Identifying Age of Improvements

General Inspection Topics General Inspection Discussion
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I have a question on resources for learning about the history of romex wiring and drywall, so that I can better identify the decade in which they were likely installed. Since this type of knowledge is something inspectors use every day, I thought this would be a good place to ask.

First, though, the saga that has led to this inquiry:

I am a residential designer in Portland Oregon, and I created permit drawings for a project that included adding a bath to an existing second story and removing some interior bearing walls. The drawings were done for a developer/house flipper who had just purchased the home. I have done hundreds of similar projects, and I have learned to never assume that any improvements to a home were legally permitted. On this project, the issue of whether the upstairs was legally habitable space was discussed with the owner at our first site meeting, and I was assured it was. As has happened before, when I took the plans into the City for submittal, I was told that the second level had never been approved as habitable space.

The home was built in 1906, and the second story improvements included ½” x 48” drywall, T&G subfloor with particle board on top that ran under the partitions, 3-1/2” x 1-1/2” studs, small aluminum sliding windows, fiberglass batt ceiling insulation, and wiring that was plastic sheathed NM 2-wire with ground, among other indicators that said to me that the improvements were from a late date. The electrical outlets included a mix of grounded and ungrounded plug types.

At permit submittal, I was told by the plans examiner, based on my description of the existing improvements, it was very unlikely that the attic could be grandfathered-in by way of a special inspection the City offers in such circumstances.

When I informed the owner of our inability to proceed with the project as documented, he promptly cut off all communications with me and did not pay me for my work. The owner apparently paid for the City’s special inspection and got it grandfathered-in. A week after my initial attempt to submit for the permit, the owner applied for the permit using a new, completely redrawn, set of plans. Not surprisingly, these plans did not include my structural details and calculations for the removal of interior walls.

I had told the owner that it appeared to me that the improvements were made in the 1960’s at the latest, but, clearly, the City’s special inspector thought the work was from a pre-code era. I have been told by City officials that the 1940’s and earlier improvements are usually grandfathered-in. To help my due-diligence in the future in judging the age and legality of existing improvements, (and this is the question of the post) does anybody know of a reference for the history of when cable sheathings changed and when standardized sheetrock sizes changed? Or perhaps someone here knows the history of these or has discussed this in a previous thread?

Thanks all.

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Brint - [/FONT]

I’ve been doing this for 35 years. I base age off internet or MLS listings from realtors. We can age / guess things due to the homes characteristics … Such as in my arena we have not used stone foundations since a certain time; we quit using aluminum wiring in XXXX. We date mechanical components by model / serial numbers, etc BUT to try and guesstimate when a remodel was done by drywall / romex wiring is NOT something we would typically do. To be truthful, why would we really care.

We’re not the city code guys / We do NOT grandfather potential problems in a house. If the 3-prong outlets are ungrounded OR the gaps in stair balusters are 9" wide they get reported as a potential safety risk, etc

What a buyer or seller does with that info is up to them / Of no concern of ours

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Thanks for the perspective Dan. I can see your point.
It answers one question that has been asked by homeowners I’ve worked with on more than one occasion in a similar situation as I describe above, where a homeowner has just purchased their home and hires me to do design. After a preliminary check on the internet to look at permit records or a call to the AHJ to inquire for work that may have been done before records were recorded electronically, I quickly determine that a major addition or some other amenity was done without a permit. Sometimes you know it immediately without a records check, because the work was done so poorly or not to code. Homeowners have been surprised that the home inspection did not reveal the non-complying work, and now they have to pay sometimes 10s of thousands of dollars more to bring the existing up to code. I assume that home inspectors have an exclusion for this type of verification, as do I explicitly in my contract. I this case, however, the developer did not hire and inspector, and, because he brought up the subject of the second floor before I did, probably already knew or strongly suspected it was non-compliant.
My original question goes more along the lines of just the general knowledge that one gains through exposure to many varying building conditions. For example, I know the approximate period that lumber mills in this region started producing today’s standard nominal sized lumber, and can know immediately if an alteration pre-dates that period. I know, having worked for an architectural historian in the Washington D.C. area some thirty years ago, that people make a study of nail, brick, moulding, etc. history (and even bob-wire), not necessarily because its particularly relevant to their profession, but because they love buildings and history, even its technical history.

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Brint as a home inspector, national trainer and code certified in all 4 areas (Bldg, Elec, Mech & Plmbg) a lot of people get confused about what a home inspector does OR does not do. To start with … UNTIL someone wanted to change the house, upgrade the electrical panel, put a new roof on, etc in MOST areas (like here in Kansas City) NOBODY has to bring ANYTHING up to code.

Think about it … Building Codes change every 3-4 years. A 10-12 year old house is NOT up to code. Home Inspectors may be able to point out some things we obviously know have been installed without a permit / code inspection (like the 4th roof; the new bedroom in the basement with the electrical panel over the bath-tub and the 80% gas furnace in a closet in the bedroom; etc; etc)

BUT unless paid to research it as an EXTRA service, we inspect and move on.

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Thanks again Dan, all very enlightening. Sounds too like you are politely telling me this may not be a good question for this forum – home inspectors don’t necessarily know history of building technology because their jobs don’t require it.
Great forum in general, however – participants always seem unusually civil for the internet.

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lol…you ain’t been reading the right threads!! :|.)