“Top-Sealing Damper Blocks a Big Hole,” By MIKE Guertin (Jun/15)

Jason Laws (online, 6/29/15): I think that a flue-top damper is a nice idea, but it would never work in my area—northern Maine. It will either freeze shut or freeze open, or the 4 feet of snow on it will put a real damper on things. Dampers should be kept inside, where they belong, out of the weather. Most people don’t use fireplaces to keep warm, so there would not be a steady stream of heat to melt off the snow and ice, as with a wood stove that is used 24/7. Any fun with the fireplace would come to an abrupt end as soon as the room filled with smoke.

Mike Guertin responds: People may be reluctant to install a flue-top damper for the valid reasons Jason Laws notes. There are many building practices and products that are not suitable to all regions because of climate, geology, or local building codes. It’s important to consider what will work best given the local circumstances.

There are several parts of the country that have conditions like Maine’s—heavy snow and long winter periods. We may actually have a worse climate here in southern New England than in northern Maine. We get heavy, wet snow that frequently ices over, freezing rain, and fluctuating temperatures hovering around the freezing point. The 2014–2015 winter was the worst we’ve had in my lifetime (deep cold, several snowfalls of 2 feet or more, 8 feet or more of accumulating snow over weeks of time that required roofs be shoveled, high winds, and the like). Despite this winter weather, there were no problems operating the four flue-top dampers on the rental houses I have.

“True Through-Wall Flashing for Brick Veneer” (Online, 7/8/15)

Fred Nowicki (online, 7/12/15): The drawing in the second slide seems a tad misleading. The right side shows brick below the rafter. That is more prevalent in a mass wall, not typical of a veneer. If the author is truly attempting to showcase proper sidewall flashing of a veneer on a sloped wood roof, a key component—a steel support angle affixed to the wood sidewall to carry the load—has been omitted. Furthermore, with that slope of roof, metal lugs need to be welded to angle to prevent masonry from sliding downward.

Randy Ward (online, 7/12/15): Why wouldn’t it be better to have a continuous L-shaped flashing with a U-shaped edge flat on the roof, with the bricks sitting on the L-shaped flashing?

Harrison McCampbell responds: With the drawings I provide to clients and contractors, I’m merely trying to impress on everyone involved the concept of catching the water and letting gravity do the work—in shingle fashion and in a permanent way that doesn’t require any maintenance.

The method I advocate for supporting the brick is to use horizontal (level) steel angle, either spanning the building’s width below the roofline (shown on page 38 of the July issue) or with short, level pieces stepped up the roof slope. If I’m following you correctly on the idea of using sloped steel angle, you might be able to cut the bricks at an angle (which is a lot of extra work) and keep them from sliding down a steel angle with metal lugs (even more work), but you are still going to need to install a true through-wall flashing.

In response to the question of a continuous U-flashing, are you going to cut the brick to sit on the pan? Again, that’s a lot of extra work. And how are you going to keep the bricks from surfing down the pan?

Most of the time on the jobsites I see, the traditional tried-and-true methods of masonry flashing have faded into the sunset and the most common approach to “flashing” is to simply do what everybody else is doing (most of the time, saw-cut flashing). But what everybody else is doing may not always be based on proven standards.

“Major Surgery for a Failing Fat Wall,” By Ted Cushman (Online, 7/2/15)

Jkrigger (online, 7/6/15): I think what you saw in this home is all too common. Builders and retrofitters trust cellulose insulation and OSB too much. Cellulose and OSB are the two most moisture-vulnerable building materials we commonly use. I have never and will never install cellulose in a floor cavity or closed roof cavity. I’ve seen it wet too many times in these types of applications.

Cellulose may be fine for walls in dry climates, I think. However, for homes in climates with more than 40 inches of rain and an average relative humidity (RH) of more than 80%, I’d never insulate a wall with cellulose. That excludes a lot of places near the Atlantic, Gulf, and Pacific coasts of North America.

The settling might have had as much to do with wetting as with inadequate installed density. Case in point from a vastly different climate zone: My sister bought a rental house in Venice Beach, Calif., a few years ago at auction without seeing it. Average temperature for the location is 70°F; average rainfall, 14 inches; average RH, in the high 70s. The home is built on a slab with stucco siding. She walked through the door and smelled mold. The attic cellulose and carpet were dry. But when she cut open the wall, she found the cavities half-full of sopping wet cellulose, and she had to gut the place and re-insulate. In Venice Beach and in Vermont, the question is, why did the cellulose get wet? Can we blame it all on inadequate installed density? Or, will persistent high RH during some years and seasons cause wetting that fails to dry?

The ventilated rainscreen might solve this and might not. I’ve been saying for 25 years that cellulose is too vulnerable to moisture for many uses, to little avail. Cellulose can absorb more than 100% of its own weight in water. The current thinking is that cellulose manages moisture well and resists wetting. But my advice is: Don’t bet on it!

Editor’s note: John Krigger is co-author of (Saturn Resource Management) and one of the foremost weatherization and home-performance trainers in the U.S.

FOAM cutting technique

Jim Stacey, Richmond, Calif., wrote: I’ve been getting since it was printed on napkins, but have never been able to contribute anything. Maybe now I can, with this experience. If you need to cut rigid foam, you can buy an “electric knife” (about $21 right now at American Science and Surplus; sciplus.com), or you can improvise for practically nothing, assuming you already have a propane torch and a long kitchen knife that no one will miss. Turn on the torch and put it where it can’t get knocked over. Mark the foam where you want to cut it. Put on a glove (this determines if you are paying attention). Put the knife blade in the flame and in a few seconds, cut the foam until the blade cools. Heat and cut. Heat and cut. Do not put knife back in kitchen drawer.