Here is a detailed multi-part video series on the Perfect Wall concept.

@Austin so Matt is a good builder and a lousy investor. What does that have to do with anything?

I am asking a straight question: what is the cheapest way to make an old home energy efficient. You are completing warping the question into some kind of weird psychological analysis of how I am cheap and do work on my own. I'm sorry, but that's not following from the question I asked. If you have an opinion about the cheapest way to make an older home energy efficient, why not just give that opinion?

I also asked what the cost per square foot would be to retrofit an old home to use an outside insulation wall, using a Perfect Wall design. Maybe it is expensive and maybe it is not expensive. I think a builder would have a perspective on the cost to do this.

The purpose of making the building energy efficient is to lower the energy bill, but generally speaking, I think it would also make the home far more comfortable because there would not be wild or rapid swings in temperature. Once brought to a target temperature, the home would tend to hold that temperature for much longer.

so Matt is a good builder and a lousy investor. What does that have to do with anything?

I am asking a straight question: what is the cheapest way to make an old home energy efficient.

My wife drives a sedan, what is the cost to turn that into a truck?

The answer to your question is that we can't know. Even a contractor looking at your house will not have a real idea until he pulls the cladding off. A general range would be expensive to ridiculous. It is entirely possible that it would be cheaper to tear the house down and rebuild it well.

Trying to turn something into something it isn't, is not going to be cheap. From a financial standpoint it is usually a bad decision. I think the point Austin was trying to make is the Matt destroyed value rather than created it.

Building an energy efficient home is a questionable investment in most climates. Converting an energy inefficient home into an energy efficient home very rarely makes financial sense. I live in a much less temperate area, a week ago we had a high of 21, yesterday the high was 65, that's just our weather 8 months out of the year. Yet, it doesn't make financial sense for me to do minor energy efficiency improvements. I am actually selling a rental property right now and the inspector flagged the attic insulation as deficient (It only has 6" of blown in insulation) I responded by sending over a year of utility bills, the highest electric bill in the summer was $95 and that was with triple digit temps.

So maybe the best way for my wife is not to turn her sedan into a truck, but rather look at what she wants a truck for and think of alternate solutions. Maybe she really just needs a trailer she can attach to it occasionally. If you want a more comfortable home, you should look at ways to make your house more comfortable, rather than trying to adopt the methods used in a new house.

Best of luck and happy holidays.

@Austin so Matt is a good builder and a lousy investor. What does that have to do with anything?

Because you used Matt as an example and 'what is the cheapest way' within the same confines of your question.

There is no number that I am aware of that is tied to 'cheap'. So until you define what the $number$ is, I think for the most part you will be widely disappointed.

other than that I think Bry911 summed it up quite nicely as well.

"I have a hard time leaving things well enough alone." Matt Risinger.

Matt's a good builder--by following Dr. Joe. Natch! But what a lousy investor. And his designs would be eviscerated if he posted here.

As for the OP, all costs are local. So unless you plan doing part or all of the renos yourself, you would be best to consult local companies. As Kevin notes in his spot-on video, the SF Bay area is likely the highest cost area in NA.

Our current un-insulated 1964 home, serviced by two mid '80s HVAC systems, is an energy-wasting monster. But it has only cost maybe $1,000 a year more to heat and cool than our last very efficient one-third larger home by a licensed custom builder.

But rather than spend $300K+ to partially upgrade, we are demolishing the home and starting over in a neighbourhood where final home prices more than support the investment.

I've lived in "older house" all but one time; parents built a new house in 1952 and we lived in it for 11 years.

Frankly, I don't like these "air tight" houses. To my mind, a house should "breathe" a little. Of course I want insulation and a good HVAC system(s) but I still want it to breathe.

a house should "breathe" a little

This has been the rationale of every HVAC Sawzall-wielding installer, speed-demon fg batt insulator, framing carpenter and plumber I've ever come across. Just a bit of tape and she's all set boss! "Gotta breathe, don't you know." (Sigh)

The OP has had a leaking, onto the floor, toilet for 3-4 weeks.

Wear “long underwear” may be the OP’s solution.

Your local Home Depot has free classes re “leaking.”

PBS show and Magazine, This Old House has remedies.

PG&E performs energy audits.

Are you willing to do your own research?

Somebody that won’t spend $5 to change out a wax seal whose leak will cause thousands in damage is not going to spend the entire purchase price of a house to retrofit it to save less than $500 annually. It’s not like the house is in MN with -20 outside. Learn where to spend and where to save. Spend the $5 rather than diapering a toilet with towels. That has a much bigger payback.

I considered a Matt Risinger idea from one of his YouTube videos for the exterior of my home, but the product he used required the manufacturer to train contractors on how to install it. The problem I ran into is the manufacturer didn't have any contractors that were trained to install it in my area.

As far as air tight, my research indicated that you don't necessarily want the home to be too air tight or mold can develop and then that's a nightmare.

@oneandonlybobjones, If you buy into the "tight home" philosophy, then you control humidity inside the home with a dehumidifier, assuming you live in a location like the deep south with high humidity. Mold is not going to develop in the framing because an airtight home has an air, moisture, and vapor barrier, and all of the holes have been properly sealed. The flashing should be allowing water to drain out without getting a chance to get into the framing.

Personally, if I had a tight home I would go for an ERV to guarantee air exchanges and get fresh air where I want it, and I would probably do the HVAC with mini-splits since those can be easily designed to provide large numbers of very energy efficient zones within the home. I would never need a dehumidifier where I live.

Tight homes aren't a trend - they are mostly a code requirement. A trend is quartz kitchens or light colored wood floors.

Tight homes are not a philosophy that you may or may not agree with. They are based on science as the best way to achieve and maintain a comfortable indoor temperature and humidity at a reasonable energy cost.

Lastly - another vote that stripping off exteriors of houses is not cheap at all. But if you are doing it for other reasons, then planning to add a barrier outside of framing might be in order.

If you buy into the "tight home" philosophy, then you control humidity inside the home with a dehumidifier, assuming you live in a location like the deep south with high humidity.

If your goal is to use a dehumidifier it will add additional 'cost' to your monthly over head. Depending on a wide array of factors, such as electric rates, humidity in the home, set points to relieve that humidity --- this can easily cost $30 to $50 or more per month in additional costs on the electric bill. Then you have another system to maintain and repair and eventually replace. --- those costs never go away. I live in the deep south in a 1970-1980's era home, my personal preference is to design a HVAC system with dehumidifying capabilities built in -- in terms of how it functions.

You see efficiency is one thing, but if the cost to maintain, run the equipment and eventually replace it -- well it has to make financial sense too. Because of the climate in which I live and the 'use' factor equipment longevity is typically in the 15 year range. Economically speaking in my climate it doesn't make sense to go over board on 'Equipment'. Not saying you can't get more than 15 years here, but that is not that common. Heavy use climate --- you run the equipment more --- regardless of brand it will fail. A 75 degree set point here and you will run the equipment upwards of 2300 hours. Lower than 75, you can easily hit 3000 hours of run time. Then throw in improper maintenance or lack thereof and equipment failure is guaranteed.

Typical pay back on 'HVAC only equipment upgrades' for my climate can range from 5-8 years to 10-15 years. Because utility costs are lower here and varying degrees of what comfort means to people --- well it's not feasible for many as they don't have plans to remain in the home that long.

I just recently made HVAC improvements at my home in Katy, Tx. By installing an Inverter Heat pump in my 'all electric' home. I expect to cut the power bill in half. I have only merely re-insulated this home. The HVAC equipment and duct work are in the attic. It wouldn't be feasible or practical to change any of that in terms of re-locating it or conditioning the attic.

The use of this home now is for me, but eventually I plan to turn it into a rental as I did my previous home. I did similar things to the previous home in terms of efficiency upgrades and reducing energy costs. That home it wasn't uncommon to get an electric bill of around $50 in the summer.

With that said, this isn't a 'bragging' expedition on my part. It may seem that way I am merely explaining why and why things aren't always so cut and dry.

....and I would probably do the HVAC with mini-splits since those can be easily designed to provide large numbers of very energy efficient zones within the home. I would never need a dehumidifier where I live.

Mini splits while efficient --- that efficiency is misleading when you start figuring in maintenance, repair and ultimately replacement costs. If you live in a more moderate climate and a smaller structure a mini split may be all you need.

Because of the amount of equipment needed for a 'high use' climate I live in a mini split is often times not worth it. It is much more cost effective here (humid south) to install a forced air duct HVAC system.

If your goal is to cool a covered patio or shed, maybe a garage for temporary use type thing a mini split 'may' be a good fit for that kind of thing here. As a primary use for in the home? I don't think it's a good idea here.

I am renovating my house right now using exterior insulation. New siding, sheathing and windows/doors. There's really no $ payback that I'll ever see, however the house needed the windows and siding so it is only a few more steps to insulate that way. I'm in zone 5 so no exposed studs!

I also live in the Bay Area. Depending on where you live, it could be that most of factors/techniques (and comments made as with Austin Air) aren't applicable or may not be worthwhile to do.

For the majority of the hours in a year, the outdoor temperature is rarely more than 20 degrees different from the desired indoor temperature - ie, average daily temperatures are rarely lower than the low 50s, lows in the 40s or more, highs in the 70s to mid-80s are the norm. And there's no summer humidity, as you know.

In my late-60s era house, the two things we did that I believe have been consequential are to put in double pane windows (which is as useful for noise as for temperature and tightness) and we added more insulation in the attic. The insulation is more useful in the summer than in the winter because the attic gets hot. We also made sure that the attic ventilation is good but it still gets hot and by late afternoon, heat radiates into the house and on hot days we turn on our A/C.

When I had the attic insulation beefed up, the insulation contractor (one of the largest in the area) said that insulating the floor over the crawl space wouldn't be cost-effective.

Good luck.

@David Cary, mostly I agree with all your points, but I would qualify them.

Tight homes *are* a trend, and that trend is reflected in the building code. Individual builders may disagree with it, and other builders are out in front, pursuing even tighter objectives than the code, at least in custom homes. A trend is simply a direction that can be defined objectively (think of a trend line that describes a set of data points). A trend - as I am using the word - is not a fashion that comes and goes.

I am with you that tight homes are based on building science. And yet it never fails that many builders, and many people in discussions online, want to talk about homes that can "breathe". Rarely does anyone base these discussions on the building science. I will let you defend the building science, and I want to just stay out of that argument entirely.

Unfortunately, this thread convinced me that there is no cost-effective basis for rebuilding an old home to use a "perfect wall" exterior. I understand your point that if you want to redesign the facade for aesthetic reasons that some variant of that idea should be considered at that time, but that's about having a lot of money to spend and getting what you want. It's not about cost-effectiveness.

Here is a variation on the original question. How much extra would it cost to re-roof a residential unit with appropriate air/water/vapor layers and a 2 inch foam layer to provide insulation, then provide a radiant layer and any type of roofing that would work with a radiant layer, such as the metal roofing used in the original "Perfect Wall" design?

Using various calculators online, I see that a simple asphalt shingle roof on a 2000 square foot residential building might cost up to $10K. How much would the roof based on "Perfect Wall" principles cost, and assume the same kind of metal roofing used in the videos I posted.

I suppose if you were going to this trouble you would probably turn the attic into a conditioned space. If the roof is properly designed, the attic should not be getting enormously warm during the Summer. At least the outside heat should not be radiating into the space.

How much extra would it cost to re-roof a residential unit with appropriate air/water/vapor layers and a 2 inch foam layer to provide insulation, then provide a radiant layer and any type of roofing that would work with a radiant layer, such as the metal roofing used in the original "Perfect Wall" design?

Perfect for whom? The builder and or contractor selling the 'add on'? Sounds kind of cynical in how I say that, but I am not trying to be cynical.

Look down the road a few miles... like when that roof is going to have to be replaced. If the roof ever has a leak and how costly that would be if just under the roof you have foam or some other insulating medium. Roof leaks are tricky enough without some form of insulation in the way.

So every time you replace the roof, you may or may not need to readdress the insulating foam layer. Over the course of my HVAC career I have been in 1000's and 1000's of different homes, built in different eras of building science.

I've been in a few 'conditioned' attics here in Katy, Texas, it's not that it can't work but as with anything cost in my opinion would be considerably higher to maintain a 'conditioned' attic. (for one --- contractors doing work on one -- in one -- would need to understand what to do --- as well as what not to do.)

With a vented attic --- as long as it's vented properly there is no maintenance, other than to re-insulate the attic floor after so long and doing so properly not to block off the natural venting of the attic. (roof eave vents)

In terms of spray foam retro fits (older homes converted) --- the foam used is more or less like a science project out in the field. If that foam doesn't cure properly you're in for a world of hurt, financially, health wise and who knows what else. (The foam off gasses toxic substances when it doesn't cure properly)

The foam more or less encapsulates which ultimately makes it harder to discover problems. Roof leaks is only one, another is termites.

And yet it never fails that many builders, and many people in discussions online, want to talk about homes that can "breathe".

It's important that there is an air exchange rate for any structure. So building a structure tight has serious flaws if the air exchange rate isn't adequate. (new fresh air being introduced, while expelling stale air)

See you don't have that problem with a home that can breathe naturally.

Confined spaces are dangerous if you don't understand this problem fully do a google search on 'confined spaces'.

NOTE: I know a home isn't considered a confined space so this is a broad leap to attempt to give clarification on the importance of a breathing structure --- confined or not.

If you want a super tight house, don’t buy a leaky house. Build a super tight house.

Going nuts over extreme measures in a super mild climate is is own version of using a bladeless jet fan to blow out one single lit match. The entire year of energy spent in such a climate won't equal one month of a leaky old Victorian in a Boston winter.

I am with you that tight homes are based on building science. And yet it never fails that many builders, and many people in discussions online, want to talk about homes that can "breathe". Rarely does anyone base these discussions on the building science.

Generally, I support tight houses, but I wonder if some of the "science" isn't a bit overblown.

As a researcher I understand that science has real, and sometimes very significant, flaws. Most research, and therefore most science, is based on an underlying assumption. If you begin to question or change that underlying assumption some of the research and conclusions can lose a lot of validity.

In the case of air tight homes, to flip the science on its head all you really need to do is change the underlying assumption to one of value. If your goal is to attempt to eliminate all the problems that air tight homes are great at attempting to eliminate, which is the current default position of building science, then they are great. However, by simply changing that underlying assumption to one of efficiently addressing those same issues some of the building science can get questionable pretty fast.

For example, I currently have a former rental property under contract. It is a story and a half home and I recently noticed that all of the insulation in the walls of the attic bedrooms had fallen down. I began a plan to attach foam board to the studs and use blown in insulation in the cavity to get a tighter home. Then I looked at the $95 summer electric bill and realized that I will never recover that cost, so I put the crappy insulation back up with insulation supports and went on about my life. Sure enough, the inspector flagged the insulation and I sent over the electric bills. The house stays comfortable for $95 per month. How much would I have to spend to get that down $20 per month?

There is the problem with building science. It largely ignores the marginal benefit and marginal cost calculation of those goals.

This is not a criticism of tighter homes, again, I generally favor a tighter home for reasons other than value. However, it is a criticism of the authority with which tighter homes are often presented.

You’re in a moderate location that water conservation likely has better payback as an environmental concern rather than home heating and cooling costs. Switching to xeriscaping for the externals rather than water hungry non natives plus rain harvesting cisterns would pay you, and help your local environment.

I agree with live wire oak, it's hard to find much payback in retrofitting unless it's a very old and leaky house. There may be payback in terms of greater comfort by eliminating drafts but even with our sky high utility rates, heating and cooling costs are as moderate as the climate.

Depending on where OP lives, we get rain during, at most, 4 months of the year. Rain harvesting doesn't provide a great benefit in water savings. Tuning up irrigation systems fixing leaks, not overwatering, and using drip emitters wherever possible can, on the other hand, be worthwhile. .

Now that we have had quite a few responses on this thread, I would like to respond to some of the major themes.

I agree with the point made that retrofitting an older home to rebuild the exterior walls with insulation is probably never going to be cost-effective. That said, I live in an area where the marginal cost of electricity is about 30 cents per kWh. You will have no problem spending $800+ per month to heat or cool a 2000 square foot home that leaks in my area. That still makes payback to an expensive outside wall change difficult to justify.

The main benefit I see to a tight home is not just the energy savings. It is comfort. If you can heat or cool the home and have it "hold" that temperature for a long time, the temperature variations within the space disappear and it is just much more pleasant to move around and be in such a space. In a leaky home, you feel like a rat in the Winter, hovering around the hot air vents, afraid to move away because the air even 10 feet away from that vent will be cold. It is just unpleasant to live in such a home, even if you spend $800/month to keep it heated or cooled.

You seem to be trying to justify this somehow. This is not just difficult to justify, the cost is an order of magnitude more than your benefits.

First, let's tackle the bill idea. How efficient is your HVAC system currently, because you are apparently using about the same kWh to heat your 2,000 square feet as I am using to heat 4,200 square feet of 100 year old home, even though your heating degree days are half of mine?

Now let's do some math about cutting that down. Let's say your total cost of the improvement is $90,000 (which it will be), let's also assume that it will cut your bill in half, down to $400 per month (which it will probably not). Using a conservative 5% discount rate we can get to a positive Net Present Value in only 57 years...

Realistically, your bill will go up over time so I think you can probably bank on getting positive in no more than 30 or 40 years. However, that assumes that your energy usage gets cut in half and that seems a stretch 12 months out of the year.

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"In a leaky home, you feel like a rat in the Winter, hovering around the hot air vents, afraid to move away because the air even 10 feet away from that vent will be cold."

That is not a leaky home, that is a wind tunnel. My area is a solid 20 degrees cooler all winter and I am completely comfortable walking anywhere in my leaky home. To get what you are describing I would have to open several windows.

However, even allowing that is the case then you are still going about this the wrong way. You really do have a confirmation bias going here. If the problem is that your house is drafty, then you need to find solutions to that problem in your house, and not decide that the solution that works for new homes is the best way for you to achieve that.

@bry911 I said "I agree with the point made that retrofitting an older home to rebuild the exterior walls with insulation is probably never going to be cost-effective." Why is there a need to further prove the point when I already granted it?

Because you really didn't "grant the point" and "probably never going to be cost-effective" is different than a giant waste of money. You are trying to paint the non-monetary marginal benefit of a tight home while downplaying the amount of the actual margin.

If it is not a cost decision then leave cost out of the discussion. If you are going to add in some monetary benefit for your decrease in utility bills to your analysis then you need to be realistic about that benefit and the associated costs so that the marginal non-monetary benefit can be analyzed.

So what you need to do is find the monthly cost where your npv is zero for your project over some time period where the benefit might be applicable. I would use maybe 15 or 20 years personally, but feel free to push it out further. You then get an analysis that is a very simple non-monetary marginal benefit. The final question will look something like this, "is a $1,200 marginal monthly cost worth a $200 discount on utilities and a warmer house?" These benefits should be calculable with some estimation.

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The title of your post is, Best Way to Retrofit a "Leaky" Home? I have been restoring 100 year old houses most of my adult life in an area with double the heating days and quadruple the cooling days, and my answer to your question is, the method you have described might be the worst way to retrofit a leaky home and is definitely not the best way. What other ways have you explored? How many professionals have you asked to evaluate your problem?

If you are paying $800 a month for utilities I think you need to better decipher where, what and how those costs are inflating your utility bill. A utility rate of 30 cents per KWH is only part of that monthly bill.

The idea here is to suggest that a leaky house may only play a very minor role in that utility bill. Why? I live in a leaky house now, my electric bill was $51 at 11.6 cents per kwh. I recently installed an Inverter 18 SEER heat pump at my house.

The attic of the house has also been re-insulated. But I didn't do anything crazy like sucking out old insulation etc. Nor did I spend any time trying to seal cracks and crevices. Primarily because I want the house to 'breathe' a little.

I have started replacing windows but nothing high end. These are just low e, gas filled double pane windows -- BG from Home Depot, Nothing special.

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So why do this... why try to cut the utility bill? Mainly because there is 'head room' within that bill. Head Room = High bill. How high is high? $800 a month.

In my case --- it was no where near $800 a month. But I live in a 11.6 cent use area. So as an example if I burned 500 KWH at .30 cent rate my bill would be $150 a month. --- I use that as an example. My last light bill was $51.

So what do those figures tell you? --- there is a lot of head room between $800 a month and $150 a month. (You know as in a comparable home to mine, with similar things done to it. It's 1910 sq. ft. btw)

Find what is 'contributing' the most to that $800 a month spend? The easiest are light bulbs. Are you still using incandescent light bulbs? Florescent?

LED's have come a long way. Start there --- replace all those light bulbs to LED. In California you probably don't have very high use in HVAC. But you need to see or some how determine exactly or close to it as to what it is costing you to run it.

Simple --- take your monthly bill from a month with little to no heating or AC usage. A month like March or April for example compared next to an August bill. That should tell you something. ( I doubt heating costs are that high in SF bay area --- so it's not likely to benefit you unless you are in all electric home, in that case you need to upgrade to a Inverter Heat pump)

Other energy robbing offenders: pool. If you have a pool at your house that thing is a energy drain. Those pool pump(s) -- have to run to clean the water via filtration. A pool pump here costs at least $150 a month at around 11 cent a KWH. Times that by three for California. --- if that's the case, that is half your bill right there. It comes down to 'USE'. Remember that. Pool pumps tend to run 24/7. People give them little thought as a energy robbing offender.

Sticking an old refrigerator or two in the garage and maybe a freezer. -- why is this a thing? The gaskets on the doors of these is probably worn. Not to mention an older appliance is very energy inefficient.

_________

Notice what I say here has little to do with a 'leaky' home.

After you investigate.... tell us what you find. It's worth it if you are paying $800 a month in utility bill.

If you just feel that you must “do something” then it’s because of evangelical beliefs. It’s not for real world math. Or real world weather.

You live in a location that has only had central air installed in homes in the last few decades, and not for any real need for it either. It’s just status. And a single fireplace can take the chill of of a 50 degree “winter” day.

Your perception that your exterior weather is the Arctic Tundra or the Mojave is not reality. Get out of your little area of the world and travel a bit. Visit a Miami in August. Then we’ll talk about needing air conditioning. Visit Minnesota in late January, and we’ll talk about how they don’t even have an $800 a month heating bill.

If you’re spending $800 a month with it being 50 degrees out, then you have a fundamental systems issue. Or you are trying to keep it at 90 inside.

$800 a month would be outrageous even with this outside.

Westes, thought I'd share what my brother did. He has a 1960s rambler in zone 7. He has been insulating the walls from the inside, room by room. The deeper walls require a wider window sill, and he has made his from oak. He is retired and in good health, so he is doing the whole thing himself. I know you were interested in insulating from the outside, but if you have enough square footage, this might be an option.

I do agree with Austin Air that you first need to get a better idea of the cause(s) of your high utility bills. Good luck!

"You live in a location that has only had central air installed in homes in the last few decades, and not for any real need for it either. It’s just status. "

Sorry, this isn't correct. It's maybe laughable. The "Bay Area" has many micro-climates - at the north end of the Bay, the Wine Country spends weeks in the 90s, as does the south end of the Bay. And places in-between are in-between. San Francisco happens to be a small area that is the coolest part of the region and if you drive out of town, in 10 minutes the weather is different. Inland areas (think Walnut Creek, Morgan Hill, Livermore) have very hot summers. Hot but with no humidity. Air conditioning is as useful here as anywhere else and in the hot areas, is hardly for status.

I live in the area. Our utilities are expensive but I can't imagine how this person can get to such lofty monthly costs unless the home has electrical resistance heating and not the most reasonable costing service - gas. Our most recent bill through the first week of January, with top tier gas usage at nearly $2 per therm, was $175 for heating. We were gone for a week, but also had some guests from SoCal and so had our thermostats a bit higher for a number of days, in a house that's a shade under 5K square feet. It was about 100 therms of usage. The weather has been mild but I've never been over about 175 therms for a month. That with two 80% efficiency furnaces and good setback thermostats that are set back overnight and off after the morning wake up period until late afternoon.

I mentioned in an an earlier post what work I've had done. My furnaces and AC are new, having recently replaced 15 year old equipment I decided was ready for retirement. If this person is heating with properly sized modern forced air furnaces with recently tested and sealed ductwork, something is really wrong.