Forming Concrete Walls

What’s the best building material for walls?

How you construct your walls ultimately depends on how you want your house to look. Some materials lend themselves to a futuristic edge, while others provide a classic more homely feel.

Apart from aesthetics, there are a number of other factors to consider that will affect the durability and cost-effectiveness of your walls.

  • Soil - While walls may not be in direct contact with the ground, their dimensions and weight will need to be considered before you construct foundations.
  • Temperature and climate - If you’re building by the coast you may need to consider stiff winds, or you may live in an area of heavy rainfall. Depending on which way your house faces, you may need to consider a different material for each facade.
  • Labour requirements - Construction complexity is the main driver of cost, and the materials you use, added to the access required to work on your site need to be calculated early on in the build.
  • Environmental issues - Different materials carry different levels of energy efficiency, and while additional layers of insulation can be added to any material, it’s good to use something that’s inherently environmentally-friendly.

Bricks, blocks and other ways to build a wall

Here are the pros and cons of the most common wall material options, many of which can be combined to construct the ideal house.

  • Concrete blocks - Available in the shape and size to suit your project. Durable and low maintenance with a relatively low construction complexity.
  • Poured concrete - Can be the most stable of wall designs, if designed and constructed correctly. Can be susceptible to cracking if not treated effectively and will require considerable waterproofing.
  • Bricks - Due to their durability, bricks will often be the first option for wall construction. They’ll survive almost any climate and are fire repellant. They do need a strong foundation and prices can be high with the manual effort required in construction.
  • Limestone - More aesthetically pleasing than the alternatives, this is a natural and long-lasting material that’s available in many varieties. Fireproof and resilient to impact, however, they do come at a considerably higher cost per block.
  • Stone veneer - Lightweight, and offering a lot of flexibility in height and thickness. This will offer a unique look to your construction and age naturally. While it’s not as expensive as natural stone, it’s still more costly than the alternatives.
  • Wood - The most traditional material, but one that’s rarely used these days in mainstream construction projects. It’s cheap to construct but offset by being highly susceptible to damp and unlikely to withstand extreme wind conditions.
  • Steel sheets - if you’re not in an area prone to erosion and not put off by the material and installation cost, steel can give your construction a striking look while being highly fire resistant.
  • Insulated Panels - An eco-friendly, strong and energy-efficient wall building option. They are made by sandwiching an insulating foam layer of materials such as polystyrene or polyurethane between two rigid surfaces made from sheet, plywood, or cement. Their size and design can be customized according to your needs and preferences.
  • Insulated Vinyl - While not something you’d build the actual wall itself out of, this is the cheapest material for cladding walls. It’s light and durable with easy installation and an infinite number of colours to choose from.

While the above options are all perfectly legitimate, precast concrete ticks most boxes as the ideal material for a wall.

  • Concrete is a natural material that can be recycled, making it an appropriate choice for eco-friendly homes
  • With waste handled during the manufacturing process, it is more eco-friendly than concrete poured on site
  • Manufactured with a high thermal mass, walls will absorb and store temperatures at a more constant rate
  • As much of the work is done up-front, the speed of construction is lower, eliminating the need for multiple tradespeople
  • Once put into place, very little maintenance is needed over its lifespan — unlike most other materials, precast concrete increases in strength over time

It all depends on the type of construction you’re creating, but the two most important things to factor in are water damage resistance and insulation.

How to effectively insulate a concrete wall

Few would deny that concrete is strong and durable, but when it comes to offering natural insulation, that’s not one of its main characteristics.

However, it does offer a range of customisible insulation options. Which one you choose will depend on the type of construction project, pus your budget.

  • Spray or injection foam can be used on top of concrete blocks prior to outer wall layers being added.
  • Foam fibreglass boards are not quite as effective as spray foam but can be added prior to adding the exterior finish.
  • Polystyrene beads poured into concrete cavities are a great option, unless you’re planning on adding windows or service pipe holes to your wall post-construction.
  • Loose minerals insulation (such as sand) is the most environmentally conscious option out there. Lightweight and free from any chemical additions.

While they have been around since the 1970s, it’s only recently that insulated concrete forms (ICF) have become a popular construction option.

Consisting of lightweight blocks that fit together on site, the airtightness, and overall costs are very favourable in comparison to other wall construction options.

Some love it, seeing it as the future default construction method, while others despise it, proclaiming it as a blot on the construction industry as a whole. With many proclaiming a major benefit as the ease of construction, there is a danger that people may set out to use ICF without adequate training.

As with all construction, it's best left to professionals and the concrete pour remains crucial to getting it right for long-term durability. There is a risk of the walls distorting or even bursting open at pressure points.

Concrete wall finishings and coatings

Your wall is up, it’s properly insulated, so now it's time to make it look like you want it to.

Whether it’s for the interior or exterior of your project, exposed concrete is possible to leave looking relatively rustic and raw, or highly polished for an industrial gallery-feel. If this is the look you’re going for, it’s a good idea to know what areas you’re planning on leaving exposed before you begin.

  • Adapt the angle that formwork faces allowing the concrete finish to be a smooth texture
  • Consider the placement of any bolts, to try and avoid them being visible on the exposed wall (unless you want to make a design feature out of them too)
  • Remember that concrete become lighter as it cures — you may want to consider creating a test panel early on if you're looking for a specific shade
  • Let all your tradespeople know what sections of your wall are to be left exposed so they can exercise greater care when carrying out their jobs

Obviously, some blemishes are unavoidable and should be considered as part of the character of the room. That’s why you chose concrete in the room in the first place; for its individuality.

If you want the concrete wall finish without going for the full original concrete option it;’s possible to get a faux poured concrete finish, which is applied like plaster and looks incredibly close to real concrete. It’s not quite the real thing, but not a bad backup option.