McMansion Tent Survey
Posted on Jan 7th, 2009 by Doug Marsh VP, CR, CAPS, GBP | 2 Comments
McMansion Ordinance Tent Survey
If you are building a 2 story addition and/or adding a 2nd story on top of an existing structure be prepared to produce a McMansion Tent survey to complete the framing inspection: you will not be able to proceed into the insulation stage without it.
Currently there is a fairly large gap in understanding between what the City says it wants (they seem to somewhat clearer about it since December 08) and what the survey companies understand how to produce the document required.
The best first step is to understand that there are two “tents” in play: the standard building tent and the modified building tent.
http://www.ci.austin.tx.us/zoning/downloads/061808_revised_ordinance_effective062808.pdf
In both cases there are clearly defined protrusions that are allowed to extend past these tents. The modified tent designation used in adding a 2nd story on top of existing is a little odd. It’s odd because the ordinance reads:
D. Side and Rear Setback Plane Exceptions for Existing One-Story
33 Buildings.
35 1. Except as provided in paragraph 3 below, an applicant
36 proposing to add a second story [This subsection applies] to a
37 one-story building may choose either of the following side
38 setback planes for the portion of the project that is within the
39 building footprint [was] originally constructed, or permitted for
40 [received a building permit for the] original construction, before October 1st 2006
a. The side setback plane required under subsection A.
5
6 b. [1. For the portion of the construction that is within the
7 footprint of the building that was originally constructed
8 or received a building permit before October 1, 2006,
9 the] The inwardly sloping 45-degree angle side setback
10 plane that begins at a horizontal line directly above the
11 outermost side wall at a height [that is] equal to the
12 height of the first floor wall plate that was originally
13 constructed or received a building permit before October
14 1, 2006, plus 10 and one-half [ten] feet. See Figure 12.
15 The wall plate is the lowest point of the existing first
16 floor ceiling framing that intersects the exterior wall.
17
18 2. Except as provided in paragraph 3 below, an applicant
19 proposing to add a second story to a one-story building may
20 choose either of the following rear setback planes for the
21 portion of the project that is within the building footprint
22 originally constructed, or permitted for original construction,
23 before October 1, 2006:
24
25 a. The rear setback plane required under subsection B.
26
27 b. An inwardly sloping 45-degree angle rear setback plane
28 that begins at a horizontal line directly above the rear
29 property line at a height equal to the height of the first
30 floor wall plate that was originally constructed or
31 received a building permit before October 1, 2006, plus
32 10 and one-half feet.
33
34 3. The side setback plane required under subsection A, and the
35 rear setback plane required under subsection B, apply to:
36
37 a. any [For the] portion of the proposed construction that is
38 outside of the building footprint originally constructed, or
39 [received a building permit] permitted for original
40 construction, before October 1, 2006[, the side setback
41 plane prescribed by subsection A. above applies.]; and
Date: 6-12-08 COA Law Department
McMansion Ordinance – Task Force Recommendations 10 of 17 Responsible Att’y: Brent Lloyd
They state that a tent is still in play as a way to corral any possible protrusions that may occur however the governing issue here is that you are allowed to be 10’ 6” above the existing (before 10/1/06) wall plate: bottom of new framing on top of old plate to top of new roof deck measured at a vertical line at the exterior of the new wall.
The curious issue that arises is that the City will not allow this height to measured by anyone except a surveyor and drawing tent lines on top of building lines in a CAD drawing does not show up. The only way to document this height is by measuring. Surveyors use a 1/10 scale (surveyor’s tape measure) tape measure and are not familiar with the practice of measuring this situation. When a building is built the only way to avoid measuring is to shoot it with a transit therefore it is best to order the survey after the building is decked but before any sheathing or soffit is completed. However narrow side yard situations will not allow use of the instrument to measure in this fashion hence the need for measuring the various components that will make up the 10’ 6”: height of truss or joist plus any plates; subfloor; 2nd floor wall height; height above 2nd floor plate of truss or rafter; thickness of roof deck. This calculation can be noted on the survey page with an accompanying diagram that clearly shows the before mentioned components with the applicable dimensions.
The surveyor must also provide the regular McMansion tent (explained above) superimposed over: the beginning building line and elevation (front). Then the building must be shown, “sliced through” in a side to side view (section) with the tent superimposed over this section at 40’ increments from the front to the rear of the building. With a 2nd story built on top of an existing structure the tent lines superimposed on top of the building become difficult to discern however the dimensional drawing with the various components should clarify the situation.
It is our fervent desire that the City of Austin develop and implement a clear and concise procedure for directing the Public and Building community on this matter instead of the current situation where one individual is in charge of approving the survey (the pertinent building inspector merely delivers the piece of paper); communication between that individual and the survey company is hazy at best; and if that individual is out of the office for whatever reason the project withers on the vine costing the Client time and the Contractor money.
Comments
On Jul 21st, 2009 LnddMiles said:
Great post! I
On Jan 6th, 2010 johnnylawisit said:
So I think that there is good information here. Thanks for the contribution!