Tuesday 9 July 2013

Build an Affordable Concrete Home / LONGER RANGE ISSUES

Build an Affordable Concrete Home / LONGER RANGE ISSUES
Some contractors are discovering new possibilities in the affordable housing market
By Joe Nasvik
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Custom-built homes are commonly gracing glossy magazine covers. That's because people in the U.S. have been in love with the idea of owning a large elegant home. For architects and designers, there is more opportunity to present interesting ideas and work with unusual concepts. But with the decline in the residential housing industry over the past year, large custom home building followed suit, as well as the affordable home building industry. However, there is greater interest today in concrete home construction in the more affordable price range on the part of a number of builders. This attention is largely focusing on sustainability, green building, disaster resistance, energy conservation, and safety.


WHAT INFLUENCES AFFORDABILITY?
There are many different ways to define what makes a house affordable in today's market. All homes are currently more affordable because of declining home and property values over the past couple of years. Labor and material costs have dropped some as well. In the end, however, the affordability of a house correlates to its size. Homes ranging from 1000 to 2000 square feet are more affordable than larger custom-built ones; though there is a trend toward smaller custom homes. In terms of building philosophy, some builders achieve lower prices by constructing several homes at the same time while others keep costs down by building one at a time.

Judging affordability by the selling price of a home is beginning to change as more attention is given to operating costs over time. The builders of concrete home systems tend to have a long-term view in mind.



Roomscapes in Miami built this approximate 1600-sq.-ft. affordable house for about $600 more than a masonry block home. But savings for heating and cooling plus insurance more than make up the difference. Notice that the roof has no gables to catch the wind.
Credit: Roomscapes

LONGER RANGE ISSUES
In some parts of the country, homeowner insurance is becoming a very significant part of home ownership. In the southeastern states, for example, insurance rates skyrocket for homes built close to the ocean or in hurricane-prone areas. Insurance for homes built to withstand high-wind forces can be quoted much lower rates depending on the state and the insurance company. The same can be true for fire-resistant homes. When a homeowner applies for homeowner insurance, the first question the insurance company asks is “what's it made of?”

Chuck Vance is the fortified program manager for the Institute for Business & Home Safety (IBHS) organization. It is a nonprofit entity, supported by more than 200 insurance companies, charged with researching and recommending better methods for building disaster-resistant homes and commercial construction. When disasters occur the IBHS investigates the effect on structures in an effort to develop better building methods. IBHS shares its findings with code authorities and works to improve building codes. It also administers a program called Fortified...for safer living, which certifies that a home is built to the standards of the program. The process includes inspections during construction to verify that all the requirements are followed. Vance says these homes currently must be built to withstand winds 20 mph higher than local minimum codes. The goal is to reduce the risk from all types of natural disasters, including wildfires, making homes safer in the process. It also increases their affordability because they don't have to be replaced due to the effects of high winds.

In an age of declining resources, the energy to heat and cool homes is becoming increasingly more costly—directly affecting the cost of ownership over time. Owners and renters want to live in more energy-efficient and cost-efficient housing.

It's often reported that building a concrete home can increase costs over wood construction from 5% to 15%. But some builders report that they are able to build more affordably than with wood. Here is how some are doing it.


Steve Luria, the owner of Roomscapes, says that one way they keep costs down is to design homes with open kitchen, living room, and family areas. This reflects current tastes and eliminates additional interior wall construction.

Credit: Roomscapes


BUILDING LOW-INCOME HOMES IN MIAMI
Steve Luria is an architect, designer, and the owner of Roomscapes, Miami, a 10-year-old design firm that specializes in interior spaces. Five years ago he formed the nonprofit Haven Economic Development organization to focus on low-income housing. Now he says this housing construction is 60% to 70% of his business. Homes average 2000 square feet, featuring 1600 square feet of living space, and sell for approximately $225,000.

Luria says that Haven Economic Development both designs and builds homes in order to maintain control of costs. The houses are designed with affordability in mind and not a lot of fluff. Designs are simple, bare bones, and yet spacious with open floor plans for the kitchen, dining area, and living room—thus requiring less wall construction. He adds that the footings, floors, and exterior walls are concrete. All the homes feature hip roofs with no gables for increased wind protection.
“We use insulating concrete forms (ICF) made by Reward Walls, Omaha, Neb., for the exterior walls,” says Luria. “These walls are a little more expensive than a standard wood-frame construction but there are important savings in other ways.” The R-value of the ICF walls is R-22 and with high energy efficiency and reduce air infiltration. The concrete walls can easily handle the 146-mph wind code requirements. Other construction details include asphalt shingles with high-wind ratings, impact-resistant windows, steel studs for interior wall construction, stucco finishes for exterior walls, wood trusses double strapped to the walls for increased wind protection, ceramic tile throughout, recycled composite wood for trim work, standard drywall with no wood paneling, and the careful sizing of air conditioning units. Significant dollars can be saved by sizing air conditioning systems for concrete rather than wood-frame homes.

Luria says they are also part of the IBHS Fortified...for safer living program and, depending on the location of their homes, it's possible for owners to qualify for insurance savings of up to 40%. If homes are purchased through the Miami-Dade Infill Housing Program, first time owners can qualify for up to $50,000 loan reductions.

To date, Haven Economic Development has completed 15 homes and is building 10 more.

BUILDING REMOVABLE FORM WALLS
Jim Bassett and Mike Zeanchozk own a concrete foundation business in Elmora, Penn. About 3 ½ years ago, they decided to incorporate Matrix Concrete Construction to go aboveground, building concrete homes in Florida. They completed up to six houses a week until the market dried up. Now they are building concrete duplex housing close to the coastline in Gulfport and Bay St. Louis, Miss., where Hurricane Katrina hit. Bassett says their average unit is 1049 square feet with a 317-square-foot garage and a small porch, which sells for $250,000. Building features include 8-foot-high cast-in-place exterior concrete walls, concrete demising walls to the top of the roof, wood-frame interior walls, and wood truss roofs. Bassett says that Mississippi recently adopted Florida's wind code requirements, so their homes are built to resist 146-mph winds. He says that mass producing homes using Western Forms handset aluminum forms is one way they stay affordable.

In northern Florida, Ken Krantz, who has a structural concrete background, focused his concrete construction on commercial work until four years ago. That's when he got excited about concrete housing and started Safewalls of North Florida, Jacksonville, Fla. Until recently the company focused on large custom home work but decided that there was opportunity in the affordable housing market. He built several in the Pensacola area and is set now to build in Jacksonville.


Roomscapes decided to use ICF construction methods for the exterior walls. Walls are cast in five days with a total of 4 in. of insulation. They easily exceed Florida codes requiring 146-mph wind resistant construction.
Credit: Roomscapes

Safewalls' homes are all concrete, also constructed with handset aluminum forms, approximately 2000 square feet, and sell for under $150,000. They include 6-inch-thick exterior walls with inside insulation, 9-foot-high ceilings, high-quality impact-resistant windows, upgraded roofing systems to resist 146-mph winds, appliances, and wood or stucco exterior siding. (The wood siding is wood fiber cement siding secured by nails shot directly into the concrete wall). Krantz says that he orders low-shrinkage 4500-psi concrete with 0.45 water-cement ratios and adds 20% fly ash to his concrete mix design. In addition, his homes have Energy Star ratings.

Krantz emphasizes being efficient on the job-site. His company uses forklifts to move everything around on construction sites, moving away from the use of cranes and knuckle-boom trucks to handle forms. By using handset forms instead of gang-forming systems, designs can remain flexible. They are also more efficient when you are building one house at a time.

“When I decided to build concrete homes, I knew I would have to market directly to the end user,” says Krantz. “People don't have much interest in concrete until they walk through a home and see and feel the benefits. Then they want it.”
Safewalls has patented a way to install a complete concrete room(s) including walls and ceiling in any existing wood home. In the event of a storm, such as a hurricane or tornado, families can take shelter in the concrete room and remain for hours if necessary. Krantz says there are millions of existing wood homes out there with absolutely no protection.


One of the most sensitive locations for hurricane and tornado resistance is the junction between walls and roof. Shown here, roof joists are secured with two steel straps to headers, which are solidly attached to the concrete walls.
Credit: Roomscapes

BUILDING WITH BLOCK
In Athens, Ga., Patrick Halloran, owner of Halloran Masonry, would like to be involved in affordable housing construction. He is convinced there is demand for this kind of housing construction in his area and that reasonable profits are possible. His company's current focus is custom home and commercial construction. They perform as general contractors when jobs require it. He thinks that incorporating subtrade work into his company's offerings makes it possible to provide affordable concrete block house construction at less than market prices. They proved the concept to themselves with the recent construction of an 1800-square-foot home. The affordable market in the Athens area is dead right now, as the result of subprime mortgage issues plaguing the country. When the housing industry comes back he plans to be involved.




Contemporary concrete building systems

Contemporary concrete building systems
Whether they think of it as “building green” or “sustainability,” today’s consumers expect homes and other low-rise structures to have minimal environmental impact, yet meet or exceed their lifestyle needs. They want properties offering comfort and security with low energy bills and low maintenance. They also demand healthy interiors that promote well being. And they want all of this in an attractive package.

Contemporary concrete building systems offer features that purchasers and builders value; strong and solid construction that provides comfortable shelter from typical weather, and minimizes property damage while protecting occupants from extreme weather, like natural disasters. Yet strength and durability alone are not enough: the systems have to be easy to design and build and be versatile to suit any architectural style. Concrete systems are that and more.

They form tight building envelopes that minimize air infiltration, simplify the addition of insulation, and provide thermal mass for more consistent temperatures and decreased energy usage. This is beneficial from an environmental standpoint, and can contribute toward a building’s greenness in many rating systems and some codes.

Even though many concrete building systems have been around for a long time, consumers (and some builders) may not be aware of them. Or they may have only a limited understanding of them. PCA began a targeted promotion of concrete systems for residential applications in the mid-1990s, intended to introduce a new audience of buyers and builders to the wide variety of structural concrete products suitable for building homes. Systems included concrete masonry (“block”) and poured in place concrete (removable forms), precast and tilt-up, shotcrete, insulated concrete forms (ICFs) and autoclaved aerated concrete (AAC) which is a lightweight concrete formed as blocks or panels. Construction of above grade walls for concrete homes increased from about 3% at that time to nearly 11.1% in 2008, or about one out of every 9 homes built.









Build a wood house

Build a wood house
1. Basic description of the construction
The house is assembled from prefabricated, full-width timber frame panels (wall units). These panels are made in accordance to the documentation of VS DOMY,a.s. and also to the construction documentation of a particular house. In case of a difference between these two documentations, the documentation of VS DOMY,a.s. is valid.
2. Terrain modifications, foundations
If not otherwise stated, terrain modifications, supporting plate incl. its finish and service connections, chimney, external access ways or stairways etc. are performed by the customer. The customer has to ensure also ground-water and radon insulation between the cellar (foundations) and the first floor.

3. Composition of walls and floors
3.1 Exterior walls
Loaded exterior walls are produced as a timber frame construction according to the static calculation. The composition of the wall (interior to external side):
15 mm FERMACELL plate
0,2 mm PE-foil (vapour barrier)
140,0 mm timber frame construction with 140,0 mm thermal insulation
15 mm FERMACELL plate
60,0 mm thermal insulation plate
4-5 mm plaster incl. installation net and putty
3.2.Interior walls
Loaded interior walls
15 mm FERMACELL plate
140,0 mm timber frame construction with 140,0 mm thermal insulation
15 mm FERMACELL plate
Other interior walls
15 mm FERMACELL plate
75,0 mm timber frame construction with 75,0 mm thermal insulation
15 mm FERMACELL plate
3.3. Ceiling body
The composition of the ceiling body (from upper side down):
floor system (see 3.5.)
15,0 mm OSB plate
240,0 mm timber ceiling beam with 75,0 mm thermal/noise insulation
0,2 mm PE-foil (vapour barrier)
12,0 mm OSB plate
15,0 mm gypsum plasterboard
3.4. Deck of the 1st floor
The composition of the floor body (from upper side down):
floor system (see 12.)
20,0 – 25,0 mm FERMACELL plate
thermal insulation - 60,0 – 100,0 mm according to the foundations type
20,0 mm FERMACELL fill
0,4 mm special foil against residual moisture on the supporting plate
3.5. Decks of the 2nd (3rd, 4th,…) floor
The composition of the floor body (from upper side down):
floor system (see 12.)
20,0 mm FERMACELL plate
10,0 - 15,0 mm plate - footfall sound absorber
30,0 mm fill - footfall sound absorber

3.6. Roof design, roof covering, rainwater goods
The composition of the roof (from upper side down):

concrete roof tiles
40,0 – 50,0 mm roof battens (according to roof inclination)
40 mm counter battens
diffusion foil – safety waterproof layer
rafters according to static conditions with thermal insulation 160 mm
80 mm wooden lath with thermal insulation 80 mm
0,2 mm PE-foil (vapour barrier)
12,5 mm gypsum plasterboard
Draining of the roof is performed by circular-shaped gutters and outside located downpipes in titanium-zinc leading down to supporting plate. End lap of the roof edge makes ca 600 mm (or ca 500 mm at gable side) with timber profile finish at bottom side.
4. Windows / terrace doors
As the standard equipment, we use plastic windows with double glazing unit (U=1,1 Wm-2K-1), with five-chamber frame/window profile and full-circumference metal fittings. Windows can be opened, closed or tipped to micro-ventilation position. For extra charge, we can deliver windows in special colors, shapes, with divided glass or timber windows made from EURO 68 profiles.

As to dormer windows, we equip our houses with timber windows ROTO. For extra charge, we can deliver plastic dormers ROTO, VELUX dormers and full range of accessories.
                              
5. Blackout jalousie, window-shutters
For extra charge, we can deliver all the lamella types of jalousie (plastic or aluminium) in casing with thermal insulation and revision cover built in cladding panel, or jalousie in arched casing built in facade

Window-shutters are available in plastic or timber according in accordance to the window material.

6. Window sills (parapets)
External parapets are made of titan-zinc. Interior parapets are made of Postforming. For extra charge, it is possible to deliver stone parapets.

7. Main door
Plastic front doors are delivered in solid core execution or glass door (with double glazing units) execution with ornament and security smithing and security lock. Door is equipped with handle and knob. Standard frame and door has 5-chamber profile. Design of the door is available according to the offer of VS DOMY a.s. (U = 1,10-1,24 Wm-2K-1), as well as range of timber front door.

Sapeli Standard internal doors are delivered in oak, mahogany or beech veneer with veneer door casing and with shine or dull handles. Many other types of door are available incl. special fireproof door, massive door, shift door, folding door etc.

8. Interior stairways
Standard stairway is designed opened and completely beech massive. Many other types of stairway are available in different finish, shapes, materials and accessories. Access to ceiling can be equipped with collapsible stair and thermal insulation.

9. Electrical accessories and connections
Standard equipment:
Living room, bedroom
1-2 connections for light with switch
2-5 plugs
(according to acreage of the room)
Kitchen, kitchenette
1-2 connections for light with switch
3-5 plugs
1 connection for cooker, fridge, dishwasher, cooker hood
Bathroom
1-2 connections for light with switch
1 plug for light on wall
1 plug for washing-machine
Toilet
1 connection for light with switch
1 connection for ventilator
1 plug
Workshop
1 connection for light with switch
1 plug for washing-machine (if situated here), dryer or ventilator
3 plugs
Hall
1-2 connections for light with switch
1-2 plugs
(according to length of the hall)
Terrace
1 connection for light with switch
Entrance
1 connection for light with switch
1 connection for bell
Ceiling room
1 connection for light with switch
1 plug
Other standard equipment
1 plug 380 V
1 plug AP
2 TV connections with 2 cases + interior wiring without plugs
2 phone connect. with 2 cases + interior wiring without plugs
1 consumer unit type HAGER incl. connection
Note
Warning device, data-transfer net, interior phone wiring and similar systems are available for extra charge.
10. Heating
Our houses are equipped with warm-water heating with central regulation and plate type heating bodies with thermo-regulating valves. Distribution tubes are made of plastic. Hanging gas (or electric) heating boiler is equipped with tank.
Direct heating systems, underfloor heating, heat pump, solar panels, hot-air heating etc. available for extra charge.

11. Sanitary fittings and equipment
Water supply is made in plastic tubes incl. warm water circuit. Connection for garden water tap, kitchen and bathroom connections (for washing machine, dishwasher, kitchen sink) are delivered in standard, hot and could water supply is leaded to kitchen, bathroom and toilet.
Water meter, press regulator incl. filtration system is available for extras charge.
Standard sanitary fittings equipment (standard colour white):
Bathroom
Metal bathtub 170/70 cm, with lever-operated mixing valve + pendant shower bath
Basin - china type, with lever-operated mixing valve
Pendant toilet bowl with close-coupled cistern
Toilet
Pendant toilet bowl with close-coupled cistern
Basin - china type, with lever-operated mixing valve
Shower bath, enclosures, angle basins, valves and taps and other equipment in many types available for extra charge.

12. Floor covering
Pavement – on air lock, kitchen, toilet and bathroom floor area, standard price 9-10 EUR/m2 (without VAT)
Carpets – on living room floor area, ended by gripper strip (wooden or plastic), standard price 9-10 EUR/m2 (without VAT)

Type of floor coverings can be adapted according to customer’s wish (laminate, PVC, cork or similar coverings).

13. Walls and ceilings finish
Papering + painting – standard finish of all the rooms excl. areas covered by tiles:
Bathroom + Toilet – ceramic wall tiling up to ceiling (standard price 9-10 EUR/m2 without VAT) accepted by customer
Kitchen – ceramic wall tiling between shelves (standard price 9-10 EUR/m2 without VAT) accepted by customer
Many other types of cover (textile hanging, lining, plaster coat etc.) are available on customer’s wish.