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CMU vs IFC two story house. thermal mass

Last Post 13 Jan 2020 07:28 AM by Dilettante. 4 Replies.

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rebar

New Member

Posts:31

11 Jan 2020 11:25 PM
Sure, CMU is heavier and takes longer than ICF for DIY.. But if time was not a issue, da da da, and you lived on site, shouldn't CMU be considered since its less than half the cost of ICF? CMU also allows you to place all the insulation on the outside, so the concrete wall can be used as thermal mass. And CMU filled with concrete would also be storm resistant considering I'm located in tornado alley.. I think the storm resistance maybe the top advantage of concrete for me.. But does thermal mass like this in Iowa actually save energy if the block was exposed and had a stucco/plaster finish inside? Or is that BS, and do the complications of installing CMU as Ive described out weigh the advantages and savings? Thanks!

Dilettante User is Offline

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Posts:503

12 Jan 2020 01:49 PM
You're trying to compare grouted CMU wall, with insulation added to ICF. ICF is essentially a continuous, monolithic hunk of concrete that comes pre-insulated. You may see savings on a per cubic foot of wall for CMU. But you're going to see a commensurate increase in labor costs and time to completion. As you have to build the wall (essentially brick-laying). Then you have to grout it (pouring concrete in). Then you have to insulate.

rebar

New Member

Posts:31

12 Jan 2020 11:56 PM
Posted By Dilettante on 12 Jan 2020 01:49 PM You may see savings on a per cubic foot of wall for CMU. But you're going to see a commensurate increase in labor costs and time to completion. May see a savings Dilettante? How about less than half the cost of iCF materials which is about 5 a square foot. Labor costs? What labor cost? My Union mason bud can get me started for a case, and I could care less if it takes a year because I'm spending my time, doing what I want.. I'm having trouble answering a question though.. How do I insulate, or which insulation under my 30x12 footings? Thanks!

Dilettante User is Offline

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Posts:503

13 Jan 2020 07:20 AM
Material cost: Is that including the cost grout fill? Or just the plain, unfilled CMU block? Labor Cost: You didn't specify "case of beer" labor. Just make sure he gets the case AFTER (not DURING) the construction of the CMU walls. Or you could run into funky layout problems "Hey Bob? Why are the mortar lines on the east wall 1/4" and the mortar lines on the west wall 3/4"?" "The west wall was Miller time!" "Oh..."

Dilettante User is Offline

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Posts:503

13 Jan 2020 07:28 AM
As for insulating your footings. 1: You COULD go with insulated concrete raft. 2: Dig your footings slightly deeper and construct footer forms out of EPS/XPS. Note: Have an engineer calculate the point loads being put into the foundation first, and make sure you use a foam of appropriate compression strength. Don't simply use a single thick layer of foam. Use two thinner layers. It should help avoid any blowout in the footer.