Brit Builds an ADU: The Surveyor and the Height Problem

Hey! It’s been a while, huh? We are out of spring and well into summer, and our project finally is getting into the swing of things. I owe y’all a few updates.

Lot 22

A snippet of our surveyor’s work showing backyard elevation and our lot number.

When we last left off, we were concerned about what type of accessory dwelling unit (ADU) was possible on our property. So, we hired a surveyor (cost, about $1,600) to give us precise measurements of the property: where exactly our neighbors live and our height relative to sea level. It turns out, we are about 840 feet above sea level. Our house is a typical 1.5-story bungalow with an eave height of 852 feet and a peak height of 862 feet, so our peak is 22 feet above the ground!

Here’s what surveyors’ documents look like. 

ADU code says “(Detached) ADU cannot exceed the height of the principal structure or 20ft., whichever is less. The height point of the ADU’s roof cannot exceed the highest point of the roof of the main home

We’re good for two stories, right?! Our main house roof has a peak of 22 feet. But let’s re-read that first sentence. What is the height of our home? It turns out our home is not 22 feet tall. When you calculate the height of a single-family home with a gable roof, which ours has, you add the peak height and the eave height, then divide by two. For some reason.

So, our home is actually about 16 feet tall. That means that, without a variance, our ADU cannot be taller than 16 feet, even though this is 6 feet shorter than our roof peak — at which height you wouldn’t be able to see the ADU from the street behind the main house anyhow. A 20-foot height restriction is already somewhat short for an ADU over a garage. Single-family two-story homes can be as tall as 28 feet by right even in R1A, the most restrictive zoning district in Minneapolis. And remember, all of these heights are peak heights; the roof of the ADU cannot exceed them.

So, what are we going to do? If we stick to the 16-foot height and don’t request a variance, we cannot build a second story, and this is just going to be a weird garage with some offices. No ADU, no additional income to offset mortgages, no ability to help house family, friends or neighbors. No comp plan needed. After all, there’s no benefit to low-intensity infill, right? No.

Instead we will be asking for a variance for a 20-foot-tall ADU, which is just enough to build the space we want so long as we have a flat roof.

A flat roof? Won’t that be terrible for winter? Eh, our architect reminds us that the commercial buildings around here get by just fine. And a modern/contemporary building will be a nice offset to our more traditional post-war stucco home. Plus, it gives us plenty of space to stick some solar panels on top and help offset some of our electricity costs and carbon footprint. Yea!

But, wait a minute . . .

This height restriction really is a problem. (Is it for aesthetic reasons? I don’t understand.) If we are saying not only that ADU’s cannot be as tall as a typical two-story home (20 feet vs. 28 feet), but must also be shorter than the main/street-facing home itself, this means that a large proportion of the homes on my block cannot build an ADU and have a garage. The main floor of an ADU cannot exceed 676 square feet. The total square footage cannot exceed 1,300 square feet, including the garage or other non-living space.

Additionally you may have only one accessory structure — whether it’s a dwelling unit or not — on your lot in addition to your home. Technically if you have a shed and a garage, you may be violating the zoning code. Our home is 1.5 stories and clocks in at 16 feet. My block alone has about 11 homes that are as tall as or shorter than ours. Why should some homeowners have more rights to building more homes on their property simply because they chose a larger or smaller home appropriate for their neighborhood and lifestyle?

A bungalow is a beautiful house to live in, and adding an ADU to the property increases the property value and provides all that lovely flexibility we talked about at the beginning of this series. This code encourages teardowns replacing these lovely, small older homes simply because you would improve your property rights for an ADU by removing an older home and building a City McMansion, thus increasing the potential ADU height and value.

Currently the city is considering variances as a solution to these issues. Variances add uncertainty, time and expense to the homeowner and cost the city time on its docket. But variances are useful in cases where discretion is needed or the choice has the potential to intensely and unfairly impact neighbors. On the other hand, we could change the height restriction entirely while we’re reviewing it for the 2040 Comprehensive Plan changes.

I’m fine with having a height restriction on ADUs. It makes sense that people might not want a 2.5- to 3-story (typically 33-35 feet) tower on a tiny piece of their neighbor’s lot. But given the already limited square footage, a simple maximum height limitation in line with existing two-story homes makes a lot more sense and would allow homeowners to build a wider variety of spaces appropriate to their needs and roof preferences.

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18 Responses to Brit Builds an ADU: The Surveyor and the Height Problem

  1. Sean Hayford Oleary
    Sean Hayford Oleary August 12, 2019 at 2:36 pm #

    I’m confused on the midpoint / peak issue. I understand how that hurts your total height as measured from the house, but doesn’t it also benefit the total height measure of the new ADU?

    That is: they should be comparing midpoint of house to midpoint of ADU, not comparing midpoint of house to peak of ADU. Is that not how it works?

    • Brit Anbacht
      Brit Anbacht August 12, 2019 at 2:46 pm #

      My understanding right now is that it is midpoint of the main house to peak of the ADU. Regardless, 16 feet is too short for a two story building given that you would need a ceiling height plus the height of each transition space to be less than 8 foot each. While this mostly works for our main house (the upper floor has kneewalls/dormers and much less space) and thus it does not work for making a fully functional apartment over a garage.

      • Andy E August 12, 2019 at 3:54 pm #

        If the height restriction is only in terms of air height, I don’t see how a 16 foot restriction would impact your ability to have a two story ADU. Build down – sink the ADU 5 feet into the ground. That would allow for an effective height of 21 feet, or 10 feet for garage, 8 feet for living area, and 3 feet for roof and flooring. Or with an 8 foot garage there would be (easily) 3 feet to put railing around the roof if you wanted to allow for a rooftop deck/patio. This could also create some interesting design/landscaping options.

        The removed dirt could also be re-used for landscaping or sold to a project that needs fill

        • Brit Anbacht
          Brit Anbacht August 12, 2019 at 4:37 pm #

          Andy, that is certainly an interesting proposal, and the landscaping could possible alleviate the issue as the height is measured from the ground in a particular way, but i think would end up being very complicated with regards to storm drainage, and exact geometries for how to get in and out of a garage and offices that is about 5 feet lower than either the backyard or the alley itself.

          Thanks for your thoughts on this. 🙂

      • Brit Anbacht
        Brit Anbacht August 12, 2019 at 4:34 pm #

        Reading this again, I would agree that the height is midpoint to midpoint, but let’s look at that a little closer. Our midpoint on our main house is 16′. The upstairs of the main house is a half-story with significant height loss near the edges of the livable space and creates insulation difficulties. Variance from a flat roof puts our eaves at a lower spot. So, from a 22 peak to 10 eave height on the main house to something like 18-14 still results in a loss of usable floor space as you get closer and closer to the walls/pinch point. We are already working with a small overall square footage max of 1300 sq ft and 676 as our first floor base. A 16 ft eave height with a flat roof would alleviate the issue of space lost to height problems, but is also basically impossible. The eave height is not only the height of the wall/air space in the first floor and second floors, but also we add the height of the slab/foundations above ground, the height of the utiity and duct space, and the height needed for insulation and roof stuff. 18′ is a more reasonable minimum two story building height for most purposes.

  2. Serafina Scheel
    Serafina Scheel August 12, 2019 at 2:53 pm #

    I’m curious–how much does the detached ADU need to match the style and materials of your existing home? Does that matter?

  3. Bob Roscoe August 12, 2019 at 3:28 pm #

    Two suggestions:
    1. Fire your architect. He or she does not understand what the ADU code actually required.

    Go to CPED and get advice on how those regulations apply to your proposed ADU. They are knowledgeable and can find a solution for you.
    Your surveyor gave you wrong information. Your house’s roof ridge above sea level has no practical value.

    I prepared architectural drawings for a very similar ADU, and got approval right away.

    • Brit Anbacht
      Brit Anbacht August 12, 2019 at 5:14 pm #

      Bob, thank you so much for your concern. I would like to kindly suggest you go re-read the comment guidelines, especially parts 2 and 3. I have full trust in the people I have hired to have my best interests at heart and to know what they are doing. They are fully licensed and certified and I have actually asked for their advice.

    • Andrew Evans August 22, 2019 at 4:45 pm #

      Bob,

      Right?

      Some of this is rocket science, some not. It would behoove a homeowner to know the ordinances and roughly the measurements of their home/property. If for no other reason than keeping the people they hire honest.

      Just guessing but they could go from a sea level measurement but then would need a defined point in the yard to measure from. Would be much more helpful as yard height and then whatever the yard slope is. It’s not like the builders are going to measure height from sea level.

  4. Rosa August 12, 2019 at 3:33 pm #

    I wonder if the height restriction is intended for safety? Also selfishly I wonder if you’re replacing an existing structure you can match the current height.

    I say that because we have a two-story garage – it’s original, it was a barn with a hayloft. And it blocks our view of the alley, which is a crime-safety issue in real terms. We also were told when we had to do a major repair that if we repaired the existing structure we could keep the height, but if we replaced it we could not build at the same height.

    Though we also have a full two story house which means our height allowance would be….20′? Because it’s whichever is less?

    As always thank you for the update!

    • Brit Anbacht
      Brit Anbacht August 12, 2019 at 4:42 pm #

      That’s a cool garage! It’s always sad when the zoning means we can’t replace buildings with the same thing that already exists. (Though this is a major issue also for people who have older ‘plexes in single family zoning areas.) But yeah, your max height for an ADU would be 20’ with potential higher roofing due to how roofs are measured. Different kinds of roofs are measured differently.

      • Rosa August 13, 2019 at 8:29 pm #

        I would really like to hear the reasoning behind that rule.

  5. JOEL NIEMI August 12, 2019 at 11:02 pm #

    I won’t ascribe malice to the writers of your zoning code when mere inattention to the existing code is a likely explanation. Perhaps they didn’t know how building height was defined in your local code.
    The planning department staff is handed a rule to enforce. If they were involved in writing the new zoning text, maybe they were too rushed to think everything through.
    FWIW there are a lot of houses with 7′-6″ ceilings. You do need a few more feet to work with, though.

    • Sean Hayford Oleary
      Sean Hayford Oleary August 12, 2019 at 11:20 pm #

      I have 7′ ceilings in my (finished) basement, life goes on — but if you’re trying to do an apartment and get a reasonable market rent for it, I think anything less than 8 will be conspicuous. Most new apartment buildings have 9′, or even higher for more luxurious ones.

  6. J August 13, 2019 at 11:16 am #

    My guess is you’ll probably end up getting a few extra feet by using a little bit of each of your available creative solutions – variance, flat roof, digging down 1-3 feet, steel floor joists & ductless heat pump/minisplit (if you’re really hard up for a few more inches), lower garage height (if you’re ok with parking the Hummer on the street).

    Sometimes you don’t need a silver bullet when you’ve got a dozen regular bullets and clear priorities.

    Thanks for posting your challenges – I look forward to your next post. Good luck!

  7. Nathanael August 20, 2019 at 12:08 am #

    This makes mes come up with the impish suggestion that you raise the roof of your main house by 6 feet and convert it to a flat roof — which is totally legal, I believe, as you then have a 28-foot-tall house. And then the ADUs allowed would suddenly be much larger.

    Probably not popular with your neighbors, but the spectacular ceilings on the second floor of the main house would be pretty cool.

  8. Andrew Evans August 22, 2019 at 4:40 pm #

    Why did this come up so late? Last time I read it the ordinance was pretty clear about height and distance from the house.

    Then fwiw my friend in north paid $600 for a survey. I was lucky enough and found all 4 stakes.

    Also fwiw the city doesn’t require a permit for a small removable or diy shed. Not sure one would count as a extra building unless it was pretty extensive.

    The height rule is a good idea to keep the look of the neighborhood.

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