I am new to ICF and still learning. I have talked to people who own grid wall system and say they're as good as a flat wall as far as energy goes. I talked to a flat wall contractor who also said the same thing and said flat is preferred because of lower costs and better strength. Any thoughts please ? Thank you !

Depends on the grid system. How do you feel about nothing but foam between you and the wild blue yonder?

If its a grid system that has areas of beams and columns infilled with thinner areas of concrete, this won't be a problem but are you sure that these thin areas can be properly consolidated?

Take a look at Buildblocks' new Global block it looks like a smart alternative to a flat block especially if you are using a stucco finish. I would think this grid block would have a higher r-value since it contains more eps

Castle Rock Homes.

I would think that in a climate like Phoenix that more mass would be more beneficial than more insulation due to the relatively large day/night swings in temperature. This would make the flat wall ICF system more desirable.

Thank you everyone for your responses. dford, are Castle Rock Homes the same as ICF Specialists ? Can I please PM you ? Thanks.

Yep.

Grid systems have increased flexural strength above grade. Higher labor costs due to llintel details, except perhaps with Buildblocks new form which is interchangeable with their flat wall system but does not facilitate ease of attachments for finished wall products. Grid walls show Less versatility for future- post pour- door and window retrofits as they would demand lintel structural upgrades, and grid walls take more skill to consolidate; proper mix design, slump, and slower pour times are in effect to offest the cost of cheaper block and less concrete. They are very efficient, but in southern states maybe think about termites travelling through foam, vs. flat wall design concrete.
We pour either. Generallly flat wall systems may be considered a workhorse all around fantastic cost/benefit option, with grid systems allowing flexibility for certain price points and designs.

Don't let grid walls scare you, holllow fill CMU is done everywhere; but be aware of the practical differences and don't get caught up in the 'block and concrete cost savings' listed on most of the grid wall brochures.

Thank you irnivek for a thorough comparison.