Marvin Fiberglass Windows

September 30, 2008, by Debra Lynn Dadd

Question from Suzanne

I purchased several Marvin Fiberglass windows and had them installed two and one-half weeks ago. Right after installation we smelled a strong acrylic odor throughout the house, which has only abated a little bit. 

After two weeks of research I discovered that the fiberglass is actually coated with something called "acrylic capstock". I have searched everywhere and cannot find out how harmful this odor is and when it will stop outgassing. 

I have respiratory problems if I am in the house longer than a couple hours. Fiberglass is being touted as environmentally friendly and safe for sensitive individuals, but they don't ever mention the acrylic outgassing. 

Does anyone know anything about this product and how I can find out how harmful it is to have my children sleeping in these rooms. Marvin says they have never heard of anyone complaining about the smell of these windows, which is hard to imagine because everyone who comes into my home smells them. It is getting colder and colder in Minnesota and I won't be able to have the windows all wide open much longer. 

Debra's Answer

I didn't know wha "acrylic capstock" was either, so I looked it up.

I found a reference that said, "acrylic resin family of products for capstocks". While I couldn't find a definition of capstock, from reading it in many contexts it appears to be a kind of protective coating that is applied to various materials, to provide exceptional durability and performance characteristics, including UV weathering resistance.

Acrylic is made from acrylonitrile, a special group of vinyl compounds. In my book Home Safe Home I noted that acrylonitrile is included on the Environmental Protection Agency's list of sixty-five "priority pollutants" recognized as being hazardous to human health. Scorecard: Chemical Profiles: Acrylonitrile notes that it is a carcinogen. Acrylic is also known to cause breathing difficulties, vomiting, diarrhea, nausea, weakness, headache and fatigue.

Marvin should be able to tell you the brand name of this capstock and from there you should be able to get an MSDS from the manufacturer.

If the smell is bothering you and you are having symptoms from it, then you need to do something to protect yourself and your children. Opening windows is great, an air filter would help, and you may even need to remove the windows or apply some kind of vapor barrier finish over the fiberglass parts.

There is a possibility that these windows are faulty in some way. Perhaps the acrylic resin was not completely cured or there is some other manufacturing defect.

Updated 2020:  Several readers have commented on this same issue.  One reader speculated that is could also be the caulk used to install the windows.  Make sure a low-VOC caulk is used during installation.