What happens here?

What happens here?

Buildings, energy, energy policy, indoor air quality, problems, triumphs, successes, failures and the people and processes that affect them.

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Thursday, March 14, 2013

Old houses are like old people. You can learn a lot from them if you take the time and respect them.

One of my indulgences is taking time to look at a detail in an old house and trying to get into the head of the craftsman who made it. I can't say that every try is successful, but when I do figure it out there have been some great "Aha!" moments. More than a few times it's taken years and some other discoveries to see what was going on.

Sometimes it's a structural choice; how were two pieces of wood joined, why was that support here and not there. It could be material choice or why did that window go into THAT corner. Sometimes there's a really good, smart reason, other times it's tough to figure and there are some clear mistakes. These are lessons that are sitting right there waiting to be learned and many of them are still applicable today.

One important thing about successful (surviving) old buildings is that they could dry out if they got wet. Quickly too. And that's the important part, if wood stays wet it rots. If it dries quickly it's fairly forgiving of some periodic wetting. If you let it get too wet too often your building won't survive for future generations to see how stupid you were.

How did they dry and are there lessons about that for today? They dried because of lot's of air and energy flow and materials that don't trap moisture. No insulation and free air movement in wall cavities are a recipe for drying. Interior horsehair plaster dries very rapidly which also helped keep the walls dry. Of course in the 18th & 19th centuries showers and hot tubs were in short supply and indoor swimming pools were even rarer. So buildings had lower moisture loads to deal with and had good drying potential. That's a good way to make a building that will last.

We have become more regular in our hygiene and with high energy costs we want insulation in our walls and ceilings. This puts us in a bit of a bind because we just messed up our building longevity strategy. What to do? Let's go back to our original building and see what else we need to change. Well, if the walls won't dry, maybe we should keep them from getting wet! Some of those old details will still work for us and some won't. If we are expecting better thermal performance we need to give the walls (and other building parts) better water management so they can make it to the next generation and beyond.

With future posts I'll explore the details, but new construction will have different solutions than rehab, probably. With rehab or retrofit you have to think more carefully about what the strengths and weaknesses of the building are, what the extent of the planned work will be and what can realistically be done within those constraints. The reason I love working with older buildings is that I can use all those lessons I mentioned earlier and, with luck, get some more.

Oh, one more thing. When you do undertake a rehab on an old building remember to leave a penny with the year you completed the work where someone will find it when they get around to their own project in the future. They'll know that you were thinking about them and maybe take the time to learn a few lessons of their own.


  1. Hi Bill,

    As an unapologetic old building geek, I could not have said this any better. Trying to read a very old home, and decipher things earlier craftsmen had intended, is totally spot on.

    And active air flow, and the wetting and drying cycle you describe, is certainly one of the more key observations about why some historic homes have survived for so long, and why things often go wonky when modern weatherization methods are thoughtlessly applied to them.

    What I find really unfortunate is how so many older homes were sustainable for many decades, or even centuries, and then suddenly were rendered neither sustainable nor comfortable, in more recent times, by the widespread adoption of fossil fuel-based heating systems, and what we've finally recognized, only very recently, as their concomitant need for insulation and air sealing.

    Unfortunately, this only helps to support the notion that "old" is bad or useless, and ought to be replaced. As you said, just like with old people, one needs to get to know an old building and its inherent logic better in order to appreciate its true value, and why it's worth keeping around. As well as how to start going about treating it a more appropriate manner.

    Great observations here. Thanks, and please keep more postings like this one coming! :-)

    ~ John

    1. Thanks very much John.

      I like to think of old buildings as a university. Spend enough time in them, pay attention and you're bound to learn something.

      Too often when old buildings are "upgraded" the process doesn't honor the original thought that went into it. That requires some thought about the past as well as the future. It's so much easier to just rip away whatever is there to impose a new vision on a building.

      I used to get criticized when I worked on old buildings for being slow. I always preferred to start with a nail puller rather than a sledge hammer. I'm sure I could have increased my profits but it would have been at the expense of my education.

  2. Thank you, I enjoyed this post. We have an early 19th century home with little, or no, insulation. I'm glad that I saw your post now before we did anything to harm the building! I'll be watching for your future posts.

  3. Excellent posts. I agree it is very unfortunate when an old building is suddenly rendered obsolete. For several years I worked on the Montana State Capitol campus & one of my favorite buildings is a circa 1935 concrete & steel Art Moderne 4-story office building with a western exposure. Every one of the windows on this elevation has an air conditioner sticking out of it & I realized that even though we have climate change (& Montana is certainly experiencing it in a big way), what has really changed is our perception of “comfort”. The siting of this building was a deliberate decision to maximize light & passive solar but now, rather than using passive means like window shades to control heat & light, the building is now cooled inefficiently & expensively with fossil fuels powering the air conditioners. The building hasn’t changed, it’s we who have changed.

  4. I just purchased a 110 year old shotgun in New Orleans. The Katrina damage was minimal - the water only rose seemingly to the top of the brick piers or around 2'. The walls were made of exterior siding, studs, lath, and plaster. While reconfiguring some rooms I have noticed no mold which is a topic of conversation in this city becasue modern attitudes about making the building as tight as possible prevail. I have opted to not insulate and condition the space as minimally as possible by using overhead fans and the fantastic crosswinds from the French doors on the side etc. I want the house to breathe like the builders intended so hopefully the home will last another 100 plus years. Thanks for the encouragement!

  5. I am glad others find this fascinating AND a lesson for modern times. My cottage is about 500 years old (very modest - nothing grand!) and a tad drafty but there is no damp, which I am sure there wodl be if I were to adopt a contempary approach to insulation etc.
    We also need to be REALLY wary of paint which claims to deal with damp walls - all it does is seal in any wet! Let it breathe! Chris

  6. Great article and an easy enough for the new old house owner to understand. So many of them are insulation crazy. I will save this link and pass it on to my readers. Ken