[Greenbuilding] Passive solar home--concrete overlay re thermalmass

KTOT (g) ktottotc at gmail.com
Mon May 13 12:20:25 CDT 2013


I am not clear on what you are saying. Are you saying simply applying overlay material (as was originally used in a bathroom, which is not thermal mass so was not an issue re overlay vs. bare concrete) will not work, that something else is required? Or a layer between the concrete and the overlay?

Also my understanding is density isn’t the issue specifically re thermal mass, rather is an issue of earth materials (stone, water, clay, etc.) vs. non-earth materials.

Re the slab, it appears the cement was left sitting in the truck multiple hours with no retardant added and a very excessive amount of water was added, curing/finishing was likely improper, and possibly more. I probably didn’t mention the very severe cracking throughout the floor in my original post. People also have different opinions on whether one can just cover a defective slab or if cracking will cause problems in the future as well. Some of those issues are still be sorted out. Meantime, I’m focusing on the thermal mass aspect of overlay atop a slab.

From: John Salmen 
Sent: Monday, May 13, 2013 10:58 AM
To: 'Green Building' ; topher at greenfret.com 
Subject: Re: [Greenbuilding] Passive solar home--concrete overlay re thermalmass

The bonding of a tile or dissimilar material to a concrete slab usually requires a separation or slip sheet of some sort as well as a trowel pattern that will create air pockets. This is different that simply a concrete resurfacing material. Resurfacing is typically a very finely graded cement product with modifiers to allow for bonding and movement. The density of these materials would be typically high possibly exceeding the concrete slab. I can’t see an issue that would involve removing a slab unless it is totally f_____ for other reasons.

 

From: Greenbuilding [mailto:greenbuilding-bounces at lists.bioenergylists.org] On Behalf Of Vadurro, Rob, EMNRD
Sent: May-13-13 8:07 AM
To: topher at greenfret.com; Green Building
Subject: Re: [Greenbuilding] Passive solar home--concrete overlay re thermal mass

 

I believe the concern is the transfer of heat between different materials. I can’t remember where I saw it, but there was a table showing the transferring heat between base and finish materials, say tile to concrete slab below in passive solar conditions and the rate of transfer was much less than one might think. The joint between the two impeded the heat transfer, in other words. I would think an acrylic additive may impede the transfer even more. The best is always to not cover the slab, only color it, if heat retention in the slab is the goal.

 

Rob Vadurro, AIA

Park Architect

New Mexico State Parks

1220 South Saint Francis Drive

Santa Fe, NM 87505

505-476-3383

505-476-3361 fax

 

From: Greenbuilding [mailto:greenbuilding-bounces at lists.bioenergylists.org] On Behalf Of Topher
Sent: Monday, May 13, 2013 8:39 AM
To: Green Building
Subject: Re: [Greenbuilding] Passive solar home--concrete overlay re thermal mass

 

On 5/13/2013 1:07 AM, KTOT (g) wrote:

  Does anyone have experience or knowledge about this? Using or not using a concrete overlay product for the top layer of a floor for thermal mass, vs. a plain darkly stained concrete slab 


A concrete overlay product is likely to be roughly similar in thermal characteristics to a concrete slab.  Meaning that you will just have a thicker thermal mass.  It seems unlikely that you should be worried about too much thermal mass in a passive solar house.  The overlay product might have a lower specific heat, or conductivity, wither of which will reduce it's effectiveness somewhat.  Remember to stick with a dark color.

Thank You Kindly,

Corwyn

-- Topher BelknapGreen Fret ConsultingKermit didn't know the half of it...http://www.GreenFret.com/topher@greenfret.com

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