Tips on replacement windows

Q. A while ago you mentioned replacement windows in your column. You mentioned "Replacement by Anderson" and I think "Marvin" replacement windows.

I don't think you knew about Pella replacement windows. I am thinking of replacing our windows because they are 29 years old and I would like to have that information about replacement windows again to be sure I can get a good replacement product.

My wife and I enjoy your column and the information you provide. Thank you in advance.

A. I am aware of Pella's replacement windows, but, in my consulting practice, I have experienced negative responses from Pella in regard to claims of product failure. After mentioning these experiences in my column in answers to questions similar to yours, I also heard from several readers with similar problems.

Granted this was quite a number of years ago, and Pella may have changed their business practices. Pella windows and doors were of great quality in the 1950s and '60s when we used to install a lot of them, and they stood behind their products in those days. During the same decades, we also installed many Andersen products with similar success, and Andersen was also very good at honoring their warranty, but I have since heard complaints from several readers about Andersen's lack of response to warranty claims. Not having investigated any of these claims, I cannot vouch for their legitimacy.

By contrast, Marvin has superior products at very competitive prices and a record of honoring their warranty, even several years after installation, which is why I have used, and recommend, Marvin products over any other brands.

Q. Could kindly give me your opinion of 2-inch-thick, exposed DOW Thermax, with a reflective aluminum facing installed on a basement concrete wall of a house in Illinois? I'm interested in this insulation product in regard to fire.

A. Any polyurethane product is flammable and will emit hydrogen cyanide when burning - a quick disabler and killer. The insulation should be covered with an approved fire code material, such as five-eighths-inch, fire-rated gypsum board.

An interesting discussion about housewraps: "I am, as my signature below states, a DuPont trained and educated Tyvek specialist. Your recent response on Barricade versus Tyvek and other housewraps was forwarded to me by a few of my customers. They were shocked by your reply that there is not much difference between housewraps. I am quite surprised as well. There are many comparisons between housewraps, and there are many types of housewraps.

"Tyvek is spun-bonded polyethylene. It is one of a kind in the industry being spun bonded, and as it comes from DuPont, a science-based company, it respects and allows the rules of physics to work. In particular, the wet moves to dry rule, or moisture vapor permeability. Tyvek is a high perm (58) product, while most of the competition comes in with a perm rating below 20. OSB and plywood have a perm rating of about 20, so when your housewrap is lower than 20 perms, it slows the drying rate, trapping moisture, which can lead to mold issues.

"Some manufactures have woven or pin-perforated products that help with drying, but also let in air and water. So the solution actually adds to the problem.

"There is much more to be understood in regard to housewraps, and I would be willing to sit down with you and discuss so you can fully understand the product category. Maybe you have some time in your schedule when we could meet to discuss?

"Lastly, you mentioned a different use for Tyvek as DuPont's original intention for the product. I am curious as to what you think that use is.

"Here to help. Sincerely, Matthew Reed, market development manager, senior certified DuPont Tyvek commercial specialist."

A. Thank you for the education about the difference between housewraps. Over the years, I have noticed the proliferation of various brands of housewraps and the fact that some building-supply houses put their own brand on them.

Tyvek no longer seems to be the most prevalent housewrap used on commercial and residential buildings. Is it because of the competitive advantage of these other brands? And if Tyvek is so far superior, how has the competition managed to convince builders and general contractors to switch to other brands?

My research shows that there is a wide variety of opinions regarding the best housewraps and each manufacturer claims its product is superior to all others. That's understandable, but in the building science community, there seems to be general agreement that no one housewrap stands out above all others.

Most building scientists are quoted as saying that proper installation is more important than the type of housewrap used, and some prefer, as I do, using asphalt-impregnated felt paper instead of housewraps, having found fewer problems with felt over time (see research by Paul Fisette, emeritus faculty, building and construction technology, University of Massachusetts).

Tyvek has other problems you do not mention. In my travels from site to site over many years, I have seen Tyvek in shreds because the builders left it exposed to the elements too long, which caused it to disintegrate. Tyvek is also affected negatively by the surfactants in certain wood species, while other housewraps are more resistant to these surfactants.

Years ago, I was called to be the expert witness for a large project at a major resort where cedar siding applied over Tyvek and OSB had caused serious structural problems. Water had worked its way behind the siding (a common occurrence), soaked the Tyvek, which was moldy and so rotten it could easily be peeled off in shreds by hand. The OSB was also rotting and so were some of the studs, beams and plates behind.

Tyvek is a vapor permeable, water-resistant synthetic fabric, but it is not waterproof, and it will not only get wet but allow the transmission of moisture in liquid form to underlying materials if in contact with wet siding. This was verified by my conversation with a Dupont Tyvek engineer with whom I spoke at the time and who told me that Tyvek, once soaked, is not able to dry if it remains in contact with wet siding over a period of time.

As to Tyvek having been developed for another purpose, long ago I learned in a lecture given by the senior scientist of a most respected residential research association that Tyvek was originally developed to be applied over attic insulation to eliminate the problem of R-factor degradation of fibrous insulation caused by air currents while allowing any moisture convecting and permeating from the conditioned spaces below to work its way out into the attic. But this was deemed impractical because of the prominent use of trusses, so the Dupont engineers thought of using Tyvek as an air barrier while allowing moisture in vapor form that may accumulate inside walls to convect to the outside.

• Henri de Marne, a former remodeling contractor turned columnist and consultant, is the author of "About the House with Henri de Marne" (Upper Access Publishing). He continues to take questions from readers for this column and his website, www.henridemarne.com. Email questions to aboutthehouse@gmavt.net.