building a house

[svon89]

If you decide to go with 2x6 walls and foam, don't forget about insulating the headers and corners. Sometimes framers will build the corners closed(so that it can not be insulated once the outside sheathing is on) and the headers with a 2x6 top and bottom with the 2x8 2x10 or 2x12s on the inside and outside. Once those are in there isn't any insulation in between the header stock. You can drill a couple of holes and shoot the foam into the closed corners and headers, but you have to remember all of them. Also when you install the windows and doors use spray foam around them, just make sure that you use the stuff meant for windows and doors. It doesn't expand too much and push either the door or window out of alignment.

I did go into one house at some point in time that used 2x8s for the top and bottom plates, then had 2x4's staggered every 8 inches so the interior sheetrock was not in contact with any of the studs that were on the outside wall except the top and bottom plates and the corners. I am sure it was a lot of work, but the house was extremely quiet and tight.

 

[mtfallsmikey]

And...watch out for that corrosive Chinese drywall!

 

[AIM]

Use the BEST doors and windows money can buy!!!

Common thing around here is 2X6 walls with a skim coat of spray foam and then batts. Seems to do an excellent job.

Did I mention to use the BEST doors and windows that you can buy...

 

[Flapjack23]

When I built mine a few wears back I went with 2X6 and wet cellulose in the walls, sprat foam in all the corners, headers, and bonds. Attic was 14" or 16" of cellulose. Put in geothermal. Needed about 60,000 BTU unit, it has never been short. 2600 ft. with about 2 weeks in the winter where it doesn't get over 0F. I wish I would have put in a decent soapstone stove instead of the gas fireplace though. Would be nice to have a fire at night to help give the geo a rest.

I helped a buddy build a house with SIP's for his parents. Took 3 of us to put up the panels and screw them down. Heck of a ridge beam though.

Andy

 

[John D]

2x6 walls are fine,Icynine spray foam,(should be govt rebate too) on that.triple glazed windows doors.R10 around the concrete slab/walls,and 2-4 fr underneat the outer edges of the slab its a slab on grade.You will need an air exchange system with that setup it will be so tight.

 

[Rob G.]

There is another way to frame a 2x6 wall to make it insulate better.
The insulation slows heat loss in the stud bay, but there can be heat loss from the studs themselves (I forget the term, maybe heat transfer?). One way to stop this is to frame so that no studs touch the sheetrock and the sheathing. To do this you use 2x6 sole and top plates, but 2x4 studs that alternate between touching the sheetrock and touching the sheathing. Then when insulating the majority of the wall has the same insulation as a 2x6 wall, but where the studs are there is about 2" of insulation instead of none. Structurally, the compression strength of the 2x4's is plenty. The main reason that houses are framed with 2x6's is for insulation. I don't remember the stud spacing, but I think that it might be 12" oc so that 24" wide insulation will fill 2 stud bays or maybe 16" oc and use foam insulation. Of course, any non standard framing will be more expensive due to increased labor and material costs.
Hope this helps.
Rob

 

[FIRESMOKE]

Use 2 x 6 walls with spray in foam insulation, then put 1/2" or 1" styrafoam on the outside then osb wall sheeting. It will increase R - value some for you.

 

[Slick]

I like Rob G's alternating 2x4 stud idea, I've seen it used before for sound insulation/isolation in home theaters etc, it works great and yes it would add more insulation.
I'm not sure if I agree with everyone that 2x6's are enough though...what is enough? Not that many years ago 2x4's were "enough" insulation..now 2x6's are? Energy is only going up....

 

[Slick]

forgot to add...if SIPS gets your attention check out ICF's...as tight as it gets.

 

[kielbasa]

ICF is such a no brainer, I'm surprised someone hasn't mentioned it sooner......I wouldn't even THINK of building something out of two by sticks........

 

[kielbasa]

note to self...next time read entire thread before posting - i see a couple of you guys mentioned icf already.....
seriously, if you want to build a house once and build it right, you NEED to study up on ICF construction....

 

[Taxmantoo]

Use 2 x 6 walls with spray in foam insulation, then put 1/2" or 1" styrafoam on the outside then osb wall sheeting. It will increase R - value some for you.

IMO, foam sheet is a total waste of money when you put it over sprayed in place foam.
Last quote I got (a couple of years ago) was somewhere around $2.80 per square foot for 5 1/2" of sprayed foam. It's good stuff, but I won't pay that for it. Blown in cellulose is more like $0.01 per R number per square foot, or $0.30-0.35 per square foot for R-30, and it's pretty good at sealing and quieting outside noises. (cellulose is not as airtight or as quiet as foam though)

 

[davec]

If you use conventional stud framing, then foam board over the outside is a very good aid to the total wall efficiency as the studs are very poor insulators (no matter what wall insulation is in between the studs. The foam covers them up and adds overall insulation value and air sealing. Wet-laid dense pack cellulose is cheaper than spray foam but does not seal as well. But it is still much better than fiberglass. Fiberglass is really poor insulation, especially with many other alternatives available today.

If you are going to frame conventionally there are techniques called "advanced framing" (or something) that use 24" stud spacing by lining up studs under roof trusses, which also allows single top plates due to better load path transfers. You also are wise to design and build to the 24" spacing as much as possible for windows and doors to eliminate as many additional cripples and other studs that could be needed typically.

Roof trusses should be "energy trusses" or "raised heel" trusses that allow deeper insulation over the top plate than conventional trusses do.

The double wall trick also works well, though it is a PITA to frame. If you are going to do that you should use 2x8 plates for some real good insulation depth for not a lot of additional cost (extra insulation and 2x6 vs 2x8), if you are going to all that effort already. You are going to have to make jamb extensions for just about any window in a wall that is deeper than 2x4 anyways.

ICFs are a good alternative that several have mentioned. They are very solid, but you need to watch installation carefully to ensure the concrete pumper gets a complete fill without voids. It is hard to do.

Personally I like SIPs a lot. Some stud framing techniques as described above and by others can also be done very well and don't require significant additional skills. No matter what you pick, there are trade-offs and drawbacks to any system.

This is not a trivial topic. There is a lot of science built up over the years in building energy efficiency and air sealing. That science is worth significantly more than the opinions of a few people on a firewood forum.... If you are serious about doing it right, you have some research ahead of you. You can read for hours at www.buildingscience.com (no affiliation, I just find their work to be impeccable). www.finehomebuilding.com is another good resource and www.jlconline.com (journal of light construction)

-Dave

 

[mtfallsmikey]

If you use conventional stud framing, then foam board over the outside is a very good aid to the total wall efficiency as the studs are very poor insulators (no matter what wall insulation is in between the studs. The foam covers them up and adds overall insulation value and air sealing. Wet-laid dense pack cellulose is cheaper than spray foam but does not seal as well. But it is still much better than fiberglass. Fiberglass is really poor insulation, especially with many other alternatives available today.

If you are going to frame conventionally there are techniques called "advanced framing" (or something) that use 24" stud spacing by lining up studs under roof trusses, which also allows single top plates due to better load path transfers. You also are wise to design and build to the 24" spacing as much as possible for windows and doors to eliminate as many additional cripples and other studs that could be needed typically.

Roof trusses should be "energy trusses" or "raised heel" trusses that allow deeper insulation over the top plate than conventional trusses do.

The double wall trick also works well, though it is a PITA to frame. If you are going to do that you should use 2x8 plates for some real good insulation depth for not a lot of additional cost (extra insulation and 2x6 vs 2x8), if you are going to all that effort already. You are going to have to make jamb extensions for just about any window in a wall that is deeper than 2x4 anyways.

ICFs are a good alternative that several have mentioned. They are very solid, but you need to watch installation carefully to ensure the concrete pumper gets a complete fill without voids. It is hard to do.

Personally I like SIPs a lot. Some stud framing techniques as described above and by others can also be done very well and don't require significant additional skills. No matter what you pick, there are trade-offs and drawbacks to any system.

This is not a trivial topic. There is a lot of science built up over the years in building energy efficiency and air sealing. That science is worth significantly more than the opinions of a few people on a firewood forum.... If you are serious about doing it right, you have some research ahead of you. You can read for hours at www.buildingscience.com (no affiliation, I just find their work to be impeccable). www.finehomebuilding.com is another good resource and www.jlconline.com (journal of light construction)

-Dave

That there is a mighty fine post, Dave...rep for ye!

 

[slowp]

Wanting to build a new house, been living in an old drafty house. Wondering what your opinions are on the exterior wall thickness over the standard. I am wanting to built the most effecient house possible.

What is your budget for building the house? I moved into mine in July. I have a simple, low end house. It actually came in just a bit below the estimate.

I have 2x6 exterior walls with fiberglass batting, and batting in the ceiling. The windows are some kind of filled pane ones. Our style here is to have a lot of windows in the living room areas.

The builder, and it may be code here, installed a whole house fan to offset the air tightness. The windows have little vents that can be opened and closed to work with the fan. I have not shut them off so far.

The house stayed fairly cool during our heat wave of 100 degrees. That is extreme weather for here. The heat did build up to where one night it only cooled off to 79.

I couldn't orient it to the South, but it has the big windows on the East and West sides. I do have friends with a passive solar house and it works well for them.

The house has Cadet wall heaters in each room. I'm not a fan of air ducts.
I have a woodstove which is working real well. There's a cathedral ceiling in the main room so I have a ceiling fan. My first power bill is on the low side, but we have cheaper power here than anywhere else, so that is a moot point.

I believe 2x6 walls are now pretty much standard here. Start now while the lumber market is still tanked. Make sure your lumber comes from Warshington State--shameless plug for us. It's better from here.

 

[Curlycherry1]

Another big vote for a whole house fan. We have a ~36" one in our attic connected to the envelope part of our house. I can open windows and turn that fan on and exchange every molecule of air in the house in just a few minutes. So for those days when things cool off I can open a window and suck that cool air in and not need the A/C. It works fantastic and I would not be without one now.

 

[davec]

Another big vote for a whole house fan. We have a ~36" one in our attic connected to the envelope part of our house. I can open windows and turn that fan on and exchange every molecule of air in the house in just a few minutes. So for those days when things cool off I can open a window and suck that cool air in and not need the A/C. It works fantastic and I would not be without one now.

Air exchange is another whole area that is important and can also be done very wrong... If you are not careful with things like whole house fans, you can backdraft many combustion appliances. Since this is a Wood Heating forum, one obvious potential problem is a fireplace or woodstove. Other sources that could be a CO problem are furnace, water heater, gas fireplaces, and gas-fired clothes driers.

Nowadays (at least up here) almost all forced-air furnaces are high efficiency condensing types, so they are sealed combustion (drawing air from and exhausting directly to the outside). Water heaters are getting to be more commonly sealed combustion, but there are still a lot of conventional draft units around. I don't know of any sealed combustion gas clothes driers, though they may exist (haven't looked...). Electric driers don't have this problem of course, but with the downside of higher use cost of electric vs. gas. But if you have a highly efficient house overall, that may be a good tradeoff to make vs the risk of CO/backdrafting.

Whole house fans can be great, but you need to know what you are doing with them. In general, fresh-air ventialtion is a serious issue with tighter houses, and it needs to be planned for and incorporated in a new design. This is one area where finding a local residential HVAC expert can really help you out.

As I said before, house construction is really a serious science. While there ar those that understand it, most people have no idea what is even possible or right/wrong. And it varies by climactic region. I count myself as "well informed" but by no means expert. I try to help where I can...

-Dave

 

[Flapjack23]

Air exchange is another whole area that is important and can also be done very wrong... If you are not careful with things like whole house fans, you can backdraft many combustion appliances. Since this is a Wood Heating forum, one obvious potential problem is a fireplace or woodstove. Other sources that could be a CO problem are furnace, water heater, gas fireplaces, and gas-fired clothes driers.

Another option to aid with air exchange and prevention of CO/backdraft issue with wood burning is adding a heat recovery ventilator. Basically a heat exchanger/exhaust vent combo. All bathrooms, kitchen, and laundry room vents tied together and go through heat exchange unit, exchanging heat with incoming outside fresh air before exhausting. They are controlled by a couple fans, but are able to replace air lost through combustion or chimneys. More of a new construction item though.

Andy

 

[ktm250rider]

I like the double 2x4 staggard wall system for the thermal break between the outside and inside walls. I also like the SIPS panels, wish I had used them like I was going to when I built my house. Finally, I should have used a spray foam insulation. The cost was 3x that of batt insulation (close to 18grand). Even though I heat with wood, if I knew then what I know today, I would have spent the extra coin. You can remodel a kitchen, bath, finish a basement but its fairly difficult to redo all the insulation in the house.

 

[Curlycherry1]

You can remodel a kitchen, bath, finish a basement but its fairly difficult to redo all the insulation in the house.

Of all the costs of building drywall is pretty cheap. And so for remodels it is not all that expensive to take drywall down on the outside walls and then have foam put in place. The value one gets back from good insulation is a good payback over the full life of a house.