Zoning codes often have quite different definitions of from where a maximum building height must be measured.

The lower point may be the average existing grade which can be measured in several different ways and usually applies to the original grade not the final grade. The upper point may be to a ridge or deck excluding a guard rail or including it or it might be to a point half way between the roof ridge and eave,

To help you we need to know the zoning ordinance definition of building height.

The minimum deck guard height will be determined by the local building code rather than the zoning ordinance but it is rare for it to be higher than 36".

In the US, zoning ordinances usually limit the number of stories as well as the building height and for a 30 ft height limit the story limit is usually 2.5. I've never seen 3 stories allowed in a single family district. A roof deck would not usually count as a story.

Besides checking the precise definitions of how height is determined in your jurisdiction and whether three storeys are permitted, consider applying for a minor variance from zoning to allow more height if necessary.

I've built in neighbourhoods where virtually every new home varies in depth, height and setback from the antiquated zoning.

Often builders have skirted the three-storey prohibition here by having a slightly below grade garage and a finished basement with a full wall walkout at the rear. Or, if you're daring (and rich enough) build on a sloping lot.

It sounds like the zoning is designed to prevent homes over two stories. If so, you are swimming upstream.

While you are checking on the zoning, check to see if the 30' includes or does not include the roof or the mid-point of the roof.

Split levels?

[ODD beat me to it!]

Is that what that's called? "Split levels?"

For the life of me, I couldn't figure out what to call it, lol. I started off with, "a design in half-stair fashion," which just sounded like a bad dress, and then thought, "half-stories," which sounded like I fell asleep during a kid-bedtime routine.... And now I'm like, "Split levels, yeah. Boy, am I *blonde*!"

Never lived in one of these, obviously, nor in a part of the country where they are popular. ;-) Thanks, Oak.

Thanks. I read the land use code again after writing this question:

Other Features. Open rails and planters may extend no higher than the ridge of a pitched roof permitted under subsection 23.44.012.B or 4 feet above the maximum height limit in subsection 23.44.012.A. Planters on flat roofs shall not be located within 4 feet of more than 25 percent of the perimeter of the roof. For any structure with a green roof and having a minimum rooftop coverage of 50 percent, up to 24 inches of additional height above the height limit is allowed to accommodate structural requirements, roofing membranes, and soil. Chimneys may extend 4 feet above the ridge of a pitched roof or above a flat roof.

A structural engineer could design a floor system that is only 8" thick. Some possibilities are: a flat plate slab floor, a metal deck and concrete composite floor, or light weight steel. Or a 10" thick floor with 1 3/4 x 7 1/4 LVL's and a 7'-10 ceiling height.

But if you check the zoning ordinance I suspect you will find a 2 1/2 story limit unless you are in a multi-family zone but then the building height would probably be higher.

I am thinking parapet would not be considered "open rail" but wire or glass fencing should count(?)

I understand 3 stories (up to 30 feet) + pitched roof is allowed in Seattle.

With the rooftop deck, we would use a flat roof, or at least partially a flat roof.

Put one level underground.

One level underground would require substantial grading to be done. But as long as railing can go beyond 30 feet, it should work out fine.

I wouldn't want to live next door to someone with a rooftop area. I like my privacy when in my garden and don't want people looking right down on me.

Why in the world would you even consider a flat roof? They're a nightmare.

Here, in the jurisdiction I sleep in, the "building height" is loosely defined as the average height between the roof eave and the roof ridge, above finished grade. The maximum "building height" is 28 feet. So, if I design a house with the roof eave one foot off the finished grade, the roof ridge height could be 56 feet.

So put it all underground. And lots of dormers in the attic?

******

Always interesting how the residences of the master class fall under no such restrictions.

Governor's Mansion California