Block Materials


Please follow this general outline if writing a new topic page for this site. Refer to existing sections for a general idea of what to include.

CSI Number

If you know the CSI number, it can be helpful to designers and spec writers if you supply it here.


Define your subject matter. Typically 1-3 paragraphs.


A general overview of what needs to be included in deciding whether or not to use this material or technique. Not all methods and materials work well in all climates, for instance. Typically 3-4 paragraphs.

Commerical Status

How well developed is the commercial support for this? We typically look at three areas:

Cost (typically initial cost only, though you’re welcome to include typical payback periods or other lifetime cost analyses)

From one or two words (ie, “limited”, “widely available”) to one sentence or phrase (“5% to 10% higher than conventional installations.”)

Implementation Issues

How easy is it to implement? Three major areas are:

Public Acceptance

Again, typically one word to one sentence.


Block Materials

(see also adobe in Earthen Materials)

Aerated Concrete Block

Insulating Concrete Forms (ICFs)

1.0 Aerated Concrete

Aerated concrete blocks have been in use since 1924 in Europe, though they didn’t make an appearance in the US until around 1992.

Aerated concrete block is typically made from a combination of sand, cement, lime, water, and gypsum. Small amounts of aluminum oxide or other compounds are added as foaming agents, reacting with the mixture to form hydrogen gas. The gas bubbles act in a similar way to closed-cell foam insulation, forming small bubbles uniformly distributed throughout the mixture.

Many manufacturers autoclave the resulting material to increase its strength and stability. Others instead include microfiber in the mix and are thus able to reduce the energy footprint while maintaining a strong and stable block.

The resulting block is lightweight and insulating, with a typical weight of between 35-40 lbs/sf of 8ft high wall.

Insulation and Fire

Aerated concrete typically achieves a 4-hour fire rating with as little as 4 inches of thickness.

Insulating quality can vary from one manufacturer to the next, but typically range between R-1 and R-1.25 per inch (compared to a typical R-0.125 for conventional masonry). The thermal mass of the concrete portion of the block further contributes to the comfort and energy performance.

– also available as panels from some manufacturers

structural and insulating
fire resistant
can work (nail, saw, screw) with regular tools

break easily until plastered
iniital cost
Few manufacturers, shipping costs may be a concern (non local, transportation energy raises carbon footprint)
When autoclaved, initial energy footprint is quite high
Can generate a fair bit of waste on the jobsite from broken block, cutting to fit.

2.0 Insulating Concrete Forms (ICFs)

3.0 Earthen and Earth/Composite Block

compressed earth block (CEB)
hand compressed (cinva ram)
machine compressed

mega block

4.0 Papercrete Block



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