Is EXTRA insulation STUPID? - The Truth About Diminishing Returns

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[TinyGiraffes]

It's funny how boring this sounds vs how interested I am.

[MarkSDCA]

I believe the rate at which ice melts is dependent upon the type of beer stored in the cooler. The worse the beer the less the cooler is opened, hence the ice will last longer.

[TunafishSmoothie]

Comfort is an undervalued benefit. People spend a ton of money on high end finishes, but have an uncomfortable house. I would rather spend that same money (probably less) on insulation and sealing and be comfortable.

The resilience aspect is not considered enough. When I moved in to my old house 16 years ago we endured a bunch of multi-day power outages (thanks Pepco!), with the worst being the DC Derecho of 2012, where we ended up being without power for 8 days. This is a 75 year old house on slab, so with no power it takes very little time for the inside temps to match the outside temps and humidity, although the walls are CMU so that gives a bit of extra buffer. It was so miserable We gave up after 3 days and drove to a family's place out of state.

We broke down and bought a generator, big enough to power a room AC unit, refrigerator, and our well pump or water heater (don't need to power both at the same time). Since then we have used it exactly once, after hurricane Irene came through. It's a bit annoying to have paid that money and not needed it, but as a friend once told me, no one ever complains that their insurance didn't have to pay for their house burning down.

Thanks for another great video Matt.

[sebastiansylvan]

I think the real question is the tradeoff between wall insulation and e.g windows. If 90% of your heat flow is going through your windows already, you're better off spending more money on upgrading the windows than you are slowing down that 10% a bit more. That requires some modeling.

[GeoFry]

I have a 2x6 stud house (00s) I'm adding in as much as I can (25R) on the East, West, and South walls, because the electric bill was spiking over $400 a month in Tampa FL.

My buddy down the road has an old house (80s)with 2x4 studs second floor, 2x6 first floor. He has so little insulation that you can actually see light through the walls in spots. His electric bill is $70 a month at a nice comfortable setting. Might have something to do with the 10Kw solar panels on the roof.

Insulation requirements are relative to your electrical, mechanical, and structural situation.

[wetrock]

I built my house in 1985, in Montreal. I'm not a tradesman but a businessman in the field of work safety equipment. I did a lot of research and went with the new (then) research in energy management. My roof is R40, walls R30 with staggered 2 by 6 outside walls, full basement R 20 insulated with outside and inside extruded foam including the floor.. I have been heating and cooling my 1200 square feet house with a 2 ton heat pump and when the temp drops to zero and below my central heating of 9kw is plenty enough to keep us toasty. My utility bill for a family of five was on average 1800$ a year for the past 30 years. I have to say that in Québec we have the lowest electricity rates in North America.

[mikecampanella]

As someone who owns a 1951 cape, I dense packed my upstairs celing after i furred it down with gussets and 2x4s to 18 inches deep. We have an r70 ceiling throughout, with double stud walls that are 1 foot thick and dense packed with cellulose. I have air sealed mostly everything, new double pane windows, rockwool in all of my main level walls, and xps foam on my basement walls. My basement floor has insulated r4 panels on it.

I live in connecticut and have a 42k btu furnace for all three levels of my house. My furnace ran for just over 40 hours all winter.

Air sealing and insulating to a higher amount are always worth it.

[WebWondersUS]

Our 1930 bungalow had zero insulation. Ripping out walls, adding Rockwool has changed both the comfort level and noise level inn with our beautiful Wisconsin stone home. Best investment if you plan on being in your home more than 3 years. I am addicted to your videos - concise and explained to my novice level of knowledge but with enough technical advice to help us learn and understand. Please keep up the great work.

[sleze]

Matt, you have to bring up the ROI using just the cost of HVAC. Comparing the price delta of using better insulation to the up front cost is likely the MOST compelling argument. Even though my renovation budget was blown by pandemic lumber costs I still opted to also go over on insulation in the attic (making it conditioned). After increasing my square footage and adding a second HVAC to the house, my monthly energy bills stayed the same. Based on the costs of the open cell foam, it will be paid back in another 6 months or so. I wanted closed cell but it was more expensive and not any significantly better ROI than the open cell.

Great video, once again.

[lrc]

I know you touched on it in the beginning but if you have air blowing around the insulation the R value goes out the window.
When I managed the exterior renovation of our 15 building condo community in NJ 15 years ago we removed all the foam board sheathing and installed ZIP system. While the walls were open and all the batt insulation was visible people would ask me what were all the dark areas on the fiberglass batts? MOLD? I said no. It's dirt. There was a trail from the entry point and exit point of air leakage into the building - typically outlets. The fiberglass was basically just a filter.

[imtheonevanhalen]

I've lived this topic. ALWAYS insulate as well as you can afford. My wife and I bought an acre of land with a train wreck house built back in the 1930's, originally as a church.
After looking it over and realizing how good the basic bones were (balloon framed, 4x6 rim joists, we stripped it back to the studs and found out it was rock solid. There was no way the original plan for demo was going to happen. Rough sawn 2x lumber in the entire house (a REAL 2x4!!..)
So the house was essentially free, and you ain't gonna find lumber like that anywhere corners were braced with 2x4 lumber wit cripple fills, so we used R-Max 3.2 poly-iso for sheathing, put R-19 in the walls, furred the attic with 2x4's and dense packed the rafter runs....R-60 blown in for the horizontal attic space.
After all of the attention to detail, sealing it up TIGHT, installing a 2 ton water source heat pump with 2500 sq.ft. total living area....this old/new house is by far THE most energy efficient in my area!! Duke Energy includes audits of 2500 homes in my area (they have replaced the power meter 3 TIMES sure we're cheating!!...lol...) with the monthly power bill. Million dollar houses all around us.
All electric, my energy bill is never over $125/month. And do note....the water source heat pump is fed by ground water, so no huge trenches or bored heat exchangers. Install the heat pump, plumb in the water lines.
It seems I've lived in poorly insulated homes all of my life....I had NO idea spending a few hundred extra bucks could do in energy savings. All total above code cost was around earned that back the second year.
It's a complete no insulate, then insulate some more!!

[monteglover]

In 1963 my father had a house built near KC Kansas payed for added insulation and did som air sealing, according to him the payoff was about 2 years.

[matthewelberson]

A large part of the diminishing returns is related to thermal bridging from the wood framing, that's why adding exterior insulation is most effective

[captainobvious]

I grew up in a “superinsulated” house my dad built in the late 70’s. It has 18” of blown in insulation in the walls with a separated offset studs inner wall, and nearly 3’ of blown in insulation in the attic. He spent about $50 for electric resistance heating the whole winter. This is in Northern Utah. If it were standard practice to build every house superinsulated we would probably be using less energy than even minus what the renewables generate, as a country.

[patglenn]

When I super-insulated my home I went from R12 to R22 in the walls and R40 to R200 in the attic. My gas bill went from $160m to $78 per month. I can cool the house with a 12, 000 BTU window A/C. And in the winter (when we had a blackout at -42') the house lost about 1 degree per hour.

[johnbodnar]

It's funny about the amount of heating and cooling to keep comfortable. I started to use less heating and cooling because of cost going from $80.00 every 2 months months to $496.00 every 2 months. House use to be 19 degrees in winter, now 13.5 degrees in winter, due to cost only

[kiltedpiper]

Great episode! So important to break down the facts. As you have heard “the only statistics I believe are the ones I make up “. Zooming in on the chart makes such a difference.

[imzjustplayin]

All that needs to be remembered is that doubling the insulation halves the heat movement. If you want to double the performance from R40 you have to go to R80. Trying to compare the difference between R2 and R4 and R36 and R38 gives the impression that R40 is sufficient rather than just showing how little R2 insulation is. The biggest benefit of high insulation means fewer temperature swings and better comfort when the temperature outside is extreme. Another reason I like having lots of insulation is because if the power goes out for some time, the house isn't going to freeze or boil. It's a good idea to build a house in a way that lots of low cost insulation can be used because achieving high levels of insulation with expensive insulation makes the cost benefit not worth it.

[nathanddrews]

I've got a small 1950s rambler that I remodeled. I furred out the walls and ceiling from 3.5" to 5.5" (some placed are thicker for structural reasons), then had the whole thing sprayed with closed cell foam. Roughly an R-35. With the same ambient outdoor temperature and full sun, completely unconditioned, the attic went from 116F to 83F. Now my only issue is air sealing at the exterior doors - I haven't replaced them yet.

If I had to do it over again, I wouldn't. I would have sold the house as-is and built a small (sub-2, 000^ft) "bomber" spec house on some acreage far away.

[michaelcook]

While bulk insulation has its place, composite insulation is the future. Sandwiching bulk and reflective layers together is just one of many examples that can be tailored to suit the requirements, ie. fire resistance.
And don't even get me started on phase change materials, that stuff is just so cool.