Insulating a radiant slab (C) Daniel FriedmanSlate Thermal Mass for Heat Storage - Design Details for Passive Solar Heating Systems

  • SLATE THERMAL MASS for SOLAR HEAT STORAGE - CONTENTS: Use slate as thermal mass for storing solar heat in passive solar design?What is the coefficient of expansion for slate - how much will slate expand in length per degree in temperature rise?How should slate be bonded to the concrete slab for thermal mass storage and heat transfer? Solar Age Magazine Articles on Renewable Energy, Energy Savings, Construction Practices
  • POST a QUESTION or READ FAQs about the use of slate as thermal mass for storing solar heat in passive solar design
InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

Thermal mass effects of slate:

This article discusses the properties of slate as a medium for thermal mass in passive solar heating system design and greenhouse or sunspace thermal mass material.

Our page top photograph shows a ceramic tile floor installed in Buenos Aires, Argentina. Using ceramic tile finish flooring over a rock bed heat storage system is one method of design for a solar-heated radiant heat floor system.

Green links show where you are. © Copyright 2017, All Rights Reserved.

Active Solar Heat Storage Using Rock Bed Storage Systems

Photos of red slate roofing material in good condition

[Click to enlarge any image]

The question-and-answer article below paraphrases, quotes-from, updates, and comments an original article from Solar Age Magazine and written by Steven Bliss.

Thermal Properties of Slate for Solar Heat Storage and Radiant Heated Solar Floors

Question: how to install slate for use as thermal mass for sunspace or greenhouse passive solar heat storage

A client of mine has a unique storage material to use in his solarium - 30 one-inch thick slate pool table tops.

Will the thermal expansion and contraction affect the thermal bond to the concrete slab below?

Should we buffer the joints between the slabs of slate to prevent damage to the edges? - Tom Deal, alternative energy consultant, San Francisco CA


Slate's coefficient of expansion is 0.0000058, meaning that for every foot of length slate will expand 0.0000058 feet, or about 0.00007 inches for every degree Farenheit of temperature rise.

A 60 degF temperature rise will cause an 8-foot long slate slab to increase in length by 0.0336 inches - roughly 1/32 inch.

If the sunspace experiences wider swings in temperature, the expansion and contraction of the slate will of course be greater.

Kevin Callahan at the National Concrete Masonry Association recommended using Type M mortar, which has a higher compressive strength than mortar normally used for concrete blocks. He commented, though, that the mortar might not bond very well to the slate, which does not have a very porous surface.

Bedding the slate in mortar should, however, create a fine thermal bond.

Gray roofing slates (C) D Friedman

For more on radiant slab floors see "Radiant Floors", Solar Age 5/82, and the following articles online:

Other articles you'll want to see on passive solar floors, ceilings, and walls, include

The question-and-answer article above, quotes-from, updates, and comments an original article from Solar Age Magazine and written by Steven Bliss.

The link to the original Q&A article in PDF form immediately below is preceded by an expanded/updated online version of this article.

Thermal Mass Articles

Readers should also see BLOCKBED RADIANT FLOORS - SOLAR DESIGN for an alternative to block bed solar heat storage

For supporting heat storage design details see FLOOR, CONCRETE SLAB CHOICES and PASSIVE SOLAR FLOOR TILES, PHASE CHANGE.


And at FLOOR CHOICES OVER CONCRETE SLABS we illustrate a floor slab (with incomplete under-slab insulation) that provides thermal mass helping to stabilize temperatures in a cabin in torthern Minnesota.


Continue reading at THERMAL MASS in BUILDINGS or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.


Suggested citation for this web page

SLATE THERMAL MASS for SOLAR HEAT STORAGE at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


Or use the SEARCH BOX found below to Ask a Question or Search InspectApedia


Frequently Asked Questions (FAQs)

Click to Show or Hide FAQs

Ask a Question or Search InspectApedia

Questions and answers about the use of slate as thermal mass for storing solar heat in passive solar design.

Use the "Click to Show or Hide FAQs" link just above to see recently-posted questions, comments, replies, try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.

Search the InspectApedia website

Comment Box is loading comments...

Technical Reviewers & References

Click to Show or Hide Citations & References

Publisher's Google+ Page by Daniel Friedman