Hey guys I have been looming on here for a while now and am at the point where I really need to hammer some things out. I will be breaking ground as soon as the weather permits. I am building a 32x42 timber frame (I have a mill and 200 acres so the timber is what makes this possible). This is in Maine within about 3 miles of the coast. My plan is PERSIST. WALLS: frame tongue and groove grace ice & water 4" iso or xps (leaning xps because of cost here) Tar Paper or house wrap strapping vertical then horizontal across those board and batton siding ROOF: frame tongue and groove grace ice and water 6" iso or xps tar paper or rooftop guard 2x4 strapping vertical then 5/8 osb tar paper metal roofing HEATING: Slab (with 2" xps underneath) with radiant On Demand system for domestic and radiant Wood Stove (200 acres of wood) HEV system The wood stove will be the primary heat. The on demand system is to keep the slab at around 55 to 60 degrees. And to make sure it stays fairly warm if we leave for a few days or so. Ok this is a new way of building for me so I am open to any criticism. My questions are: 1. Does this make sense or am I causing problems here? 2. Is this safe to have a wood stove in? Not killing my family is high on the list. 3. Is this enough board insulation or should I go 6" on the walls and 8" on the roof? I have a lot more questions but I will start with that. Thank you guys very much for getting me this far and for any help from here on out.

do you have good solar exposure? Overall your plans sound good, but I'd increase your depth of iso as much as possible. As valuable as increased R value is that the house be as airtight as possible. that requires that the woodstove be airtight also, that it be connected to an outside air vent and, as with any tight house, install a good heat recovery fresh air ventilation system.

Ok that makes sense. I was planning on using a wood cook stove I have that has been in the family for a long time. Does that sound like a bad idea then or is there anyway to make that work? Its not a huge deal but I would really love to use it. I do plan on having an HRV. When you say connected to an outside air vent do you mean something specific for the stove by itself or the HRV? I am on pretty flat terrain where the house is going to sit so there will be some southerly exposure.

ideally the air duct would go directly into the stove. I know what you mean about the cookstove; we had one for years & now it's in my daughters starter house where she used it for the sole heat for several weeks this winter until the gas heater was installed. I loved using the stove, but it was/is very leaky. Woodstoves and fireplaces are difficult subjects, especially in New England, in airtight houses. The toxic gases produced weren't big issues in our old drafty houses, but can be huge issues in today's better build tight homes.

In a superinsulated house with some passive solar gain you shouldn't need much auxilliary heat, so the "need" for a woodstove is reduced (it could well overheat the space). I can't tell you how well they work in such a house, but we're just finishing such a house, which will have a new airtight woodstove and a wood burning fireplace. Both have direct air intake and the fireplace has a chimney top damper. We know we'll lose heat from the chimney; how the air quality is affected is something we'll have to find out.

Here's a radical suggestion that I've used for many years. About once a week or two, during the winter we go around our house and open every single window as wide as possible for about 5 or 10 minutes. Preferably do this when there is a breeze. This does a wholesale replacement of the air in the house without cooling off any of the mass of structure and furniture. It works very well when there is a woodstove in use and that woodstove "aroma" has built up. I'm all for ERV's and HRV's and they do work but they are a bit like trying to replace the water in a bucket by putting a few drops in and taking a few drops out as opposed to dumping out the whole bucket and refilling it. Yes, there is an energy hit to "purging" the house but I think it's small as the only energy lost is the energy embedded in the volume of air in the house - there isn't time enough for the thermal mass of the house to give up its energy. In my experience the boiler only runs very briefly to recover and the house is back up to temp in minutes after closing the windows.
A interesting side story - I am an architect and have designed many schools and renovated many old ones. I spoke with an elderly nun who taught in an ancient Catholic school (with huge hot steam radiators under the large windows and no real control) She told me that about 1:30 or 2:00 the kids, full of lunch, would start to nod off (I suspect rising CO2 levels as well). At 2:00 she would open all the huge classroom windows for 5 minutes even it it was -5 out. She said all the kids were alert and good for the rest of the day after that. There's a low tech solution for every high tech problem! The other single best thing you can do for IAQ, in my opinion, is a central vacuum system that exhausts directly outside. My wife has severe alergies and this has changed her life!

HEATING: Slab (with 2" xps underneath) with radiant On Demand system for domestic and radiant Wood Stove

Is that 2" of rigid foam code minimum for Maine? Have you looked up Frost Protected Shallow Foundations? You will need insulation around the edge of your slab, and, very likely, extending outwards like "wings". You're going to need a minimum of 4" and for a radiant slab, you will probably want 6" in places.

And, not only do you want a direct vented fireplace, but you also want it sealed, both for pollution and for efficiency, not to mention the safety.

Ok so if I had a high efficiency epa rated stove and an HRV system would I need an outdoor air supply?

Interestingly enough, the "EPA Certification" only deals with the fireplace emissions and not with the suitability for an energy-efficient home. You need a sealed unit with an independent combustion air supply that can be ducted from the outside. Anything else uses your room air for combustion to varying degrees and sends it up the chimney.

I can appreciate the nostalgia of the old cook stove (I lived with one for years in Vermont and except for 45 minutes to make toast in the morning I loved it) but if this house is going to be sealed so tight (I question 100% coverage with Ice & Water though) and wood is the primary heat perhaps an outdoor wood boiler is the answer. You loose the nice part of standing next to the woodstove when you come in from out side but you also eliminate the make up air issue and the IAQ issues. The boiler could heat a large buffer tank that would then feed the radiant and adjust with a mixing valve.

If you want the heat from a stove maybe a dinky stove like the Sardine http://www.marinestove.com/sardineinfo.htm would do it ;-) !

Thanks guys. I definitely want an indoor wood stove. I am willing to part with the cook stove in favor of something less "leaky." I have thought about an outdoor boiler and it is a great way to go just not what my wife and I have in mind. I am thinking that maybe I need to re examine what I am doing here. Wood stove is a must yet high efficiency is a must as well. If I start from square one. Just the frame. What should I do to make this work any ideas? You say you question 100% Grace as do I it is just what I have read. What are my alternatives? I was in residential and commercial metal roofing for quite some time. The standard in commercial was roofdeck, 8" minimum of ISO, then grace, then the steal panels screwed to the roof deck bellow. That seems to be backwards from what I am reading. I think I am getting more confused and further from a decision......there is a lot of conflicting information out there....

I am also reconsidering how much foam under the slab. I have always used 2" (My father has built log homes in Maine for 30+ years), however, I recognize that that is simply because "that is how we have always done it." All of those homes were either cedar log, or stick built pink fiberglass homes, none of which would be considered high efficiency....

I think the roof issue has to do with moisture, which is always generated in a home (people breathing, cooking, bathing etc). The commercial roof you describe is a version of what Joe Lstiburek (Building Science Corporation) calls the perfect insulation system, as it is completely outside the building's structural envelope. Converting this to a residential application means determining what is happening to the interior moisture so that it does not become trapped inside the walls and cause rot and mold. In short, the concept is that the exterior wall must be allowed to breath and dry to the interior, the exterior or, ideally, both, while remaining airtight. With exterior polyiso, exterior drying isn't possible, so it needs to be able to dry to the interior. Buy and read Joe Lstiburek's book "Builder's guide to Cold Climates" which goes into great detail about all of these issues. you can also go to his company's website http://www.buildingscience.com/ for additional information & studies, and the website http://www.greenbuildingadvisor.com where you'll find articles about specific houses as well as ongoing discussions with experts about these topics. Note that there are several articles there about superinsualated projects in Maine.

Thank you Bob I will do!

Use at least 4" under the slab, but 6" would be wise in your location. A thermal break at that location is important, and can be done as follows: have the subslab washed stone brought to 2" below top of the footing, and butt the bottom 2" foamboard into the footing. the top 2" foamboard extends to the foundation wall, covering the footing, and a vertical 2" piece against the wall (adhered with foam compatible adhesive) provides a thermal break at the edge of the slab. This whole assembly ensures that the slab is not a highway for heat to be drawn out of the house. Cover the foam with a layer of 6 mil poly, tape the seams, pour the floor.

You might look up Quadrafire stoves and see if there is something in there that is interesting to you. It is one manufacturer that I know has "outside air kits" available. This is a confusing item, because when I was getting bids on my fireplace, the subcontractors kept dropping the requirements for the "outside air kit". When I mentioned it, they would always say that those are only required on mobile homes *snicker*. Turns out the requirement is because only mobiles are built tight enough. That is changing, of course.

Bob do you know if there is a detail of what you are describing to look at anywhere? I think I get what you are saying but looking at it would be a benefit for sure. ICFHYBRID, a problem I see is how I get a duct of air to the stove. It will be in the middle of the house on the slab with no walls from the exterior walls to the stove. It will be against a brick partial wall that separates the dining room from the living room and is open walkway on each end which extends all the way up to the cathedral ceiling.

A couple of comments:

US style outdoor woodboilers are an air-pollution nightmare compared to right-sized EPA-rated woodstoves due to their bang/bang type controls that instantly air-starve when the buffer tank's aquastat is satisfied rather than modulating with load, leading to 10s of minutes of EXTREME sooty-particle emissions at the end of every call for heat.

High-R houses have very low peak loads compared to the output of most woodstoves, so it's important to do a Manual-J or I=B=R type heat load calc before buying a stove. (The LAST thing you'd want to do is go with a "heats xxxx square feet" type of rating for the stove!) Going with anything with a firing rate more than 2x the design day heat load would force you to burn at firing rates below the best efficiency/lowest pollution (by the time you get the thing up to a temp where the catalytic converter or secondary burners on a non-catalytic stove light off consistently the place might feel like a sauna.)

You can get around this somewhat by going with high thermal mass ceramic or soapstone stoves, or for a lot more money, high mass masonry heaters. Hearthstone sells some reasonably small (< 40KBTU/hr max fire) EPA-rated soapstone stoves that have exterior combustion air options. Wittus makes a nice range of soapstone clad stoves with <30KBTU/hr max output, (optimized for high efficiency @ ~20KBTU/hr) that have outdoor air kits optional too.

The down side to high mass stoves is when you want to bring the temp up quickly in the house, but a high-mass stove can still be dumping heat into the house several hours after fire has died back to near-nil, and you can space burns rather than the more frequent reloading you might have to do with a tiny cast-iron stove. If rapid heat up is a desired goal, Morsø has some pretty small cast iron stoves that take piped in combustion air that may make sense, but the smaller the cast iron stove the less likely you are to get an overnight burn out of them. The Vermont Castings Aspen is a classic little 18kbtu/hr unit that has an outside air kit available too, but I doubt you'd get an overnight burn out of it.

There are others. Calculate the heat load, see where it is, but unless you have a lot of glass a tighthigh-R house that size is likely to come in under 20kbtu/hr at the 99% outside design temp. For 99% design temps see:

http://www.energystar.gov/ia/partners/bldrs_lenders_raters/downloads/Outdoor_Design_Conditions_508.pdf

Find a nearby listed town and guesstimate, &/or compare weatherspark.com data to a listed town.

a problem I see is how I get a duct of air to the stove.

Form a chase under the slab, or just bury the duct in it directly.

new airtight stoves should have a connection to attach an air intake duct.

Thank you Dana, my 99% outside design temp is -2 F. Increasing the insulation to 6 on the walls and 8 on the roof gives me right at 20K btu/hr with the rvalue of xps. I really love the look of some of the stoves you mention with the soap stone but my budget definitely wont allow me to spend 5k on a stove. I will start looking though. ICF I was thinking that about going under the slab any ideas on where to go with it when it comes up out of the ground?