Structural Brick Wall Design

From the seventeen hundreds to the nineteen hundreds, load bearing masonry construction was the most popular construction method for large buildings. However, nowadays this method doesn't enjoy the same popularity it did back in the day when it comes to large buildings, but it seems that it is a great choice for small residential scale constructions.

It basically consists of heavy and thick masonry walls made of either stone or brick that support the whole structure. This includes the horizontal floor slabs that can be made of steel members, wood or reinforced concrete.

On the other hand, it seems that the majority of constructions done today are frame structures of strong, yet light materials that are capable of supporting floor slabs. These also have very light and thin external and internal walls.


So what's the main idea behind this type of construction?


The answer is simple: each wall acts as a load carrying element. When it comes to load bearing structures, punching a hole in a wall for connecting 2 rooms is just not possible. By doing so, you're going to damage the structure. The great weight of the walls is what's stabilizing the building against external forces and also holding it together.

In the past, when building European load bearing masonry structures, horizontal planks, joists and wooden beams were used for making the floor slabs. The sloping wooden roofs of these structures were finished with metal plating, stone shingles, wood shingles or clay tile.

However, there were also buildings that featured flat terraces which were built by pouring a layer of concrete over a wooden floor and then using either stone or tile to provide a waterproof and durable finish. Below it, each wall featured a simple continuous strip foundation. In fact, if you visit Europe, you'll probably be quick to realize that the majority of classic buildings there are built using load bearing masonry construction.

Louis Khan, a famous American architect is famous for using load bearing construction for the IIM in Ahmadabad. Instead of concealing it under decorative skins, this structure deliberately expresses the construction system. For this project, he used concrete exclusively for members in tension. These are practically ties which tie together the 2 ends of the brick arches.

Panorama Ahmedabad via Wikimedia Commons
By Mahargh Shah (Own work) [CC BY-SA 3.0], via Wikimedia Commons

Load bearing wall construction and why it's not that popular these days

There are quite a few reasons why load bearing masonry is not used so often nowadays:

  1. Load bearing construction is very material intensive, so constructing one such building requires a lot of bricks. This results in a building that’s definitely not green and one that’s also very heavy as well.
  1. It's very labor intensive, since it's generally built using handmade masonry. Compared to modern construction methods, the construction speed is also very low.
  1. Lastly, such buildings don't perform well in earthquakes and most of the times suffer the greatest damages. If you're currently living in one such building in a seismic area, you may want to think about moving into a modern structure that has better chances surviving and protecting you in case of a disaster.

Failing Brick Wall
Brickwork Restoration in Chicago

If you've tackled a few home improvement projects by now, then you certainly heard about the term masonry. If you don't know what it means, masonry is basically the process of constructing structures from individual units that are laid in and bound together by using mortar.

Let's talk about various issues those walls encounter, sometimes caused by human error, elements, and time. Periodical professional inspections of masonry walls are crucial in detecting problems and preventing dangerous structural failures.

Solid Masonry Walls

The majority of older properties around the US, in Chicago for example, are build by making use of stone or brick masonry (full thickness), but the properties in the south which are newer make use of wood frames at the 2nd floor and concrete masonry units at the first floor. But regardless of the case though, both of these types of structures are going to deal with cracks.

Brick Wall Cracks Caused by Corroding Lintel

In general, the normal setting of the house and the shrinkage in the mortars are two of the main factors that are going to cause this to happen. Now when the house will be inspected by the inspector, he will need to assess if the cracks are actually flaws or not. Naturally, cracks with movement or bigger cracks need to be evaluated further, since they allow water to penetrate the structure and lead to more damage.

Usually, structural inspectors assume that cracks which are bigger than one eight of 1 inch or one quarter of an inch in masonry walls require further evaluation. Better yet, if there are enough hairline cracks that add up to a quarter inch or more can signal more than usual movement. In case the cracks exhibit a vertical or horizontal offset movement, it's necessary that they're verified by a structural engineer to ensure they won't cause structural problems.

It's necessary to look for more evidence of movement that can be consequential or causative to the cracking noticed in the masonry wall. Some examples in this regard would include sloping floors, interior cracks, etc.

Assessing bulges for instance is a lot easier compared to assessing cracks due to the fact that bulges in masonry walls signal movement. Since in this case there's a high risk of failure, more evaluation should be considered at the soonest.

There are many areas that need to be carefully inspected in solid masonry walls, including penetrations in windows, but also in doors. The majority of solid masonry walls aren't barrier walls and what this means is that they do allow a bit of moisture to infiltrate, but to allow the water to escape by draining at the bottom, they depend on wythes.

In consequence, if there are horizontal interruptions in the wall, such as the top frame of doors or windows, this can lead to a slowdown of moisture penetration. When this occurs, moisture is going to be absorbed by the wood frames which will then start to rot. There's also a good chance that the moisture can penetrate the interior.

In general, older walls made of solid brick or stone masonry used mortar for strengthening purposes. The mortar a bit soft and it was made using a lime based material. As you may expect, it was indeed porous, which means that it was easy for moisture to escape between the stone or bricks.

eavily Deteriorated Mortar and Brick

When the mortar would eventually deteriorate, it had to be scraped off in order to install new. Keep in mind that when re-pointing / replacing the old mortar the new one needs to be the same in terms of consistency and ingredients used in original mix.

Using different ingredients is going to cause the masonry walls to absorb moisture and result in brick spalling. Spalling means that sections of the face would simply start to pop off. Due to the sensitivity of this type of job, it's recommended that you hire a professional to handle this project. Be sure he has good knowledge of vintage masonry buildings before hiring him.

Spalling Bricks

Veneers

While they can basically be any material, in general they're faux stone and sometimes brick. The way it works is that metal straps placed at twenty four inches on the middle each way are going to be used in order to anchor the veneers to the wood frame walls. It's necessary that the materials need to be installed with air spaces of around 1 to 2 inches between the wood frames walls and them. By doing so, it'll make it possible for the moisture to drain at the bottom and exit the wall through the weep holes.

In the majority of cases, weep holes are going to be placed at a maximum of thirty three inches on center based on the IRC. However, based on the recommendations from the Brick Institute of America, you should consider 16'' for wicks and 24'' for the weep hole.. As for the weep holes, they need to be made above grade.

Brick Veneer Separating from StructurePlastic mortars are then used to glue the adhered veneers to the building. Prior to starting work on this part of the project, a metal lath, but also some building paper have to be used on wood framing (external side).

After that, a scratch coat of stucco that is around three eights of an inch in thickness needs to be installed. Wait for a while until everything is dry and glue the adhered veneer on the joints and apply mortar on them. Keep in mind that moisture needs to have an exit at the lowest part of the wall.

The general conditions that require the veneers to be evaluated and repaired include the moisture intrusion into the property due to the absence of a moisture exit, blocked weep holes and the absence of weep holes.

Metal headers or lintels are used for supporting the masonry veneer above the penetrations. Therefore, it's not unusual that after several years they're going to start corroding. The problem with this is that if not serviced as soon as it has been detected, over time cracks in the mortar will become larger and might result in significant brick displacement.

Concrete Building StructureThe most common type of buildings that you see whenever you go out are concrete frame structures. As the name suggests, these buildings have a frame that’s made entirely out of concrete, with the vertical parts of it being called columns and the horizontal parts being called beams.

When it comes to these structures, the columns are the ones that have load bearing properties and if a beam were to be damaged in a building, it will affect the column and therefore increase the risk of the entire building collapsing.

Concrete is also known as RCC which is basically concrete that contains rebars or steel bars. This combination is the best for building most structures these days since steel is extremely strong in tension and concrete is extremely strong in compression.

Concrete with rebars

Making reinforced concrete is not hard at all, but first of all a mold needs to be made which gives the concrete the desired shape for the project you're working on. Next, you'll have to take a good look at the drawings made by the engineer to place the rebars properly and then tie them using wire.

Tying Rebar ReinforcementWhen the steel is properly tied up, the builder will need to prepare the concrete. He does so by mixing stone chips, sand and cement in a wide range of sizes, but he also adds water in the cement mixer and then, when ready, the liquid concrete is going to be poured into the formwork.

It's very important that the right amount of each ingredient is mixed in order to make sure that the concrete is going to have the right consistency and strength when it dries up to ensure the building won't crack or collapse at the first earthquake.

While different concrete mixes are used depending on the project, in general standard mixes are used. To offer some examples of such mixes, they include M40, M30 and M20 concrete mixes and in this case, the number refers to the concrete's strength in Newtons per square mm.

What this means is that M3 concrete has a compressive strength of thirty Newtons per square millimeter. Keep in mind that the maximum aggregate size can also be specified in the standard mix. So for instance, if an engineer were to specific M30/20 concrete, ten what he means is that the M thirty concrete has to have a maximum aggregate size of twenty millimeters.

Pouring Concrete on Rebar

So to sum things up, a concrete wall structure is basically made up of connected frame members that are very well connected to one another. When it comes to steel structures, hinge connections are the ones which are used most, yet when it comes to the concrete frame structures, they feature connections in ninety nine point nine percent of the case.

Due to the fact this frame will eventually become really strong, it can and will resist the wide range of loads which are undoubtedly going to act on a construction during its lifespan.

Some Examples of These Loads are as Following:

Dead loads

This refers to the building's downward force that comes from its weight.

Live Loads

This refers to the building's downward force that comes from the weight of its occupants, but also their possessions. The loads can vary if the building is an industrial, office or residential construction. For residential buildings, the minimum load is around two hundred kilograms per square meter. 

Dynamic Loads

Generally occurring in bridges, these loads are created by traffic, such as accelerating and braking loads.

Wind Loads

These buildings are designed so they can withstand extreme conditions occurring once every one hundred years. These kinds of buildings will therefore withstand wind forces of about one hundred and fifty kilograms per square meter.

Earthquake Loads

When an earthquake takes place, the building will be shook both vertically and horizontally which may cause it to fall apart. The thing is that if the building is very heavy, then its chances of collapse are much higher.

Since the concrete frame is resting on the foundation, the earthquake's force will be transferred from the building onto it and finally to the ground.

Other Essential Components of Concrete Frame Structures:

When it comes to high rise buildings, you should know what shear walls are very important elements. So basically, they are very big columns which can be as long as 9-10 feet and as thick as 16 inches.

Because of their size, they appear to be walls and not column. The reason they're integrated in a building is because they deal with the horizontal forces that act upon the building, including the forces generated by earthquakes and winds.

A building is also subjected to vertical loads which are usually due to gravity. The good news is that these types of loads are also carried by the shear walls, however, it's essential that you understand these walls will only be useful for handling horizontal loads in a single direction. Therefore, given their function, you won't actually find these walls built into low rise buildings.

As you may expect, each high-rise building will have elevator and the elevator shafts are basically vertical boxes that allow elevators to move down and up. In general, elevators are enclosed in their own box made of concrete. But what you don't know is that the shafts are also excellent structural elements that carry vertical loads and help resist horizontal loads.

Walls in Concrete Frame Buildings

Concrete Building Walls CladdingOne thing you need to know about concrete frame structures is the fact that they are not only economical, but they're also very strong. Because of that, you can basically use any type of wall material with them and if you want to lean towards the heavier options, they include stone, concrete blocks, but also walls of brick.

On the other hand, lighter options may be a good idea, deepening on your preferences and needs and some of them include wood studs covered with sheeting material and masonry walls of brick.

The truth is that most of the times when concrete or brick blocks are used, the entire surface will have to be plastered using a cement plaster. This helps form a long lasting, but also very durable finish.

Cladding of Concrete Frame Structures

One of the best things about concrete frame buildings is that you can easily clad them with just about any cladding material. Some of the most popular ones include ceramic facades, stone sheets, but also aluminum panels and glass. Since these types of buildings can be designed for heavy loading, you can also choose to clad them in stone, brick or solid masonry walls.