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kspritchett

Q&A Forums Registered User
Posted: 5/16/2010 10:16 PM EST

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High humidity level in spray foam house
I just had a house built with spray foam and have been living in it for less than one year. Throughout the winter I have had excessive condensation on my windows to the point of ice inside the house on the windows. I have mold growing in almost every window in my house. I found my humidity level was almost 70%! I've had one "expert" tell me I need vinal windows instead of aluminum, and another tell me I need an energy recovery ventilator, and a central dehumidifier. The builder has made no effort to help me figure out how to solve this problem. I have done a lot of research on the internet and can't find anyone who agrees, or knows for sure how to fix my problem. I need to know what will fix my house? Please help!

jimcoler  

Q&A Forums Registered User
Posted: 5/17/2010 7:25 AM EST

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RE: High humidity level in spray foam house
It sounds like the foam did a great job at sealing up the house - as it was supposed to! So, the question is where is the moisture coming from???? Is the basement floor water proofed? Are the basement walls water prrofed? Tehse are the tow most common areas of mositure migration!!

Mason  

Moderator
Posted: 5/17/2010 9:47 AM EST

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RE: High humidity level in spray foam house
You have to find the source of the moisture and then reduce the amount of moisture coming into the house and increase the amount of moisture leaving the house. 70% humidity level is very high even for a well sealed home.

Some things to look for.
Mechanical vents in kitchen, bathrooms and laundry rooms should in good working order and vented to the outside. Sometimes contractors take the vent ducts to the attic instead of to the outside. (Remember you have to turn them on in order for them to be effective)

People, pets and plants (aquariums too) provide a lot of moisture in a building. The more you have the more moisture is created.

As Jim suggests, check the basement and foundation walls.

At first glance it would appear a ERV would be in order if the moisture build up is due to the house being extremely tightly sealed.

Get an building science expert to check out the house and make recommendations.




Get a professional in to

kspritchett

Q&A Forums Registered User
Posted: 5/17/2010 9:51 AM EST

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RE: High humidity level in spray foam house
I live in east Texas, and we have no basement. We have central heat and air. Yes, the spray foam has sealed the house tight, but the builder is not educated in how to properly ventilate the house. I have also been told that a fresh air vent would solve this problem. The humidity level right now is at 49%. But, it is summer in Tx and the a/c is running. I am positive this high humidity level will return in the winter. I was cooking a pot of beans yesterday, and so they were constantly boiling, letting off humidity, and even though I had the vent a hood on the whole time, my humidity level got up to 58%! Once the beans were turned off, the humidity came down. I've done research on how much humidity we should have, and take all the right steps. Our house is 1957 sq.ft and only 2 adults and a baby live here, we aren't letting off more humidity than the house should control, and my husband checked, we have no water leaks! The only problem I can figure is the house is sealed so tight, only so much humidity can be sucked out, no fresh air is coming in to make up for what's going out. The builder's answer is that it is normal and will go away after a year. WRONG! Please help!!

Mason  

Moderator
Posted: 5/17/2010 10:20 AM EST

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RE: High humidity level in spray foam house
Get a HVAC contractor that knows sprayfoam applications to take a look at the house and the current ventilation situation. From what you describe, additional ventilation is required to reduce your humidity. They should be able to calculate the size and type of ERV to help out your situation. The units typically can be installed into your current duct system. Costs vary but I would estimate around $1500.

kspritchett

Q&A Forums Registered User
Posted: 5/17/2010 10:43 AM EST

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RE: High humidity level in spray foam house
I have had 3 HVAC experts! The first one said to change the windows from alluminum to vinal and that would fix the problem, I did research, and I disagree, until the humidity problem is solved any window will sweat! The second did a blower door test that was acceptable, and said I needed an ERV, and a central dehumidifier, total estimate, $9,250!! I did some more research and am thinking an ERV defeats the purpose of a spray foam house. The one they would install was going to exchange the air in my house 8 times a day! How is that efficient? Also, I read HVAC guys love to rake you over the coals w/these ERV's even if they're not really neccesary. Finally the third says a fresh air vent, like they install in houses with fireplaces, which I do not have, would fix the problem. I'm now thinking that is the smartest solution, new, fresh air would only be sucked in only when needed to let air out, like fom my exhaust fans! By the way, my fans are all vented to the outside, and I always use them! I'm thinking though, that I also need a central dehumidifier to contol any extra the house can't get rid of! That's the biggest part of my problem, I just wanted to build a great, energy efficient home that I would live in for the rest of my life. Not even a year and I have a MOLD problem, and from what I read even the excessive humidity levels aren't good for me or my house, and I have a baby!! I believe I'm looking in the right direction, only problem is EVERY EXPERT has a DIFFERENT opinion! Since the buider really isn't that educated in this area, I am having to educate myself. Every where I look, different answers! I just want the best way to permenately fix my house!!

jimcoler  

Q&A Forums Registered User
Posted: 5/17/2010 11:17 AM EST

Related Link:
www.coler.com

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RE: High humidity level in spray foam house
So, it sounds like it's a slab on grade type of construction??? What do you have for a floor finish material? Carpet? How much carpet?

An ERV or some other mechanical device only tries to eliminate the symptoms,not really addressing the root cause. The Root Cause is that you have too much moisture coming in the hoem from somewhere. I would suspect it's coming in through the slab whcih is why your builder said it will go away in about a year or so!!!

There is another product out there which can be used for slab on grade type of applications that it will work as a carpet pad and a moisture barrier all in one! We've used it many time as carpet padding or under the concrete as a vapor barrier and have not had a problem. If you want to email, me I can give you the name and can hook you up with a distributor of the product.(jim"at"coler.com)

I agree with your mindset that you're addressing the symptom and not the root cause! Your moisture level should be about 30-50% year round with a family of 3 in a 2000+/- house!
JIm Coler

kspritchett

Q&A Forums Registered User
Posted: 5/17/2010 11:33 AM EST

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RE: High humidity level in spray foam house
We do have a slab on grade constuction. We have 1392 sq. ft. of carpet and carpet cushion and 523.20 sq. ft. of sheet vinyl(linoleum). The builder is saying it goes away in a year because he built his daughter a foam house a couple of years ago, and said hers sweat the first year then it went away. Only, she never had excessive moisture that caused mold! So every house isn't the same. There is a house about 2 miles from mine that he built and she is having the exact problem. Her house was built in the winter and her mold problem is even worse than mine! I believe he is saying it will go away after a year because that is when my warranty gets limited! I have also researched that amount of moisture a new construction house has is a little more than normal due to the wood, carpet, etc. letting out the moisture that may have been soaked in during the building process, however I just don't see the slab causing THAT much moisture, wouldn't my floors be at the least moist? From what I have learned, there is absolutely NO excuse for my humidity level to have ever been that high! The high humidity didn't go down until the ac was turned on for a while, I believe that when winter rolls around and the heater is back on we will have the exact same problem. More suggestions please!

kspritchett

Q&A Forums Registered User
Posted: 5/17/2010 2:23 PM EST

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RE: High humidity level in spray foam house
It seems like 50% of the people you talk to are for and 50% are against spray foam houses. Most that are against it are people with problems like mine. I think it's still fairly new to most and there are no set rules on ventilation, at least none that I can find. I wish someone knew or could figure out the right specs for builders to have to know and follow when using spray foam. Spray foam was highly recommended to us and we were excited, but it seems lack of education and regulations on spray foam houses has ended up hurting us. It has been highly recommended to us by many sources that we take our builder to court, but thats not what I want. I just want to figure out from someone with credentials and authority to give me a solution that I could take to the builder and say this is the answer GUARANTEED!! Then give the builder the option to comply with something I actually had definate proof would work!! Anyone have any answers?

Mason  

Moderator
Posted: 5/17/2010 2:49 PM EST

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RE: High humidity level in spray foam house
I teach courses on the application of SPF for the building envelope. There are 2 chapters on building science principles and design. We recommend that the sprayfoam contractor partner with a HVAC contractor to make sure the home is sealed and ventilated correctly.

One problem is that most homes are so leaky (even new construction) that HVAC contractors assume that the house will have a greater amount of air exchanges per hour than it actually has. The furnaces, vents, intake air and air conditioners must be sized correctly to account for the air tightness of the home. So that is why it is important for the sprayfoam contractor and the HVAC contractor to discuss the relative air tightness of the house based on the type of construction, type of windows, and where the foam is installed.

As a rule of thumb the HVAC contractor should assume the SPF insulated house (walls and ceiling) should have around 30% to 50% greater air tightness than a house without the foam. For example if the HVAC contractor assumes a .55 air exchanges per hour, the SPF would most likely tighten it to .20 air exchanges per hour (on a new home)

On existing homes where the SPF would be installed in the attic and basement only, the relative air tightness would be less and most likely would not require additional intake air. But in new homes, you would most always require additional air.

Still, the home builder should be responsible for this snafu. If they knew the SPF was being installed they should know that additional air would be required.

kspritchett

Q&A Forums Registered User
Posted: 5/17/2010 3:29 PM EST

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RE: High humidity level in spray foam house
In my opinion, that is why I hired the builder. He suggested spray foam to me and all the benifits, no negatives. I figured he as the builder would know how to build my house properly, I knew nothing about building a house or spray foam. I figure I paid him to know these things for me, guess I was wrong. The blower door test showed the amount of leaks were acceptable for a house of my size. We have a tree ton ac and all three expert who have done a manual j on my house have told me that is ok. The one thing they all agree on! I have learned all of this stuff over the last few months, normally I would have no idea what a manual j is! One of the things that is so frustrating to me is that the builder doesn't seem concerned with what a problem this is coming for me and about 7 other homes that I know of that he has built. I trusted he knew what he was doing with spray foam seeing as how he put it in his daughters house. Come to find out, we are only the 2nd or 3rd house he's ever done this for. Mason, please tell me what your suggestion for my house is. Are you saying you think the fresh air vent would work? Do you think we also need the central dehumidifier, and is an ERV really neccesary in my case?

airpro  

Q&A Forums Registered User
Posted: 5/17/2010 5:07 PM EST

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RE: High humidity level in spray foam house
The first thing I see from your info is that this is a slab on grade construction probably with a moisture barrier underneath, when concrete dries the water has to go somewhere and it can’t go down so it comes up into the house, as a rule it takes 6-12 months for concrete to fully dry depending on weather and still could have a large water content after that in fact concrete cures getting harder over many years.

You could verify that the moisture is coming from the slab with a moisture meter. The floor may not seem wet but still have water evaperating from it.

If this is the case the only way to solve the root problem will be time.

As an HVAC contractor I would probably recommend a Heat Recovery Ventilation system connected to the bath vents and controlled by a humidistat this would provide the make up air that you may be lacking when running the exhaust fans. This would relive the moisture problem in the winter without loosing energy savings.

2nd I would recommend a thermidistat (thermostat/humidistat combination) and connecting a dehumidify cycle to your AC, all this does is slow down the blower speed lowering the coil temp and removing more moisture from the air, this only runs in the summer when an HRV may bring in more moisture than it takes out depending on weather conditions. This is an inexpensive fix that most new HVAC equipment has built into it.

And yes you could bring a fresh air vent into the house but remember to have a P or S-trap installed (like in plumbing) to keep excessive cold air out.

Also make sure that you HVAC system isn’t oversized and short cycling this can effect the humidity. I started writing this before your last post and would say if manual J called for 3tons I would have put in a 2.5 ton AC or a 2 speed 3 ton heat pump with electric or gas furnace backup (the most economical system).

In short your AC if properly sized should run 75-80% of the time during the hottest days this gives you a 20% reserve for the extreme weather, or about 4 8-10min cycles per hour and maintain a constant temperature with around a +or- 2deg variation.

You shouldn’t need a dehumidifier the 3 ton AC is a dehumidifier though it will dehumidify with wiring change above.

I have over 20 years in the HVAC trade before getting into the spray foam business and I still am learning about new problems when we create the climate isolation that we have been working so hard to achieve for so long.

hope this helps
thanks
Airpro HVAC and Spray foam

kspritchett

Q&A Forums Registered User
Posted: 5/17/2010 7:28 PM EST

Reply

RE: High humidity level in spray foam house
Thanks for all your help! Do you think the fresh air vent in combination with a central dehumidifier will do the job, or do you still suggest an HRV? If so, why the HRV instead of an ERV?

airpro  

Q&A Forums Registered User
Posted: 5/18/2010 12:01 AM EST

Related Link:
Fantech HRV/ERV page

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RE: High humidity level in spray foam house
Depending on your location and climate you should not need a dehumidifier your AC should provide all the dehumidification that you need in the summer and during the winter if you have enough indoor to outdoor air exchange you still should not need a dehumidifier as long as the air outside has a low humidity.

The choice of an ERV or HRV would be the manufactures recommendation for your climate check Fantech’s website at: http://www.fantech.net/hrv_erv.htm they have a good website that can help you with that choice.

You can accomplish the same thing as a HRV or ERV with a fresh air vent although you will be dumping your heat (and $$$) to the outside; a HRV minimizes the lost heat (and $$$) by recovering the heat and warming the incoming air.

Also check your furnace control board for a dehumid terminal and ask your HVAC contractor why it isn’t used.

Hope this is helpful

Airpro

Mason  

Moderator
Posted: 5/18/2010 7:46 AM EST

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RE: High humidity level in spray foam house
Airpro is giving good advice and information. I would defer to his experience as a HVAC contractor.

As he suggests, it is important to obtain information from folks who are familiar with SPF and HVAC ventilation requirements.

We have to remember that in this forum we can only provide so much detailed advice. Many cases require an analysis onsite by SPF experienced professionals.

But if your local HVAC contractors are not familiar with working with SPF, then they should be informed that they cannot use the same calculation assumptions on SPF insulated homes as on conventionally insulated homes.

For example, when I had my townhome sprayed with foam in Northern Virginia. After 2 years I replaced my furnace and AC. I told the HVAC contractor to recalculate his assumptions for the size of the units to account for the extra sealing benefits of the foam.

As a result, we went from a 2.5 ton AC to a 2 ton AC and reduced the size of the furnace 2500 BTUs.

My humidity level in the house tightened up from a previous 65% in summer and 15% in winter to no more than 55% in summer and 35% in winter. This is without adding any additional ventilation, ducts or make up air.

As Airpro states, your AC unit must run consistently to take moisture out of the air

Mason  

Moderator
Posted: 5/18/2010 8:22 AM EST

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RE: High humidity level in spray foam house
I was re-reading your original post and had another observation.

1. Windows: I may agree with the advice on changing to vinyl from aluminum windows to reduce the potential for condensation. Aluminum is a good conductor and would be closer to the outside temperature than the rest of the wall assembly.

This could cause condensation inside even if your humidity levels are fairly moderate. For example, at an interior temperature of 70 degrees F and a humidity of 50%, you would have a dewpoint of 50 degrees F. Even at 35% humidity(the lower end of the sweet spot for comfortable humidty) humidity, the dewpoint would be slightly above 40 degrees F.

It is possible (depending on the window case construction) that the aluminum in winter would go below the dewpoint temperature on the inside causing condensation on the frame.

jimcoler  

Q&A Forums Registered User
Posted: 5/18/2010 10:11 AM EST

Related Link:
http://www.coler.com/pdf/Low-E_Therm_E_Pad.pdf

Reply

RE: High humidity level in spray foam house
SO, you have 1392 sqft of carpet with concrete under it and it can only dry to the inside?? I believe this is the problem! The carpet and carpet padding don't act as a moisture barrier and the moisture from the conrete can evaporate into the house. You don't notice it or feel it because it's much like a door wide open. The volume of air may be moving through the door but when you close it down to an inch open, you'll then feel it because of the velocity of the air.

The vinyl/linoleum flooring can reduce the moisture penetration but the rest of the floor 1392 is open to air out - especially in the winter time when the house is closed up tight and the heat is on. Then on top of that, you have aluminum windows which can conduct the heat quicker, causing condensation on the bottom of the windows.

The soultion is to reduce the amount of moisture coming up through this floor square footage by using a carpet pad that is also a vapor barrier or paint the floor under the carpet and padding to prevent moisture vapor from rising up through it. The product we use is called ThermE Pad and it's a carpet pad and a mositure vapor barrier all in one.

Let us know how it works out.
Jim

Mason  

Moderator
Posted: 5/18/2010 11:02 AM EST

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RE: High humidity level in spray foam house
Another thought. You mention that 3 HVAC contractors provided the same HVAC equipment and ventilation recommendations based on their manual j calculations. Ask them if their recommendations would be the same or different if using fiberglass or cellulose. The answer should be different. If it is the same, they are not taking into consideration the extra air sealing characteristics of the foam

As you can see by the thoughts, analysis, observations and recommendations, that many things could be contributing to your problem. This reinforces the idea of having an SPF experienced HVAC or building science professional take a look at your situation

kspritchett

Q&A Forums Registered User
Posted: 5/18/2010 3:21 PM EST

Reply

RE: High humidity level in spray foam house
FINALLY!!! You guys are great! Today's answers are really making sense to me. Let me add that my first expert was, in case you've heard of him, if not you can google him, was Richard L Rue. He lives about 3 hours from me and did all the work over the phone. He is what I consider an expert, just check out his credentials. I had him on the phone with my builders ac guy so he could tell him what needed to be done. First, he told the builder's ac guy to change my 3 ton unit from 20 killowatts to 10 killowatts, and to remove 2 heat strips? We are all electric. Second he said all windows should be changed from alluminum to vinyl and my problem would be solved. He also assured me that if my builder refused to make these changes(the windows) that he would be more than happy to go to court with me, he assured me they would not go against his suggestion because they did not want to go to court againt him. I informed my builder about his suggestion to change the windows, he was screaming mad, and refused. I still do not want to go to court, and when I got off the phone with him I started doing more research. I couldn't find anyone else to say foam houses REQUIRE alluminum windows. I also discovered that alluminum windows are stronger and maybe better than vinyl. I started to think my problem won't be solved by windows, I figured we needed to control the humidity level in the house first. In the meantime my builder called me to schedule a time to come install my new vinyl windows! I told him I was re thinking Richard's advise and he said good, I don't agree with him either! Apparently he figured Richard to be an expert he didn't want to question, or be sued by. He then told me Richard was nuts and his ac guy thought so as well because he only removed half of what Richard had told him to because he didn't agree with him. That kind of upset me that his ac guy who apparently had no knowledge or expertise in spray foam house ventilation decided to go against an obvious expert. That's when I decided to look for my own HVAC guy! So I had a local buisiness with a very good name here in east tx, that has been in the ac buisiness for many years come out to my house. He is the one that did the blower door test and suggested an ERV, and a central dehumidifier, all for ONLY, $9,250.00!! Again, my builder refused this proposal as well. My builder who has ABSOLUTELY no knowledge in ventilating a spray foam house is the one who suggested his guy could put in a fresh air vent for a couple hundred bucks if that's what I wanted, but threw up his hands and said I don't have a clue what will fix it!! Which leads me to where I am now, more research. So I guess my next question is, how do I know I'm getting an SPF experienced HVAC guy? They have all told me they are SPF experienced HVAC guys yet all disagree and have their own opinions. They don't have to be expeerienced to say they are right? And, how would I find a building science professional? Is he some one who would actually know and guarantee a solution?

airpro  

Q&A Forums Registered User
Posted: 5/19/2010 12:55 AM EST

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RE: High humidity level in spray foam house
It is a sad fact that it is really hard to find a good contractor most of them that have been in the business a long time got their license under a grandfather clause and didn’t have to show any training or take any tests. Others went to classes so they could just pass the test but don’t keep up with the new tech. And still others hire salesmen to sell expensive fixes that will work and if they don’t they made enough profit to cover their ass.

I have 30 years in the HVAC and building trades mostly as a service tech fixing other peoples screw ups at times I found that the installers from the contractor that I was working for gave me job security due to their poor installations.

It makes sense that you need to control the humidity in your house if your windows are sweating no matter what they are made of and yes vinyl or wood frames do have a higher insulation value and shouldn’t sweat as badly.

2nd it sounds like you have a 3ton heat-pump with a 20kw backup heat kit this does sound to be excessive but I don’t know your climate (I’m in Indiana) but if the system is setup with the proper controls (thermostat) the heat should come on in stages 1st the heat pump 2nd the electric backup and the electric should also come on in stages 5kw at a time. If setup correctly the blower in a system like this should run almost constantly in cold weather. And most of these systems have a dehumidification cycle built into the air handler requiring no modifications only some wiring and a new thermostat.

Question, where is the air handler installed? Where is the ductwork?

I do think the water is coming from the slab and will get better with time but I also know that doesn’t help right now. One fix would be a portable dehumidifier until the slab dries out.

Call me if you need help getting the dehumidify cycle wired I can talk the tech through it 765-808-4262
Airpro

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