Remodeling the office (new floor, ceiling & adding insulation) passive house retrofit
 

This weekend we took our first step toward remodeling our office. We've been talking about doing this since we bought the house. All of the 1st floor rooms have been remodeled except this one. It has some pretty beat up and stained carpet that is falling apart in places. The ceiling is also pealing due to some water damage that was done years ago from the previous owners. The problem has been fixed long ago thankfully. Also, I don't think that the exterior wall is insulated at all besides the thin piece of foam under the siding outside.

Anyway, the first step was picking up the new flooring. I'll be adding hydronic heat to the floor and will be putting bamboo over it. We picked up the bamboo this weekend. Its semi-thin (around 1/2" I'd guess) tongue and groove pieces.

I'll get pics of all this stuff up later.

I am very interested in how you approach this phase of your re-model.

As I recall, you already have fossil -fueled hydronic heating in part of your house.

And your solar panel rack and heat storage tank, both seem aimed at solar space heating... and may likely have lower temperature heat available to you.

I have experimented with Watts Radiant RadiantWorks and have found it very interesting and useful, especially when doing some 'what-if' trial runs. It has helped me understand how varying certain parameters can affect the system performance.

As for myself, I am beginning to favor the use of 3/8" PEX, spaced much closer than usual (3" or 4"), using a multi-tube spiral arrangement, as illustrated below.


...I am also favoring aluminum spreader plates like Gary's floor, topping the plates with 1/4" Hardibacker and finishing the floor with Marmoleum, which has very low R-value.

Best of luck with your project.

-AC_Hacker

Right now I have electric/hydronic heat since my gas tank water heater died. The only form of hot water I have right now is my on demand electric unit that is just enough for a shower. I do not plan on using it to heat the house this winter. I do plan on having the solar setup done before winter rolls around though and it will run off of that and the natural gas forced air.

But, I am unsure how I am going to do the floor. I am definitely leaning toward not pouring the floor in concrete and using the aluminum spreaders like Gary. I have not played around with tubing sizes though. I'll have to do some more reading through the DIY hydronic floors thread to catch up on whats being done. However, I do know I want close spacing so I can fully utilize the solar hot water for heating purposes. I'll definitely have to check out that link. Any suggestions are welcome.

I've usually kept this type of comment to myself on topics where people are remodelling, but I'm going to throw it out there anyway and will shut up if it's not appreciated.

FWIW: I'd strip the drywall off of the outside walls, inspect for wood damage and check out the wiring and then I'd have spray foam insulation sprayed to fill the cavity. Instant vapor barrier and best available insulation. Add new drywall, finish it, paint it and feel good about my work. I can't help but believe it would be more than worth it over the long term, unless I were planning to move really soon. Even then, with some photos of the open walls, it might be a great selling point to someone who was afraid of how much it would cost to heat and cool.

Definitely don't keep it to yourself! :)

I'm actually planning on doing a bit more than that. This one room will help me determine what I'll be doing to my upstairs which also needs hydronic flooring and wall insulation.

The current plan is to do something to further insulate the wall beyond just normal fiberglass batts. Spray foam is a great start for sealing purposes. Perhaps I'll try one of those DIY kits. However, beyond that, I'll also be thickening the wall. I'd like to end up with an R40 wall once everything is said and done, but I think that may be a bit much to ask for. I might have to settle with around R30. Since a traditional wall 2x4 wall is only ~R11 once you take into consideration the thermal bridging, that is quite a step up. I'm thinking of something similar to the mooney wall. I don't know how deep I'm going to make the wall yet though.

OK, let's go one step farther then. After the wall is spray foamed, before you drywall it, you add a layer of extruded polyeurethane in your choice of thickness. I know it comes in 1/2" up to 2" in my area. This takes care of that thermal bridging problem at the cost of a very minimal amount of lost room dimension. While the sprayed insulation + sheet foam insulation may not bring your number quite up to R40, I'd bet it would be quite nice and cozy.

OTOH, to meet passive house standards, mooney walls are probably the best choice. It's hard to beat a 14" or thicker wall with blown in insulation. In my area at least, homes as old as yours typically have large enough rooms that would accept a mooney wall setup without feeling cramped, with the likely exception of the bathroom.

I'll be following along on whichever choice you make.:)

I suggest you get some recycled polyiso, cut it to fit the cavities and spray foam it in place. That will give you a good air seal and an immediate R 16. Then I'd Larsen truss to the inside with plywood gussets and 2x3's and dense pack. You could easily get R 40 that way and it would be a lot cheaper/healthier than a full load of spay foam with a much higher R value.

S-F said
I'm not doubting you, but I'd love to read up on the research that speaks of health issues by spray foaming. If spray foaming is unhealthy, I'd sure like to take a different route than my current plans.

Even with 2 inches of polyiso I'm not seeing how I can get R16?

Larsen truss is a great idea that is also in the ol noggin for this project. I'm just not sure exactly how much I want to thicken the wall yet.

The current wall is 4" thick (old rough cut lumber). I'd definitely be willing to double that, and I think even add up to 6" (10" total thickness) to the insulation cavity (so drywall = extra). If I did two inches of polyiso foamed in place, and blow the rest in cellulose, that would get me to ~R40.

The other thing is that I do not have 6" to spare in the upstairs. The rooms are already pretty small and the less room I loose the better.

Most of the recycled sheets of polyiso are 2.25" which are something like R 15.7. They are called R 16 boards.
There is a growing body of evidence suggesting that spray foam , while nothing like UFFI, may still have some negative qualities. The catch is that once it cured it's supposedly completely neutral, but only when mixed properly. Apparently when it's not mixed properly there can be a lot of issues. And also it appears to be pretty difficult to get the mix correct. Even for seasoned professionals.

And besides, cellulose is awesome. Sure the R value is a little bit lower but the other benefits are fantastic. The hygroscopic value of it is amazing. I wish my walls were 12" of cellulose. It's also probably the greenest insulation there is.

Where does one find this recycled polyiso? I don't think I've ever seen anything but normal polyiso.

Good question. There are insulation recycling places all over. I know of two within 100 Mi. of me but that doesn't really help you. I'm sure one of the places here could ship to you for about $500 but unless you were getting a lot it probably wouldn't be cost effective. You can often find smaller insulation recyclers on craigslist. Just search for "insulation". If you get a price break on larger orders and you have storage space it might be advisable to get as much of the stuff as you'll ever need. I'm thinking about the portions of your upstairs walls which don't meet the attic but the roof. How are you going to get those areas to R 60?

Take my basement project as an example. All the polyiso was recycled. I got the boards for about $13 a sheet for 2.25" instead of something like $37 for 2". Shipping was a couple hundred and is calculated into the total cost per sheet. I think I also got a 5% discount due to the large volume.

An other option is EPS. It is still a petrochemical but it's a lot cheaper, is much more vapor permeable, is still an air barrier and it made all over the place. And you can order it in any dimensions you want.

Me personally, I wouldn't use foam boards at all. I'd spot caulk/foam the sheathing and just dense pack. But I'm not going to do that in my house because I don't want to loose 8" at every wall so I'm going to dense pack the existing cavities after pulling the fiberglass out and then take a REMOTE like approach to outsulating.

Outsulating may be in the future, but not the near future. Especially not if this works well. :)

I'll definitely have to weigh the differences between spray foaming the cavity with a DIY kit and doing foam board. I think both are good options for sealing though.

Here is a bit more info on the office. I will get pics up yet! But, here is the layout of my house. As you can see, only one wall of the office is an exterior wall. The room isn't tiny at about 14.5' x 14'. But, this should be a relatively easy/small project to test out how I want to do all the walls upstairs.

http://ecorenovator.org/forum/attach...1&d=1312904917


The angled upstairs ceilings will definitely need some good insulation, much better than what is there now. I haven't even really thought about how I'd do those yet.

After doing a little research and pricing I think I'm leaning toward using rigid foam and great stuff. There is added work there to install it, but the price difference is pretty huge. A 200 board foot kit of spray foam would cost me $425 shipped. That would give me about 1.75" thick layer on the wall with an R value of just under 11. Alternatively, I can get 1" polyiso with an R value of 6.5 for $60 for the whole wall. Great stuff would be an additional $20 maybe? If I wanted to double up the polyiso I could easily do that and still be at half the cost of the spray foam.

As I've been fixing the basement in small pieces here and there I've used rigid and great stuff in the small cans. It lets me do it a couple of feet at a time if need be. end result may not be the best but it's a hell of a lot better then the nothing that I had before

This is the technique I have been using in my house.

At first I was cutting the foam to be a tight fit, very, very time consuming. Finally I realized that if I left about .25" all around and used Great Stuff to fill these gaps, it was both faster and more effective. Care must be taken to keep the great stuff from getting behind the foam panels, as it will push the panels forward.

-AC_Hacker

So you found a source of recycled polysio? I personally recommend polyiso for this application which is not foil faced. The foil make a complete vapor barrier which you don't need. You want the wall to be able to dry to both the outside and inside if possible. One of the great benefits of the recycled stuff is it's faced with fiberglass and paper so it is still mildly vapor permeable. And it's worlds cheaper.

I checked out craigslist and wasn't able to find anything unfortunately.

However, I was thinking about moving the polyiso layer to the inside of the wall. With a thin layer of furring strips on the outside I could utilize the foil facing as a radiant barrier in addition to the excellent conduction barrier the thicker wall will be. Since the wall's r value will be so high to begin with, do you guys think that there is any benefit to doing this?

Can you get Polyiso which isn't foil faced? I'm all for not demanding that moisture stay in one place because you can end up with problems if there is too much of it. Talk to some local green builders to see if they can point you to recycled foam boards. Call all of 'em if you have to. This is going on all over the country.

About your idea, if you later decide to outsulate you might be in a bit of a pickle. It's not advisable to have two vapor barriers in a wall. The moisture that inevitably gets trapped in there has no avenue of escape and you get rot and mold. Personally I think it's nuts that people sandwich OSB/CDX sheathing between spray foam and foil faced polyiso but there haven't been any disasters yet that I've heard of. Maybe in 30 years we'll see the truth. But none the less, putting fiber glass or cellulose between them is a no no. Also it's best to have your air barrier (polyiso and 1 part foam sealant) on the outside to minimize unconditioned air entering the cavity and convecting. All your insulation is next to useless if you have cold air cycling through there. The big advantage of the foil on polyiso sheets is that you can quite easily seal them together with foil duct work tape. Otherwise you need to seal boards together with spray foam. Some people say you can use tyvek tape but in my experience that stuff doesn't last more than a decade.

Oh, one more thought. You could put the foam boards on the inside if you air sealed the sheathing properly. This is effectively no different than putting it on the outside of the sheathing as far as moisture is concerned. You just completely eliminate the wall's ability to dry to the inside. Just don't make a vapor barrier sandwich and make sure that outside air doesn't get in. That's why I originally recomended the boards and 1 part foam. It's a relatively cheap (compared to filling the whole wall with spray foam or even filling it 1" deep) way of creating a fantastic air barrier. You kill two birds with one stone there. Oh and if you do try to dense pack the wall yourself you will have no way of knowing if you did it right. At first dense packing can be a little tricky. Even today I still am uncertain when dense packing a cavity I can't test. Well, at least I can't test it until the cold weather hits and the thermal camera shows me what a stupid job I did. :P

And your price on the spray foam looks berserk. I think that's about what I paid for the 600' kit. I think even on the Tiger Foam page they list it at $250 for the 200'' kit.

my used polyiso has some sort of paper backing that looks a lot like tar paper. I've never seen anything other then this but polyiso isn't the most common up here.

I'll have to dig into this more. I've only seen foil faced in the big box stores though.



Thanks, I wasn't thinking about the outsulating. I would imagine that would be an issue, especially since I don't have A/C and my house gets incredibly humid during the summer months.



I was looking at their site just the other day and the 200' kit is $335 and $90 for shipping! :(

Call around to your local suppliers then. You might be able to have a lumber yard that sells green building products order one. Or you can see if you can get a contractor's account with Tiger Foam. Then you get a discount.

I came across this very well written article on roof venting, but there is much in here that will apply to your remodel.

Oddly, it prohibits your being able to print it out... but we have ways...

-AC_Hacker

I've been thinking more about how to do the hydronic floor and I'm looking for a bit more input. I'm definitely going to go the route of tubing with heat spreaders instead of a poured floor. I haven't yet been able to download the watts program and play with it. Is there a large benefit from going to the three 3/8" lines in parallel vs just a single 1/2" line?

{some of this was covered here}

I came across a study by Siegenthaler (the guy who wrote the book) and he was comparing the effects of using several different PEX diameters...


As I recall, the bigger the diameter, the better the heat transfer, tube spacings being equal. However, the difference between 1/2" and 3/8" was very small... as I recall it was around 3% difference... pretty small, all things considered.

I've also seen studies, and learned from working with computer models (this is where RadiantWorks was so helpful) that the increase in heat transfer that results from decreasing tube spacing is large.

And the bending radius of 3/8" is favorably smaller, too.

When I first came across the concept of Low Exergy Heating (AKA: low temperature heating), I spent a couple of weeks on a massive google-blitz from which I learned that there was not much work that had done on Low-Ex heating in the US, and that the really important work had been done in Europe a decade+ ago. So that lead me to all kinds of installations and products that had been developed for this purpose. And there, over and over again, I found very closely-spaced tubing configurations... like around 3 to 4 inch spacing (or closer).

One of the most interesting studies I found was Chinese (they are graduating 400,000 engineers per year as opposed to our 80,000) where they experimented with an extruded plastic floor with small heated water channels, side-by-side. The material tests were very, very favorable.

Nowhere during my pursuit of Low-Ex heating information did I come across spacings of 9" and 12"... This is American fossil-fueled foolishness.

Back to wet system (poured concrete), one of the big determiners of spacing is a desire for even heating. The radiant-heating trade even has a term for cold spaces that result from tubes being spaced too wide. they call it 'striping'. Striping results in parts of the floor that feel cold to the feet, so it is to be avoided. So tubes are spaced more closely to avoid striping.

Thick slabs are less likely to stripe than thin slabs... Minimum thin slab thickness is about 1.5" before striping occurs... But in all these considerations, tube spacing was in the 8 inch range.

And again, if you look at Gary's thermal photos of aluminum plate spreaders, the heat falls off as you move away from the tube... closer tubes, less heat fall off.


So the heat that comes off a floor is the average heat of the surface of the floor. Floors that have a large variance in temperatures will need a higher feed temperature than floors that have a lower variance, to achieve a given heat output.


If you are using cheap fossil fuel (remember that stuff?) a difference of a few degrees is hardly worth concern. If you are going solar, it means more days that you can use 100% solar, if you are using a heat pump, the energy savings are very large.

I can certainly see that if you are a tradesman, installing radiant floors, you would want to get in, get the job done, and move on to the next paying job, and not fiddle around with a swarm of closely-spaced tiny tubes.

But then there's DIY...

Regards,

-AC_Hacker

PS: I think spending a couple of hours with RadiantWorks is much more educational than spending that time reading a book... and it's free.

Great info AC Hacker, thanks!


Just stashing info here for the time being.

BASSI,LLC

Since my flooring is only about 1/2" I'm guessing the R value is around 0.50.

RadiantWorks has a very interesting chart that will give you the water temp for the space you are working on...

It takes into account outside design temp, inside design temp, insulation of all surfaces and windows, etc.

You can change individual components (floor covering, for instance), do a re-calc and see what effect that has on feed temp.

Very informative.

-AC_Hacker

Is this software only for radiant heat?

Well, it is designed to support a radiant heating supplies company.

It does heat loss calcs so that you can select the appropriate equipment, which of course, they sell.

It does do a good job of heat loss calcs, so you could use that part of it only.

-AC_Hacker

Is it for mostly in floor radiant or does it also cover baseboards?

As promised, I got some pictures.

Here is a circle of pictures of the office. Yep, its a horrible mess as we're still moving things out. Obviously the wall with the door is the outside wall that will be thickened.

http://ecorenovator.org/pictures/office001.JPG

http://ecorenovator.org/pictures/office002.JPG

http://ecorenovator.org/pictures/office003.JPG

http://ecorenovator.org/pictures/office004.JPG





This is the wonderfulness that we will be fixing as we go along.

http://ecorenovator.org/pictures/office005.JPG

http://ecorenovator.org/pictures/office006.JPG





Here we have a sample of the bamboo flooring. As you can see it is an engineered board and it is prefinished. Its also about 9/16" thick.

http://ecorenovator.org/pictures/office007.JPG

http://ecorenovator.org/pictures/office008.JPG

http://ecorenovator.org/pictures/office009.JPG





This is the stack of flooring I have in the sunroom right now. It is 100% FSC (Forest Stewardship Council) certified. I'm going to have to read up a bit more about what that exactly means.

http://ecorenovator.org/pictures/office010.JPG

http://ecorenovator.org/pictures/office011.JPG

They are a radiant floor outfit.

There's a company called Slant Fin that does floors & radiators. They used to give away a dandy little program that did it all. I think they still give away a spreadsheet version that does the same thing.

Both of these companies assume higher feed temp water (fossil fueled), but can be tweaked to the low end.

I don't know of an American company yet that specifically goes after the low temperature radiant heating market.

Upinor used to have a free program, but no more.

Taco has design software that might work for you.

Here's a computer tool resource page.

-AC_Hacker

Hey Daox, have you continued to troll craigslist? I was just browsing the local one and saw two new entries for board insulation in the past week. Your climate is probably a little harder in the winter than ours so I imagine people have been using this stuff there for years so there must be a market for recycled materials. It comes off the roofs of warehouses and is great because it's 1/4' thicker and isn't foil faced. And it relatively cheap.

Yeah, I've been searching here and there and still no dice.

We started with the actual work today. We started by removing the old trim. Then we moved on to taking out the ceiling. It was quick and easy, just drywall.

http://ecorenovator.org/forum/attach...1&d=1314493364

http://ecorenovator.org/forum/attach...1&d=1314493462



Lastly, we pulled up the carpet which was quite a mess. The foam was fairly well stuck to the wood. I assume this is a factor of time and moisture. We scraped it as best we could but there is still a layer of foam here and there. I don't think it'll be a problem since we'll be putting everything over the top of it and it doesn't stick up much at all.

http://ecorenovator.org/forum/attach...1&d=1314493421

http://ecorenovator.org/forum/attach...1&d=1314494660

http://ecorenovator.org/forum/attach...1&d=1314494660

So, this is how the floor looks now. I'm debating taking a random orbit sander to it just to smooth things over. Some of the carpet foam pulled the wood right up and there are splinters that need to be dealt with.

One question I will pose to those out there. What is the best way to deal with the drywall and carpet?

http://ecorenovator.org/forum/attach...1&d=1314494949

Oh Snap! I have been wondering about this project!
Nice work.

About the padding, it's probably a good idea to get it up. Just my opinion. You'd probably be fine leaving it there though. If you use an adhesive for the floor you'd certainly want to get it up. A heat gun, a putty knife and a cold beverage would take it up with no damage to the subfloor. Sanding can get really messy. The kind of mess that's hard to clean up because it gets in every little crevasse that you will never know about. But on that note, you'll be doing drywall so... you're screwed like that any how.

About getting rid of the demo waste, I have found that for small jobs it's cheaper to get a junk removal guy to take it away. They might even give you a break if you help them load it up. Dumpster rental is usually for a week or so and is pretty expensive. If you only need it for one hour it makes no sense. That's what I've always done for my personal renovations.

Nice work!

I have a truck so carpet goes to the dump(the only option for disposal here) and drywall goes to a recycling center which is also the only option here. If bringing in a dumpster or one of those junk removal companies they'd force two loads since they are doing the same thing in the end.

For more creative uses I've heard of people using the carpet as a liner pad for ponds and drywall can be broken up and mixed into gardens but that's assuming it's pure. No paint, no filler with strange additives... I wouldn't do it with used stuff and I doubt it's worth the hassle if it was brand new

Regarding Hydronic Pump Selection...
 

Daox,

I don't know if you have done hydronic heating before, or if you have gone through the steps to size and select the proper pump...

The reason I mention it is that the process of selecting a pump for a hydronic floor is essentially identical to selecting a pump for a GSHP loop field.

I have discovered that the way you construct the piping for the loop field (and radiant floor) has a great deal to do with the power that the pump is required to have, and thus the cost of running it over time.

I really wish I had known all this before I put in my loop field.

I found that this document published by Taco is very clear, very useful.

I have also discovered that the various pump manufacturers are now making 'smart', variable speed pumps, that have the ability to monitor their own output and to self-adjust for maximum efficiency (they use permanent magnet motors and use a variable frequency scheme to adjust speed). Additionally, they are able to use the most effective phase angle for startup, and to feather it out to a different phase angle for steady operation.

This Gundfos pump is one example of that type of pump.

These smart pumps are more expensive initially, but will be cheaper in the long term.

Lastly, if you choose your materials and components carefully, you can avoid the extra expense of a bronze or stainless pump.

Good luck on your project...

Regards,

-AC_Hacker

I'm still debating how exactly I'm going to do this all. I'm all for any input you guys can give.

The solar hot water panels will be a drain back system. This means that the tank will be open to the atmosphere. I was originally thinking of running the floors right off the solar water tank, no heat exchanger. Remember, I'll also have a boiler in the mix here as backup for the solar. So, I'm guessing it'll need to have a stainless heat exchanger and the pumps will need to be bronze or stainless as well.

The other option would be a closed loop / low pressure system for the hydronic heat. It would use a heat exchanger in the solar hot water tank to pickup heat. Using that and oxygen barrier PEX tubing would allow me to avoid the bronze/stainless components.

Yet another option would be to run the boiler on a tiny loop just to heat the solar tank should the temperature drop too low. This would allow me to ensure the boiler never short cycles, but I don't like the idea of keeping the water at X temperature. I'd rather it just vary as the solar provides heat, and just use the boiler when absolutely necessary.