While 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
When 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.
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!
Founder & Senior Editor
I love old houses, working with my hands, and teaching others the excitment of doing it yourself! Everything is teachable if you only give it the chance.