Retrofit Insulation (Dana’s ca. 1960’s Cape Retrofit) and Heating in Home with Siding as Only Sheathing
Lindaloowho
| Posted in General Questions on
Hi Everyone,
We are looking at using some electric baseboard heaters for our old wood cabin that has no insulation in the walls. My husband wants to put the heaters closest to the windows. I say we should keep them as far away from exterior walls as possible to avoid warm air meeting cold.
What do you all say?
Thanks in advance!
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Back when minimal insulation was the norm, the traditional wisdom was to put the source of heat in the coldest spot in the room. The thinking was it evened out the temperature. In old houses the radiators were always under the windows.
It is true that doing so does result in greater heat loss. But keep in mind that the entire point of heating a house is occupant comfort. If you are going to sacrifice occupant comfort for efficiency, why not just heat less?
"But keep in mind that the entire point of heating a house is occupant comfort. If you are going to sacrifice occupant comfort for efficiency, why not just heat less?"
That's very well put.
Thank you. I'll acknowledge it may be an overly broad statement -- heating the house keeps the pipes from freezing, and at a certain point does keep the occupants from freezing to death. But once you get beyond about 40F it's all about comfort. It's easy to lose sight of when you start talking efficiency. The most efficient thing would be to keep your house just warm enough that the pipes don't freeze and nobody dies. People lived that way for centuries.
I worked this summer on an 1850's farmhouse in New England. It had cupboards built into the side of the chimney in the kitchen. They were for storing things that couldn't be allowed to freeze. In the winter it was the only spot in the house safe from freezing. People lived in that house for 100 years before they had central heat.
Having lived in a 1902 farmhouse with zero insulation, heated entirely by electric baseboard heat, I can confirm that placing them below the windows is the best idea.
There is no reason to avoid “warm air meeting cold”. You are, after all, running cold air into the heater to make it warmer :-)
Putting the heaters in the coldest area of the room will help to even out the temperature gradient in the room somewhat. You’ll have a more comfortable room this way, and there isn’t really going to be any difference in terms of efficiency. If you want to improve energy efficiency, consider adding some insulation to allow you to maintain your temperature setpoint with less input energy. If you have no insulation at all now, anything you add will make a big difference.
Bill
Darn it, you guys. You make too much sense...I get caught up reading so much about theory, that I forget about practicality sometimes.
Hi Bill, I’m afraid to put insulation in the walls. We’ve got thick wood siding , then two by four studs, then drywall. I’ve heard this is the worst assembly for blowing in insulation and that it can encourage rot, especially on north and east sides of the cabin.
>"We’ve got thick wood siding , then two by four studs, then drywall."
So the siding is the only sheathing? Is it board & batten, ship-lap, or ...??
That isn't a safe assembly to insulate unless installing another layer of siding, but if it has deep roof overhangs on all sides blowing in low density (1 lb per cubic foot) fiberglass isn't TOO dangerous. Leaky plank sheathing has the "benefit" of being able to dry to the exterior even through the insulation, as long as the insulation isn't too air retardent.
I've recently been consulting on (and sometimes even doing some of the grunt work) on retrofitting a ca. 1960 Cape style house that had full-dimension 1x board & batten siding (no sheathing) where some of the walls had been insulated with R11 and R13 batts over the decades, with much of the house uninsulated. (Yes, it leaked air like a tennis racquet :-) ). Even though the roof overhangs are minimal at that house it was air-leaky enough to the exterior that even the stud bays insulated with mid-density R13s showed no visible moisture issues, saved by the air leaks in the siding(!). About a month ago it was dense-packed over the pre-existing batts with cellulose (by yours-truly), then more recently the battens were pulled and a fully-adhered WRB was installed to improve air tightness. (Think of 4' wide air sealing tape. :-) ) This week a layer of 1/4" Obdyke Rainslicker was installed over the WRB, and as of yesterday PM about half the house was already shingled with red cedar- they will probably be finishing up early next week, finishing this phase of the project. (There will be improved HVAC and rooftop PV phases coming soon enough.)
As a side note, it's remarkably easy to force a dense-packing hose through crummy R11s, a bit harder but still not a major PITA with R13s. Even though some contractors shy away from it, it's really not a big deal to leave batts in place and dense pack over them. This house was blower-door tested last spring (I don't have the cfm/50 numbers handy) as part of an initial air sealing & weatherization effort, and it was just barely able to fully pressurize to 50 pascals even after fixing a number of large air leaks. Even without use of a blower door the "before air sealing & insulation" IR imaging showed major gaps in the wall insulation, and lousy performance on many of the bays that were fully insulated. IR imaging (without benefit of blower door) after dense packing to verify that nothing had been missed- a necessary check before going forward with siding to avoid having to come back and fix it later in a messier fashion. (The house is and has been occupied continuously during this project.) Between the dense pack and the fully adhered WRB I'm sure the next blower door test will be "much improved".
Interesting stuff Dana, I'm working on a house where I'm considering dense-pack, it too has been erratically insulated over the years and it's good to hear your experience.
To the original question, I would worry that the walls in a cabin are not going to be at all rodent-proof, a mouse only needs an opening the size of a dime. They're probably nesting in there already, but if you add insulation you've created luxury accommodation.
Hi Dana,
Yes, ship-lap siding is the only sheathing, and it has deep roof overhangs on all sides (with no soffit). Good to know fibreglass wouldn’t upset the drying of the wall assembly too much. I think it was cellulose that was the offending insulation in the article I read warning about retrofitting old home walls with insulation. Really cool to read about your latest project. Btw, Just painted the siding with water based exterior latex paint...probably just made my siding less leaky.
Hi DC,
The siding is in really good shape...haven’t see one gap.. and the cabin is on piers so I hope those little guys haven’t managed their way into the walls...hopefully they’re all busy in the ground under the skirt. I haven’t heard or seen any signs in 4 years, but if they aren’t in the walls already, they’ll be doing their darnedest to get in when we attempt to heat this place through the winter months, I’m sure.