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Insulation for a Cold Climate

Insulation for a Cold ClimateWhile I may live and work in Florida, I’m not unaccustomed to living in the great white north. For years I lived in New York and Boston and suffered through my fair share of winters before heading south. Insulating an old house is very dependent on the climate. You can’t necessarily use the same materials and techniques to keep a house in Miami cool in the summer as you would to keep a Cape Cod cottage toasty all winter. They may both be beach houses, but that is where the similarities end.

I’ve written about Insulation For a Hot Climate previously, so I thought that January was the perfect time to write about Insulation for a Cold Climate. I know you northerners will be keen to discuss the topic right now as you freeze your baguettes off so I’m gonna drop some knowledge bombs on you to help keep you warm this winter.

Tip #1 Air Sealing is Key

Hot or cold climate, air sealing is the elephant in the room that is often overlooked. Yes, air sealing is not insulation but it is, in my opinion, MUCH more important. Old houses breathe and to an extent that is a good thing, but too much of anything is no good and most old houses could very easily have their envelope tightened up without problems developing.

Doors and Windows

These are easy solutions with the plethora of permanent and temporary weatherstripping options available. Check out these easy ways to tighten up your windows and doors and stop the cold drafts.


The next spot to think about when it comes to sealing drafts is your chimney. Is there a flue and does it close tightly enough to keep your warm air from flying out the roof? Make sure it’s opened for fires and closed as soon as the embers have died out. A lot of folks leave it open all night after a fire and that cold air pours right in.

Electrical and Plumbing Penetrations

Anywhere a pipe or wire goes in or out of your house and then makes another penetration through the wall that is a big place drafts come from. On the outside of the house caulk any of these penetrations. Consider adding something like these gasket covers to your outlets and light switches because they are essentially big holes cut into your walls.


The junction between your wall and floor is notoriously bad about creating drafts. On most old houses there have been enough coats of paint that this isn’t an issue but if you notice the joint between the baseboard and the plaster is not sealed, go ahead and caulk and paint it.

Tip #2 A Cold Roof is A Good Thing

ice dam on old houseWhen it comes to insulation for a cold climate a cold roof is a wonderful thing. You want the underside of your roof insulated well enough that you don’t get melting snow which leads to ice dams and other not so fun problems. Heat rises and without sufficient insulation under your roof, you will be loosing all that precious (and expensive) heat out of the top of the house.

In the northern parts of the country (zones 5-8) EnergyStar recommends insulating your attic to somewhere between R49-60. That’s a ton of insulation, but you need it in these cold climates. That means 14-18 inches of insulation if you are using traditional materials like fiberglass or blown-in cellulose which has an average R value of R3-3.5 per inch.

Check out this post on How to Install Blow-In Insulation which is an extremely DIY friendly insulation technique.

Tip #3 Crawlspaces are Cold Spaces

For hot climates, this isn’t much of an issue, but the crawlspace in a cold climate can be ridiculously cold, so insulating under your floors is super important here. Yes, it’s dirty and difficult to maneuver under your house, but a couple weekends of suffering will bring years of energy savings.

I prefer rock wool or fiberglass batts between the floor joists because there are usually so many wires and pipes that using something like rigid foam is almost impossible. The batts can be cut and worked around the penetrations under the house to allow easier installation.

While you’re under there bring a caulk gun or some Great Stuff foam to spot treat and seal up those penetrations we talked about that are under the floor.

Tip #4 No Foam Zone

I know it’s tempting to use closed or open cell spray foam on your old house, and while it may be a good solution for a new building I don’t think it is a healthy solution for an old building. Old houses function different than their modern day counterparts and spray foam usually causes more trouble than it’s worth.

For spot treatment around plumbing and electrical penetrations it works well, but when you coat the entire wall, roof, or floor that’s when issues come up. Yes, I know it’s a powerhouse with major R-value (up to R7 per inch!) but it seals an old house so tightly that it can create massive moisture issues that were not accounted and planned for in the original design. Not to mention foam is not easily reversible if there is a problem in the future.

Tip #5 What to Do About Walls?

Soooooo many questions about this! Should I blow insulation into the walls of my old house? Doesn’t that cause rot and moisture issues? What can I do? This is as contentious a topic in old home restoration as there is, and I’d like to offer some guidance.

Insulating your exterior walls in a cold climate is very important and ultimately should be done, but it must be done wisely. Blowing insulation in a wall cavity willy nilly is a sure fire way to create rot and mold issues. Old houses often have no building wrap or the wrap is 100-year old felt or kraft paper that has begun to degrade.

This means water can easily and regularly get into the wall cavity. Without insulation, the water evaporates harmlessly, but once you add insulation (aka a sponge) into the wall the moisture can’t evaporate and it sits and begins rotting your house from the inside out potentially creating hazardous mold issues.

My opinion on this has changed over the years and right now here’s where I stand. If you want to insulate your exterior walls the only way I recommend you do it is by fully removing the siding and installing a building wrap and then a couple inches of rigid foam insulation and then a rain screen before reinstalling the old siding. This upgrades the exterior envelope in a way that it can function as a unit and be free of water issues.

I understand that this is a lot of work and expense, but if you want it done right this is the way to go. Do you need to do this? Absolutely not. Your old house will be fine without insulation in the exterior walls and you may actually save more money by upgrading the efficiency of your HVAC system then by going with this wall insulation system.

If you want the short cut of blowing insulation into the wall cavities, proceed at your own risk. I have seen people do just fine with this method, but be aware of the risks you are taking because too often I have seen the opposite results. Is it worth the potential damage and extra expense? I don’t think so, but you may think differently.

Where to Start

Insulation for a cold climate is an important topic you should definitely be thinking about more and more the further north you live. Start with the low-hanging fruit. The easiest for your abilities and wallet. Rope caulk your windows and caulk those penetrations. Weatherstrip your doors. Check your chimney. Those can all be done for cheap.

Once you’ve hit those easy items move your way through the bigger items like insulating your attic and crawlspace. Start looking at your HVAC system to see how well it is performing as well. And if you still haven’t reached your efficiency goals then keep going until you do. While you’re making your way through this list a nice warm blanket can do wonders to tide you over. Good luck and stay warm!

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17 thoughts on “Insulation for a Cold Climate

  1. It’s my first winter in my 180 year old house in New York’s North Country. I’m investigating options for insulating underneath the wood floor since it sits directly on the joists over our unheated basement. I’m wary of fiberglass since I can literally see my basement through some of the cracks in the floor but would Rock Wool pose similar issues?

  2. I had never considered crawlspaces and other similar areas as places to pay attention to in order to insulate them properly for the cold climate. When I decided to renovate my house so it can stand up to the freezing temperatures better, the roof was my number one area of concern since I recall that my friend stated the roof has never been changed before he sold it to me. Once I find a roofing contractor in the area, I’ll make sure I ask them about the attic and crawlspaces while we’re doing the job.

  3. Ok, I read your instructions for older homes in the North. I am in Canada. I take it that qualifies for some serious insulating on this 150 year old house that has seen 4 generations of our Family.

    The problem with insulating from the outside is that we do not have siding. We have brick.

    My plan, so far, is to remove the plaster and lath from outside walls in one room at a time, lay Tyvek between the studs and then install mineral wool insulation before laying up 1/2″ drywall.

    Is there a better way than this?

  4. Hello Scott, thanks for the article. I have an old house that’s been vinyl sided, previous owner confirmed no wall insulation in the majority of the house (where there’s plaster walls) and old stone basement (northern climate). The basement ceiling has been insulated with fiberglass batts (before we bought the house) and my concern is the rim joists. My plan was to remove the fiberglass from the rim joists (at the very least) and air seal around the edges with spray foam. You are saying foam can be ill advised for insulating in an old house- can you clarify if in this application foam board plus sealing edges is recommended? I’m concerned about moisture retention with the rim joists and fiberglass batts but I don’t want to make matters worse. Thanks!

  5. I live in a 98 year old 3 story solid brick house in the Minnesota. The house has an updated furnace and HVAC but the outside walls are still the old plaster and lath. The walls starting on the outside are 4in brick then 12in clay block and then the inside studded out 2×4 wall with the plaster and lath on it. We have experienced a lot of cold coming in from those walls and we are definitely paying for it with the heating bill. I have been toying with the idea of taking all the plaster and lath out on the outside walls and insulating them and then sheet rocking it all up. Would this be the best way you would do this? I do not mind doing the work or living in the mess. If you recommend this route what would you use for insulation? I am open to spray foam, bats or blow in. Thanks for the article.

  6. The exterior of my home is desperately in need of paint. After getting 3 quotes, all around $10k, I started thinking that maybe I would put the money to better use since I am handy. I know I can purchase Hardie board for about $7500 and even with the cost of house wrap and rigid foam, I would likely still come in under the $10k mark. On top of it all, I know I need to replace at least 5-7 windows that are broken or the seal is gone, but all my windows are 36 years old and don’t operate well anymore. It always seems that small jobs always leads to many more jobs and I’m just not sure there is any value and taking all of them on, however, I can get a much better seal if I deal with everything at once. Thoughts?

  7. We have a 110 year old house in Wisconsin. The house in general seems to be fine as far as heat retention and insulation goes. There is, however, a small (maybe 5×4, 4 foot high “cupboard” in our mudroom that sits atop the stairwell to our basement. I would like to use it as a storage cabinet/pantry, but it is in really original shape – lath and plaster in pretty bad shape, some kind of wood flooring, lead paint, the works. It has 2 walls that face the outside of the house – the others face our kitchen and our mudroom. There is no heating/cooling vent connecting it to the rest of the house (there isn’t a vent in the mudroom either, which is about 5×6, both would be heated/cooled by whatever ambient heating/cooling there is in the rest of the house) so there are huge swings in temperature in the cupboard based on whatever the weather outside is doing since it is uninsulated and only receives indirect temperature control from the house. Being it would be a storage closet and hopefully extra pantry space, it doesn’t need to be insulated to absolutely the same level as the living areas but it would need something to make it so it isn’t 95 degrees in the summer and 0 in the winter. What would be the best method to insulate a small space like this to make it usable?

  8. In our 1880s Victorian here in Maine, we are going to try a double layer installation of Reflectix in our crawl space (installation instructions create two 4.75″ air spaces-one in the middle of the joists and one at the bottom to seal off the floor above); with a dirt floor and limestone foundation, moisture is always a given and so rock wool or fiberglass batts between the floor joists don’t seem to hold up (also, our floor joists are almost all 3′ apart- making a friction fit close to impossible). Combined with adding some gravel to the floor (to control dust/ etc) and repointing the foundation this summer, it should make a for a much more comfortable home (we hope).

  9. I have a home built in 1931 in Buffalo NY. It is brick on the first floor exterior. I recently got beautify new windows that are great quality and well built(and expensive). The interior is plaster and lathe of course. My problem now is the new windows are sealed tight and cold air is leaking around them somehow(instead of though them, like the old ones). I actually believe it is coming from the wall cavity below the window between the lathe and brick. I think this because the cold air is really only at the bottom, not all around. I have the window company coming back out again to try and remedy but expect them to say it’s the house problem as they installed to existing brick opening and sealed everywhere they installed. How do you recommend I tackle this. I considered cutting out the plaster and lathe below the window and sealing/insulating. Your thoughts? Thanks for your help!!!

      1. They are full replacement windows where the window installer/manufacturer took out all old framing and installed to the brick on the sides including installing new frame and sealing it right. At the bottom of the window they placed it on top of the existing 2×4 stud that was in place. Which is where I believe the air is coming from as there may be no insulation in the cavity under. They are coming back out today and I asked them to continue to look for the issue. Including remove the exterior flashing and seeing if it was sealed properly from the outside for air infiltration also. They already removed and replaced the interior extension jam, casing and trim and filled any small cracks or gaps the original installer for them neglected to do. I thought that would fix the issue but did not. He windows are Renewal by Andersen made with the Fibrex etc. I have done pretty much my whole house and this last round is the first issue I have had with them.

  10. I am putting R38 fiberglass ecotouch insulation in the roof of my garage. Then i might put something else over that but not sheetrock because i dont want too much xtra weight. I think I’ll also pop the sheetrock which i put in each joist bay in the basement then stuff some insulation back there and reposition the sheetrock which acts like a firestop too. The basement is pretty tight for a 110 year old house. Thanks for focusing on this helpful topic. It’s suppoaed to go near zero next weekend in eastern PA

    1. Brick is a big sponge and will wick moisture during rain and snow so Inwoukd avoid putting any blown in against the brick. It may be frustrating but it’s better than having a warm house full of dangerous mold.

      1. I had a feeling that’s what you’d say 🙂 any reason not to put up insulation on a exterior wall in a gutted room being remodeled? Thank you for this article and all your advice… since I bought my big beauty I’m on here all the time

  11. Living in the Midwest is a treat because there’s both the cold climate and the hot climate. In a home over 100 years old, by no means ancient, but insulating for one or the other only covers a fourth of the year. If you would point me to suggestions for insulation that address both at the same location I’d be ever so appreciative.

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