Hempcrete for Brooklyn Brownstone Extensions

We at Eco Brooklyn have been in love with Hempcrete – a mix of lime and hemp for walls – for years. A hempcrete wall provides strength, protection and insulation all in one.

Compared to stick and frame building it uses much less wood and is much more solid of a structure. A hempcrete home feels solid. And the soundproofing qualities are amazing.

The one drawback is that you do need a thicker wall – at least 12′. In space starved NYC this can be a problem. The wall doesn’t, however need any kind of finishing (sheet rock for example) so space is saved there.

We think a Hempcrete application is perfect for a brownstone extension. It is so much greener than the cinder blocks often used. And in terms of comfort it is unmatched. No air leaks or thermal bridges.

Eco Brooklyn is a New York Hempcrete installer. We feel that it has it’s place in the NY green building lexicon. More and more, though, the green building lexicon is simply becoming building lexicon. Green building makes sense.

We are eager to install more hempcrete walls. Even if it is just one wall that acts as a centerpiece, the visual beauty and tactile comfort of hempcrete is makes it practically a work of art. Optionally you can plaster the wall with clay, another beautiful material.

Check out this video on how a hempcrete wall is built. You will notice how very simple it is.

Hemp Lime Hempcrete in New York

Hemp mixed with lime, aka hempcrete, is not concrete and thus needs structural support. It's main use is insulation and air sealing. In this photo it is stick frame. In the future we suspect somebody will find a way to make it structural. A skilled green builder could use this for NY extensions as well as insulating existing brick structures.
Hemp mixed with lime, aka hempcrete, is not concrete and thus needs structural support. It’s main use is insulation and air sealing. In this photo it is stick frame. In the future we suspect somebody will find a way to make it structural. A skilled green builder could use this for NY extensions as well as insulating existing brick structures.

My friend Jim Savage from Build Green just sent me his latest presentation on Hemp-Lime, also called Hempcrete. His company is gearing up to provide the New York area with hemp that is sourced on this continent. Us green contractors are very excited by this prospect.

Hemp is still imported from Europe where it is widely used in France as a building material with great success. But to import it to the US is not the most carbon friendly process. As a New York green builder the lack of hemp-lime installation in our services offered is a real pain. With Build Green’s efforts we are hopeful that hemp will soon become available more locally and more affordably.

When you mix hemp with lime it creates a wonderful substance that outperforms many of the current semi-structural insulation products available on the market, at an exponentially more ecological impact.

Please check out the brochure below. It outlines hemp-lime’s historical use and its many key benefits.

GreenBuilt_Eco-Brooklyn Hemp-Lime

Hemp grows quickly and as it does it absorbs massive amounts of CO2. When you cut it and put it into buildings you are sequestering that CO2.
Hemp grows quickly and as it does it absorbs massive amounts of CO2. When you cut it and put it into buildings you are sequestering that CO2.

Building Passive House with Hempcrete

One of the challenges we face when doing High Energy retrofits of NY masonry brownstones, by the Passive House standard for example,  is how to install insulation that will both be effective and maintain the historical integrity of the building. Most existing insulation materials have limited usefulness when installed on the interior of the envelope, due to condensation risk and potential freeze-thaw issues.

Enter Hempcrete. Hemp-lime insulation, due to its vapor permeability and the material’s virtual thermal mass, has proven to be an effective way to retrofit historic masonry buildings for improved insulation, and is now being used widely throughout Europe.

This opens up exciting possibilities for effective and affordable ecological renovations of New York’s many historical brick buildings.

Although well established in Europe, this technology is new to the USA. We have studied it a lot and Eco Brooklyn is eager to be a NY hempcrete installer. Since hempcrete can be either insulation or actually act as an insulating semi-structural material (like SIPs but without the plastic), we think that it offers a lot of options for high efficiency NY Brownstone renovations.

Hempcrete

Hemp is actually one of societies oldest cultivated plants and has only in the past century gotten a bad name mostly due to political and financial interests wanting to dissuade its use. But recently it is becoming more popular again as a building material.

Check out these videos on the topic. They show how hemp is a very good alternative to many conventional building techniques.

Part 1

Part 2
They mix one bale of hemp with three bags of lime.

French hemp building
“Stronger than cement and 1/6 the weight.” The builder is held back only by legal restrictions on hemp production.

1st Permitted Hemp House in the US
About Hemp-Technologies.com. Lime is better than cement because it does not need to be heated like cement. Lime draws CO2 out of the atmosphere and gets harder and harder over time. The walls last for thousands of years. It doesn’t start out structural but over time it becomes structural. Hemp dries out a lot better than straw bale and thus is better in terms of mold.

Spraying Hempcrete

Hemp production and construction
Film done by Lime Technology, another hemp player. Shows blow on hemp, skim coats and lime wash paint process. Hemp by Tradical hemp producer.

Hempcrete reuse
Unlike cement, hempcrete can be recycled.

Hempcrete.ca
How to make a hemp house in three minutes!