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Community and Q&A

Failed Rim Joist Insulation Job

tom01773 | Posted in Expert Exchange Q&A on

I recently had a contractor install foam rim joist installation in my basement. They indicated the foam would be 2 to 3 inches thick. It appears the foam was not properly installed as it seems to be only about 0.75 inches thick over most of the joist and has puddled at the bottom. The installer also indicated that after installation the foam was spray ‘painted.’ Based on what we felt was the failure of the contractor to deliver the promised specs for the job, we withheld a significant portion of the payment for the work and requested that the manager of the company come and inspect the job with us.

I have a couple of questions. First, is this a failed job and if so what caused the failure? Second, is it realistic to think this job can be fixed by the addition of more foam as the installer suggested at the time? My concern is with the layer of ‘paint’ will the additional foam actually adhere? How can we confirm this would actually be the case? I don’t want to pay them for the complete job if it’s really not going to deliver the performance we should be getting.

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  1. Expert Member
    PETER G ENGLE PE | | #1

    If there are no objectionable odors from the foam and it is firm to the touch but not crumbly, then it probably cured properly. They may have just not sprayed enough foam, sprayed at the wrong angle, or any of several other possibilities. If that is the case, spraying more foam would be the proper solution. Don't worry too much about the paint - the liquid spray foam sticks to everything.

    1. tom01773 | | #2

      Thanks, Peter. Is the fact that it is very thin an indication that it might have been applied too cold and didn't expand properly? Also would that be confirmed by the fact that the foam appeared to flow downwards to the bottom of the joist and pool on top of the cement foundation? Does this suggest I need the contractor to be more attentive to the temperature of the foam they're applying? Thanks!

      1. Expert Member
        BILL WICHERS | | #3

        Temperature does play a part, but I'd be surprised if it would expand to 0.75" instead of 3" unless it was REALLY cold. I think your installer probably either didn't spray a thick enough layer (a "lift"), or went too fast and didn't get a good application due to moving too quickly. Either way, as Peter mentioned, if it cured OK then you don't have a bad mix, you just have a too-thin layer. If the foam is gooey or crumbly, it didn't cure correctly. If the foam is just thin, it's just an insufficient application. Use a cut piece of wire coat hanger, or other stiff wire, as a probe to measure depth by poking through the foam.

        Spray foam is super sticky stuff, it's like foam glue, so I wouldn't worry about it sticking to the paint. As long as the paint itself sticks to the previous layer of foam you should be OK. If the paint peels easily, then it could act as a "release agent", which would let the second layer seperate. Even this probably isn't an issue, since the new spray foam will still seal to things along the perimeter. I'd check what paint they used though -- ask them if it's an intumescent coating, which is a type of fire retardant coating.


  2. walta100 | | #4

    How thick the foam looks is subjective stick a wire thru the foam and measure how deep the foam is. Talk about facts and not your feeling.

    How sure are you that your contract has a written specification for the foam thickness?

    My guess is that the contract is written by them and to their advantage and is likely to have a loop holes for them.


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