On Shutters and Water Management
How to tell good shutters from bad shutters — and what you can learn from water stains on siding
I recently walked through a neighborhood in a Massachusetts town on the South Shore. As you might expect, the homes facing the ocean tended to be more luxurious, while the homes a few blocks in from the beach tended to be more humble.
It’s fun to look at houses from the sidewalk (or, in this case, the beach). During my stroll, I ruminated on house design and construction quality. In this blog, I’ll focus on two themes: the first concerns shutters, and the second concerns flashing and water-management details.
What are shutters?
Shutters serve many purposes. During a storm, they can protect window glass from wind-driven projectiles. When the homeowners are away, they can provide security against burglars. In crime-ridden neighborhoods, they can allow residents to sleep with an open window that admits fresh air while still excluding intruders. On a hot afternoon, they can exclude sunlight while still allowing a breeze to enter the house. In Alaska, they exclude bears.
Traditional shutters are usually made from wood. They can include louvers that permit ventilation, or they can be solid. In most cases, the width of a shutter is equal to half the width of the window it protects. Shutters hinge outward, and are usually secured in the open position by simple hardware so that they don’t flap in the wind.
Sadly, shutters have fallen on hard times in the U.S. In many cases, builders no longer include any hinges, turning the shutters into useless decorations. The shutters are simply screwed to the wall and can’t even be closed. Here’s what I don’t understand: if the purpose of the shutters is decoration, why can’t the builder get the proportions right? Why are decorative shutters almost always too narrow — less than 50% of the window width?
If the designer gets the proportions wrong, the shutters fail to fulfill their decorative purpose. The observer looks at the shutters and thinks, “Hmm — when those shutters are closed, they won’t even meet in the middle. Something is seriously wrong here.” A jarring element doesn’t decorate the house; it disturbs the viewer.
Here is a typical example of decorative shutters that scream, “Someone specified the wrong size shutters!”
Will you look at that! Functional shutters!
Since decorative shutters are now ubiquitous, you can imagine my delight when during my walk I discovered a house with functional shutters. How refreshing! These dogs can hunt!
Too many bump-outs
A little further down the beach I came across the huge luxury duplex shown in the photo at the top of this page. The house is less than ten years old. Since it faces the Atlantic Ocean, this building needs to have topnotch water-management details if it is to have any chance of being durable. So how did the designers and builders do?
I’d have to say that the jury is still out. But there are a few warning signs that there may be trouble ahead.
First of all, the designer of this building succumbed to a classic designer's temptation: gussying up a perfectly good building by affixing a hodgepodge of bump-outs, balconies, and towers. Each of these bump-outs is an energy-performance liability as well as a water-management liability. Each transition from one plane to another introduces a seam where water can penetrate, and each transition requires the builder to think about where the water wants to go, and what type of flashing is needed to kick the water away from the walls.
Siding stains are clues to flashing performance
Because the building is a duplex, it's possible to compare the condition of an area of siding on the left unit of the building with the condition of the corresponding area of the building's right unit. For example, let’s look at the condition of the siding under towers’ south windows.
Hmm — stains on the right, but not on the left. What's going on here?
I'll admit that I'm not sure. But the photo reveals an important truth: very small differences in flashing and trim width can make an important difference in flashing and trim performance. I had no opportunity to inspect the window trim up close, but I do know a bit about detailing window trim. Because of capillarity, water can travel sideways, curling under horizontal trim. To interrupt this troublesome phenomenon, the builder needs to provide a hidden kerf to interrupt the water's travel; such kerfs are common on the underside of window sills. If you forget the kerf, water can dribble down your siding (or even enter your wall cavity).
If you don't want to trust a kerf, put some metal flashing at the seam of dissimilar materials — for example, where trim meets siding. But be sure that the flashing extends beyond the siding, and be sure that the flashing includes a drip leg. If you forget these details, or make an important component 1/8 inch too short, you'll get water dribbling down your wall.
It looks like the builder did a good job on the left tower, but did something wrong on the right tower. Whatever the error, it was serious enough to show up as stained siding.
The two sides don't match
In the two photos below, you'll see that the flashing details under the right balcony are better than the flashing details under the left balcony. Again, the detail that caused the premature staining may be extremely subtle; the defective component may be piece of flashing that lacks a drip leg or is just a bit too narrow.
Flaring out the wall
In the next photo, you'll see another designer's conceit: the wall was flared under one of the windows to provide a little excitement to the wall. What's wrong with that?
Well, once you flare out a wall, it's no longer a wall; it's a roof. If you use cedar shingles for siding, as this house does, perhaps there's nothing wrong with converting parts of your wall into a roof. After all, cedar shingles can be used for roofing.
The main drawback of this designer's conceit, ironically, is aesthetic: the flared wall gets much more exposure to the weather, so it turns gray very quickly. The eye is drawn to the stained siding — oops, I mean roofing — and the stains look like defects.
Notice also that the horizontal orange trim under the flared section of wall lacks any metal flashing to kick the water away from the wall. As a result, the water curls under the horizontal trim (through capillarity) and stains the siding below.
Last week’s blog: “Just Two Minisplits Heat the Whole House.”
- Martin Holladay
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