# Filling a cinderblock with sprayfoam?



## drewdin (Jan 21, 2013)

I have some cinder block foundation peices that are broken, I can see the two hollow spaces in between them. Would it be ok to fill them up with spray foam? I was thinking that it would be fine but i wanted to check first. 

Is there anything I should look out for or can I just go to town!


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## nealtw (Jan 21, 2013)

Non- expanding foam?
http://www.sprayfoamfacts.com/core-fill-foam-insulation/


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## drewdin (Jan 22, 2013)

Thanks for the link, do they sell that at the box stores? I was going to use the DOW spray foam but I know it expands a ton. Maybe the window and door foam?


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## nealtw (Jan 22, 2013)

Don't know, just found the that site.


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## drewdin (Jan 22, 2013)

i didn't see anything when I searched other than that site. I guess as long as the top of the cinder block is open its OK, that way the foam has a place to expand. There are only a few spots and they are open ended.


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## nealtw (Jan 22, 2013)

I would be worried about blowing them out. But if you are not going to do the whole wall, you would still want to build a wall inside and insulate that. I'm not sure you get much gain with just doing a few.


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## drewdin (Jan 22, 2013)

I am just sealing cracks right now, I can see tiny areas where there is a space between the wood foundation and cinder block foundation.

One specific area on the right side I cant get in close enough to fill the gap as its the corner and there is a pipe there. I cant get around the pipe to get at the opening. My thought were to fill the center of the cinderblock and the overflow would fill the gap. 

I do plan on adding a 2" foamboard to the wall, using liquid nails(Unless you recommend anything else) but thats is in the future.

I can supply some picture later if needed, thoughts?


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## Wuzzat? (Jan 22, 2013)

Is the foam insulating value is greater than the insulating value of the dead air in the hollows?  There is also air infiltration which the foam may help with, or just use caulking.

Even then it may not be worth it in energy savings over a 10 year period ('investment horizon').


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## drewdin (Jan 23, 2013)

I tried the spray foam last night, i was unable to get it to stick as the crack was too high and it wouldn't bond to the concrete. Ill have to seal the gap with silicone from the outside as I know the location.


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## nealtw (Jan 23, 2013)

Have a look at caulks made for concrete, they may be better than silicone.


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## mudmixer (Jan 23, 2013)

The spray foam, calks and epoxy injection are just band aids and not repairs.

Addressing the cause of the cracks. Usually, heavy wet soil combined with drain tile is the long term situation. For an existing home with extensive landscaping and steps, sidewalks and attached garages exterior drain tile is high cost and takes time subject to weather. If you have reasonable soil, interior drain at the level of the bottom of the footing can work and be much cheaper and provide long term stability since they work continuously to draw off the moisture and are not affected by short term storms if the gutters and surface drainage is adequate. The allow some of the band aids to perform better and be more effective. 

The main load on a basement wall is from the external soil/water and not vertical loads. If it were not for the soil. a basement or first floor could be built with a 6" thick block, but usually more width is needed for bearing details for the stick framing or brick ledges.

Dick
Do not fall for the plastic barriers at the floor wall junction or the antiquated shallow eastern floor trenches the collect only the water after it has leaked in.

If you have deep pockets, the ideal is excavating around the house, building new basement wall, replacing the soil and putting in new exterior drain tiles, but that is slow, costly and takes time. - Probably not realistic.

Dick


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