Author Archives: Jim Flasch


Metal Roofs on the Rise

A durable and energy-efficient alternative to shingles, metal roofs are now more attractive than ever.

Metal Roofs

Photo: Metal Roof Alliance

There is no material more capable of protecting a structure from wind, rain, hail, fire, or rot than a durable and energy-efficient metal roof. The initial cost to install may seem high, but a standing-seam metal roof is the least costly roof option over the life of the roof because it is virtually maintenance-free and can last 50 years or more.

Related: Debunking 5 Metal Roof Myths

Standing Seams
A standing-seam metal roof consists of metal panels running vertically on the roof deck. Each panel has two seams that stand up vertically and are crimped together to seal the joint and keep the elements from penetrating. A standing seam also keeps water from collecting on the surface, causing leakage.

A metal roof is durable, like an iron sentry standing guard over the top of the house. William Hippard, president of the Metal Roofing Alliance, in Seattle, WA, says the building trades have taken a shine to metal roofing because of its attributes. “Without a doubt, metal roofs are cheaper in the long run,” Hippard says. “Many metal roofs will easily outlast any warranties that the company provides.” Warranties up to 50 years are common, but it’s not unusual to find metal roofing that has been in use successfully for 100 years. Copper, galvanized steel, and aluminum (Galvalume is the galvanized version of aluminum) are the three metals most commonly used to build standing-seam or other types of metal roofs. All offer virtually the same durability, aesthetics, and finishes.

Beauty and Durability
Metal roofs once got a bad rap for their bright shiny colors and metallic look, but finishes are now much more compatible with home exteriors. Metal roofs have lost their “barnyard” image and now sport a host of colors, matte finishes, and profiles. Virtually any color is available, the metal can be finished to remove that “high gloss” metallic look, and the end product can be formed to resemble any roof product from tile to asphalt shingles or cedar shakes. Distressed-look metal roofs have an irregular pattern so that heavy hail storms won’t affect the surface appearance of the roof.

Dave Uppgren, a principal in Uppgren and Associates, the architectural firm that covered the headquarters of Domino’s Pizza in the largest standing-seam copper roof in the U.S., likes copper roofs because they are beautiful, durable, and almost maintenance-free. “About 90 percent of the decision to use copper for the roof was based on aesthetics,” Uppgren says of the stunning installation. “There really are no maintenance problems. As with any metal roof, snow sliding off can become a big issue and we’ve probably spent more time preventing snow from falling onto the public areas than to repair leaks.”

Energy Efficiency and Value
From an appraisal standpoint, Hippard says metal roofs are so durable and desirable that they add approximately $1.45 per square foot to a home’s overall value. Insurance companies give discounts of up to 35 percent to homes with metal roofs because when properly installed they are virtually impervious to wind, hail, and fire.

Metal roofs are also energy efficient. A metal roof can reflect the sun’s energy and block heat transmission from the roof to building members and living space. “ Paint manufacturers have also come up with good reflective properties for the coatings so you can reduce your cooling bills in the summer by 25 percent,” Hippard says. There are also currently tax credits available for putting metal roofs on your principal residence. Properly ventilating the roof is vitally important to its efficiency and lifespan.


Strengthen Your Roof with Trusses

Engineered roof truss systems even stand up to hurricanes.

Photo: caudilltrussandmetal.com

After hurricanes ravaged Florida in recent years, building codes were strengthened to keep future damage to a minimum. Officials and builders have learned that keeping the lid on a house means forming a tight bond between the sail-like roof deck and the walls below. That job falls to the engineered roof truss system that holds it all together.

Trusses Surpass Traditional Framing
Carpenters used to use two-by lumber to frame into stringers and rafters. Engineers and architects now design roof trusses built of 2x4s in triangular configurations that are joined together with metal connector plates. The result is a cohesive roof truss that stands up to state, local, and national building codes. Trusses perform to such a high degree because the lumber is uniform in size, density, and quality, and metal connector plates ensure rigidity at joints.

Engineered trusses have been on the building scene for 35 years, a track record that impresses many builders and homeowners. Kirk Grundahl, executive director of the Wood Truss Council of America (WTCA), in Madison, WI, says homeowners can be assured their roof trusses are engineered to exacting design standards nationwide since manufacturers must meet the standards set by WTCA and the Truss Plate Institute (TPI).

Sean O’Connor of Robbins Engineering, in Tampa, FL — designers, plate fabricators, and truss system engineers — explains that roof trusses create a stronger roof structure because they are engineered using CAD (computer-aided design) design techniques and computer analysis for worst-case scenarios.

“Because every one of the roof trusses are engineered, it literally takes into consideration all the forces acting on the truss, from gravity loads to wind loads, seismic loads, and uplift loads,” O’Connor says.

Roof Trusses Allow Open Floor Plans
Trusses have many pluses, including their overall strength, ability to be placed quickly, and span capability. Since they’re built from shorter lengths of lumber, roof truss systems are typically less expensive to build than roofs with conventional framing.

Trusses are engineered to span larger distances than conventionally framed roofs. Since they transmit weight from the roof to the exterior walls, none of the interior walls needs to be load bearing. This opens up interior space and allows for many interior design options.

Wood, Steel, and Engineered Timbers
Roof trusses, historically composed of wood with metal connector plates, now have competition. As steel-framed homes catch on, so have all-steel roof trusses. O’Connor says that to date steel roof trusses are typically reserved for the light commercial and industrial markets, with wooden trusses still dominating home construction.

Engineered wood products such as I-joists have also made a big surge in the market. “They can be used almost like framing lumber, but unlike conventional lumber, they’ll span up to 60 feet in length,” O’Connor says.

Wood roof trusses with metal connectors can also be treated with fire retardant and have an “excellent fire rating,” according to O’Connor, “and from a budgetary and quality standpoint, are the price point winners.” When they are properly engineered and put together, the wood roof truss with low-cost connector plates will perform to engineered lumber parameters. “So they are a nice, low-cost solution to framing problems,” O’Connor says.

Coupled with hurricane straps for fastening the trusses to the walls, the roof system is typically better than any stick-built roof, according to O’Connor.

Roof Trusses Allow Open Floor Plans
Trusses have many pluses, including their overall strength, ability to be placed quickly, and span capability. Since they’re built from shorter lengths of lumber, roof truss systems are typically less expensive to build than roofs with conventional framing.

Trusses are engineered to span larger distances than conventionally framed roofs. Since they transmit weight from the roof to the exterior walls, none of the interior walls needs to be load bearing. This opens up interior space and allows for many interior design options.

Wood, Steel, and Engineered Timbers
Roof trusses, historically composed of wood with metal connector plates, now have competition. As steel-framed homes catch on, so have all-steel roof trusses. O’Connor says that to date steel roof trusses are typically reserved for the light commercial and industrial markets, with wooden trusses still dominating home construction.

Engineered wood products such as I-joists have also made a big surge in the market. “They can be used almost like framing lumber, but unlike conventional lumber, they’ll span up to 60 feet in length,” O’Connor says.

Wood roof trusses with metal connectors can also be treated with fire retardant and have an “excellent fire rating,” according to O’Connor, “and from a budgetary and quality standpoint, are the price point winners.” When they are properly engineered and put together, the wood roof truss with low-cost connector plates will perform to engineered lumber parameters. “So they are a nice, low-cost solution to framing problems,” O’Connor says.

Coupled with hurricane straps for fastening the trusses to the walls, the roof system is typically better than any stick-built roof, according to O’Connor.


Soundproof Your Floors

Learn the ins and outs of soundproofing your home.

Photo: Flickr

Paying attention to what’s underneath your floors can have a profound effect on noise reduction and sound control in your home.

Like other room components, floors respond to the four steps of sound deadening, which include absorption, blocking, breaking, and isolating sound. When attempting to control noise and noise transmission, it is important to consider each of these areas and how you can use them to reduce sound transfer.

Isolate Noise in New Construction
The key to proper sound deadening for floors is to do the work during new construction when subfloors and joists are exposed. A number of manufacturers offer sound-isolating floor mats and anti-sound boards that are installed beneath new floors to keep sound locked in place, rather than transmitting it to upper or lower levels.

Mats or sound-deadening underlayments may be constructed of lightweight closed-cell foam, recycled rubber, or heavy barrier vinyl. When properly installed below one or two layers of 1/2-inch sub floor, mats will isolate vibration and noise from foot falls and dropped skillets. Sound-reducing mats can be used beneath hardwood floors, carpet with pad, ceramic tile, vinyl, or wood-laminate flooring.

Another component best installed during new construction is an acoustical sound board, which is placed beneath the sub floor. The sound board, like other subflooring components, isolates the sound before it has a chance to reflect up into the room.

Sound Absorption
An easy solution to quiet a noisy floor is to install carpet and padding. The quality or thickness of the underlying pad will directly impact the degree of noise control and the wear of your carpet — the heavier the pad, the longer the carpet will last and the quieter your room will be. An additional layer of the acoustical underlayment can also be installed beneath the pad for added sound reduction.

Noise Blocking
When adding the acoustical board, cut the pieces to fit the room’s outline and leave 1/8- to ¼-inch gaps around all edges. Then use an acoustic sealant or silicone on the back of the acoustical sound board before nailing or screwing the boards in place. Once the new acoustical subfloor is in place, seal the edges along the 1/8th-inch gap with silicone or acoustic sealant to both block and break the spread of noise from one layer to the next. Once the silicone sets, new tack strips can be installed and the pad and carpet stretched into place as usual.

In existing homes, the only practical solution may be to approach the problem from below. Sound-deadening insulation or sound-muffling mats can be added beneath the sub floor between the floor joists. This solution may only be possible between the first floor and the basement where the floor joists are accessible. If the basement has a suspended ceiling, the existing ceiling tiles can be temporarily removed to weave insulation in between the joists.

Appliances like washers, dryers, and dishwashers on first or second floors may make sound deadening an extra challenge, but manufacturers have conquered much of the problem with rubberized mats that are placed beneath the machines.

Sound Breaking
Squeaky floors occur as homes age and components pull apart. Squeaks can come from gaps and separation between the surface flooring and the subfloor or gaps between the subfloor and the joists. Eliminating floor squeaks is easiest from below if the joists and subfloor can be accessed. First have someone walk the floor to locate the squeak. Once located, decide what problem is causing the noise. If it is a gap between the subfloor and the joists, use a shim shingle and push it between the floor joist and the subflooring. Gently tap the shim home to secure it and eliminate the void causing the squeak.

Another way to stop squeaks that occur between the joist and subfloor is to use a 3-1/2 inch to 4-inch drywall screw angled into the joist and subfloor where they meet so that it pulls the joist and subfloor together. Be careful not to penetrate the flooring above when attempting this fix.

If the squeak is because of gapping between the finish flooring and the subfloor, you’ll have to fix it from the finished side. If the subfloor is exposed, walk across it to locate any squeaks. With a power screwdriver or drill, drive a 3-1/2 inch drywall screw through the subfloor into the joist below. To locate joists, use a stud finder, look for the line of nails along the joists, or find the joints where the plywood or oriented strand board meets.

With carpeting, getting to the squeak is a little more difficult, but not impossible. There are a number of products that allow for a coarse-thread screw to be screwed through the carpet and the pad into the sub floor. The screw threads are coarse to prevent the thread from catching the carpet nap and twisting it around the screw. If you’re hesitant to trust the technology, try one in a corner or inside a closest where a mistake won’t show. Once satisfied that it won’t catch on your carpet, go ahead and drive one home in the offending area. Once the screw is in place, the top part of the shank breaks off below the carpet line to make the fix invisible.


How To: Install a New Door

To install a new door, take your time, learn the basics—and don't be afraid!

How To Install a Door

Photo: flickr.com

Most homeowners are installing a new door to replace a old door that’s been damaged or cut short to fit existing flooring, a simple enough fix if you take the time to measure. If the door is short because you’ve changed flooring, measure from the door top to the new floor height. Write down the height for later reference. Push out the hinge pins with a punch, tapping up from the bottom. Have a helper hold the door as the pins come out. Lay the door on sawhorses or work table. Remove the door knob assembly and hinge leafs.

A new core — a door without holes, hinges, or lock mechanism — can be ordered from a lumberyard or home center. Just measure the existing door for the right measurements. When you have your new core, lay it on top of the old one. Check the tops of both doors to see if they’re grooved or chamfered a bit. Doors are usually beveled from three to five degrees on the “strike” side of the door where it hits the door stops. Make sure both doors have the bevel running in the same direction because it’s imperative that your new door face the same direction as your old door. The hinge mortises must be cut on the correct side and face of the door to achieve this.

Align the doors perfectly to see if the new one will fit into the jamb. If it’s larger than the old door by about an eighth of an inch on the sides, it will have to be cut down using a circular saw and a straightedge — don’t worry about the top and bottom height just yet. If it only needs about an eighth of an inch taken off the sides to make it fit, use either a jack plane or a belt sander to size it. A belt sander is useful to knock the sides down but will make a lot of dust. The jack plane will also trim it to fit and isn’t as messy. Place the door on edge using a portable vise or pipe clamps to act as feet and hold it vertical for planing. Once planed, put the core in the jamb to check for fit.

Cutting to Fit
Once it’s cut to the proper width, it’s time to cut it to length or width. Cutting the bottom is much easier than cutting the sides, so try to get a width that fits to within an eighth of an inch or so on each side. When cutting the length, make sure you know where that beveled top edge is — you don’t want to disturb the bevel that helps the door close properly, so you’ll only want to cut it to size from the bottom. Now refer back to that door height you wrote down before you removed the existing door. The new height is the measurement from the top of the jamb down to the floor minus half to three-quarters of of an inch. You usually want about a half-inch opening at the bottom of the door so it glides over obstructions like carpet. The three-quarter-inch opening gives more clearance if the floor isn’t level.

Before you trim the bottom, wrap masking tape around the door where you’ll cut to keep the surface veneer from splitting. Mark the cut line, then score it with a sharp utility knife. Use a straightedge or a straight 1×4 clamped to the door to guide the cut with the circular saw. Check for equidistance from the edge of the saw guide to the mark across the entire width of the door bottom.

Mark for Hinges and Door Set
Place the new door on top of the old door again and mark the hinge locations. Use a combination square to connect the vertical lines for the top and bottom of the hinge. Also mark the knob holes and the backset hole. Use a utility blade to score where the backset face plate and the hinges will go. Score down as deeply as the hinge. Use a chisel to cut a number of lines in the mortised area. Then chisel carefully to remove the waste, one section at a time, keeping the mortise at the proper depth.

Place the hinge in the mortise, mark holes for a center punch and carefully drill small pilot holes for the hinge screws. Be sure to check packaging first before setting the holes. Most standard door knob assemblies use a 2-1/8-inch hole saw to cut the door knob hole and a 7/8-inch spade bit to drill out the hole for the backset. Place the backset into the hole and trace around the front plate for the striker, then mortise it in with a utility knife and chisel the same way you did it for the hinge leaf. Install the knob and you’re ready to hang the new door.

Enlist your helper again to mount the door, putting the top hinge in first and sliding the hinge pin down part way so it holds. Slide the bottom hinges together and put that pin in. Tap them both into place.

Pre-Hung Doors
If you go the pre-hung route, the steps are the same but much simpler. Carefully remove the trim or casing around the door. If you’re hanging a new jamb, you’ll need to remove all framing parts. The pre-hung door comes with all the hardware and hinges attached.

Open the package but do not remove the cross bracing that holds the door jambs in place. Set the complete door in the framed opening and shim the header jamb and side jambs with wooden shims. Make sure that you place shims behind the hinges. Don’t force the shims in or you’ll bow out the jambs. Slide the shims in gently until they stop.

Check to make sure the door is square in the frame and check both jamb sides for plumb. Check the top jamb for level. If everything is square in the frame, you can nail the jambs to the frame using finishing nails. Countersink the nails after they’re driven in and fill the holes with putty. An alternate method is to attach the door frame with trim screws. The head is a bit larger than a trim nail, but is still easily covered with putty once countersunk. An added benefit is that you can take them out if the door frame shifts during installation. Cut off the excess shim material, and install the trim around the door.

Finishing Touch
If you’re planning on painting rather than staining the door, use automotive body filler. Use this two-part product to fill the trim nail or trim screw holes and any other imperfections in the door or jambs. It’s quick, easy to work with, sets up fast, and sands beautifully for an extremely fine finish.


Hurricane-Proof Your House with Impact-Resistant Windows

Impact-resistant windows offer serious protection.

Impact Resistant Windows

Photo: elitelifestylesunrooms.com

Impact-resistant windows consist of impact-resistant glass surrounded by a heavy-duty frame that is securely fastened to the interior window header and frame. Their construction and anchoring keep hurricane winds and debris from breaching your home’s outer envelope.

The idea for shatter-resistant glass windows for homes came from the automotive field, where laminated glass has been in use for years to protect occupants. There are two common types of impact-resistant glazing for your windows. The first is laminated glass consisting of two sheets of glass with an inner shatter-proof membrane between them. Once the glass receives a significant impact, it may shatter but the inner membrane holds the pieces firmly in its frame so that the barrier is not broken. These windows are designed to handle wind-borne debris hurled at high wind speeds, as well as repeated impact from would-be intruders. In both cases, penetration of wind or water is nearly impossible. Interior lamination varies from .015 inch to .090 inch in thickness and the inner film can be ordered in a variety of color tints helping to reduce or eliminate sun fading and UV damage in your home.

The second, less-hardy variety of impact-resistant glass uses window film applied to the surface of the glazing. With filmed windows, shatter-resistant film is placed over the glass to keep the window shards in place if broken. Since these films are added to the glazing, they may not function as a complete system. Their durability really depends on how well the glass and protective laminate stay in the frame and window assembly.

Protecting the Building Envelope
Windows offer a significant opportunity for combined wind and water damage in hurricanes, but manufacturers originally came up with impact-resistant windows to save structures from destruction. A broken window provides a point of entry for wind, which enters the house, increases pressure, and seeks another way out. “When a building envelope is breached, the difference in air pressures inside and out will cause a building to lose a roof or a wall, and when that happens, the building is done for,” says Brian Hedlund, national product marketing manager for Jeld-Wen Windows & Doors. The only way to protect against damage from wind entry is to keep it out. This means deflecting wind and driving it around the building. This is why hurricane measures have been enacted in Florida for new building in hurricane zones. Residents must install impact-resistant windows or a permanent shutter system.

For homeowners in existing homes, replacing standard glass windows with impact-resistant windows brings peace of mind. “Take Florida for example,” Hedlund says. “Typically you have homeowners living there who will leave the state for periods of up to six months. If they know that a hurricane is coming, they have to return before it hits to either put shutters or plywood over the windows. If they have impact resistant windows, however, they have the peace of mind that they don’t have to take any special precautions and that their windows won’t be breached.”

Frames Add Strength to Glazing
It takes an entire window system to make an impact-resistant opening. Frames for impact-resistant windows or doors may be constructed from wood, metal, vinyl, or any combination thereof. However, frames are generally heavier than for regular residential windows, because although the glass may not break, a strong force could hit the window hard enough to cause the entire frame to give way.

“The frame can be any material, but they have stiffeners and reinforcement inside to help them bear the impact,” Hedlund says. “A lot of the windows have frames that are reinforced with steel, which makes a really solid structure. It takes much more to make an impact-resistant window than just putting in the glass,” he adds.

Testing for Total Security
Not every window on the market can claim to be impact resistant. There are testing standards set forth by the American Society for Testing & Materials (ASTM) that must be met before the window is certified as being impact-resistant. One of the most stringent of the requirements comes from the South Florida Building Code, which has been concerned over the increase in the number and force of hurricanes in recent years. Beginning in July 2001, the South Florida Building Code required that every exterior opening in a house be protected against flying debris either by shutters or impact resistant windows.

Also, according to the code, the windows must meet requirements for large and small missiles. It specifies that for large missiles, the window has been tested with an impact from a six-foot-long 2×4 weighing nine pounds, traveling at 50 feet per second. The test is done in a laboratory setting with the lumber fired from a cannon into the window. The window glazing must remain intact after the impact.

The small missile test exposes the window to a variety of impacts with 30 pieces of roof gravel traveling at approximately 80 feet per second or 50 miles per hour in order to meet the certification requirements. Current tests actually use steel ball bearings for uniformity in test conditions.

The windows are marked and graded according to the South Florida Building Code to ensure that you are getting exactly what you’re paying for. You can rest assured when buying impact-resistant windows that the product will perform as advertised when installed according to manufacturer’s specifications.


Impact-Resistant Windows Installation

Modern windows designed not to shatter can protect your home and family from inclement weather and hurricane-force winds.

Photo: pgtinc.com

Hurricane winds deliver force to building exteriors and elements. It is by far the debris these winds carry that most threatens a home during a wind event. In high winds, roof sheathing, branches, roof tiles, or garbage cans become projectiles or missiles that are hurled at neighboring homes. The key to keeping your property intact is to keep the envelope tight so that wind and water cannot enter. Windows are a key point of entry, so it is essential that they resist the damaging force of wind-borne debris.

There are only two secure ways to protect the openings of your home when hurricanes begin to blow — shutters and impact-resistant windows. Protecting your home and your family from flying debris requires that windows, doors, skylights, and patio doors all meet the tougher building standards mandated by agencies and regulations like the South Florida Building Code, which has become a leader in materials and fastening upgrades in hurricane zones.

Window Design and Installation
When they first entered the market about 20 years ago, impact-resistant window styles were somewhat limited. Since then research and development have caught up to the demands of stricter building codes, and now nearly any type or style of window is readily available. Windows with impact-resistant designs now include fixed-pane, awning, casement, horizontal roller, and single-hung and double-hung models. Skylights, door glass, and patio doors are also available in impact-resistant formats. Today, virtually all of the major window manufacturers make high-grade, impact-resistant windows that have been certified to meet all protective standards.

A window is part of a total house envelope, so it must be installed correctly in order to maintain its integrity. According to Brian Hedlund, product marketing manager at Jeld-Wen Windows & Doors, each manufacturer specifies how its impact-resistant windows must be installed in order for them to offer the maximum amount of protection when confronted by storm-driven debris. “The installation methods are typically set forth by each manufacturer, and a lot of times test reports [on how a window responds to debris and wind in a laboratory setting] will dictate what the installation method should be,” Hedlund says.

Dave Olmstead, spokesman for PGT Industries in Venice, Florida, agrees that no matter how strong a window is, the attachment to the building structure is critical. Olmstead says a window that is 53 inches by 76 inches would have 28 square feet of exposure, and with a wind speed of 146 mph, a Category 4 hurricane would result in a load on the window equivalent to 1,958 pounds of pressure. For the window to perform correctly, the load has to be transferred to the building itself, which is done by using suitable anchors to transfer the load from the window or door frame to the rough opening without causing failure.

Keep Windows Tight
A key factor when installing impact-resistant windows is a watertight caulk seal. “Caulking of the window is also critical to prevent water intrusion,” Olmstead says. “Both the window bucks [the square box or frame within a concrete foundation for future window installation] and the window itself must be thoroughly sealed to the building.”

Oftentimes, the closer the home is to the coastline, the more stringent the requirement for fasteners. Homes on the beach typically require stainless steel screws to stand up to the salt spray. Those further inland may require galvanized screws. Screws rather than nails are specified because nails are less resistant to pull-out when lateral force is applied to the window and surrounding wall. Screws pull material together and won’t pull out.

Cost and Availability
Impact-resistant windows are available nationwide by special order, but are most readily available in coastal states that mandate their installation through tougher building codes. They can be ordered and shipped anywhere, however.

According to an independent study by the North American Laminated Glass Information Center, adding impact-resistant windows will only increase construction costs by a few thousand dollars on an average new home. As with all building enhancements, the familiarity of the crew with the product will directly impact how long the windows take to install and how much labor will cost. Compare the cost of the product, installation, and any insurance benefits before making your decision.

Insurance Benefits
Benefits from impact-resistant windows extend beyond the storm belt to broader security concerns. Impact-resistant windows are considered to be security features — they are so difficult to penetrate or separate from their frames that they reduce break-ins, theft, and property damage. There are insurance breaks for new homes built with impact resistant windows, and for existing homes remodeled to include the tougher windows and frames. Check with your homeowners insurance carrier to see what kind of a discount is available.

Storm-Ready Building Codes
It’s not just Florida that needs protection from wind and wind-borne debris. Since tougher building codes took effect in Florida following the devastation of Hurricane Andrew, numerous other states have followed suit by adopting storm-ready building codes of their own. According to the International Building Code, the following states now require impact-resistant windows in new construction and remodeling: Alabama, Connecticut, Delaware, Florida, Georgia, Maryland, Massachusetts, Mississippi, New York, North Carolina, Pennsylvania, Rhode Island, South Carolina, Texas, and Virginia.


Concrete, Block, and Slab Foundations

Climate, including high water tables, frost lines, harsh winters, and vulnerability to storm surge and high winds, will determine whether a slab or below-grade foundation is chosen.

Concrete Foundations, Block Foundations, Slab Foundations

Photo: concreteworkz.com

When building a house, two main types of foundations are used: slab-on-grade or below-grade foundations with a basement slab. Climate, including high water tables, frost lines, harsh winters, and vulnerability to storm surge and high winds, will determine whether a slab or below-grade foundation is chosen.

Poured Footings
Poured and block foundations both sit on concrete footings, or poured pads that serve as a base for the walls. Footings are constructed in trenches dug beneath the level of the basement floor. These trenches are wider and longer than the walls they support and function like feet to distribute the weight of the wall and the structure above it. Footings provide a firm surface to resist sinking or shifting into the ground or substrate. A footing trench ranges from six inches to three feet deep, depending on the building size and soil characteristics.

Poured Concrete Walls
Poured concrete is more popular for basement construction than block because it is seamless and resists water intrusion. When pouring an integral foundation, aluminum or insulated wall forms are placed on the footings, clamped together, and supported to maintain their shape while the concrete is poured.

Once the forms are set, rebar is placed vertically inside the wall channel to support and add additional strength to the concrete wall once the molds are removed. Concrete is then poured into the mold to form the walls.

Concrete walls should be created as a continuous pour to ensure good bonding and avoid seam cracking where a first concrete layer has already set.

Cement can be poured in place with a cement-pumper truck, or offloaded down the chute of a ready-mix truck if it can get close enough to the foundation. Set-up time depends on the slurry used, the time of year, heat, and humidity. Temporary forms are usually taken down after one week, at which time the concrete is cured enough to support itself. The concrete will continue to cure and emit moisture for much longer. When using insulated concrete forms, they remain in place and insulate the home.

Reinforced Block and Concrete Walls
Block foundations use cinder blocks (8 x 8 x 16 inches) that are stacked on each other and cemented in place with mortar. The process starts on the top of the footings with each row forming its own course. The blocks are then reinforced with rebar placed vertically in the holes or cells and filled with concrete.

Block walls can also be used to form stem walls that support a slab above. When building stem walls, block courses on footings are set below grade and reinforced with rebar before concrete is poured in a continuous pour for a seamless, integral slab. Stem-wall slab foundations prevent water intrusion and the separation of the slab from the substrate that can be caused by uplift or hydrostatic pressure.

Both poured and block foundations are reinforced with rebar. With poured walls, a pencil vibrator is inserted into the slurry to vibrate the concrete into place and ensure there are no air pockets or voids left in the wall.

Finishing the Basement Floor
When building slab foundations, the concrete pour comes after the footings have set and before walls are erected. Dirt is compacted and backfilled with four to six inches of gravel. Typically, a six-mil polyethylene sheet provides a vapor barrier between the soil and the slab. A two-inch layer of sand goes on top of the vapor barrier, followed by a 6×6-inch wire-mesh grid that reinforces the concrete. If radiant in-floor heating will be used, the plastic tubing is placed on top of the wire mesh. Once the tubing is pressure-tested, the four-to-six-inch concrete slab is poured.

When building with poured walls, the basement floor is prepared as if it were a slab floor, often with the concrete floor poured after the top floors are in place and the roof, windows, and doors are set.

Basement plumbing for floor drains and piping must be roughed in before the pour. Like a slab floor, the basement floor will be lined with a six-inch aggregate bed followed by a six-mil polyethylene vapor barrier. One to two inches of foam board can go on top of the vapor barrier for insulation and further waterproofing. Wire mesh comes next for structural strength, and flex tubing is set in place if using in-floor radiant heating. Finally, the concrete is poured on top and leveled with a screed.