rewiring of historic residence

[malachi constant]

I'm an engineer who has been hired by an architect to create bid documents for remodeling of a historic residence. For what it's worth I worked in the field one summer and have since rewired my 1920s era house (which was all in conduit!).

The residence in question is 1940s era, upper midwest part of the country. Most of the branch circuits do not include a ground. It appears the wiring is predominantly 2-wire, cotton-braid insulation, in some sort of flex cable. The cable appears too tight to pull wires through.

From my own experience I know it is not too difficult to get new NM fished up through walls from the basement to the first floor interior walls.

Again from my own experience I know it is rather difficult, but still possible, to fish NM cable from the basement up to a receptacle on a first floor exterior wall. So QUESTION #1: is this a recommended approach? As a contractor, would you refuse to fish up this way due to the absurd amount of effort required? Any suggestions?

The residence has a second floor, but does not have an attic. It does have crawl spaces on either side of the second floor. I'm really not sure how to get at some of the second floor devices without tearing open a wall or using wiremold (surface raceway). QUESTION #2: any thoughts on how to get to these devices?

Generally speaking if you have pointers I'd love to hear them. The building has been abandoned for a little while, long enough to create one of the dampest, moldiest basements I've ever seen. The panel and all basement wiring is coming out. In only makes sense to try to upgrade all the wiring upstairs while I'm at it.

I suppose I am going to have to get a hold of the local inspector, and maybe also get an electrician to do some field investigation. I'd like to have done a little research beforehand.

Any comments are appreciated. I have a few photos I can upload if anyone wants to see them. Thanks!

 

[Dennis Alwon]

First off the flex cable is probably ac cable aka bx cable. Secondly if I were restoring a home from the 40's in that cold climate I would not think twice about taking the sheetrock off the exterior walls in order to get good insulation. Fishing takes time but is definitely possible however you could kill 2 birds with one stone.

 

[hurk27]

Wiring old structures is an art, it is very time consuming and will drive the price through the roof, I have done several National Lake Shore properties that were registered historic buildings/homes, for the National Park Service, which in their specs was nothing but 12 AWG conductors or larger, no damage to any surfaces and removal of all existing wiring where assessable. I have developed a knack for mapping out the structure and finding connecting walls or chases to wire from the basement to attic or crawl spaces such as you have, up stairs once you have your home runs pulled up to a crawl space can be fished under the floor from the crawl space to anywhere you need to go, down stairs can be fished from the basement, down stairs lights can be accessed the same way you wire the up stairs under the floor in the crawl spaces, but you need to map out the house so you know how to lay out the wiring.

Now the most important thing is having the correct tools, there are many tools that make jobs like this go much faster.
Heres just a small list of some of the things you need:

Flex drill bits plus extensions that will reach the attic.

Fiber glass fish rods that you can reach the attic or across under the upstairs floor from the crawl spaces.

A good stud finder that also detect metal, can also detect your fish tape to find where it is in a wall.

A small worker who is flexible in getting around attics, and knows where not to step:rant:

Sometimes you can find HVAC chases or over sized chimney chases that you can use to get between floors, but there are times when you might have to remove up stairs flooring to access a top of a down stairs wall to snake your conductors over to another wall up stairs to reach an attic.

In any case make sure you cover your time as it will be a very timely job to do.

The last one I did was over $18k and took a better part of 7 days to do.

Also if this is for the GOV then expect a long wait for your money.

 

[augie47]

Baseboards can be your friend.... along with that light footed, skinny, contortionist helper.

 

[malachi constant]

All helpful posts, thanks! As it's historic I don't know if the architect will allow sheetrock to come down. Otherwise all the other ideas are dead on. Hurk has pretty much done what I'm trying to design - government-owned historic-registered lakeside home. So that reassures me that I'm on the right track with what I'm asking of the bidding contractors. I will be as clear as I can the level of detail that is required and the restrictions the contractor will have to deal with. Thanks again, I'll check in later to see if there are other comments!

 

[rt66electric]

floor boards

floor boards

One I have learned from a 1920's?? plumbers is to cut/pull-up floor boards then cut notches in the joist for pipe/wire, then replace the floor-boards.

I have cut "scuttle holes" in closets to access wiring under the house.

If the house is "balloon-framed" removing the upstairs base-boards can be very advantageous. To find studs, look at the baseboards for nail holes.

:thumbsup:

 

[readydave8]

If it's 40's era, is that sheetrock or plaster? If sheetrock, is it original? If not original, would that affect possibility of opening walls?

Personally I rarely cut sheetrock, have fished and found acess in walls that I had no idea how to do until I set my mind to it.

But I have stepped thru 2 ceilings. And had diversibit come out the other side of wall.

 

[Dennis Alwon]

Interesting fact that the sheetrock can't be removed.Around here you can gut the place as long as the outside remains historic. It is rather silly to see historic homes with every modern thing in the world and they say we want to keep the house historic. Heck they change the siding windows etc... what so historic about the house when its done.

 

[renosteinke]

The 'cloth covered cable without a ground' sounds like the first generation Romex. You can't pull it out because it's stapled at least twice inside each cavity.

Also routine in buildings of that era is wood blocking halfway up the wall- making it nearly impossible to fish. If you are going to try fishing, it's absolutely a two-man job, with excellent teamwork mandatory. If, instead of drywall, you have wood walls ... expect blocking every two feet.

The device boxes are smaller than what we use now, and you'll have trouble fitting your pigtails in - let alone a GFCI.

Code changes have greatly increased the number of required circuits; instead of the handful you have, a complete rewire will require dozens of circuits.

This is even without considering the requirements of the alarm guys.

Heck, I'm rewiring a 1957 house, and that's going to have to be a complete gut. I don't see how you can avoid it.