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Elevation and Floor Plan Thoughts?

Last Post 26 Jan 2011 12:49 PM by Dana1. 12 Replies.

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cards66

New Member

Posts:18

20 Jan 2011 07:43 PM
I am looking to build in the next year or 2. I have attached a copy of the floor plan we plan to build with some modifications done to the garage side of the house. This includes making it only a 2 car garage. We will also only have a 10-12 foot cathedral ceiling in the living room. I plan on stick building with 2x4 with blown in cellulose insulation. We plan on doing geothermal for heating and cooling. I wanted to get peoples thoughts on the floor plan and ideas to make it more energy effecient. WOuld putting in active dormers or clerestory windows to allow some solar gain be a good idea? Changing some of he floor plan arrangement, other ideas on insulation or building would be greatly appreciated. This is being built in the St. Louis, MO area. http://www.globalhouseplans.com/plan_details.asp?id=28729
Attachment: Floor_plan.gif

arkie6

Veteran Member

Posts:1453

21 Jan 2011 12:39 AM
One of the most important things I can think of is orientation of the home. Which side of the home will be facing south? I would try to maximize windows on that side of the home with sufficient overhangs to block summer sun. Use low e high solar heat gain windows on this side of the house if you can find them. Then minimize windows on the east and west side to minimize summer solar heat gain. Reduce the number and size of windows on the north side and go with the lowest U value windows you can afford to minimize winter heat loss. If you are just using 2x4 studs with cavity insulation, I would go with at least 1" of EPS, XPS, or better yet Polyiso exterior foam insulation such as Rboard to reduce thermal short circuits through the studs and plates. Tape and seal edges to minimize air intrusion. Blow in at least R49 cellulose in the attic. Locate HVAC equipment and ducts in the conditioned space if possible. If not possible, insure ducts are tightly sealed and well insulated (R6 minimum). If in the attic, cover them with blown cellulose in addition to the duct insulation. Crawl space, slab, or basement? If crawl space, consider a sealed and insulated crawl space. If slab, insure adequate edge and underslab insulation (at least 1" EPS, 2" would be better). Basement? Go ICF.

ICFHybrid

Veteran Member

Posts:3039

21 Jan 2011 01:52 AM
You have a big enough cooling season that you need to be careful about opening it up to Winter sun or you will get smoked in the Summer. The covered porches on both sides work against solar, and the other windows have no overhang at all to protect them in the Summer. You could use PV panels over them as shades, but that would impact the look of the home pretty heavily. If you were to turn one of those porches into a true enclosed sun-space (on the kitchen side) and face it South, that might get a little something going, but the cost of sunspaces can be high if you want to utilize it year-round. You could also get external shades that completely cover the windows in the Summer, but that is another pretty big appearance and function issue I think your best bet with this design is to forget modifications for (passive) solar and put the effort into PV panels or solar hot water panels - active systems.

Eric Anderson User is Offline

Basic Member

Posts:441

21 Jan 2011 04:09 PM
This is not an easy plan to make energy efficient or use passive solar. Issues: Plumbing is very decentralized more costly and longer times to get hot water to fixtures. 5 separate plumbing clusters. 13 exterior corners in the heated envelope = harder to insulate 14 different roof planes are more expensive to roof and harder to prevent leaks,on the flip side the high pitch helps a lot I don’t like fake dormers with windows, just another place to leak with no functional value. 2X4 construction not amenable to well insulated structure without using outsulation Change to 2x6 with 1” outsulation Change to casement windows if possible Garage and house share common wall, something I dislike- potential for exhaust fumes in house when depressurized. It can be beat by a exhaust fan in the garage Bonus space is often taxed fully- make sure you know the tax implications I would eliminate the second covered porch I would add an outdoor shower near the master bath I like the outdoor kitchen I would put the sink directly opposite the main kitchen sink and fridge on the common wall, then ad a small patio right beside it to put the grill on, add a slider window over the dishwasher to act as a pass through with a table on the other side It is along walk to the kitchen from the 1 car garage with groceries Master bath- I would make the shower larger You have lots of redundancy Just think about eating, you can eat at the bar, in the dining room, on the covered porch, and on the patio It is a good looking plan though. Lots of things to think about.

Think Energy CT, LLC Comprehensive Home Performance Energy Auditing

Dana1

Senior Member

Posts:6991

21 Jan 2011 06:08 PM
What they said. The fake dormers might be daylighting for the Great Room(?), but even so, I'd nuke 'em in favor more reliable air sealing, less water-leakage potential. If some amount of daylighting is desired fixed (not openable) skylights would be a better option, but keep them small and heat-rejecting. At that roof pitch going big and high-gain using skylights for passive solar would roast you in summer. Short of a true passive solar design, bang-for-buck you're better off down-sizing the glazing on the E, N, & W aspects, but going up a notch or two in quality, and using high-gain versions on the S side adding exterior shades for dialing it back in the warmer weather. (Casement or awning windows- YES! Forget about double-hungs- too many inherent thermal shorts, gaps, & air leakage points.) 2x6 20" o.c. framing costs about the same as 2x4 16" o.c. framing, with similar strength, and you'd be boosting your R-value by ~50% at minimal additional cost. As others have said, exterior rigid foam over the structural sheathing will enhance that even further. A 2x6 + 1" foam (XPS or iso) wall has literally half the heat-gain/loss of standard 2x4 framing, with a fairly modest uptick in construction cost. With ~ R22-R25 clear-wall values go at least R40+ on the attic/roof insulation, and at least R10 for basement or foundation insulation. ICFs would be appropriate, even for a stubby stem wall for slab-on-grade, and detailing the foundation to allow the outsulation to be flush with the foundation insulation eliminates a common (often significant) thermal-short in the thermal boundary. (With the depicted brick veneer it's more complex, but do-able.) At St.Louis deep subsoil temps, insulating under the slab may not be worth it unless you're going much higher R on the rest of the package. If slab-on-grade with skimpy or absent exterior stem-wall insulation , insulate at least the 2' perimeter aganst the ground to R5 or higher (1" XPS), and against the stem wall by R10 (2" XPS), to just above the foundation sill. In a full basement with ICF foundation walls you might skip the slab insulation entirely. (If beefing up the clear-wall to R30+ you might reconsider- or maybe model the solar gain vs. the air conditioning benefit of the ~58-60F subsoil before deciding.)

cards66

New Member

Posts:18

23 Jan 2011 02:38 PM
Thanks for all the feedback. I guess I left out a couple of things like the house will face south and will have a full basement. I haven't read much on ICF's. however, sounds like that is what is being recommended here. Is that more for the insulation purposes or what are the advantages? I know the house isn't really going to be a passive solar home. i am just trying to take advantage of the south facing orientation. I tried to attach a floor plan that is more like what we will build. We are going to be sitting down with the architect in the next few weeks and I am trying to figure out how to make the house the most effecient. Such as, I plan on moving the master bath and Laundry room so they butt up agains each other so I can take advantage of one less water run. Is going to 2x6 rather then 2x4 framing worth the extra cost in lumber and windows and such. Sounds like spray foam with blown insulation is a popular idea. Is the cost of the foam worth it compared to just blown cellulose? I have relatives in the construction industry but I don't think many have run into many green homes or ideas. So trying to figure out if getting them involved for cheaper labor is worth it or not. I guess I just have a lot of questions as I start this process and trying to get the best ideas for the shell and envelope. Thanks again.
Attachment: Floor_plan.gif

Alton

Veteran Member

Posts:2164

23 Jan 2011 02:59 PM
Cards66, Since you mentioned that you will have a full basement you might be interested in using a concrete-insulation-concrete (C-I-C) wall called Easi-Wall by Precise Forms Inc. They furnish a preassembled insert that contains insulation and a double-rebar grid. Their web site is: www.preciseforms.com and they are located in Bates City, MO which should reduce the freight. Another CIC wall is by Thermomass which requires assembly at the job site.

Residential Designer & Construction Technology Consultant -- E-mail: Alton at Auburn dot Edu Use email format with @ and period . 334 826-3979

arkie6

Veteran Member

Posts:1453

23 Jan 2011 06:45 PM
What is the advantage of those C-I-C forms over more standard I-C-I ICF forms, especially in a basement application? Also, wouldn't you get a lot of thermal conduction through the foam insulation with those metal wall ties? I notice the site listed is extremely vague regarding wall R value.

Alton

Veteran Member

Posts:2164

23 Jan 2011 08:51 PM
I do not know all of the advantages of this new system. However, I like the idea that the rebar grid and insulation board is preassembled and that the sections can be ordered in 8' widths up to 24' tall. Although the Thermomass system is very similar, it does require quite a bit of field assembly for cast-in-place walls as compared to Easi-Wall. Energy wise, ICF may be more efficient since the EPS insulates the wire or plastic ties. Yes, this system uses metal wall ties just like any metal formed concrete wall. I think that will lower the whole-wall R-value but I do not know by how much. The spacers that hold the foam board in place are not metal and do not penetrate through the concrete. The thickness of the insulation can be increased as well as the size of the rebar. Since I know a lot of basements have been built without any type of insulation I think C-I-C and ICF's would be an improvement. I do not sell any products nor receive a commission from any suppliers. After saying that I will share my pictures of this system with anyone that sends me their e-mail address.

Residential Designer & Construction Technology Consultant -- E-mail: Alton at Auburn dot Edu Use email format with @ and period . 334 826-3979

Alton

Veteran Member

Posts:2164

24 Jan 2011 12:37 PM
I have received some requests to share my pictures of the Easi-Wall insert. However, for the people that used Green Building Talk, I have no way to comply since this forum does not include return e-mail addresses. If any of you that used this forum to send me an e-mail are still interested, please use my e-mail address from below my signature block to send me a request. Then I can reply to your e-mail. I am not collecting e-mail addresses. Just trying to share and spread the word about new building systems and products. Also keep in mind that I donate a lot of my free time to alternative construction projects in the Southeast that interest me. I have been doing that since I retired in 2004 from teaching in the School of Architecture at Auburn University. War Eagle!

Residential Designer & Construction Technology Consultant -- E-mail: Alton at Auburn dot Edu Use email format with @ and period . 334 826-3979

Dana1

Senior Member

Posts:6991

25 Jan 2011 11:55 AM
Posted By cards66 on 23 Jan 2011 02:38 PM Thanks for all the feedback. I guess I left out a couple of things like the house will face south and will have a full basement. I haven't read much on ICF's. however, sounds like that is what is being recommended here. Is that more for the insulation purposes or what are the advantages? I know the house isn't really going to be a passive solar home. i am just trying to take advantage of the south facing orientation. I tried to attach a floor plan that is more like what we will build. We are going to be sitting down with the architect in the next few weeks and I am trying to figure out how to make the house the most effecient. Such as, I plan on moving the master bath and Laundry room so they butt up agains each other so I can take advantage of one less water run. Is going to 2x6 rather then 2x4 framing worth the extra cost in lumber and windows and such. Sounds like spray foam with blown insulation is a popular idea. Is the cost of the foam worth it compared to just blown cellulose? I have relatives in the construction industry but I don't think many have run into many green homes or ideas. So trying to figure out if getting them involved for cheaper labor is worth it or not. I guess I just have a lot of questions as I start this process and trying to get the best ideas for the shell and envelope. Thanks again. Going with 2x6 24" o.c. vs. 2x4 16" o.c. is not a cost-adder, and is sometimes a cost reducer. It's the same number of board-feet, but lower labor cost (fewer boards to cut.) Using advanced framing techniques for reducing thermal bridging and maximizing whole-wall R is similarly cost-neutral, well worth the detailing to achieve the performance edge. Foam cavity fill is not always a good value for new construction, since A: It doesn't guarantee an air-tight wall, even though it's pretty good and B: Air tightness can be achieved by other means. Air sealing by caulking/gluing sill plates as they go in, and caulking/foaming the sheathing/stud or plate interfaces in EVERY cavity is worthwhile. Wet-sprayed cellulose fills about as well as half-pound foam, with a similar R value, but has significantly more thermal mass. It is typically much lower in the cost in terms of $/R, and will outperform the foam R for R in many real-world applications due to the thermal mass aspects. (With retrofits in existing homes foam is sometimes the easier/better option though, since you'd be looking at more labor & material-intensive dense-packing the cellulose to be able to achieve similar air-tightness, and without exterior rigid foam, you'd need to go with closed-cell foam to get anywhere near the same R value. But it's costly- a premium product at a premium price.) At least 1" of exterior XPS or iso rigid foam is also well-worth it, and brings the clear-wall R of a 2x6 24" o.c. studwall up to ~ R25-26, which is more than 2x the R (half the heat gain/loss) you'd get out of 2x4 16" with mid-density batts, open cell foam, or spray cellulose. But layering it up with 2 layers of 1.5" goods (total 3" of foam) you can hit ~R38+ for not super-huge premium. (R30-32 clear-wall values are about the minimum you'd need to get a large fraction of your heating out of a passive solar design.) Play around ,with this tool a bit (they only model it for 1" EPS- for XPS add R1, for iso add R1, to the clear-wall numbers. For even thicker foam, add R6/inch for iso, R5/inch for XPS, R4/inch for EPS.) With a full basement DO use insulated concrete forms (ICFs) with, a minimum R of 2/3 the R of your studwall to make it roughly comparable in average heat loss per square foot as your first-floor. If you're only taking it to R25 clear wall, don't bother insulating the slab, but if you're going for the whole passive-solar shebang there's a rationale for R12-R16 of Type-II EPS under the slab. Also if going over R18 on the ICFs, look into assymetric ICFs, placing most of the R on the exterior, arranged such that the exterior foam of the ICF lines up in a plane with your studwall's exterior foam, making it easy to get a perfect thermal break at the foundation sill. (And lining up the stud plate with the concrete, with a minimum of cantilever.) It's probably useful to use the PassiveHouse tools to model your house & modifications, to work out the best value options.

Bob I

Veteran Member

Posts:1435

25 Jan 2011 04:26 PM
I agree with most of what Dana1 says, but disagree strongly about insulating the cellar slab. The slab is probably the hardest part of the house to retrofit - so if you decide in ten years - or thirty years- to finish the basement, you're stuck with an uninsulated slab drawing the heat from the room. Adding 2" when you build is very inexpensive and a good move in making the house adaptable into the future. Since Passive House was brought up, I'll mention that one of the goals of PH is to build for the future. Houses often aren't substantially retrofitted for 50 -100 years, so what we do now when we build may be there throughout this century. Bob I

Bob Irving<br>RH Irving Homebuilders<br>Certified Passive House Consultant

Dana1

Senior Member

Posts:6991

26 Jan 2011 12:49 PM
Bob's points are good, but consider that the subsoil temps in this location are close to 60F, which is close to room temp, and even an uninsulated slab will be a few degrees above that- it'll be comfortable enough in winter without slab insulation. (That's 12-15F above your local NH subsoil temps, Bob. In New England I wouldn't put less than R10-R12 under ANY new construction slab, and there's a reasonable argument for R20+ slabs in a better-insulated homes here. But St. Louis, not so much.) Also note, my recommendation for possibly skipping the slab insulation is only if going with R25 (or less) clear wall values- the slab insulation money would be better spent addressing the (much higher) above-grade heat gain/loss issues in this location. Even in much-colder subsoil Minneapolis (subsoil temps ~45F) the effect on annual heat loss to the home isn't so dramatic without first insulating the foundation walls. From a comfort point of view it's HUGE in places like that though. See figures 3 & 4, comparing heat loss simulations in Minneapolis MN : http://www.buildingscience.com/documents/reports/rr-1003-building-america-high-r-foundations-case-study-analysis In St. Louis the slab losses through an uninsulated slab during the heating season would be dramatically lower than in Minneapolis- about ~70-75% lower. If there isn't a big comfort issue, and the money would buy lower energy use elsewhere, I'm still recommending it be spent elsewhere. But, 3" of EPS is still relatively cheap, even if the money might be better spent on upgrading to better windows in a sub-R25 clear-wall house from, a net-present-value analysis on utility cost savings. Retrofitting it later would be a huge cost multiplier, as would boosting and existing house to R38 from R13 clear walls as a retrofit, compared to doing it during the initial construction. Since getting to R22-25 is just SO cheap an upgrade from ~R13 2x4 studwalls in new construction it's almost a crime not to. The argument for taking it all the way up to R40-ish is a longer-term issue from a financial POV in St. Louis (but can still be NPV+ in a 25 year financial analysis if done right). But from a comfort POV during peak-winter coolth it's a real winner in a simple 1-year comfort-factor analysis. It DOES get cold there, even if the average winter temps aren't severe.