There are three main reasons to make sure you have a well drained lot:
1 To stop basement leaks,
2 To decrease hydrostatic load on basement walls, and
3 To preserve the bearing capacity of the soils under your foundation.
Your basement is a hole in the ground lined with an imperfect concrete structure–a porous material with cracks, holes, and joints. It is a very cheap pool attempting to keep water out.
There are three things that keep a basement from leaking:
Unfortunately coatings don’t last forever, and the drains can clog or become crushed from improper installation. If these systems break down, then you’ll need to direct water away from the house as best as possible. Wet soil is heavier than dry soil and increases the weight upon your basement walls, which leads to cracking and other damages.
In addition, when the home was built, dirt was excavated, the foundation was built and some of the old dirt was used to fill the gap. Over time that dirt settles, vegetation grows, and soil dries and shrinks away from the structure, changing the grade and causing water to drain toward your house.
Here are some basic changes that almost anyone can make to avoid improper water drainage and subsequent damage to your foundation and basement:
More drastic changes include adding drains or significantly changing the grade of your yard. Curb drains can help redirect some of the water that is coming toward the house from a slope above the property. Another option is a French drain that diverts water away from the foundation and down the hill to either a dry sump, a decorative pond or, the street.
Changing the grade will often involve some kind of excavation machinery. This could be something as small as a rototiller to a large tractor with a blade. If the job requires more than adding dirt near the house you should hire a professional as more harm than help can happen.
If those aren’t enough reasons to change your drainage here’s an added bonus: many plants require well-drained soil. So do your house and plants a favor and get that yard draining right.read more
Carbon fibers are only about 1/10th the thickness of a single hair but five times stronger than steel and twice as stiff. These strands are heated to various temperatures depending on the desired product. At the end of the final heating process, when the impurities are burned off, the strands are left as almost pure carbon which allows for exceptionally strong elemental bonds.
Carbon Fiber Reinforced Polymer (CFRP) has become an increasingly notable material used in structural engineering applications due to its lightweight yet powerful strength. A four-inch wide carbon fiber strap can withstand over eight times the stress of a steel I-beam even though the strap is less than 1/8th of an inch thick.
CFRP typically has a large impact on strength reinforcement (doubling or more the strength of the section is not uncommon) yet only moderately increases stiffness (approximately 10%), so it is applied to reinforced concrete structures for flexure.
Retrofitting with CFRP has become more dominant in civil engineering; applications include increasing the load capacity of old structures (such as bridges) that were designed to tolerate far lower service loads than they experience today, seismic retrofitting, and repairing damaged structures. Retrofitting is popular because often times repairing a deficient structure using CFRP is more cost effective than rebuilding.
For concrete walls that need to be reinforced, such as basement walls, carbon fiber straps can be used to stabilize and strengthen a wall. Unlike using beams as reinforcement, which reduces square footage in the basement, carbon fiber straps occupy no extra square footage. Not only is the wall more than doubled in strength, it is also stabilized indefinitely as these straps will not stretch over time due to the carbon fiber’s stiff nature. The straps allow for a solution that requires no excavation, is less intrusive, and is maintenance free.
In many cases you avoid using steel beams to reinforce your basement walls and avoid losing usable square feet. This allows you to keep the aesthetics of a your basement and do so much more with it.read more
It is very common to encounter a type of surface bonding cement under manufactured homes that has been applied as an upgrade to bring the foundation into compliance with HUD standards. However, I have never been able to understand how or why this is the case. There seems to be an interpretation among some engineers that the September 1996 Permanent Foundations Guide to Manufactured Homes (PFGMH) requires that CMU blocks always be mortared together and that the use of such a bonding cement will meet that requirement. In my opinion, this is wrong on both counts.
First, there is nothing in the definition of a permanent foundation in the PFGMH that requires block stacks to be mortared together. There is a section that does address masonry piers. The most common quote is taken from section 503.4 which states “All masonry piers and walls shall have mortared bed and head joints.” What is usually left out is the following statement, “Reinforcing and grouting shall be in accordance with the foundation concept selected from Appendix A.” Appendix A is a collection of pre-approved designs which are guaranteed to meet HUD requirements. When you look closely at what this requires, you find that the total approach requires several components seldom found, including: (1) a poured concrete footer, (2) voids in the CMU filled with concrete, (3) rebar connecting the CMU to the footer, (4) an anchor bolt coming out of the top of the stack and (5) the I beam securely bolted to the stack through the anchor bolt (with no wooden shims). This is a very complete structural stack that will meet every HUD requirement. Unfortunately, it is rarely encountered because it unnecessarily adds thousands of dollars to the set up costs and is not structurally necessary.
However, this entire design is not mandatory for existing construction for two reasons. One, the PFGMH clearly allows alternative designs that do not require the mortaring of CMU blocks. The PFGMH includes possible designs in the Appendix, but those designs are only examples and are not mandatory. Two, the PFGMH clearly addresses requirements for existing foundations in Chapter “101-2. EXISTING CONSTRUCTION. . . Upgrade of existing anchorages and footings shall meet the intent of the definition of permanent foundation stated herein.” Note that only the anchorages and footings are required to meet the “intent” of the new requirements. Piers stacks on existing construction do not have to meet the same requirements as new construction. So even if the mortared CMU blocks were universally required for new construction, which they aren’t, existing construction doesn’t have to meet these requirements.
This should be enough to eliminate the use of this product in this application, but there are several other even better reasons why it should not be used. The first is a matter of common sense. A manufactured home sitting on a pier stack will slip at the point of least resistance. On a pier stack, the point of least friction is where the I beam sits on the wooden shims—smooth surface on smooth surface. If that is not addressed, and the use of bonding cement does not touch this area, it doesn’t matter how strong the stack beneath the I beam/wood shim connection is, the stack will still slip at exactly the same applied force as it did before. The surface bonding cement does absolutely nothing to actually strengthen the overall foundation, so why use it?
Another reason is administrative. The usual HUD document referenced is the HUD Materials Release 907f which addresses the use of Bonsal Surface Bonding Cement in various applications. There are three reasons why this document is not applicable to existing foundations on manufactured homes:
Nowhere in this document is the specific application of upgrading foundations on manufactured homes even mentioned. This application was designed for agricultural block buildings, not residential housing;
The document expired in October 2007. I can find no evidence on HUD’s website (or anywhere else) that it was reviewed or re-released. The document clearly states ” Failure to apply for a renewal or revision shall constitute a basis for cancellation of the MR.” Based on its expiration, the MR can no longer be used;
Most importantly, the manufacturer’s installation instructions must be followed and their requirements are such that this product cannot be used for existing manufactured home foundations. Under the manufacturer’s instructions are statements such as “The first course of concrete blocks is laid in a full mortar bed,” “Bonsal. . . shall extend down to the top of the footing.” This product is designed to be used in buildings that (1) have a poured concrete footing and (2) have the first row of blocks mortared to that footing. There is not a manufactured home in this country that meets these two requirements that doesn’t have the rest of the block mortared. I have seen this product used in hundreds of manufactured homes and in every one, the piers are sitting on grade.
Based on the above, I never recommend the use of surface bonding cement to upgrade a foundation to compliance with HUD rules. However, when I encounter a foundation with this surface bonding cement, I usually don’t require the homeowner to do anything else because he has already spent (sometimes) thousands of dollars on this. It is not fair to a homeowner to continually require additional upgrades because the engineers can’t agree on what should be required.
image via http://www.flickr.com/photos/russellbernice/191313823/read more
Did you know that up to 50% of the air you breathe on the first floor comes from the crawl space?
Why do we care about humid air in the crawl space? As air flows upward through a home, humidity rises from the crawl space and infiltrates the air inside the house, which can cause serious problems such as:
From the EPA.gov site: “The way to control indoor mold growth is to control moisture.”
Where does the moisture come from and how do you treat it?read more
Helical piers present contractor and engineers with a valuable tool for new construction in bad soils or remediation of structures that have sustained settlement damage from loss of support by the underlying soils.
What they are:
Basically, a helical pier is a giant screw that you drive into the earth to resist compressive or uplift loads, or both. It consists of a helix, a shaft, and a bracket of some sort at the top. The pier can have more than one helix, and the shaft can be solid square steel or a pipe section.
Depending on the size, helical piers are driven with portable or with equipment-mounted rotary drive heads. The drive head screws the pier into the ground while monitoring how much torque it takes to drive the pier.
How they work:
When a helical pier is driven into the ground, the helix pulls itself and the shaft down through the poor soils at the surface to competent soils below. Once it reaches an appropriate depth, the competent soils support the helix which supports the shaft which supports the load – feel free to sing a round of “the thigh bone’s connected to the hip bone” here.read more