Insulation in an older house

[sideofcash]

We live in a house that was built in the 1880's. It is plank construction so there is no insulation in the walls to speak of. At some point, someone put drywall up (I assume directly over the plaster and lathe) my question is If I wanted to build the exterior walls out with 2x3's and insulate (and put the electric in the walls) should I remove the drywall and plaster and lathe? Or would it be OK to just skin it out over top of the existing?  I think I know the answer, but don't think I want to do the work. What a mess.

Thanks, Eric.

[Jack]

If you're annoyed at whoever put up the drywall without removing the plaster/lathe first, just imagine how pissed off the next guy will be at you.

Also, insulating the walls but leaving a cavity might might lead to condensation/mold problems. (I don't know for a fact that it would, I only know enough to be aware that it's something to consider.)

[GoldenStache]

Have you tried drilling to see if there is any space at all?

There are ways to drill/spray/plug.  Not the greatest results but better than nothing and a lot easier than a full demo.

[Cromacster]

Whats your attic insulation situation?  If its bad, I would address this first.  You lose most of your heat through your attic, something like 85%.  I would ensure that it's air sealed and properly insulated.  Then I would address any gaps around windows, doors, and other penetrations.  Then, if you feel it necessary, address the walls.

[sideofcash]

Attic was done as soon as I moved in. I am thinking about siding this summer and wrapping with tyvek to stop the majority of drafts. Just thinking about this in addition to to battle some of the cold. I agree that condensation may be an issue.

Also, like I said the electrical runs through conduit at the baseboard.  I would like to get it in the walls, but it is easier said than done with the Plank construction.

Thanks for the feedback!

[Josiecat]

1892 house here.  I had the insulation company drill the holes on the inside and blow insulation into the walls.  No need to remove the drywall that way. 

[sideofcash]

I replaced several windows last year. The plank construction leaves no room for blow in. I have never seen this type of house. It isn't your typical stud wall. The plank is the outside and inside wall. The lathe is attached to the plank. I don't know how to explain it any better than that.

[deborah]

What is your foundation? I had a 1900s house with stumps and lathe and plaster. When the stumps were replaced, all the plaster lost its key. Best to pull it down and replace with dry wall rather than have dry wall over the top. As you say, it's a real mess though! Good luck.

[Josiecat]

There is a wealth of old house knowledge on one of the boards I frequent.

Those windows could have been refurbished instead of replaced.  There is a window expert over at wavyglass.org if you are interested in learning how to save your old windows.

Also, you could ask the forum your old house questions about insulation.

www.wavyglass.org
http://historichomeworks.com/forum/

[Jack]

I replaced several windows last year. The plank construction leaves no room for blow in. I have never seen this type of house. It isn't your typical stud wall. The plank is the outside and inside wall. The lathe is attached to the plank. I don't know how to explain it any better than that.

Are you saying that your walls are solid tongue-and-groove 4" thick beams stacked horizontally on top of each other, or something like that? If so, then that's a damn log cabin!

[Greg]

Are you saying that your walls are solid tongue-and-groove 4" thick beams stacked horizontally on top of each other, or something like that? If so, then that's a damn log cabin!

Does sound like that.  Square-log cabin.

[sideofcash]

Are you saying that your walls are solid tongue-and-groove 4" thick beams stacked horizontally on top of each other, or something like that? If so, then that's a damn log cabin!

They are actually 3" thick planks stacked VERTICALLY with a 3 to 4 inch gap between each making a 6" outer wall. The lathe is attached to the planks.

The foundation is stone with a crawl space that was added probably in the 1930's or 40's

[iamsoners]

We live in a plaster and lathe walled house (circa 1927) but it sounds like our construction method was a bit different (balloon framing so that it has the typical studs and wall cavity). I don't have any opinion on building new walls inside your house, except that it sounds like a huge pain and probably not worth it to address the relatively minor heat loss that occurs via walls.

if you are considering adding siding to the exterior of your house, then consider putting polyiso foam board over the exterior, taping it to make it air tight and then putting your siding over that. From what I understand, applying the insulation to the exterior of the house is the way new "green" construction is happening and if you are planning to modify the exterior anyways, you may as well retrofit there.  My only thought/question before proceeding in that manner would be whether this a problem trapping too much moisture inside against any existing lathe.

**Edit** I just read this thread: http://historichomeworks.com/forum/viewtopic.php?t=884 which you'll find interesting because it advocates NOT doing what I just suggested and the user jade has a very interesting suggestion about how to handle your electrical issues w/o conduit.

[Jack]

if you are considering adding siding to the exterior of your house, then consider putting polyiso foam board over the exterior, taping it to make it air tight and then putting your siding over that. From what I understand, applying the insulation to the exterior of the house is the way new "green" construction is happening and if you are planning to modify the exterior anyways, you may as well retrofit there.  My only thought/question before proceeding in that manner would be whether this a problem trapping too much moisture inside against any existing lathe.

**Edit** I just read this thread: http://historichomeworks.com/forum/viewtopic.php?t=884 which you'll find interesting because it advocates NOT doing what I just suggested and the user jade has a very interesting suggestion about how to handle your electrical issues w/o conduit.

I think the important conclusion to draw from this is not that if you own an old house you should throw up your hands and leave it uninsulated, but instead to realize that houses are built as a system and changing it piecemeal without understanding how all the parts interact can cause problems.

In the example above, the issue is not that exterior foam board insulation is a bad idea, it's that it needs to be combined with a rain-screen wall and detailed correctly.

This site might have some good articles for how to consider a house as a system.