Problems with incorrect bathroom and kitchen venting

Posted12/23/2018 6:00 AM

Q. Over the years, I've noticed you always tell people to only vent the bathroom fan through the gable wall. Never through the roof or the soffit. Now, I own a two-story house in a 1,000-plus home subdivision. The subdivision is no more than 15 years old. Every house that I have viewed (including mine) has the bathroom venting through the soffits.

In the winter there is never ice forming around the discharge. Assuming this is not ideal, how could this have been part of the design of all these homes? Is this something I should fix? I had a home handyman come over to install more insulation, and I asked him to look around for mold and he found no evidence. What are you thoughts?


A. It is not ideal, but I can't answer your question about it being part of the design. Unfortunately, there is a lot of ignorance on this subject.

The absence of the frequent problems associated with soffit venting could be that the soffits are not vented, are blocked by insulation, or that there is no ridge vent to draw air from the soffits.

However, we can't argue with success. Let's remember the old saying: "If it ain't broke, don't fix it".

You and your neighbors are fortunate, but, over 61 years in the construction industry, I have examined many houses with considerable problems caused by improper bathroom -- and kitchen -- venting. And over 45 years of writing this column, I've heard from so many readers about the serious problems caused by various venting techniques in cold and moderate zones to have come to the conclusion that there is really only one safe way to do it.

Q. Thanks for the response regarding my roof. I hope that comments provide some insight for readers to understand the complexities and importance of correct flashing and ventilation on roofs.

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My contractor was GAF pro-certified and used the GAF ridge vent (and all GAF products) to comply with the warranty. I have attached a photo of the old decking. There was no damage to it, and the insulation used was Kraft faced insulation. Only a couple of pieces were replaced where moisture had penetrated the old roof.

By the way, can you let your audience know where to get your book; it makes an excellent holiday present.

A. Your roofer seems to be conscientious and well trained. I see from the photo that your decking is made of standard 1-inch-thick boards, so the rafters were either 16-inch or 24-inch on center and not as I had thought they might be (2- to 3-inch thick decking with wide spacing of rafters) when you mentioned that the decking had to be removed from your cathedral ceiling to investigate and repair a sagging roof.

I am glad to see that the underside of the deck boards are free of mold, which shows that there was not the problem I feared when you said the roof deck was sagging. A sag can be an indication that moisture buildup over the years has affected the rafters and they are weakening -- a potential structural problem. Perhaps the rafters were undersized, as it is not normal for properly sized rafters (length, spacing and width) to sag. So all appears to be well.

Thanks for asking about my book, "About the House with Henri de Marne." Quite a number of brokers, home inspectors, real estate lawyers, etc., have purchased it as gifts at closing or at the completion of a home inspection over the years. Homeowners, parents and friends have also given it as holiday gifts. The book can be purchased through my publisher by calling (802) 482-2988 or by clicking on the "Books" tab at You may also email the publisher at The book is also available as an e-book compatible with all editions.


Q. I had glass block windows installed in my basement windows about 25 years ago. Recently one section of the glass block in five of the seven windows has a crack in it. My guess is that it is from the house settling. My question to you is can they replace the individual cracked block or does the entire glass block window have to be replaced? The entire glass block window is cemented in. There are 10 separate glass blocks in each window with cement around each glass block. Can they cut out the one cracked glass block and replace it?

A. Yes, single blocks can be replaced. The best person to do the replacement is a mason or experienced general contractor, but some people who are very handy can do it if they know how.

Q. Sometimes I have to replace a common brick on my house. I feel I am making this project too hard. The brick measures 8 inches long, 3¾ inches deep and 2¼ inches high. What would be the best way to do this? Please, cover both removal and replacement.

A. You haven't said how you are removing the damaged brick, so I can't tell you if you are making the project too hard.

There is more than one way to remove a single brick and it depends on whether the brick is still good enough to be flipped over to show its back face.

Always wear protective gear, including safety glasses. Probably the easiest way is to start by drilling holes as close together as you can in the mortar joints on all four sides with an 8-millimeter masonry bit. When done, use a pointed cold chisel to chip the mortar out until you can wiggle the brick out. Clean out all remaining mortar from the opening.

Put the brick in a bucket of water to soak it before reinstalling it so the moisture in the mortar will not be drawn out and cause it to dry too soon and not stick. Also spray water on the four sides of the opening before resetting the brick.

Choose the right type of mortar, which may be tricky. Apply a generous bed on the bottom of the opening followed by buttering the sides of the opening. Apply a generous bed on the top of the brick and gently wiggle it into place. Using a small pointed trowel, insert more mortar to fill the perimeter of the brick and tool the joint with the trowel handle or other suitable tool or section of garden hose.

If the brick cannot be salvaged, drill as many holes as you can in the brick and, using a flat blade cold chisel, break it up.

The brick can also be removed using a 4-inch masonry blade to cut the mortar out carefully after the holes are drilled or by itself, but that's trickier for those without experience, and it requires completion of the cut with other tools.

• 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, Email questions to

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