lime stucco mix for that upper exposed south-facing wall. Below the porch roof on that same wall we plan to use clay even though it will be a greenhouse and therefore humid -- we won't have any planters against the walll.

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