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Craig Deim Posted: Mar 05, 2011 10:29 PM	CC shrinkage We are on our second go around trying to get a 1500 sf additon insulated. First attempt using a soy based cc resulted in 80 percent failure due to severe shrinkage away from studs and plates. Contractor and supplier removed and replaced product where we thought it failed. Second attempt now has 80 percent success (so seems). Product has actually seperated king and trimmers at window locations and lifted backing in others. We have cut foam in several locations where we think it is good with a nice adhesion to studs but once opened up has a 1/8 to 3/16 gap between product and stud. My question then is that typical with a proper install? We can identify the bad spots, how do I have confidence to call the sheetrockers? I haven't noticed any pics posted but I am a first timer.
jimcoler I have over 10 years of experience specifying and installing open and closed cell spray foam. I've sold my business but I'm still selling for the new owners and consulting on large and custom specific jobs. I've expanded my knowledge into t Posted: Mar 06, 2011 01:39 AM	What your seeing is typically due to the moisture content in the wood if it was sprayed on ratio. The moisture content in the wood can cause shrinkage and I would expect it to be much less the second time around. The areas you're seeing shrinkage seems to be in the larger mass areas - am I correct in this statement? Thanks, Jim
Daniel X Posted: Mar 06, 2011 02:16 AM	This can also happen if the applicator tries to install to thick of a lift all at once. My max is 2" per lift and I allow the foam to cool before my next lift...
mason Posted: Mar 06, 2011 09:06 AM	I have investigated dozens of cases of foam shrinkage similar to what you have experienced. In most cases, the foam was sprayed in thickness greater than 2 inches and/or subsequent lifts of foam were installed too soon after the first. One thing I teach applicators to measure the interior temperature of the foam. It should not exceed 220 degrees F at anytime. If it exceeds 220 degrees F, the foam cells will be affected. You will have more open cells, weaker foam, possibly fissures and cracks within the foam and in some cases a lingering odor. I also recommend that they wait 10-15 minutes between lifts to reduce the amount of exothermic heat build up in the foam. This of course varies depending on the foam formula, substrate temperature, foam temperature, thickness of the lift and other variables. Generally the thinner the lifts of the foam, the sooner you can install the next layer. They could also be installing the foam with the wrong gun configuration, which would cause the foam to not be mixed properly. This can also cause more open cells and shrinkage. It makes a difference which dirction they spray the foam. Spraying back and forth between studs causes the foam to have slightly elongated cells in the direction of the rise. The foam would tend to shrink (or grow) away from the studs. This makes it more likely to separate from the studs. Spraying lengthwise parallel to the studs causes the foam to be more dimensional stable because the growth or shrinkage of the foam cells would be parallet to the studs instead of perpendicular. Picture framing also helps by providing a high density skin against the studs which reduces the potential for dimensional instability. Sort of like a reinforcing layer before the actual foam lift is sprayed.
Craig Deim Posted: Mar 06, 2011 09:07 AM	I didn't test the wood for moisture content but kept checking temp and humidity in the house. Temp was 55 to 65 deg and humidity was running 35 to hi 40s perc. We were heating the area with vented heaters. Actually noticed severe shrinkage in both size spaces. Narrow spaces next to wdos probably got filled too fast. Second attempt contractor was more watchful of not lifting too much at a time. Timing between lifts may still have been an issue. I am still concerned about the comment on another post about shrinkage still possible 6 months later. Once these jobs are rocked its all over. I certainly don't want to think about removing a wall section and finding a shriveled up piece of insulation.
mason Posted: Mar 06, 2011 09:51 AM	I don't see problems in the wall as often as in the attic or crawls spaces where the thickness is greater. But I have seen shrinkage in walls, particularly if the foam is installed in significantly varying thickness. Jim has a good point about moisture in the studs or joists. They can hold a lot of water, if they have been sitting outside for any length of time. Be sure to measure the moisture content of the studs as well as the wood substrate. It should be less than 18% moisture content. You can use a Delmhorst moisture probe to measuure it. You can get them online for around $150.
Daniel X Posted: Mar 06, 2011 01:32 PM	What is the overall thickness of the foam? If you cut a chunk from the wall, how many skins are inside it?
Craig Deim Posted: Mar 06, 2011 02:39 PM	I just cut another section from the wall. It is averaging 4" in thickness and viewing a cross section has 4 - 5 layers some not all the way across as I assume he was building it up as he saw a need. Pressing into the cross section with my finger it does seem as though some lifts have a different density than others.
Daniel X Posted: Mar 06, 2011 08:06 PM	Very interesting... I hope the contractor you hired is taking good care of this situation, we don't need the negative press from poor application methods.
Bob Silverman Posted: Mar 07, 2011 10:09 PM	This is NOT typical of spray foam that is installed correctly. Although moisture in the framing lumber can cause poor adheasion and lighter density foam that is dimensionally less stable, it is not always the culprit. Did you use the same brand of foam from the same manufacturer for both attempts? You mention that you didn't check for moisture in the framing lumber, did the contractor? Or the manufacturer rep the second time around? Does the contractor have the proper spray foam equipment from a reputable equipment manufacturer? Or does he have some "homemade" equipment, for lack of a better term. Has the brand of foam been fully tested with ICC report? Push up against the overspray on the side of the studs where it meets the full thickness of the foam. If the foam moves, cut it back to see if there is a gap underneath. If you can find some gaps, measure the size of the gap as accurate as possible. Cut a wood shim so that it fits snug in the gap to measure the width of the shrinkage. Mark it and wait a couple of weeks or a month and see if it shrinks more. What state are you in? The foam is going to be stressed when it gets hot outside, especially the foam that is in the roof. Good Luck
Posted: Mar 10, 2011 01:13 PM	could be a system formulation gremlin??,,,, or,, sounds like consistently resin rich foam,,, or,, hey jim,,i dont spray h2o based cc's,,do you need to spin em?? if so,,could this be a case of underspun resin,,much like underspun oc resin??too small blades,,too few blades,,too short of time,,you know the drill,,,

Author

Comments

Craig Deim

Posted: Mar 05, 2011 10:29 PM

CC shrinkage

We are on our second go around trying to get a 1500 sf additon insulated. First attempt using a soy based cc resulted in 80 percent failure due to severe shrinkage away from studs and plates. Contractor and supplier removed and replaced product where we thought it failed. Second attempt now has 80 percent success (so seems).
Product has actually seperated king and trimmers at window locations and lifted backing in others.
We have cut foam in several locations where we think it is good with a nice adhesion to studs but once opened up has a 1/8 to 3/16 gap between product and stud. My question then is that typical with a proper install? We can identify the bad spots, how do I have confidence to call the sheetrockers? I haven't noticed any pics posted but I am a first timer.

jimcoler

I have over 10 years of experience specifying and installing open and closed cell spray foam. I've sold my business but I'm still selling for the new owners and consulting on large and custom specific jobs.

I've expanded my knowledge into t

Posted: Mar 06, 2011 01:39 AM

What your seeing is typically due to the moisture content in the wood if it was sprayed on ratio. The moisture content in the wood can cause shrinkage and I would expect it to be much less the second time around. The areas you're seeing shrinkage seems to be in the larger mass areas - am I correct in this statement?
Thanks,
Jim

Daniel X

Posted: Mar 06, 2011 02:16 AM

This can also happen if the applicator tries to install to thick of a lift all at once.

My max is 2" per lift and I allow the foam to cool before my next lift...

mason

Posted: Mar 06, 2011 09:06 AM

I have investigated dozens of cases of foam shrinkage similar to what you have experienced.

In most cases, the foam was sprayed in thickness greater than 2 inches and/or subsequent lifts of foam were installed too soon after the first.

One thing I teach applicators to measure the interior temperature of the foam. It should not exceed 220 degrees F at anytime. If it exceeds 220 degrees F, the foam cells will be affected. You will have more open cells, weaker foam, possibly fissures and cracks within the foam and in some cases a lingering odor.

I also recommend that they wait 10-15 minutes between lifts to reduce the amount of exothermic heat build up in the foam. This of course varies depending on the foam formula, substrate temperature, foam temperature, thickness of the lift and other variables. Generally the thinner the lifts of the foam, the sooner you can install the next layer.

They could also be installing the foam with the wrong gun configuration, which would cause the foam to not be mixed properly. This can also cause more open cells and shrinkage.

It makes a difference which dirction they spray the foam. Spraying back and forth between studs causes the foam to have slightly elongated cells in the direction of the rise. The foam would tend to shrink (or grow) away from the studs. This makes it more likely to separate from the studs.

Spraying lengthwise parallel to the studs causes the foam to be more dimensional stable because the growth or shrinkage of the foam cells would be parallet to the studs instead of perpendicular.

Picture framing also helps by providing a high density skin against the studs which reduces the potential for dimensional instability. Sort of like a reinforcing layer before the actual foam lift is sprayed.

Craig Deim

Posted: Mar 06, 2011 09:07 AM

I didn't test the wood for moisture content but kept checking temp and humidity in the house. Temp was 55 to 65 deg and humidity was running 35 to hi 40s perc. We were heating the area with vented heaters. Actually noticed severe shrinkage in both size spaces. Narrow spaces next to wdos probably got filled too fast. Second attempt contractor was more watchful of not lifting too much at a time. Timing between lifts may still have been an issue. I am still concerned about the comment on another post about shrinkage still possible 6 months later. Once these jobs are rocked its all over. I certainly don't want to think about removing a wall section and finding a shriveled up piece of insulation.

mason

Posted: Mar 06, 2011 09:51 AM

I don't see problems in the wall as often as in the attic or crawls spaces where the thickness is greater. But I have seen shrinkage in walls, particularly if the foam is installed in significantly varying thickness.

Jim has a good point about moisture in the studs or joists. They can hold a lot of water, if they have been sitting outside for any length of time. Be sure to measure the moisture content of the studs as well as the wood substrate. It should be less than 18% moisture content. You can use a Delmhorst moisture probe to measuure it. You can get them online for around $150.

Daniel X

Posted: Mar 06, 2011 01:32 PM

What is the overall thickness of the foam? If you cut a chunk from the wall, how many skins are inside it?

Craig Deim

Posted: Mar 06, 2011 02:39 PM

I just cut another section from the wall. It is averaging 4" in thickness and viewing a cross section has 4 - 5 layers some not all the way across as I assume he was building it up as he saw a need. Pressing into the cross section with my finger it does seem as though some lifts have a different density than others.

Daniel X

Posted: Mar 06, 2011 08:06 PM

Very interesting...

I hope the contractor you hired is taking good care of this situation, we don't need the negative press from poor application methods.

Bob Silverman

Posted: Mar 07, 2011 10:09 PM

This is NOT typical of spray foam that is installed correctly. Although moisture in the framing lumber can cause poor adheasion and lighter density foam that is dimensionally less stable, it is not always the culprit. Did you use the same brand of foam from the same manufacturer for both attempts? You mention that you didn't check for moisture in the framing lumber, did the contractor? Or the manufacturer rep the second time around? Does the contractor have the proper spray foam equipment from a reputable equipment manufacturer? Or does he have some "homemade" equipment, for lack of a better term. Has the brand of foam been fully tested with ICC report?

Push up against the overspray on the side of the studs where it meets the full thickness of the foam. If the foam moves, cut it back to see if there is a gap underneath. If you can find some gaps, measure the size of the gap as accurate as possible. Cut a wood shim so that it fits snug in the gap to measure the width of the shrinkage. Mark it and wait a couple of weeks or a month and see if it shrinks more. What state are you in? The foam is going to be stressed when it gets hot outside, especially the foam that is in the roof.

Good Luck

Posted: Mar 10, 2011 01:13 PM

could be a system formulation gremlin??,,,,
or,,
sounds like consistently resin rich foam,,,
or,,
hey jim,,i dont spray h2o based cc's,,do you need to spin em??
if so,,could this be a case of underspun resin,,much like underspun oc resin??too small blades,,too few blades,,too short of time,,you know the drill,,,

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