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Musings of an Energy Nerd

Problematic Roof Designs

Architects and builders keep making the same mistakes when designing roofs

My motto: Keep it simple. This type of gable roof is likely to be trouble-free. Note that the chimney penetrates the roof near the ridge.

Some roof design errors are the work of designers who have never climbed a ladder, repaired a roof leak, or learned to bend flashing in a brake. Others happen during a remodeling project. Whether these design errors are examples of architectural sin or inexperienced builders’ boo-boos, they are painful to look at.

Valleys concentrate water

This valley concentrates the flow from the roof and funnels the flow to a chimney. [Photo credit: Martin Holladay]
The “chimney at the bottom of a valley” problem can be seen in some very expensive homes. [Photo from Landsearch.com]
OK, I know that valleys concentrate water. Where should I direct that water? Maybe I’ll send the water to the edge of a skylight. Extra credit here for the lack of kickout flashing at the bottom left. [Photo credit: Martin Holladay]
The “skylight at the bottom of a valley” problem is surprisingly common. [Photo credit: Martin Holladay]

Where is the flow directed?

Welcome, visitors! These two gable roofs send a good portion of the water they collect to a narrow slope directly over the entry door. The gutter above the door is likely to be overwhelmed during a hard rain. [Photo credit: Martin Holladay]

Concentrated flow

Designers need to consider how their proposed roof will shed water, of course. But they also need to consider how the roof will behave when it is blanketed with deep snow or a layer of ice.

Pity the poor dormer in the center of the roof. It is assailed from all sides, in all seasons, receiving gallons of water along with the usual measures of snow and ice. [Photo from Landsearch.com]

Snow management

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22 Comments

  1. antonio_o | | #1

    In a topic detour, the author writes:
    "Designers, take note: a real stone wall needs to continue down to grade. Real stone walls don’t float in mid-air."

    This is not necessarily factual. One may not like the look, but I have seen multiple cases of real full depth stone stacked on angle iron attached at points well above grade. Though such an installation is a wall of stone stacked outside a freestanding wall structure, I suppose the author might argue that the stone is not the "real wall." Obvious. However, that would apply to many brick veneer facades as well.

    1. charlie_sullivan | | #2

      The fact that it applies to brick veneer facades as well doesn't make it any less true.

    2. MartinHolladay | | #4

      Antonio,
      When non-structural brick veneer was first installed as cladding on the exterior side of wood-framed buildings, the veneer was an attempt to fool casual observers, leading them to believe that the house they were looking at was a brick house (that is, a house with structural brick walls) when, in fact, it was not.

      When the designer of a brick veneer house or a mason is oblivious enough of the history of brick masonry to install brick veneer that doesn't extend to grade -- in other words, brick veneer that sits on angle iron, with air beneath -- I feel justified in calling this travesty an aesthetic error.

      Indeed, as you write, "one may not like the look." I am a critic who does not like the look, and this opinionated piece of writing happens to be my blog, so I get to call them as I see them.

      Whether we are talking about glued-on pieces of stone veneer, or brick veneer installed on angle iron, the failure to extend either type of cladding to grade is an aesthetic error which is disturbing to a knowledgeable observer.

      If you are going to install any type of fake cladding (for example, vinyl siding designed to look from a distance like painted wood clapboard) the effect is ruined if you get the details wrong. (Here's how it works on a house with vinyl siding: A pedestrian approaches the house. "Ah, it looks like painted clapboard," thinks the pedestrian. She gets closer. "Oh, but something is wrong. There are two courses of siding, one above the other, that terminate at the same spot, so that their end cuts are aligned. Oh, and what's wrong with the window trim? Something is amiss." And the effect is ruined. But, as I say, it works at a distance.)

      If you're still reading, and you're a builder who installs stone veneer, here's another hint: stone houses don't have stone-clad dormers. If there is a dormer on a stone house, the cladding on the dormer must be wood cladding (or at the very least, it can't be fake stone with mortar in the joints) because stone walls need to extend to grade. Below is an egregious example of such an error.

      1. antonio_o | | #5

        Martin,
        I certainly did not intend to upset you. It was not clear to me that you were expressing an (apparently very strongly held) opinion. The rest of the article was pointing out design errors that could lead to degradation of a home--serious informative content. My reading of your writing led me to belive that you actually meant that if a builder or designer wanted to mimic how "real" stone "must" be installed, the installation must extend to grade level. I was simply pointing out that actual, full-depth (not cast cement, not veneer) geological stone does not have to be installed as you stated. Now that I know that you were not making an assertion of fact but rather an assertion akin to "real men don't drink lite beer," I plead no contest.

        I would point out however that if you think that a designer or homeowner is necessarily attempting to "look from a distance like" something else or to fit into some historical aestethic context, that may be a faulty assumption in many cases. Often the appreciation for the synthetic product is the fact that it allows one to achieve a look that is not possible or not as easily achievable using the product that may appeal to the "knowledgable observer" viewing it critically through an assumed aesthetic standard. For example, I'm well aware of the historical context of brick veneer facades as a simulation for a structural brick building. I live in an old house that has as its exterior structure a double wythe of masonry--one brick and one block. I absolutely love the look of the brick exterior. However, were I to build the house and had the option of a structural brick exterior or a brick veneer with stud bays that I could fill with insulation, with certainty, I would choose the latter. In addition, I doubt that I would constrained the mason to install header courses every seven courses to make the brick installation appear as if it were structural.

        Having said that, designers beware. Martin may come across your house one day and not like it. Ha, ha. :)

        1. MartinHolladay | | #8

          Antonio,
          Relax -- you didn't upset me. In fact, I rather enjoy discussing these topics. For the record, it's my belief that real men can drink whatever they want.

          And I agree with you: I'd rather live in a brick veneer house with insulated walls than in an old house with structural brick walls.

          1. Expert Member
            Michael Maines | | #9

            Martin, I agree with everything in your article, and the stone-veneer-on-wood-deck is always painful to see. I will disagree mildly with your stone dormer comment, though--there are many historic examples of flush dormers made of stone, such as here: https://www.glensfallsliving.com/blog/road-trip-fort-ticonderoga. But for a typical, traditional-looking North American house with setback dormers, they should absolutely not be made to look like stone. (Slate tile cladding can be appropriate, however...)

          2. MartinHolladay | | #10

            Michael,
            I agree! When the face of the dormer is co-planar with the structural stone wall below, it can obviously be made of stone. But dormer cheeks generally can't, unless a mason is capable of advanced trickery. Moreover, the photo I posted simply screams "fake."

            Thanks for you comment, Michael.

  2. sscogin | | #3

    Reminds me of McMansion Hell: https://mcmansionhell.com/

    1. Expert Member
      MALCOLM TAYLOR | | #6

      sscogin,

      Always a nice way to slide into the weekend. Just looking at Martins' photos as given me anxiety!

  3. dankolbert | | #7

    In our book, I wrote that a PGH ideally should look like how a kindergartner would draw a house. Minus the chimney with smoke curlicues.

  4. ROBERT OPALUCH | | #11

    This article was fun to read. I got a good laugh from photos 4 & 5 "roof valley terminates at skylight." Hopefully they had the foresight to make the skylights operable! ;-) You never know when you need to air out the house before a thunderstorm...

  5. bob_swinburne | | #12

    A tour de ouch!
    I'm still patting myself on the back for designing the Sugar Bush house with zero roof penetrations and a single plane.- The plumbing vent comes out high on the wall. But I may never manage to pull that off again.

    1. MartinHolladay | | #13

      Bob,
      Well done. My only comment: if it were my house, I would have installed a vertical chimney that penetrates the roof, in spite of the need for chimney flashing. I'm not a fan of exterior chimneys, which tend to collect creosote and draw poorly compared with interior chimneys.

      1. bob_swinburne | | #15

        I agree. Being a passive house, we figured the wood stove would almost never get used. I always worry about snow taking out the chimney.

      2. Expert Member
        MALCOLM TAYLOR | | #17

        Taking cues from Ted Benson's ideas on Open Building, I've changed the way I detail chimneys on metal roofs. I now build a curb much like you do for a skylight, and mount the chimney flashing and storm collar on top of it. That way you can replace the chimney and flashing without disturbing the roof panels.

        1. MartinHolladay | | #19

          Malcolm,
          Great idea.

        2. Expert Member
          Michael Maines | | #20

          That is an excellent idea, Malcolm.

        3. bob_swinburne | | #22

          with a snow slicing prow! We just build a plywood box and give it to the roofer.

  6. Deleted | | #14

    “[Deleted]”

  7. bob_swinburne | | #16

    I agree. Being a passive house, we figured the wood stove would almost never get used. I always worry about snow taking out the chimney.

    1. Expert Member
      MALCOLM TAYLOR | | #18

      Bob,

      Fantastic house with a beautiful multi-use porch.

      1. bob_swinburne | | #21

        thanks Malcolm. I call the style "carpenter modern"

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