Usually when thinking about planting a new tree, landscape aesthetics and shading plays a very big part in the decision-making process. However, proximity to your structure should be a consideration as well. While a tree may appear to be a reasonable distance away from you structure, tree roots can spread as far as five time the radius of the tree canopy and can grow underneath foundations and, in extreme cases, through cracks in your foundation walls. These roots can swell and contract during heavy rains and prolonged droughts, respectively, disrupting the soils below the foundation and leading to potential settlement of the foundation. Roots of trees too close to retaining walls can place intense pressure along the rear of these structures, causing bulges to form or even causing the wall to fail completely, as seen in the adjacent photograph. Foundation and retaining wall issues can be extremely costly to repair and greatly impact the lives of residents in your structure, as opposed to removing improperly placed landscaping before they cause structural issues. If you have any concerns regarding landscaping impacting your structure, ETC can help you examine your options before they become a problem!
As with all building components, concrete slabs, beams, and columns will inevitably deteriorate and need repair throughout the lifetime of a building. Most concrete deterioration is linked to the corrosion of embedded metal elements, such as steel reinforcement bars. As the steel elements rust, it expands and occupies more space than the original steel, slowly building up pressure on the concrete until the concrete separates from the steel reinforcement. In the most extreme cases, the concrete will separate from both the steel and surrounding concrete, resulting in a condition known as “spalling.” Spalled concrete can be easily identified by visual inspection; it would be hard to miss a chunk of concrete missing in a wall or beam!
However, deteriorated concrete that separates from the steel rebar, but not the surrounding concrete, can be trickier to find. This deterioration is known as “delamination.” Identifying delaminated concrete requires non-destructive testing, such as sounding of the concrete elements, which tends to be the most common cost-effective option. Areas of delaminated concrete can be found by listening for hollow areas, which make a low, drum-like noise, while sounding the concrete with a hammer or by chain dragging. The hollow sound is caused by the air gap between the separated concrete and rusted steel. If you’ve noticed some suspicious-looking concrete in your building, reach out to ETC to help evaluate your building today.
Glue-laminated lumber (also known as Glulam) is a versatile and innovative material widely used in the construction industry and has become increasingly more popular in recent years for its many benefits. Glulam is composed of wood laminations that are bonded together with high-strength adhesives to form a strong member.
Glulam members are customizable to be formed to specific lengths and curvature to fit the needs of most residential and commercial wood-framed properties. Most notably, in 2019, the construction of an 18-story building in Norway was formed from solely glulam and laminated timber beams. Glulam beams also have a much better environmental impact compared to steel or concrete beams for their carbon storage capacity. Furthermore, glulam beams have good fire resistance and can outlast steel beams due to a charred carbon layer that is formed on the surface of the beams which insulates against heat. In our industry, they are typically utilized to span large openings that regular timber beams cannot, like balcony door and breezeway openings.
While the benefits for glulam beams look to be impressive, the necessity of glulam beams over other engineered lumber beams may not be the most cost-effective solution, as the cost for glulam beams are higher than they are for many other engineered lumber. Deterioration of glulam beams is common due to high humidity areas and water intrusion through improper or unsealed flashings. While glulam beams are often marketed for their ability to be exposed to the natural environment, they are often very susceptible to deterioration due to construction methodologies. Glulam beams are prefabricated to an exact size; therefore, if the beams need to be cut to fit new dimensions, the entire beam can become susceptible to deterioration if the cut portions are not properly protected with a sealer material on-site.
Having a Certified Welding Inspector (CWI) on your project will help increase the overall quality, consistency and repeatability of welds and welding processes. A CWI is trained and certified to perform inspection/observation in four major areas of welding: 1) Materials and Design, 2) Qualification of Welders and Welding Processes, 3) Fabrication, and 4) Inspection.
- Materials and design: The CWI will review design documents (i.e. drawings and specifications) to confirm that the designed welds and welding materials conform to applicable welding codes, such as American Welding Society.
- Qualification: The CWI will review Welding Procedure Specification(s), as well as all welder qualification records, to confirm that all welding personnel and processes to be used on the project are certified/qualified as required by applicable codes.
- Fabrication: Prior to the start of welding, the CWI will review the welding equipment and materials on site, as well as condition and surface preparation of base metals, to confirm compliance with the design documents and all applicable welding codes.
- Inspection: The CWI will visually (nondestructively) inspect welds during and after installation to confirm compliance with the design documents and all applicable welding codes. Where other nondestructive testing (NDT) is required, the CWI will observe the testing procedures and will review test results.
Please contact Savannah Penn, CWI at: firstname.lastname@example.org
Stroll down any street in Baltimore or Washington, D.C. and you are bound to find numerous brick buildings sporting a fresh coat of paint. The trend of painting brick facades has become popular over the last several years and while painting brick can provide an updated appearance, it may not be the best idea.
Brick masonry is naturally porous, meaning it contains small holes which allow liquid and air to pass through. Two common types of masonry wall assemblies we see locally are drainage wall systems and mass wall systems, both of which manage the water that inevitably enters through the porous masonry. Drainage walls contain an air cavity between the brick veneer and the back-up structure, allowing water to travel within this cavity and exit through flashings and weep holes. In comparison, mass walls contain multiple layers of brick masonry which rely on the wall thickness and bond between the bricks to resist water penetration into interior spaces. The majority of older and historic masonry buildings consist of a mass wall system.
Most paints readily available are not vapor permeable, more commonly known as breathable. Therefore, when paint is applied to bricks, they lose their porous nature which is critical for allowing evaporation in mass wall systems. The loss of porosity can cause any moisture that enters the wall system (through small cracks or other defects) or was present prior to paint application, to become trapped. This can cause bricks to deteriorate faster and can potentially trap moisture against interior framing elements, resulting in structural damage. Trapped moisture can also cause the paint to blister and flake, creating an unappealing appearance.
Additionally, masonry requires periodic maintenance. Painting brick can make it difficult to identify defects, such as cracked bricks and mortar, that should be repaired. Paint is also relatively permanent. Once brick is painted, removal can be very challenging and could result in significant damage to the brick walls.
However, there are options for updating the appearance of a brick façade, including brick stains and some breathable coatings. If you are interested in modifying the appearance of a brick structure and are looking for professional help, ETC can provide a solution.
One of the most pressing questions when designing repairs for concrete slabs is whether or not the slab is post-tensioned, and if so, the locations of the stressed tendons. Accidentally cutting through a stressed tendon will decrease the slab’s load carry capacity, could possibly endanger the structural stability of the entire slab, and may result in injury to those in the building.
If present, the tendons and other imbedded items can usually be located through the use of ground penetrating radar equipment, but locating the tendons would be more accurate if the original building plans and shop drawings were available for review. It is imperative that property owners keep a copy of original building plans and documents and a comprehensive running log of all building studies, repairs, etc. in order to provide engineers and repair contractors with the most complete picture of their building’s history; these documents can be incredibly helpful when trying to understand your building and should be preserved. Providing ETC with as much information as possible will help us provide you with a comprehensive repair plan and avoid hidden headaches during construction.
It looks good and it feels nice underfoot, but carpeting is one of the worst things you can do to a balcony. Carpet, artificial turf and similar floor coverings tend to hold water, impair drainage and retard evaporation. The longer water remains in contact with concrete, the more opportunity it has to exploit small cracks and the natural porosity of concrete in pursuit of a favorite target… steel (in this case the embedded reinforcement). When water contacts steel, it usually results in corrosion (rust). Rust occupies more space than the parent metal and the force that accompanies its formation is more than enough to shatter (spall) concrete that confines it.
If you simply cannot live without carpet on your balcony, at least coat the concrete with a protective surfacing; but beware, appropriate coatings are not cheap (and mere paint will not suffice). It should also be noted that carpeting will reduce the serviceable lives of coatings and fairly frequent re-application may be necessary.
It’s equally ill-advised to carpet wood balconies. Prolonged exposure to water contributes to decay (rot) and distortion (warping/cupping) of the wood, as well as corrosion of steel components.
Retaining walls offer a mix of form and function. A retaining wall can hold back the soil behind it, playing an important role in preventing erosion, particularly on hills or in areas where plants can’t grow. Retaining walls are also used to create flat, usable ground on hilly terrain for things such as parking lots and sports fields. A retaining wall can also enhance landscape designs. For example, a landscape architect or designer might build retaining walls to create different levels of terrain or different elevations in a garden.
Retaining walls differ from the walls that hold up a building or another structure. While the walls of a home or apartment building are designed to support vertical loads such as ceilings and roofs, retaining walls are meant to support horizontal loads. For that reason, the design and engineering of a retaining wall differ from the design and engineering of the wall of a building.
While there are similarities in the types of materials used for building retaining walls and other types of walls, some materials are better suited for use with retaining walls. In this guide, we’ll take a look at some of the most commonly used materials for retaining walls.
When the summer heats up, we often begin looking for methods of keeping things cool while outdoors. Whether we are trying to cool our gardens, our structures, or ourselves, water is considered one of the most effective tools in this regard. But not all things will benefit from added water, even on a hot summer day.
Concrete is the most widely-used building material in the world. It is celebrated for its compressive strength, which is produced by a combination of the chemical reaction between cement and water, and the presence of aggregate within the mix. The ratio between these materials within a concrete mix can have great effects on the strength of the hardened product. In particular, excessive water can have extended adverse effects on the strength of new concrete as it hardens and cures, and therefore can compromise the integrity of the resulting concrete structure.
Because of the impact that water can have on concrete strength gain, engineers have closely studied and observed the relationship between water content and concrete compressive strength. The figure below (https://www.engineeringintro.com/concrete/concrete-strength/water-to-cement-ratio/) is a graph representing that relationship, which shows the reduction of fully-cured compressive strength as the water-cement ratio is increased. The water-cement (w/c) ratio is the value of weight of water divided by weight of cement in a concrete mix. During concrete placement, the w/c ratio increases when water is added to the mix without also adding more cement. As we can see from the graph, the proportion of water within a concrete mix plays an important role in allowing the hardened concrete to reach its design strength.
Each year, the hottest months of the summer bring plenty of concerns for new concrete, one of the primary items involving high temperatures (see our blog post, August 13, 2012). In an effort to keep a concrete mix temperature down, it is no real surprise that someone’s first instinct might be to add water. But there are other effective ways to cool concrete without compromising strength- so that we can save some water and help build stronger structures.
Always nice to collaborate with others in the industry. Outstanding work by ETC’s Chief Structural Engineer, Chris Carlson, PE and Project Engineer, Luke Valentine, PE. Job well done!