The following are questions most commonly asked about ICFs (Insulating Concrete Forms). To get more information or request a consultation, please contact us.


Q. What is the cost difference between ICF’s and wood (stick) framing?
A. The cost difference is approximately 3-5 % of the total cost of the job. If you are financing your project, then the monthly cost will be no
more for ICF’s than wood framing.   return to top


Q. What is the R-value?
A. The rated R-value is 20, the effective R-value is 40-50 due to lack of air infiltration thru the block.


Q. How much savings on utilities can be expected?
A. In the range of 30-70%, there are too many variables in life style to be more precise.   return to top


Q. Do the interior walls need to be ICF?
A. No the interior walls can be framed with wood or metal studs. However ICF interior walls make for great theater rooms and safe rooms.

Q. Does a vapor barrier need to be used on the exterior walls?

A. No the polystyrene is closed cell foam and acts as a vapor barrier.


Q. What type of finish can be used on the exterior walls?
A. Siding, brick, stone stucco, the exterior walls may be treated like the exterior walls on any other typical building.   return to top

Q. What type of finish can be used on the interior walls of ICF?

A. The interior ICF walls may be finished out just like any other building. Predominately the walls are sheet rocked.


Q. Is there any reduction in home owners insurance?
A. Usually in the range of 30-35% reduction since the building is mostly masonry.

Q. Are there any limitations to style or design of building?

A. For the most part if it can be built, we can use ICF’s.


Q. If I have building plans already drawn, but not for ICF, is it necessary to redraw the plans?
A. No it is just a matter of increasing the size of the foundation to accommodate the thickness of the block walls. This can be done by the engineer when the foundation is drawn.   return to top


Q. What type of foundation do I need?
A. This will be determined by the structural engineer.


Q. Does it take longer to erect the walls?
A. Actually in most cases the walls will be done quicker, since there is no insulation to install at a later time.


Q. Is there a limit to height of the building?
A. 100 feet high before structural steel is needed.   return to top


Q. Can ICF be used below grade?
A. ICF block is ideal below grade; just be sure that a good waterproofing system is used.

Q. Does the block burn?

A. If a flame is held to the block the polystyrene will melt, however once the flame is removed the polystyrene will not support flame spread.   return to top


Q. Are termites a problem?
A. Termites may burrow into the foam seeking out wood; however the foam is not a food source for them.


Q. Is mold a problem?
A. The polystyrene is closed cell foam, so that it does not absorb water. There is nothing organic for the mold to feed on so it will not allow
mold to grow.   return to top


Q. Is there difficulty in the placement of plumbing pipes and electrical lines?
A. For the most part there is no more difficulty running these items than with a conventional stick building. There may be a slight learning
curve with the trades on the first ICF block building they rough-in.

Q. How safe are ICF buildings in floods or wind storms?

A. Very safe and it is possible to have an ICF building certified by FEMA. https://www.fema.gov/rebuild/mat/mat_fema499.shtm fact sheet #5


Q. Can I erect the walls myself?
A. Probably, however we recommend that you use a certified installer, so that you receive the most benefit from your purchase of ICF
block. Installing the block is relatively simple, the bracing of walls and pouring of concrete is somewhat more complicated.   return to top


Q. Are there any special financing programs available for ICF’s.
A. Yes, some lending institutions offer Energy Efficient Mortgages (EEM).


Disclaimer: Please check with your local building authority for compliance with the above referenced items.

Custom Homes Helping Hands Program

Steve Sierleja, while living environmentally conscious himself, advocates a mantra in all of his company practices for Custom Homes LTD and BuildBlock of South Central Texas… “Green Building practices need to be the norm not the exception. We need to be good Stewards of this Earth for future generations. We have the capabilities presently to improve this world for all.”

Member - National Association of Home BuildersMember - Hill Country Home Builders AssociationEqual Housing - HUDEnergy StarSmart Energy BuilderICF - Insulating Concrete Forms - BuildBlock