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Re: historical preservation vs. staying warm

Replacements may be viable here, but if you go that way save everything you pull out carefully and put it in the attic so that future owners have the option of a historical restoration if they want that.
With me, unless a house/building is of great current historical significance, I tend toward the better performance and ease of maintenance you get with properly installed replacement windows. Your home, your choice.


Re: historical preservation vs. staying warm

I may be beating a dead horse, but it's a subject I'm passionate about.

You absolutely should save and maintain the original windows! Folks can argue about efficiency vs. replacements all day, but I have never heard of even a top of the line replacement lasting 50 years let alone the 200+ years yours have lasted.

Even with storms they may not be quite as efficient as an expensive replacement, but since when is a historic house judged first on it's ability to be the most efficient on the block??

Install the storms and restore the old windows. The ROI will be better and so will the resale value of the house.

(2¢ dropped)

Re: historical preservation vs. staying warm

Check out this link on the Bedford project.


You would be interested in episode 3106. You should be able to download the video of that show. It shows the restoration of the historic windows, and I agree with those who favor restoration over replacements.

After the old windows are tightened up, there are ways to make the windows more energy efficient than any replacement windows for less money. You have to take a tip from the oldest historical houses, interior shutters. With storm windows and interior shutters, you can see a total of R-5 at night, then open the shutters during the day and enjoy an actual heat gain from most windows with the most gain coming from the south facing windows.

I also strongly recommend the book "From the Walls In" by Charles Wing. He did a lot of research into why we build the way we do and why things were built the way they were in the past. He discovered a lot of lost technologies from the past. The book is no longer in print, but used copies are available on the internet. You might find a copy in your local library, that is where I saw and read it the first time. I have purchased two copies since, lost one and right now, I can't find the other.

From his research, he found that older houses with single pane glass, a little insulation in the attic and none in the walls typically lost about 30% of its heat through the roof, 20% through the walls, 20% through infiltration around windows and doors, 20% through the window glass and about 10% through the floor. He also found that older houses had up to 10 complete exchanges of air every hour, typical modern houses have about 4 exchanges per hour and some tight houses have 2 or less, but many of the tight houses also became sick houses. The book was written in the 70's and the technology for supertight houses was new at the time.

In the book, he has a design for interior shutters that is very efficient. The frames are made from 1x1 (1x2 for really large windows) and covered on both sides with a foil backed (on one side) paperboard with the foil surfaces facing each other. This creates the ideal 3/4" spacing between foil surfaces that results in a R-3 rating. If the paperboard is not foil faced, the R value drops to less than one. You can cover or paint the exteriors of the shutters as you wish.

You can also put a reflective film tint on the interior side of the storm windows to add a little extra R value, but it will also reduce the heat gain during the day.

Uninsulated walls have an R-5 value. Adding insulation does not always give the returns the homeowner expects, but I think it is still worth doing. It will however have the lowest ROI, but the ROI is usually acceptable. Just blowing insulation into the walls will bring it up to about an R-10 or R-11. About 10% of the wall is studs and the studs have about an R-5 value. The lower value of the studs compounds problem by pulling heat from the wall surfaces and conducting it around the insulation. But even then, R-11 is better than R-5, and the insulation reduces infiltration as well.

Pulling down the lath and plaster, installing fiberglass batts and a vapor barrier (and replacing any old wiring and pipes) and then covering with sheet rock will help a little more. Sheet rock has about half the surface conduction of plaster, the vapor barrier will reduce infiltration more and upgrading the wiring etc speaks for itself.

For the fastest paybacks (highest ROIs), I would start with a good layer of insulation in the attic. Then make the window interior shutters and weather strip the doors. The reason for doing this is to start saving as much money as possible to help fund the other upgrades. Then refurbish all the windows and storms and finally do the walls last.

Re: historical preservation vs. staying warm

Robb, I just went back and reread your first post, I forgot about that 1715 part. Your house might be post and beam. If you can see all the posts, then it might be possible that the plaster is applied directly to the exterior sheathing, but I don't think that was commonly done. There usually is a framed wall and a layer of interior sheathing on the inside and plaster applied to that.

There won't be traditional studs and stud bays. There will be support boards for both the interior and exterior sheathing and the support boards may be either vertical or horizontal. They are not load bearing and the spacing between them will be random, never standardized, which makes using batt insulation difficult.

Ripping into these walls may not be a good idea. Your best bet for the walls will be blown in insulation and I would suggest that you might look into a good quality, slow expanding foam. I would also look into treating the cavities with a sodium borate foam solution first, then do the blown in insulation.

Be very careful about what you use to sheathe the exterior, these walls are sensitive to moisture and must be ventilated. If you use a closed cell foam for insulation and treat the wood with a sodium borate solution first, they will be more tolerant of moisture, but I would keep them well ventilated anyway.


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