Other Foundation Types

Preserved wood foundations have become popular in some areas over the last few years. Wood in a below-grade, damp soil environment has historically not had a long life, particularly as a structural member. As a result, there are several design challenges with respect to wood foundations.

They are more likely to be successful in dry soils than in wet soils. For the most part, their modes of failure will be similar to what we will look at on most other foundation systems, with a couple of exceptions. Since wood is less brittle or more flexible than concrete, for example, cracking is likely to be less common and bowing may be prevalent. Rot and insect damage or obviously possibilities with wood foundations, while these are not issue with most other foundation and footing materials.

In most cases, the interiors of preserved wood foundations are finished as living space, and it may be difficult to identify the foundation system, let alone inspect it.

Some areas have expansive soils that make it risky to use conventional footings and foundations. A special reinforcement technique for concrete grade beams and floor slabs is sometimes used to resist the forces of the soil and to prevent differential movement of the structure.

Post-tensioned slabs and grade beams use steel cables or tendons that are laid in place before the concrete is poured. The cables are most often surrounded by a plastic sheathing. After the concrete is poured, jacks are used to pull the cables tight, strengthening the assembly. These post-tensioned cables sometimes snap, and in some cases, they shoot out from the foundation or come up through the floor slabs. Fortunately, this problem is rare, at least so far.

Foundation Systems

Houses may have spread footings that support the perimeter walls. These footings are wide pads that are continuous around the perimeter of the house. In some cases, the pads may be widened and/or thickened to accommodate concentrated loads from building components, such as fireplaces or pilasters.

A pilaster is a thickening of a foundation wall. It may be thickened to receive the concentrated load of a beam resting on top of the pilaster, or it may be acting as a stiffener to prevent the foundation wall from bowing inward.

Pad footings are similar to continuous footings except they are usually in a square, with the column or pier sitting in the middle of the square. It is common for houses to have strip footings around the perimeter and pad footings on the building interior under columns.

Piles are typically used instead of footings where the soil quality is poor. They are, generally speaking, more expensive to install and have to be driven into the ground with specialized equipment. They can work one of two ways. First, piles can be driven down to a point where they bear on bedrock or other sound substrate. Or, piles can be driven into the soil far enough that the friction of the soil against the sides of the pile is enough to resist downward movement.

Incidentally, if a house is supported on piles, they probably won’t be visible and it may be impossible to know it.

Piers are columns that may be completely concealed in the soil or may project above it. Think about the piers that are commonly used to build exterior wood decks and porches. These piers may be poured concrete, often with the concrete poured into a cardboard cylinder in a hole dug in the ground. Piers usually, but not always, have footings. Piers can either be thought of as posts or columns, or could be thought of as short piles that bear on their ends.

Grade beams are usually concrete beams that are supported on footings, piles, or piers, and are located at grade. In some cases, they extend below grade; usually they extend only slightly above grade. Grade beams transfer the loads from the building down to the footings or piles.

Caissons are foundation systems created by drilling holes and filling them with concrete. A caisson pile is a cast-in-place pile that has a hollow tube driven into the ground. The earth is excavated from the tube, and concrete is poured into the tube. Some caisson piles re flared out at the bottom to create a larger bearing surface. These are sometimes called bell caissons.

This has been a mostly technical discussion- but the important take away is that footings and foundations are important to the stability of the house, expensive, and mostly out of sight.

Footings and foundations should be strong so they can transfer loads and durable with respect to exposure from air, water, soil, and insect attack. Most modern footings are concrete (sometimes reinforced).  Footings on older buildings may be brick or stone.

Damaged and Patch Roofing

We’ve written before about how important the roof inspection is during the home inspection. We touched on some components on what ages a roof prematurely. Sometimes, however, the roof is not aged- but we find it damaged.

What are some typical causes for roof damage?

  • Falling objects
  • People working on the roof
  • Branches from overhanging trees
  • Wind or hail
  • Snow removal activities

A damaged roof covering may not keep the weather out and may allow damage to the building systems below.  It is common to find previous repairs that have been made on the roof. Patches are the result of past damage or leakage problems. Previous repairs present a high risk of future leakage. This is because of the difficulty in making a weather-tight patch, and/or because the substrate was damaged before the leak was patched, and the roof is spongy in that area.

Patches are often readily identified. They may be asphalt based products on the roof surface (roofer’s mastic, roofing cement, asphalt cement, plastic cement, elastic cement), they may be caulking, or they may show up as roofing materials of a slightly different color, texture, size or style than the original materials. Metal flashings that are unpainted or painted differently from the remainder may indicate patching. IF the majority of the metal shows some rusting, but one flashing does not, the flashing has been patched or replaced here. On some roofing materials, supports for new or patched roofing materials are visible. These may be nail heads, metal hooks or strips of metal, for example. In some cases, the patches are made with a completely different roofing material. These are easily identified.

When patches are found, we look closely at areas below for evidence of recent moisture. A moisture meter is helpful, although not necessarily conclusive. We report patches as vulnerable areas since it is very common for patches to fail and leak.

Comfort- What Causes It?

It is the peak of summer and the common complaint around town is that it is uncomfortably HOT! What is comfort? And what causes it?

We should define a couple of terms here. Sensible heat is the heat a thermostat senses. When the temperature goes up, there has been an increase in the sensible heat.

Latent heat is hidden. It involves adding or removing heat without changing the temperature. How does this happen? When we change a liquid to a gas (boiling or evaporation) we have to add heat, but we don’t need to change the temperature. Boiling water produces steam of the same temperature, for example. Similarly, we can remove heat by condensing gases to liquids, without lowering the temperature. Air contains latent heat in the water vapor that is in the air. Removing the vapor removes heat but does not lower the temperature.

Let’s think about comfort. It is easy to understand that most people are more comfortable at 70oF than 100oF. But there is more to it. Most people have experienced how much more uncomfortable it is on a hot, humid day than on a hot, dry day. It helps to understand why that is.

The human body cools itself by sweating. When moisture evaporates off the surface of the skin, there is a great deal of cooling that takes place. Dogs accomplish much the same thing by panting.

There is something called the latent heat of vaporization. The key is that it takes lots of energy to convert liquid to a gas. When a liquid changes to a gas, a tremendous amount of energy is absorbed. That’s why having sweat evaporate off our skin is so helpful in keeping us cool.

People are comfortable when humidity is lower because it is easier for the moisture on their skin to evaporate. The process of evaporation removes heat. It is easy to understand how fans keep people comfortable. As water is also evaporated off the sin, the air immediately adjacent to the skin becomes saturated and cannot hold any more moisture. The faster that air moves across your skin, the more quickly the saturated air is carried away and replaced by dry air, which allows more evaporation.

So, if we want to keep people comfortable inside their homes, we need to cool the air and lower the humidity. If we can keep the house about 15oF to 20oF cooler than it is outside, that is usually adequate. In the winter, we set our thermostats around 70oF, and in the summer 75oF is usually fine.

Wells: Part 2

Part 1 focused on Dug and Bored Wells. Here, we dive into the most common well type we find in modern construction, drilled wells.

Drilled Wells:

Drilled wells are typically 4-6 inches in diameter and are commonly 50-900 feet deep. There are wells that are even deeper! One advantage of drilled wells is that they are less likely to be contaminated because the water is drawn from a much deeper source. The wall casings are typically steel, although they can also be plastic, brass, copper, or fiberglass. Where the water is acidic, plastic casings may be better than metal.

The wells are smaller diameter but must be large enough to handle the pump systems. Submersible pumps are lowered into the well. Drilled wells usually have a casing that goes down from the top of the well into the bedrock. Once the well is into the bedrock, the casing stops. We’re not worried about contamination of the casing below this point. The fissures in the bedrock allow water to flow into the well below the casing. The casing itself is watertight so no water should flow into the well below the casing. In some areas, only the first 20 feet or so of the well requires a casing. This will depend largely on the soil type and the depth of the aquifers.

When the well is drilled and the casing is inserted, the space between the outside of the casing and the earth is typically filled with a slurry designed to seal this space. We don’t want surface water to run down the outside of the well casing and get into the well below the casing. The slurries can be cement grout or concrete, bentonite or other clay slurries or well cuttings or, in some cases, surface materials. Very often the casing protection will be a combination of these. Below the depth at which you are worried about the contamination of the casing, the casing may be stabilized with sand, gravel or surface materials dropped in around the casing to stabilize it.

In some areas, as the performance of a well deteriorated, it was common to drop a stick of dynamite down into the well in hopes that either new fissures would be created or existing fissures would be widened to improve the flow into the well. There was the risk of collapsing the well, of course, but if the performance was so bad that it had to be abandoned in any case, this was often a risk worth taking. For some other obviously reasons, this practice is now frowned on in most areas.

Some well casings do not come right up to grade level. They may not stop in a pit below grade, which can make it difficult to locate. A below grade well pit can also be a source of water accumulation and a possible source of contamination if the pit is not watertight and self-draining.

Drilled wells are supposed to be vented. The vents for wells are sometimes completely enclosed in the well pits. Sometimes the vent line will run alongside the water supply line into the house and a vent pipe will be just visible inside the home where the water pipe enters the house.

If a well is drilled 200 feet deep, a submersible pump is not put right at the bottom of the well. Similarly, an intake for a jet pump does not go into the bottom of the well for fear of drawing mud and other debris into the water supply. The intakes are usually several feet above the bottom of the well.

We hope this discussion on the types of wells and information about them has been helpful. If you are on a well and need your water tested, please do not hesitate to give us a call.

Wells: Part 1

Did you know that Parkwood inspects wells? One of the major components of a well inspection is testing the well water quality. If you have a property with a well, it is important to test your well water once per year at minimum.

There are three common well types: Dug, bored, and Drilled Wells. This week we will discuss dug and bored wells and save the most common type, the drilled well, for next week.

Dug Wells:

Dug wells are typically shallow and rarely more than 30 feet. Their diameter can be 2-3 feet, and they may be lined with brick or stone in old construction. Modern dug wells typically have precast concrete casings. These wells are vulnerable to contamination by surface water and chemicals. In modern construction, the top 8 feet of the well casings often have to have watertight joints to minimize the risk of contamination by surface water. The ground within a 10-foot radius of the well should slope away from the well to promote surface drainage away from, rather than toward, the well casing. Dug wells often have very good storage characteristics. For example, a 2-foot diameter well with 10 feet of water in it forms a reservoir of roughly 200 gallons. Dug wells are very susceptible to minor changes in groundwater levels. A slight decline could render the well useless.

Bored Wells:

Bored wells are typically 2-3 feet in diameter and are usually less than 50 feet deep, although they can be up to 100 feet in some cases. The depth is limited by how much excavation can be done without the walls caving in. A bored well also provides a good reservoir. As with dug wells, the casing joints should be watertight for pollution protection; the top of the well casing should be at least 12 inches above grade and sealed tightly at the top; and the surface grading around the well should slope down and away from the well.

Be sure to check out or next segment on drilled wells. If you need a well inspection or testing of your well water, please give us a call!

Common Issues with Exterior Wall Cladding- Part 5: Insulation Problems

This is the last segment in our series on common issues with exterior wall cladding.

Sometimes we find a large number of patched holes on exterior wall surfaces. If these are in a uniform pattern, they often indicate insulation blown into the wall. This insulation can include cellulose and controversial materials such as urea formaldehyde foam insulation. Adding insulation to a wall is a bit more difficult than adding it to an attic because, in a wall, the insulation is hidden between the interior and exterior wall coverings. Removing the wall covering to insulate the wall cavity just isn’t cost effective. It’s cheaper and easier to create small penetrations in the wall so that the insulation can be blown in.

Adding insulation through building exteriors is a retrofit to reduce energy costs and improve house comfort. This approach is usually taken when no interior renovations are planned but insulation improvements are considered a priority.

Adding insulation from the outside creates a number of holes in the exterior siding that may not be well patched. In some cases, the patches are very visible. In other cases, they are patched so well they are completely invisible. Poor patches may be water entry points. Insulation in old walls can reduce temperatures in wall assemblies and result in condensation problems where none had existed before. The insulation makes the wall cavity colder. Since insulation is often added without providing an air/vapor barrier, there is a higher risk of the warm, moist air that leaks through the walls condensing within the wall system.

Common Issues with Exterior Wall Cladding- Part 4: Plants, Gardens, or Vines

It looks stunning- but vines growing on a home can be very harmful. This is also true of plants and gardens too close to the exterior wall cladding.

Gardens should not be built against houses such that earth is held against the siding. A raised planter with three sides and the building acting as the fourth side is a poor arrangement. Siding materials are not designed to be in contact with earth. The situation is worsened when people water their gardens and the soil is perpetually damp. This will surely damage the siding and the wall structure behind and below. Raised planters close to buildings should have four sides and should be set out roughly two inches from the siding.

Several types of vines and ivies grow on buildings. Some do more damage than others. All tend to hold moisture against walls and trim. All provide pest entry opportunities. Many people are prepared to live with these disadvantages to enjoy the cosmetic effect.

Masonry walls are more tolerant of vines that is wood siding. Vines should be kept away from all wood trim, including doors, windows, soffits, fascia, and gutters. Vines should be kept off aluminum siding. A wall covered with vines cannot be fully inspected. This includes the trim, soffit, and fascia. Vines are usually grown intentionally by the homeowner; however, some vines are invasive and the homeowner may lose control of the overgrowth. We’ve see vines go behind siding towards the bottom of the home and reappear close to the roof.

As discussed, the implications may include insect and pest entry and moisture deterioration to the wall because of slow drying. In severe cases, depending on the type of vines, root systems, or attachment nodes can damage siding or enter the building, often through trim areas, often providing a direct path for water into the building. Some vines can even damage masonry.

Most home inspectors evaluate vines on a case by case basis and pull them back in several areas to look for damage, particularly at the trim. We typically recommend removal of the vines, but it is important to note that it may be difficult to remove all traces of vines, especially from rough-textured stone, brick, or stucco.

Common Issues with Exterior Wall Cladding- Part 3: Too Close to Roofs

Siding material should not be chronically wet. We’ve talked about this with respect to grade level. It is also true where the bottom of the siding intersects a roof. The best practice is to keep the siding material 2 inches above the roof Most people settle for a 1 inch clearance. There are step flashings under the siding and roof so it’s okay to keep the siding above the roof surface.

Wood and wood-based products are particularly vulnerable to moisture wicking up into and damaging the siding. End grains of wood and cut edges of hardboard, OSB, and plywood draw moisture into the wood enthusiastically. It’s common to see siding deterioration along a roof/ wall intersection. Again, water damage to the siding and possibly to the structure behind are the implications.

Most sidings discolor if they are chronically wet. Paint may peel. Stucco may soften and crumble. Brick may crack and spall, especially if the moisture in the brick freezes. Efflorescence may develop on the brick.

As home inspectors, we pay close attention to these areas to help protect you and keep you informed during your home purchase.

Common Issues with Exterior Wall Cladding- Part 2: Too Close to Grade

Wall cladding materials should be 6-9 inches above grade to protect the cladding system and the structure from water damage. This means that we can see some of the foundations above grade and below the siding. Foundations are designed to withstand the moisture in the soil. People may not like the appearance of exposed foundations, but from a functional standpoint, we want to see them.

Masonry should usually be at least 6 inches above grade. There are exceptions because some bricks, for example, are designed for use at and below grade. Most other sidings, including wood, and wood-based products, stucco, metal, and vinyl, should be at least 8 inches above grade.

Siding materials too close to grade are typically the result of either poor original construction and landscaping, or the grade level changes during landscaping or surface water control work.  It is possible that the siding is too close to grade because the building is settling, but there are bigger problems if this is the case.

Damage to wall cladding materials can include:

  • Spalling (crumbling or flaking) and cracked brick and missing mortar
  • obstructed weep holes in masonry veneer
  • rotted wood
  • Swollen, buckled, or cracking wood-based products
  • Peeling paint
  • Staining
  • Rusted fasteners
  • Rusted lath and drip screed on stucco

In some cases, veneer walls with weep holes and flashings along the bottom course suffer dramatically if the weep hoes are below grade. Water won’t be able to drain out, air won’t be able to get in, and moisture may seep from the soil into the building through weep holes. Severe spalling can occur.

The more serious and concealed implications are the damage to the wall and floor structures behind the siding. This includes rot and insect damage at sheathing, studs, sill plates, headers, and floor joists. Damage to interior finishes and components is also possible. Sometimes damage is not visible until it is serious. This may be the first indication that there is a problem.

What remedies are available if this is the problem found during your home inspection?

An expensive and disruptive solution would be to raise the foundation. More practically, if the siding is too close to grade because the grade has been elevated to form a garden, for example, the solution may be to restore grade level to its original position. If the siding has simply been installed too low, the solution may be to remove the bottom few inches of siding. This is only practical if the foundation is tall enough.