# How much insulation is too much?



## fishhead (Jul 19, 2006)

How much insulation is too much?

An R-value of 5,000 is obviously too much but what about 100? 50?

I'm going to start designing my house and would like to know what is enough. I plan on heating it with solar as much as possible to reduce future heating costs but there is no need to overdo it.


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## larryfoster (May 15, 2009)

At a certain point, it doesn't pay to keep adding insulation because the additional savings aren't worth it.
Besides, your house needs to breathe a little or condensation will be a problem


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## MushCreek (Jan 7, 2008)

They have found that sealing the envelope is nearly as important as insulation, so plan on putting a lot of work into that. Once done, you will need an ERV (Energy Recovery Ventilation system) to admit fresh air without losing heat. I recommend greenbuildingtalk.com for detailed info on building a tight, well-insulated house. Like Larry pointed out, condensation can be a problem, so it has to be built right.

To answer your question, R-38 walls, and R-60 ceilings aren't unheard of in your climate.


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## fishhead (Jul 19, 2006)

Thanks.

My plan is to make the house well insulated and very tight but build an air exchange system that captures as much heat as possible from the exiting air to preheat the incoming air. It won't be pretty or compact like the commercial units but it shouldn't be too complicated to build a counter current exchanger.


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## wannabechef (Nov 20, 2012)

Have you thought about spray Pam insulation? My business partner had his last house sprayed with the stuff and you could go into the attic on a 100 degree day and it would t be hotter than 80 degrees in his attic. He had the roof sprayed and the walls. Really cool stuff...not cheap though.


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## fishhead (Jul 19, 2006)

My budget is going to be tight so I'm planning on going with a double wall with blown in cellulose. I want to spend my money upfront so that I'm not bleeding heating and cooling costs later when my income has dropped.


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## Chuck R. (Apr 24, 2008)

Our ICF house is about complete, for a comparison the R-value is approximately R50 for the ICF blocks, and thereâs R50 in the ceiling. It has an air exchange system with the geothermal unit.

I would agree that at some point you do hit diminishing returns, unless your crystal ball leads you to believe that energy prices are about to skyrocket. While I beieve more is better, there's a chance you may not hit the break even point in your lifetime, or period of ownership. 

Chuck


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## fishhead (Jul 19, 2006)

My reason for super insulation is so that the home can be heated primarily with solar collectors. Then I don't care what fossil fuels cost and I won't have that drain on my income.


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## BoldViolet (Feb 5, 2009)

Chuck R. said:


> Our ICF house is about complete, for a comparison the R-value is approximately R50 for the ICF blocks, and thereâs R50 in the ceiling. It has an air exchange system with the geothermal unit.
> 
> I would agree that at some point you do hit diminishing returns, unless your crystal ball leads you to believe that energy prices are about to skyrocket. While I beieve more is better, there's a chance you may not hit the break even point in your lifetime, or period of ownership.
> 
> Chuck


Would love to hear more about your ICF house. It's what my husband and I dream of building eventually.


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## Chuck R. (Apr 24, 2008)

BoldViolet said:


> Would love to hear more about your ICF house. It's what my husband and I dream of building eventually.


Rather than hijack this thread, I'll start a new one with some info.

Chuck


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## fishhead (Jul 19, 2006)

Here's some pretty neat free design software. It seems pretty easy to use too.

http://www.sketchup.com/intl/en/product/index.html


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## ralph perrello (Mar 8, 2013)

Heat loss/gain areas with the most loss first.
Windows
Air infiltration (leakage due to loose and leaky house)
Doors
Ceiling
Walls
Floor

From a heat loss/gain point of view the following insulation is very good.
12" ceiling
6" to 8" walls (with a good vapor barrier)
6" floor (but do not allow the cellar with piping and canned goods to freeze)
2 or 3 pane windows well weather stripped.


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## MushCreek (Jan 7, 2008)

I am building with ICF also. Walls are R-25, ceiling R-48, but I am in a mild climate in SC.

I designed everything in Sketch-Up, including laying out all of the ICF forms for minimum waste and planning cuts.

As Ralph pointed out, there's more to it than walls and ceilings. Windows are expensive; good ones are VERY expensive. What I found from my research is that there's not much difference among double pane window ratings when new, but as the windows age, the leak more and more air (and water). In a far northern climate, I'd look at triple pane windows. Also, limiting the size and number of windows will help, but ultimately, you have to live there, and dark homes are rather depressing IMHO. The other obvious way to save money and energy is to reduce the size of the house, but Americans are still resistant to that idea. Our house is 1200 square feet, and is surely more than we need.

Weird things start to happen when you super-insulate. Our house is too small for a woodstove. The only ones that could be run efficiently without overheating the house would be a tiny one intended for a boat. The same for central AC systems- they simply don't make them small enough. We are using mini-split ductless units for HVAC. We're going to use a propane fireplace for atmosphere and emergency heat in the event of a power failure. I guess if energy costs get ridiculous, I'll find a small woodstove, or build a solar system.


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## fishhead (Jul 19, 2006)

I'm going to look into multiple pane windows as in 6 (?) panes. There must be a way to build them from scratch without having to fill them with inert gas although that wouldn't be too difficult. There's a local research project that has commercial sized super insulated buildings that are almost entirely heated with solar. They're also looking at designing home built energy efficient windows. I think the trick is to design a way for moisture to exit the spaces between windows. That's probably best done when it's below zero outside. Or maybe some kind of replaceable dissicant.

By super insulating I'm expecting to be able to heat the house with solar collectors most of the year. If necessary I could always install an outside wood stove and run hot water from it into the house to a radiator with a fan.


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## Jayfl77 (Jan 12, 2008)

Quality windows are expensive up front put are worth it in the long run. I'd go with Anderson windows (1st choice) or Jeld-Wen. Spray foam is expensive but worth it (Closed cell, not open cell). Open cell is the foam you find in cans in HD that expands a lot. Closed cell is denser, more expensive, helps make the structure air and water tight, and a better insulator.


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## fishhead (Jul 19, 2006)

I'll go with good manufactured windows for the ones I want to open.

With ice dam season on us and the frequent snows we're having I've been thinking of ways to avoid the ice dams and eliminate the need to shovel the roof.

What I've come up with is a sloping metal roof that is elevated above the walls enough to have an air gap so the entire roof is cold from edge to peak. There would be metal squirrel proof openings at the bottom and the top.

My current roof is warm because of insufficient insulation and not enough air flow to keep it cool. Any melting moves down to the overhang and freezes into a dam so I spend the winter scraping the snow off the bottom 4'.

My neighbors have metal roofing and their roof stays pretty clean.


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## stanb999 (Jan 30, 2005)

Here is what my FIL did. It was a bit of an after thought but it worked amazingly well.

He built the house himself. It was late sept. and there was no way to get it all closed in for the winter. He had a roof but no windows or doors. He didn't want rain/snow all over the place and then melting in the spring. We needed to do something as the floors were already exposed for one winter season. So we got tuff-r sheathing, 1/2". He put it over the whole outside of the house over the sheathing that was there. He taped the seams with metal duct tape (the metal stuff not the plastic). His total r is 25 in the walls 50 in the ceiling. The house is sealed tight as a drum. No drafts at all. When it came time for the windows and doors He was able to caulk them right to the foam for a total air/water tight seal, then put the flashing. He does have and ERV. Which is necessary. 

His heating load is 10 btu's per SQ. FT and hour @ 5F. Not to shabby. For a modest size home heating would be very affordable.


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## fishhead (Jul 19, 2006)

So how much is too much? Where does the law of diminishing returns kick in?


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## stanb999 (Jan 30, 2005)

fishhead said:


> So how much is too much? Where does the law of diminishing returns kick in?


It depends.

Do you have lots of time, a forest to maintain, and consider splitting wood a good work out. little would "pay"

Are you planning to use heating oil or Electric? A bunch could be quite affordable.

On average R50 in the roof and R30 in the walls. Much more and your drastically changing framing. 

One thing often not noted, Don't use fiber glass if you have an alternative. As temp differential rises the less it works.


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## fishhead (Jul 19, 2006)

I want it insulated enough that I can get the majority of the heat with solar collectors. I'm trying to get my future costs as low as possible and have a nice comfortable smaller sized house. That's going to take super insulation. I may go with compost heat too. I've seen sawdust piles produce heat for decades.

I'll be using cellulose between double walls.


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## stanb999 (Jan 30, 2005)

fishhead said:


> I want it insulated enough that I can get the majority of the heat with solar collectors. I'm trying to get my future costs as low as possible and have a nice comfortable smaller sized house. That's going to take super insulation. I may go with compost heat too. I've seen sawdust piles produce heat for decades.
> 
> I'll be using cellulose between double walls.


The only issue with cellulose is generally it isn't DIY if you want a professional job for the walls. Without proper density the tops of your walls will be void of insulation (it sags over time). To get the proper density for walls it has to be placed with a machine that adds a bit of water to activate the glue that makes it stick together. The final result is like a form of cardboard or big dry spit ball. Total seal and resilient. 

This video shows both processes. Note how when the walls are done it looks "wet" and packed V/s the attic where it's just fluffy.

[YOUTUBE]zFBVc8S6cJo[/YOUTUBE]


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## fishhead (Jul 19, 2006)

I went snowshoeing with a friend today who does energy audits and stuff. She said that an R-60 is about the limit of what is needed in the walls and ceiling. She also said that one way of making a window that is very energy efficient is to put a double pane window on each side of the wall with a space in between making 3 cavities.


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## Hoopjohn (Mar 8, 2013)

I'm certainly no expert on the subject. I see R50 as the point of diminishing returns on insulation.

I live near Eagle River WI. I built my own log house. 28' x 42' with a full finished basement. The log walls (red & white pines) I estimate have an R value of approx 12. My attic has R38. The basement has interior 2 x 4 walls with R11.
I heat with a high efficiency propane heating system. And own the 330 gallon propane tank. On average, I go through approx 600 gallons of propane per year. (my kitchen stove is propane, but hot water heater is electric).
This last year, my propane averaged $1.50/gallon. Total cost for the year of heating 2200 square feet of living space was under $1000. I keep my thermostat at 70 degrees and turn it down to 65 degrees overnight.

Yes, one can superinsulate and purchase a solar heating system. I don't see these things as cost effective in this region of the country. 

One more thing. A properly designed home in this region of the country will never have an ice dam. I have seen lots of ice dams in million dollar plus homes in the area. It generally occurs when there are lots of angles & valleys on the roof, and improper venting is part of the mix.
A simple rectangular designed house, with a attic designed for proper ventilation will never have an ice dam in this part of the country


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## fishhead (Jul 19, 2006)

I'm thinking that for $1,000 a year I can afford to use a lot of cellulose and then not have that annual drain on my income at a time when I won't have any extra to spare.

My current heating costs about $50-60 a month from Oct to May and that's more than I want to spend because it happens every year. I'd rather spend twice that now and not have the constant drain on my future income.


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## TNHermit (Jul 14, 2005)

Mush Creek has the answer.!!

I lived in a timber frame that had 12 inches in the walls and 2 ft in the ceiling. Coldest place I ever lived as they had taken no time to seal the place up. Whenever I built a house sealing up came before insulation. I got I could make them tight enough the fireplace would go out. So what MushCreek says about air supply. There are a certain number of "air changes" that are considered optimum


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## fishhead (Jul 19, 2006)

Cellulose does a great job of sealing a house. I'll just be careful to seal all the rest.

For the windows I want to open I'll use two high quality double pane windows spaced apart in the wall so there are 3 cavities.


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## spud (Feb 3, 2007)

I had spray foam insulation put in my house and my windows turned to crap and my heat budget for the year is still only 840 for the year which includes gas stove and hot water heater. I'm at the Ohio/Mich border so my winter is much milder than yours. My house is 2400 sq ft and has only minimal solar gain unfortunately. I wish I would have put a masonary heater in, always nice to back up heat source if power goes out or natural gas price goes up or supply interupted. R30 walls and R40 roof is all that is needed at most. Your bigger worry should be the whole piece fitting together. Insulation that has air movement going thru it is useless and has potential for collecting moisture, big problems down the road there. Therefore, you should concentrate on focusing on what insulation will actually give you true R value, talk is cheap is this regard, I'd talk to a local thermographer and pick his brain. Also, I would use a thin spray foam at minimum on inside to control air flow thru walls and ceiling. Like others said, good doors and windows are a must, I don't like the idea of two sets of windows on an opening, sounds like another area for trapped moisture. Flashing on walls is way overlooked also, lots of moisture damage going on in quickly, cheaply built houses in the past 20 years, vinyl siding doesn't keep moisture out. Good luck jeff


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## fishhead (Jul 19, 2006)

I believe that cellulose eliminates air movement in the walls.

I also discovered that a vapor barrier isn't recommended for walls with cellulose insulation.

I'm thinking for the windows to have a frame built out of plastic to reduce bridging that occurs with wood or metal. I'm also thinking of something similar for the top plates to go from the inside wall to the outside wall.


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