ICF Inspections 3

[CANPRO]

Hello All, just wondering what others do for ICF inspections. I've never had to provide inspections for ICF walls before...I have a small residential job coming up shortly where it will be required. Its a typical residential job and I am not too concerned with checking every square inch of the wall, but with the potential for larger jobs coming up I would like to set a precedent for my inspections. Obviously the nature of ICF construction restricts complete inspections once the wall is poured. Any input would be appreciated.

 

[CANPRO]

I was hoping this would get 1 or 2 responses...

Has anyone felt the need to check for proper concrete placement behind the ICF once the wall was poured? How do others feel about signing off on the final structure without ever seeing the quality of the finished work?

 

[Ron]

CANPRO....this is one method that begs for full time placement observation during construction. Due to the limited tolerance for vertical fill locations relative to footing dowels and the difficulty in consolidating the horizontal runs, I wouldn't sign off without it.

Infrared thermography can have some relevance to check for proper filling and consolidation, but unless you do something like hook a welding machine to the rebar and force a current through it all to heat it up, it will be difficult to get a good thermal signature....after all it is insulated!

 

[XR250]

Unless they are going to pay you to sit there during the rebar and concrete placement, they cannot expect you to sign off on anything related to it.

 

[hokie66]

I have not seen this product used. It seems to me that, as far as the inspection is involved, it is not dissimilar to reinforced masonry. It involves placement of reinforcement and grouting of voids. Without adequate inspection, there is never surety that the reinforcement is in the right place, and further that the grouting is complete. So if you inspect reinforced masonry, the same principles apply.

 

[Brad805]

Have you ever inspected a conventional form after it is buttoned up? This is no different. Bring a flashlight and add some conservatism to your design if residential. It will be difficult to inspect during the placement of the blocks. The vertical bars are fished in last.

 

[CANPRO]

thank you for the replies. I agree that as far as the reinforcing goes, it is no different than conventional formwork. I have inspected the rebar and am satisfied. My main concern is the potential for poor quality concrete placement that will go undetected. The practical minimums are beyond what is required for strength, so for this residential project I can live with minor defects if they were present.

Ron, you raise a good about about continuous supervision during concrete placement. For this particular job, I don't think it is warranted, but something I will keep in mind for larger projects (also, I've already missed my chance for that as the wall is poured). Majority of this project falls under prescriptive codes, and I doubt the City inspectors do anything more than glance at the rebar before concrete placement, if that.

If there were critical areas that I knew were most likely to have issues I suppose I could pull of a portion of the foam and look at the concrete - I just wasn't if that was standard practice among other Engineers.

 

[allgoodnamestaken]

Check for consolidation/honeycombing issues under any gap - under opening for windows, etc. Did they use a plasticizer in the concrete mix when they poured? Tap with something and listen to the sound, check for hollow spaces.

 

[emmgjld]

allgoodnamestaken has a good point about gaps under window bucks and such. I would recommend probing with a very stiff wire probe.

 

[jayrod12]

When I poured my own basement using icf forms I did a few things to ensure proper consolidation, now I go over these steps with a contractor every time they want to use ICF

- smoother aggregate in the mix, this made for a nicely flowable and easily pumpable concrete
- Added super-p to the mix as well for same reasons above
- poured and vibrated in 2 ft lifts
- For windows and mechanical openings, two 4"-6" diameter (or square) holes must be made in the bottom sill of the window buck, the first is to pour concrete in, the second is a inspection hole. Fill holes with the piece of insulation that came out of it. I sealed mine in place with spray foam.

And if you go along and hit the plastic ties with a hammer you can tell whether there is concrete or not (as previously mentioned by others)

 

[MrHershey]

In the past I've done a 2'x2' or even 1'x1' grid on wall face where you insert something (wire probe, awl, screwdriver, whatever) through the foam looking for voids. This was in response to finding some large voids. ICF was stripped away and diagnosis on review was a bunch of items could have been better. Consolidation was relatively poor (contractor blamed ICF rep for pressuring them to limit vibration out of concern ICF would blow out), mix design did not include a superplasticizer, and rebar had been detailed and placed with header/sill/jamb bars perpendicular to wall face instead of parallel and essentially formed a dam for the concrete. Contractor, mix designer/supplier, and structural engineer all had items they could have done better or differently. Probably would have been fine if one or even two of those items were present. With all three, we had a problem. Once these items were addressed the rest of the walls went up like a dream with only occasional/rare voids found with the grid. And the ones that were found ended up being relatively small pockets. Fortunately it wasn't a toxic or combative situation and everyone worked together to make the changes and move forward.

 

[allgoodnamestaken]

Jayrod12's suggestions sound very reasonable. A lot less helpful when they've already poured it and you're just inspecting, but in the future a good basis to start your requirements.

 

[CANPRO]

thanks for the input everyone, very much appreciated. They do use a plasticizer in their mix. In future, I think I may adjust my notes to specify a smaller aggregate. I think checking for voids with the wire/screwdriver is a great idea.

 

[hokie66]

My choice of tool for probing would be an ice pick.