Reader Feedback: Issue 182, October/November 2006
Flood insurance of a different kind
Recently, I got a phone call from my sister-in-law in Pennsylvania. She and her husband were nearly done building a new home on a hill, not a place I’d ever expect to see flooding despite the torrential rains that had been occurring there. But she called, nearly in tears, to ask advice about the 2 ft. of water that appeared in her basement overnight. Ruined were thousands of dollars worth of tools, books, furniture, and trim lumber that were stored in what should have been a dry basement. The site is well drained, the footing drains work, and the outside of the foundation was waterproofed professionally.
Groundwater came in through the foundation where the water line enters from the well. While the foundation had been mortared up around the pipe before backfill, this is a spot that’s subject to leakage. I know because it happened at my own house, though my experience was more of a nuisance than a disaster.
What happens is this. Utility lines—water, power, gas—are backfilled with sand. If, as is typical in much of the Northeast, the footing drains are covered over with relatively impermeable native fill before the utility trench is dug, the utility trench drains slowly, if at all. In times of extraordinary rain, the sand collects water. Particularly if the water line comes from uphill, as does my in-laws’ and mine, a tremendous amount of water pressure can build—enough to overcome most any attempt at plugging the foundation penetration.
The solution is simple, though easier to do during construction than afterward. Make sure that there is free-draining fill, such as crushed stone, between the bottom of the utility trench and the footing drains. I spent an unpleasant day with a shovel and a pickup load of gravel to fix this problem at my house. That was a year and a half ago, and despite some of the wettest months I’ve ever seen, my basement remains bone dry. I’m afraid that once my in-laws finish discarding the contents of their basement, they’re in for much the same workout.
—Andy Engel, Roxbury, Conn.
Deck footings need inspections
In the article “A Solid Deck Begins with Concrete Piers” (FHB #180, pp. 44-49), the author correctly mentioned that local building codes govern footing depth, but he failed to have the inspector check his footings before pouring concrete. Decks are structures and require permits and inspections.
I’ll offer two other suggestions. Digging a hole manually or via machine invariably disturbs the soil at the bottom of the hole. Many of the 6-ft. and larger digging bars have a flat, circular knob at the top that, when turned upside down, makes a great tamping tool to compact the soil. Also, rather than using a shovel to direct concrete from the mixer (or wheelbarrow) into the tube, use a BigFoot (www.bigfootsystems.com). Inserted upside down into the tube, it makes an effective funnel.
—Jim Finlay, Boston, Mass.
Cordless batteries can start fires
Maybe this is common knowledge, but I’ll bet at least a few others are as oblivious as I was to the danger posed by a battery pack coming in contact with a jumble of fasteners. I was dismantling a deck and had carried my tools and spare batteries in a plastic bucket. Whenever I had a handful of used screws, I tossed them into the bucket. After a while, I caught the scent of hot plastic. When I finally quit work to investigate, little flames were shooting up out of the heap of used screws. I’d not been aware of a pop or shower of sparks. The screws made contact with the terminals of one of the batteries and acted like the element in a toaster—a really good way to burn down the shop, the house, or a client’s home. Of course, the battery pack was ruined and would neither hold nor accept a charge afterward.
—Mark Koons, Wheatland, Wy.
Vapor barriers and rigid foam
In Rick Arnold’s article “Save Energy With Rigid-Foam Insulation” (FHB #181, pp. 88-91), he wrote that “the foil-faced polyisocyanurate used here is a vapor barrier, so I eliminated the interior vapor barrier of the original design.” This is dangerous advice and contradicts everything I have read in the magazine over many years. The purpose of a vapor barrier is to keep warm, humid air inside the house to prevent condensation in walls during the heating season. The purpose of an air barrier (and housewraps such as Tyvek) is to keep wind-driven water out of the walls while allowing moisture to escape. In this case, an effective vapor barrier on the outside, mated with no vapor barrier on the inside, is a recipe for disaster. Come wintertime, the structural sheathing on this house is going to be soaking wet as moisture from the interior condenses on the inside of that foil-faced insulation board. This is exactly the condition that has caused such a debacle with the application of EIFS (synthetic stucco) systems on houses that do not have proper air barriers.
Our solution has been to apply rigid insulation to the inside walls prior to framing interior partition walls. This system requires the use of sealed electrical boxes on exterior walls and allows some thermal bridging at rim joists, but winds up achieving 95% of the benefits while allowing the house to breathe.
—Christian Bandler, via email
Author Rick Arnold replies: The rule of thumb that a vapor barrier is applied to the inside of a wall assembly in a cold climate is a good one to follow. But with a thorough understanding of modern building science, you’ll find there are many ways to design an effective wall system.
The insulation system I use controls the dew point within the wall assembly so that condensation won’t occur, and it permits the wall to dry to the inside. The rigid foam applied to the exterior of the wall sheathing changes the typical temperature profile within the wall cavity. The structural wall sheathing is on the warm side of the foam insulation and is no longer a condensing surface. No condensation inside the wall, no problems. It’s important with this wall design to omit an interior vapor barrier; otherwise, you could trap moisture inside the stud cavity. Without an interior vapor barrier, moisture vapor that migrates into the stud-cavity insulation can dry to the inside of the house. Combined with a mechanical ventilation system that controls indoor relative-humidity levels and an interior air barrier such as sealed drywall, a foamsheathed wall is a safe and effective system.
My foam-covered walls are not like an EIFS wall. Moisture problems with EIFS were due to exterior water intrusion from improper installations and ineffective flashing details, not condensation of interior moisture migrating from the interior. The old EIFS didn’t include an effective secondary system to drain water leaking in through the exterior face.
Debating gable-wall details
Looking over the article “Framing Big Gable Walls” (FHB #181, pp. 70-75), I’m wondering what firestop method author Lynn Hayward uses. His framing seems to leave the wall cavities open into the rafter bay (and perhaps into the entire attic cavity, depending on the ceiling-framing details). According to the IRC 2003 and 2006, there needs to be a firestop to separate wall cavities and roof cavities.
In a couple of instances, the author notes that his framing details are lighter and use less wood. One place that I’ve found where I can save a lot of lumber and lighten up gable-end walls is to eliminate the structural headers. There’s no load on them because the author inserts a full-length rafter at the top of the wall. The headers and the jack studs can be eliminated easily on all but the widest openings.
After years of using gable-framing details similar to the author’s, I’ve become a fan of framing gable walls without inserting the rafter and using a 2x plate only along the very top. It’s faster than notching studs, and you don’t waste large rafter stock where it serves no purpose. Plus, the gable walls are easier to straighten (provided you choose a straight plate for the top) than walls framed with a rafter along the top edge.
—Mike Guertin, East Greenwich, R.I.
Author Lynn Hayward replies: I wait until the roof is on before I install blocking for firestops because I’ll have more scraps to use later in the framing process. Another reason I wait on the blocking is that I’m eager to get my roof framed and watertight so that I don’t lose days of work due to the rapid weather changes here on the Maine coast.
There is no question that you can eliminate jacks and headers because there is no real load on the gable end, but we often use wide interior- and exterior-trim stock (1x4s and 1x5s); one stud would not allow enough nailing space on the outer trim edge.
The trade-off for saving time and lumber by using a top plate rather than a rafter is giving up a continuous nailing surface for the rake ladder, subfascia, and trim; you can nail 16 in. on center only. You also would have to make a transition piece at the end of the gable to connect to the rafter tails. You’re right that angle cutting is faster than notching, but I worry that it’s not as strong because you’re nailing into the end of the studs rather than the side of the stud notch.
Not long ago, I drove by a home I built 34 years ago, and it looks as straight today as it did when I finished it. I like that.
Insul-Knife’s real price
In the old days, Fine Homebuilding listed the manufacturer’s suggested retail price when we featured a product in the magazine, but because retailers typically discount that price, it wasn’t really an accurate indication of how much you could expect to pay.
Today, though, Web-based superstores like Amazon.com make it easy for us to list what we call a “street price,” a real price that’s available to anyone with a computer. But sometimes we still get it wrong. In our recent “Tools & Materials” review (FHB #181) of the Insul-Knife (www.cepcotool.com), we mistakenly quoted an Amazon.com sale price of $16, but the product normally sells for about $34.50. We apologize for any inconvenience.
—Justin Fink, assistant editor