Guidance for designing and building a low-lifetime-cost home in North Texas
My wife and I want to build (or buy) an energy efficient home in North Texas sometime in the next 5 years. We are not strongly attached to certifications, R-value-comparison-contests, or even a particular style of home. We just want to build something cost-effective that we can live in for the next 40 years without having to maintain high-income jobs to pay for the utility bills and mortgage. I have been doing a lot of research, but I wanted to get some expert opinions to help guide me in the right direction. I have a tendency to want to over-engineer things, because it’s fun, but at the end of the day I just want to live comfortably for a reasonable amount of money. I am also interested in the environmental factor, so I’m ok with spending money on a more efficient building, even if the reduced utility usage is just break-even. However, I am definitely not into spending incredible amounts of money so that I can have the most energy efficient home on the block.
Assumptions/constraints:
- Budget for land+building should be under $300k.
- I am thinking between 800 and 1600 sq ft for the house.
- Larger lot (3-5 acres) preferred.
- Within 3 hours drive of downtown Dallas, closer is better, but only moderately important.
- Interior temperature set-point of 68-69F. This is an important issue for me, as I sweat very easily.
- No significant preference on architectural style or building materials. Whatever is most cost-effective over a 40+ year lifespan.
- Needs to house two adults, two 60lb dogs, and one child.
- No requirements for dining, entertainment, or guest quartering. We’re trying to escape from people, not have them over all the time.
- Open plans are preferred.
- Don’t need a garage.
- Don’t have a particular plot of land in mind, so I can shop for land with the best qualities for cheap building and cheap operation.
- I like the idea of solar PV, net-zero, and off-grid, but not if they significantly increase the lifetime costs.
- I am fairly handy and I have an engineering (electrical) background, so I’m interested in doing some or all of the design work, general contracting, and subcontract labor, as feasible and cost-effective.
Conclusions and questions from the research and analysis I’ve done so far:
- Solar PV seems to be a waste of money, considering electric rates in Texas around $0.10/kWh. It also seems that waiting a few more years for the price to continue dropping is likely to be an effective money-saving strategy.
- It seems that very high insulation values are not going to break-even in this region; what is an appropriate R-value to shoot for in the walls/roof/foundation in this environment?
- Building design appears to be very important. Complicated exterior walls are bad. A cube is good. An octagon is looking like it might be a bit better, but I’m not sure if the improved volume/surface area ratio is worth the increased construction complexity. Thoughts?
Any other advice, direction, links/books, etc, quite welcome.
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Replies
Maybe you can research these .
http://realpeoplehomes.com/
Closest dealer to Dallas is
Craig Chamber Construction LP
Contact: Craig Chambers
100 Chuck Wagon Trail
P.O. Box 206
Weatherford, Texas 76086
Cell: 817-239-6542
E-mail: [email protected]
Web: http://www.bestbuilders.biz
i have heard very good things about these homes . Cannot confirm but the sources are very reliable .
An 800 square foot home would not pass most HOA CC&R's. From my experience most HOA's require a minimum of 1,500 square feet for a home in order to be built.
The major infrastructure costs are in the home/site development so adding more square footage doesn't increase the costs as much as the initial infrastructure. I would go with at least 1,500 square feet.
Someone looking to minimize long-term costs and hassles would do well to avoid building within the jurisdiction of an HOA.
The major lifetime costs of a home are, roughly, mortgage/purchase price, maintenance & repair, utility bills, insurance, and elective upgrades.
Given that you are already avoiding living in a place with ridiculously high land values, to further reduce the lifetime cost of the mortgage/purchase price, the best way to do this is to keep the square footage down. Aim for closer to 800 than 1600 square feet. This is a compromise between your budget, space needs, and resale needs; an 800 sf house will be harder to sell later than a 1600 sf one. But it will also cost half as much to build, heat, cool, maintain, and insure (theoretically; there are some marginal costs that do not scale linearly).
If the square footage allows it, build a two-story house, as this reduces the cost of your foundation and roof for a given square footage7. It may be worth it to increase the square footage a bit so you can go with two stories, as the extra costs will be offset by savings due to a smaller foundation and roof.
To keep the lifetime cost of maintenance and repair down, spend your budget on better materials with a lower lifetime cost of ownership rather than more space; have the house built out of materials that are naturally impervious to the stresses and hazards they will face. This includes mundane wear items, like painted exterior trim. This trim should be metal instead. Tile the interiors or install vinyl flooring rather than hardwood, laminate, Interior walls should be lime-plastered masonry rather than painted 1/2" paper-faced gypsum drywall. Things like that.
In Texas, your major environmental hazards that will cost you money in the form of maintenance, repair, and insurance bills are going to be hail, tornadoes, other sources of damage from high wind (e.g. from hurricanes), termites, and flooding.
The most hail-resistant roof is steeper than 6:12 pitch and clad in thick metal. The lower the pitch, the more you want metal; at higher pitches it isn't as important. To minimize routine re-roofing costs, go with the metal, which will also help with summer comfort if you choose a light enough color or a bare metal roof. Bare galvalume is somewhat pretty IMHO.
Tornadoes are gonna wreck your house no matter what if they pass right over it, but you can protect yourself from the flying debris they hurl, which will help with hurricane damage as well. To do this, you want a masonry wall structure, laminated glass windows, and brick or stone siding. The roof structure should be very securely fastened to the wall structure.
Termites will eat the wood in your house and cost you a bundle of money to have the soil periodically treated and any damage remediated. Go with masonry walls again. If possible, go for no wood at all; build the attic with steel framing and the interior partition walls of lightweight masonry. Instead of wood trim everywhere, use tile baseboards and soft beveled edges on corners. They will last longer, cost less money to install, and never need painting or repair, too.
To protect yourself from flooding, you want the grade around the house sloped away from it, with perimeter drains leading to daylight somewhere far from the house. The ground floor should be a foot or two above the grade level. This implies a crawlspace or basement; a crawlspace may make more sense if you have a high water table anyway. Make sure everything in the house is impervious to water, too. No drywall, as the gypsum will liquify in the presence of standing water the the paper facing will grow mold. Instead, build the partition walls out of lightweight masonry and plaster it all with lime plaster--not gypsum plaster. This will protect the house in the case of a plumbing leak, too.
To keep the utility bills low, you need to get the house well-insulated and air-sealed. In Texas--even north Texas--your primary concern is cooling, not heating. Most of that is about dealing with solar gain. That means that your attic/roof insulation is critically important; make it thick. Have deep roof overhangs too, so the sun hits the walls and windows less. A hip roof makes more sense than a gable roof here, and it's also more resistant to wind uplift. Wall insulation only needs to be good enough; say, R-20 continuous foam or mineral wool between the interior-facing masonry structure and the exterior-facing brick or stone cladding. Use foil-faced boards for the outer layer to squeeze out some extra performance from the air gap between the insulation and the cladding. Stuccoed AAC could work well too, if it's thick enough;ideally 10" or more. Choose low SHGC windows that are as airtight as possible. A good (< U-0.27) double-pane will probably be sufficient; no need to upgrade to triple in your climate. Better air sealing will help with moisture load.
Insulate the perimeter of your foundation with non-foam materials; mineral wool or foamglas. Anything termites won't eat or tunnel through. Prefer a sealed crawlspace to a vented one.
Use a high-efficiency mini-split heat pump; it will be capable of dealing with your cooling as well as heating load. No gas appliances; all electric. No gas bill! Design the house such that one of the roof planes is ideally angled and sloped for solar PV, either at construction-time or in the future.
Then you have water and sewer costs. Eliminate sewer costs by installing a septic tank, if you're permitted to. Save water by designing the house such that all the hot water fixtures are close to another and the water heater. Install low-flow toilets, sink faucets, and shower heads. Use a drain water heat recovery device on shower drains. Install a graywater system to redirect most of the water to your fruit trees, reducing your food bills and saving wear-and-tear on your septic tank.
If you've done all this, your house will be more or less impervious to nearly every hazard it could face, so your insurance bills should be extremely low, and very little in it will ever need repair or maintenance.
Yeah, letting HOA's determine how our housing stock will develop is a really bad idea. I can see 1500 sf as maybe a fair benchmark for a family house, but for a single person?
Nate G, thank you for such a detailed answer. That is exactly the kind of guidance I was looking for. Regarding foundations, slab foundations are very common here, would a crawlspace/pier-and-beam foundation still be a better choice?
Regarding HOAs, I am in agreement with Nate and Malcom; an HOA would be exactly opposed to my goals. I don't care what my neighbors do, I don't want or need fancy manicured neighborhood parks and entrance gates, and I certainly don't need one more organization to pay off for dubious benefit. Furthermore, I suspect that many more aspects of Nate's suggestions would be problematic than merely the sizing of the conditioned area of the home. That roof seems likely to run afoul of an HOA committee, at the least.
Chase,
I don't know much about building in your climate - I live in the rainy Pacific Northwest - but it would seem to me you could increase the livability of any design by providing covered outdoor space, which would also help shade the structure.
Take a look at the work of Texas architects Lake Flato, especially the Residential ranches. Ignore the high-end construction and just look at the basic ideas and designs. You might find something useful.
http://lakeflato.com
Chase,
This article might give you one or two useful ideas or tips: Hot-Climate Design.
You're welcome, Chase. There are some things I should clarify.
A slab is fine, and if that's what builders in your area are most familiar with, go for it. A slab is cheaper and will probably result in slightly better cooling performance if you insulate the perimeter but not the bottom. A slab is also an easy substrate for a tiled floor, which is what you should do for the first floor; your feet will be nice and cool! You can also have a stained/polished concrete floor, which is probably the cheapest and most durable finished flooring option of all. And there's less wood in your structure, which is always nice from the perspective of resistance to termites, water, and fire. However, it will make future plumbing work costly and difficult, and increase the likelihood of hidden termite entry, especially if it's not a monolithic slab. If your area is not especially flood-prone, then it's probably fine to have the ground floor raised up only 6" to a foot. My own slab house has a ground floor level 6" above grade and it's perfectly adequate given the dry climate and good grading.
The suggestion of shaded outdoor space is a great one. Especially if you're in the dry part of Texas. A little shade and some big trees will make an outdoor space you can use much of the year for very little cost.
A two-story house in your climate will require a sort of brow roof to shade the first floor windows; otherwise they will soak up a lot of sun and increase the cooling bills. The cost of this brow roof will need to be weighed against the cost savings for the main roof and the foundation. If single-story houses are the norm in your area, just go with the flow. One story only will also help you "age in place."
One thing I would definitely not compromise on in your climate if I were building a house there is that the walls need to be made out of masonry. It's a no-brainer to me given the termite concerns, natural disasters possible in the area, and desired focus on long-term durability. If you find that the only local masonry experience is with ICFs, that's fine, but in a cooling climate like yours I would prefer the style of wall that reverses the location of the materials, and has insulation in the middle with concrete on both exterior facings. The interior mass will help with comfort and cooling bills, and having the insulation protected by concrete just makes sense. Like I said, AAC can work well in this kind of climate, and it simplifies the wall construction. Check out Cresco Concrete's Liteblock 38 system: http://crescoconcrete.com/liteblok/ (no affiliation). I believe they're based out of Houston. They may be able to point you in the direction of some experienced masonry walling crews.
Nate,
Masonry walls sound like a good idea for Texas, but what about critters in the foam?
Rigid mineral wool instead of foam. Or AAC instead of concrete+insulation. I would think that the foam within a concrete sandwich panel would be fairly well-protected but I have no direct experience there and would love to hear others' experience with the product one way or another.
Hundreds if not thousands of ICF homes and buildings have been built in Texas and they are performing very well and the foam is not an issue. Just use preventive measures like synthetic stucco on the exterior and termiticide treatments.
Going back to the OP request. They excluded a garage. IMHO I believe that is a mistake since storing tools, gasoline, chemicals, etc. should NOT be stored inside of a home and therefore that is why there is such a thing as a garage. Yes, a shed can be used but sheds are susceptible to weather damage and rodents. Also, what about the vehicle the homeowner has> Where is that parked? Outside in the elements so that it gets damaged by hail, debris, UV, snow, etc? At least a single car garage should be built.
Termite infestation of ICF foam:
http://www.icfhomes.com/PhotoPages/photo_termyth.htm
And this from the National Association of Building Inspectors:
"Insulating concrete forms (ICFs) are rigid, plastic foam forms that hold foundation and structural concrete in place while it cures, and then stay in place afterward to provide insulation. Insulated concrete formICFs provide some advantages over more traditional construction materials and methods, including improved durability, and protection from fire and natural disasters, as well as added energy efficiency. However, a major problem associated with ICFs is termite infestation. Because of this, some states where termite infestation is common have banned ICFs from underground use for basements and foundations. "
I like the LiteBlok idea, actually. Anyone have an opinion on DIYing the walls with LiteBlok or another AAC-like product? Obviously that's out of the question for ICF.
Also, how does building for efficiency/longevity, particularly with these materials, impact property tax assessments? Texas has relatively high property taxes, 2-3%, so keeping that assessment low would be nice.