As I was sitting at my computer enjoying life, the temperatures outside went from late-autumn warmth to a Fjordgård-like (Norway) mid-winter temperature shortly. Plus, to make the matters wackier, it brought a pinch of Silent Hill fog to the equation just for good measure. And then it struck me. Modern houses are easier to insulate from the cold, especially during the construction period.
But depending on where you, the reader, come from, many houses around where that is could/should actually be quite old. One of the biggest problems is that old houses are more vulnerable to the cold and cold ”leakages”. Today’s construction materials are leagues ahead of what builders used many years ago. Due to this reason, many old residences suffer from heat-loss and overall increased expenditures because of it.
There was once a time when it was socially acceptable to cover your house inside-out with hay for top-notch insulation, outside of rural areas of course. And unless you wish to take inspiration from the Russians and their infamous wall carpets, you must invest in good-quality insulation. That is why I am here. Welcome to today’s lesson on how to insulate an old house.
Materials used for insulation
Expanding foam
Made from open- or closed-cell polyurethane (a plastic) or special cement, it goes from soft to solid, filling all the empty spaces it encounters. Thus, it has evolved to be the most common way of insulating the interiors of walls worldwide.
Costs: expect it to come at about $1-2.50 per square foot.
Batts
No, hanging down a colony of bats from your roof will not help you with insulation. And neither will Batman. I am talking here about batt insulation. You know, the one that looks like cotton candy and which you shouldn’t eat at any costs. They are the best option for rooftops due to their density and effectiveness. However, when handling it, wear a full mask, goggles, long sleeves, and gloves, as the mineral wool can irritate the skin.
Costs: range from $0.50 (basic fiberglass and mineral wool batts) to $3 (wool) per square foot.
Loose fill
Imagine oversized, puffy, insulating Tic-Tacs. They are dry bits of insulation that are blown into wall cavities through small holes, either from the inside or outside. It is made either from fiberglass, cellulose, or mineral wool. It is the most eco-friendly of the bunch and is also the cheapest. Ultimately, this also means that it is also not the best option for long-term investment.
Costs: expect about $1-1.50 per square foot when blown from the inside or about $2 when blown from the outside.
Spray-on fiber
A close relative of the loose fill, however in a more liquid state. It is best used on surfaces and with studs that haven’t yet been dry-walled or plastered properly. This is the best solution when faced with numerous cracks and studs as its cellulose and fiberglass components will ensure full coverage. This is also a very good solution for old houses, as it can cover the walls fully.
Costs: expect about $0.40 to $0.50 more than loose fill.
Rigid panels
These are boards made from extruded polystyrene or polyisocyanurate foam that are best used for insulating the exterior of your house, especially when it comes to covering the studs (weak insulation spots). They are best used on the outside in warmer and humid climates as they also can be effective vapor barriers. On the contrary, they are best used for interiors in colder climates as they can stop the warmth from leaving through the walls.
Costs: expect about $10 for a 4 by 8 foot/1 inch-thick sheet.
The process of insulation
In this article, I will be talking mostly about foam insulation as it is the best there is. Why? It doesn’t affect your old home substantially, and it is energy-efficient, not messy, the cheapest, and provides sound insulation. There are also other methods, and I might return to talk about them in the future. Also, take notice of your climate. The foam will behave entirely different in cold areas than it does in warm/hot ones.
In regards to the process itself, it is best to do so from the top to bottom. This way, due to its ”foamy” (no-pun-intended) nature, it will distribute and flow equally through the crevices of the walls.
The attic
This is where most of the heat escapes to as everyone who understands basic physics knows. Thus, it is only natural that it should be the place to start from. However, despite being the most important part to insulate, it is also the easiest. Especially if your attic is one of those ”Attic? I have one?” types that haven’t been touched since its creation.
If you consider investing in it, the best course of action would be batt-insulation. It looks cumbersome and somewhat ugly, but hey!, since when has the attic become a place for social meetings?
First, you ought to measure the roof rafters. The nice thing about this is that the bigger, the better. By that, I mean that the bigger the rafters, the more (and thicker) batt-insulation you can fit. You have to make sure that the measurements are correct as the rafters might not be equal in size. Be warned though. There is a basic principle to apply here which is to never compact any used insulation material. This is because any insulation material loses its properties when it is compacted. Make sure that it is installed in a manner that allows it to remain light and fluffy.
After you are done with insulating with batt-insulation, it would be silly to leave it unfinished. That is why the next course of action is to reinforce it by blowing in cellulose insulation on the floor. This will make sure to keep the warmth under it in place and the one in the attic circling.
When it comes to cracks and small spaces, best fill them with either caulk or good old foam.
The walls
This is where the party starts. One of the biggest issues when insulating an old house is ”How to do it without tearing my plaster/old brick walls down?” Don’t worry though, it is achievable. In the case of very old houses, you should go to an expert who can tell you how to do it properly. And more importantly, if you can. Old houses have a nasty tendency of being actually old. Under certain circumstances, this can result in walls full of rot and mold if the process is done without taking the proper precautions.
Otherwise, and in most cases, your greatest friend will be the good old foam insulation compound. The process will be a slow and tedious one, but with patience, care, and lots of drilled holes, it is achievable.
Furthermore, most old houses present double or triple stud walls. This will make the process even harder, as it will be even harder to drill. Aside from that, the process of insulating the exterior is pretty much the same with old and new houses. However, you should take into account the integrity of the building materials used for the exterior. For the outside of the wall, go for rigid panels. For the inside of the wall, go for injectable foam.
However, and especially in the case of incredibly old houses, the best course of option might be to not do it at all. In such cases, their sorry state and old materials are not guaranteed to last through such a process without falling apart. In such cases, simply leave them untouched and invest in a proper floor and attic insulation. After all, they are the main actors when it comes to heat retention and protection from cold in a household.
The floor
Next to the attic, the floor is the most important part of the house that requires proper insulation. Also, it is incredibly easy to do since, unlike the walls, it doesn’t risk falling off.
This is especially true if the house comes with a basement. In that case, the process will be similar to the attic insulation one. The problem is that, unlike the attic, the basement’s ”roof” is not as wide and easy flowing as the proper attic. This means that the process will be particularly slow in tight places. However, once it is finished and unless something really bad happens, it will last you for a very long time indeed with all-year-round heat retention.
If you are going for the batt insulation, you should take into account the pest issue. Those little buggers have a nasty tendency to not know that batt is not cotton candy and; thus, they chew it. The best counter to them is to install rodent-proof wire screens around all openings towards the crawling spaces. Rodent-proof the crawl space first and only then start insulating.
As of how to do it, the steps are simple. First, take the necessary measurements and cut the batt insulation to the exact requirements. Again, remember to not compact it as it will lose its abilities if compacted. After, install the insulation with the vapor barrier facing upwards. If both of the house floors are heated, use un-faced insulation.
Conclusion
Winter is coming and you need to be prepared. Insulating a house is a costly endeavor and especially when reinforcing an old one. But, in the end, it doesn’t even matter. Remember, any investments made now will benefit you, your house, and your wallet in the long-term. Until next time, have a good one.