Re-Insulating the Kitchen...
 

I live in a small, 120 year old house. When I moved in there was no insulation at all. I started with R13 fiber glass in the cavities, with no knowledge of, or regard for movement of air in the wall cavity. As the project slowly progressed, my methods have also progressed. I have come to realize how serious the energy issue is and how important it is to insulate really well. So I am now at a point where I am removing insulation I previously used and updating it, using better materials and techniques.

I have settled on using EPS rigid foam board in the wall cavities, and increasing the wall cavity by 50% (to an actual 6 inches), and filling the cavity with EPS (three layers of 2" board), that is carefully cut, layered and sealed.

In the kitchen, three of the walls are exposed, and I have already insulated the ceiling, and two walls, leaving the third wall and underneath the floor to do now.

First job was to remove the sheet rock. Here is the 4" wall with the R15 fiber glass waiting to be replaced.



Here is the wall with the R15 removed. I put duplex outlets along the top of the walls, as well as the bottom for greater flexibility in lighting. The top outlet of the outlet is switched by the kitchen light switch, the lower outlet is always on... Note the caulking that I did from inside the wall... I was trying...



Because I will be making the wall 2" thicker, the electric outlets will need to be brought forward by that amount... In some cases, there is enough extra wire in the wall to allow for the outlet move, in other cases, I will need to re-wire.



Here the firring is going on. One of the last things I learned about is the importance of reducing thermal bridging, do I am using skip-spacers and filling the spaces between spacers with 1/2" foam strips. Not the very best way to prevent thermal bridging, but better than nothing.


-AC_Hacker

Hey nice wood floors. Seems like thats a bonus when you purchase an older home.

Now if only I was that brave to take the sheetrock down, pull the old fiberglass down and do what you are doing...... What do you expect for R value once you have it complete?

I bet the other benefit of the rigid is the ablity to block drafts.

Great job AC

Nice!

How are you going to be sealing the EPS? Hopefully if you get a really good seal between each sheet of EPS and all the surrounding lumber the leakiness that board sheathing should be reduced to a minimum.

Go Go Go!

Very nice. An upgrade from a semi-leaky R15 that likely gets worse as it gets colder out to a nice solid R30 is quite the improvement!

Good job. I am almost finished with a similar job on my kitchen. With all the different step for air sealing you are doing, why are you not just using a large spray foam kit? That is what I did.

What was the cost per square foot?

I'm doing this on a pretty tight budget.

There is also another factor involved here, in that my son who is helping me at $10/hr, is not able to find other work, so this is sort of a mini WPA project, to help him through the tough times.


But all-in-all, if the cost is cheaper I could hire him to do this and also other projects... There is still the space under the floors to do... That's really gonna eat up a lot of foam.

-AC_Hacker

600sf kit w/ shipping was $698. I sprayed ~3 inches over ~200sf. so 700/200 = $3.50 /sf. I also increased the thickness of the wall to 8 inches. I filled the rest of the cavities with blown in cellulose. I only needed a few bags after what I salvaged during demo. Anyway, I'd guess it was quicker and about the same cost/sf as your project.

That is the great question.

The older stufff I was buying was rated at 4 to 4.5/in., and this newer stuff I'm buying is rated at 7.8/2" or R-3.9/in. I don't know if they are using different process/materials, or if they were forced to get honest.

So, I'm expecting R-23.4 from the foam in the walls. There will be an extra R-1 for the wood, R0.5 from the sheet rock and maybe an R-1 for the air barriers at the surfaces of the wall, for a total of R-25.9 or so.

Then there is the thermal bridging thing, and with regular studs, I'll lose 18% for and honest R-21.2. My efforts at thermal bridging reduction should up that at least a bit.

It was suggested to me that a 1/2" foam layer on the inside, over the studs will go a long way to reduce thermal bridging. My grand plan is to do an outside wrap too... but that may be in the distant future. I have been purchasing duplex outlets that have screw-adjusters and that gives me the option to add the extra 1/2" foam wrap inside, if I want.


Great Stuff at all edges... After the foam sets up, I trim it back flush, then I stagger the joints when I do the next layer, and foam and trim, etc.

That is what I am counting on... zero infiltration through the wall.

Doors and windows are a different matter.


I'm afraid R-30 might be a bit optimistic, but an honest R-21.2 will really help a lot, especially considering that I live in an area with 4,500 annual Heating Degree Days.

So far, even with just 2 walls and the ceiling done this way, the infiltration reduction is quite noticeable, and already, I completely recognize the requirement of a HRV in the project.


Wow! I'm totally impressed with your method. The economics works out pretty good, too.

This project is already underway, and pretty small, but I may use your method as I progress into other rooms.

Thanks for this info.


Thanks all, for the encouragement...

-AC_Hacker

What're you using thats only R3.9 per inch? The extruded polystyrene I see in the store is all rated at R5 per inch (owens corning).

I will search it out.. Thanks.

-AC_Hacker

Here is the spec sheet for the "150" XPS. They also have a 250 XPS which I'm not sure what the difference is (perhaps tongue and groove vs flat sides).

http://insulation.owenscorning.com/a...a29e2fd5bc.pdf

With a 40°F temperature differential this stuff has an r-value of 5.5. At 75F differential it is R5.

The spray foam I used is rated at R-7 per inch x 3 inches = 21, plus 5 more inches of cellulose at R-3 per inch = 15 + 21 = R-36. I added a second offset 2x4 stud wall for the extra thickness, so thermal bridging is minimal.

hamsterpower,

Without a doubt, you are doing this the right way... possibly more right than you realize...

Your 3" of foam on the outside walls not only gives excellent R-value, and a complete seal against infiltration, but it also sets up a thermal gradient, such that moist air will never reach the dew point inside your cellulose fill.

Just couldn't be better.

Had I started with the knowledge I have now, and the technologies that are available now, I would do exactly what you are doing.

As it is I will probably do a variant of your method on the next room I tackle. My little house is only 700 square feet, and I'm trying to minimize intrusion into my living space... so some balance is called for here.

The offset studs idea is great... I think I can do a version of that, next room.

Great advice, great work!

-AC_Hacker

EPS has a lower R than XPS which is R 5. 4.something is about right for EPS.

Thanks AC, for the kind words.

I think my wife took some pictures along the way. I hope to put up a build thread of the process some time soon.

My house is only 800 sf too. We feel that if just right for the three of us.

Well, I don't know if God looks any more kindly on those of us who live in small houses, but I do know that the heating bills are less...

-AC_Hacker

P.S.: [Everybody tells me I should add onto my house, but for 35 years I have successfully resisted!]

Interesting conversation here regarding putting EPS & XPS in wall cavities, etc.

-AC_Hacker

Dunno if you posted the right link. That guy is using polyiso in his wall, not EPS or XPS... Only one other guy mentions using XPS. I think polyiso would be the way to go since its indoors and has a significantly higher r-value.

I think you're right.

I was mostly focused on the technique.

-AC_Hacker

Daox,

Gotta thank you on this one... Turns out that I can get the XPS at the same price or slightly cheaper locally, because there is a manufacturing plant close to my town.

The number refers to the ability of the foam to support a compressive load, 150 psi & 250 psi... The 250 is more dense and has better R-value, but I'm not sure what the value is.

Looks like just about all insulation has some kind of declining curve as the delta T becomes greater.

I went through the literature, and the companies do their best to make it difficult to do an apples-to-apples comparison.

Polyiso is higher R-value, but is subject to "R creep." R-6.5/in. seems to be the spec. There is also a foil face that can be used with a dead air space to increase R-value.

EPS is or should be cheaper, but for me, locally, it is not. They're coating one side with a metalized layer, and if you use it correctly, with the dead air space and all, it has higher R-value than XPS, but the EPS + dead air system takes up more space. No significant R creep. Disregarding the metalized layer and dead air space, R-3.8 to R-4+ per in. seems to be the spec. Otherwise, R-5.5 with the dead air space (3/4" to 3").

XPS has no foil, no R-creep and R-5 value. That's what I'll be using. Most people seem to be using saws with this stuff and the dust & debris from the sawing seems to be a real problem. I'm going to see if I can hack up some kind of a hot wire tool.

Thanks for the XPS tip...

-AC_Hacker

Glad I could be of assistance and learn a thing or two.

I've always had luck scoring XPS with a razor blade and breaking it myself. Its way less mess. In fact, I know some of the sheets you can buy are prescored for this reason. You can cut/break them in half or into 3rds with hardly any work.

I have cut about a million sheets of all three kinds of rigid foam boards with a knife and a saw. My personal conclusion is that the knife technique is only to be used if there isn't a suitable saw available. The cut is much cleaner. I just put a really big drop cloth down. There are some hand saws that cut with less dust than others. Last week I was working in a basement where they happened to have a hand saw sitting right next to me when I needed to cut a board. The thing made very little dust at all and the particles were pretty big. I think it was a rip saw. Just go gently. Maybe if I had all the time in the world I'd score both sides and break it but it takes too long and the chances of making a rough edge are too great.

Just my 2 cents.

When I installed polyiso board, I used a bread knife to cut. It left crumbs which plainly fell to the floor. I never thought about it at the time but a saw probably would work much easier for most of the cuts. Go figure.

HI AC!
I was just wondering if those spacers are wood or plastic? Certain materials have lower heat transfer properties, thus lower thermal bridging. Also minimizing length of spacers could be good.

Helo all,
Anyone use a hot knife of hot wire cutter? Its very clean and fast, just kinda stinks sometimes from burning smell of melting plastic.

Hey folks,
For your duplex outlets and switch boxes there are available plastic extension inserts to make room for thicker walls without having to move the boxes. I prefer the plastic ones because they are easier to install, especially after the fact, and they are non-conductive both electrically and thermally. You just need longer screws for the devices. My experience with the metal ones are they are electrically dangerous, so I wrap the devices with electrical tape to cover the termination screws.

sparkchaser,

I don't know if I understand what you are describing...

So far, I have been removing the duplexs from the wall and re-attaching to the wood for the new wall.

Like to know what you're talking about, got any photos?

-AC_Hacker

Hello, AC Hacker,
the box extension looks like this...see attached image.

The plastic one looks similar but usually has a flange all the way around the front edge. Note tape on outlet terminal screws.:thumbup:

Warming Up The Good Stuff...
 

I've been noticing that the foam I've been using takes a very long time to reach maximum expansion, and when it is at max expansion, it is more dense than I'm used to seeing it.

So I remembered a previous discussion about the need to heat foam tanks in order to get good performance.

So I put my foam into warm water and set it on the back of the stove where the oven vents (right now I'm using the oven to heat the kitchen).


It has made a big difference, foam comes out faster, expansion time is faster, density is not so 'thick', and the cans are emptier when I'm done.

-AC_Hacker

Also when the foam is applied cold the final product is rather friable and basically useless.

Nice work AC, I just started following and noticed the plastic vapor barrier you had used originally. What kind of shape was the insulation behind the visqueen? Is that a little black mold showing up? Even with your carefully applied caulk and sealed up seams, it looks like moisture can still find its way past the vapor barrier, but then gets stuck in there without a way to dry out.

Any thoughts?

I have used this technique in other parts of the house without problems. I'm using three layers of 2" foam, completely foaming and sealing the edges of each layer.

I probably will not use the plastic barrier, there is no need. The walls are sealed so completely that no air will get through.

When I removed the fiberglass insulation that was behind the plastic film, it actually looked pretty good. I didn't see any black mold, but I did see some dusty blackness where air and dust had passed through the fiberglass.

My very first attempts to use rigid foam board, I didn't realize the importance of absolutely sealing the foam. There is not so much of the house where I made that mistake, but it will have to be redone sometime later.

I had a representative from an energy retrofit company come by the house to talk about HRVs. He was very impressed with my method... in fact he said that they are using the very same method to retrofit under roofs. He even offered to let me use their blower door over-night when I'm very close to complete.

Such a deal.

-AC_Hacker

Temperature Stratification...
 

I thought I'd measure the heat loss through the kitchen floor...

Along the way I thought I'd measure the temperature stratification at intervals in my kitchen (top to bottom):

188" = 71.1F
175" = 70.7F
148" = 71.1F
116" = 69F
69" = 67.6F
38" = 65.5F
5" = 62.5f
0" (floor surface) = 60.3
bottom of sub floor = 53F
crawlspace = 52F
Ambient (outside) = 48F

Anybody have a formula for calculating heat loss?

-AC_Hacker

Insulation Question from menaus2...
 

Well, all good questions.

You can do the materials cost comparison pretty easily, so I'll leave that one to you. But I suspect that the cost of the two methods is close, with spray foam having the higher materials cost. I'd be very interested in what you might come up with.

Regarding labor, the way I have done it is very, very labor intensive. In fact, my son has been out of work for a very long time, and my insulation project was also a way to give him some work and money. I sort of looked at it as an in-family WPA project, where projects were undertaken less to save money, but more to give people jobs.

You'd be out of your mind to just hire somebody do do this for you... So figuring labor into the two methods, spray on would come out ahead.

But you need to remember that I did put in 6" of sealed foam. I don't think there are many 6" sprayed foam walls out there.

I started out with EPS foam (the white stuff) but I have come to realize that XPS (PINK FOAM) has a higher R-value, almost the same cost (last time I checked), and does not shrink. Foaming all the edges 100% is very important. If you don't you're wasting your time and money.

Then there's this... my cash flow is pretty limited, and with my method I could do it in small increments, and as I had more money available, I could continue a little further.

The insulation has made a tremendous difference, in terms of heat retention and infiltration reduction. In fact, if you do this method or the spray on, you need to know that a heat recovery ventilator will be in your future, both for fresh air and also for humidity control. That reality really snuck right up on me, I wasn't expecting it.

Another big surprise, is that in early spring, the insulation is so effective, that my house doesn't warm up early like it used to. But I wouldn't say that it is burdensome... On the other hand, I don't turn on the heat as early in the year as winter approaches, either.

Quite often, in the summertime, people ask me if I'm running the air conditioner!

So one important thing, not immediately obvious, is that neither my method, nor spray-on foam have any appreciable humidity buffering ability. I'm looking for an HRV to help with that. I do know that dense-packed cellulose walls do have a substantial humidity buffering ability, and will take up excess humidity, and release humidity, if the inside air becomes too dry.

There was a slightly different approach that I learned about after I started the layered rigid insulation project... and that was to put in an initial sprayed foam layer of 1" to 2", depending on your location, and then dense-pack the remaining cavity. This would give near perfect wall sealing, and also give you the humidity buffering of cellulose. You would end up with a less expensive wall (with somewhat less R-value) and you would have the humidity buffer of cellulose. Sounds pretty good to me, and it would go up much faster.

But I have to say that I am amazed at the big difference this has made. I'm heating my living room, and I'm not currently heating my kitchen. In fact, I have an insulating door to keep the heat in the living room. But the interior walls in the house are imperfect, and some heat does leak into the kitchen. Most of the time it's not so bad, but there are other times when the thermometer really dips. I have found that when that happens, if I turn the kitchen oven to 'warm' the kitchen gets pretty comfortable.

There's also the angle of carbon foot print and environmental damage. Cellulose wins.

So, my whole house is an experiment in progress. And that's the result so far.

Hope this helps...

Best,

-AC

just remembered this forum and thought I'd pop in
 

Looks like you're doing some great work there! I'm still looking for an old run down place to fix up that I can buy cheap... not sure when or if that's ever going to actually happen though, but insulation and the start of a solar heat exchanger are definitely part of the plan. Interested to see how you get along with the work you're doing here!