Giovanni Valle is a licensed architect and LEED-accredited professional and is certified by the National Council of Architectural Registration Boards (NCARB). He is the author and managing editor of various digital publications, including BuilderSpace, Your Own Architect, and Interiors Place.
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If you are doing any renovation work in your home, it’s important to know where chases are before creating openings in the walls. After determining where they are, you should also determine the location of the stud bays.
A chase in home construction is a vertical space in a wall, which provides an area for pipes or wires to run through. Builders strategically place chases to ensure that cables run together. A chase may run up the wall from the basement to the attic or the upper part of your home.
The rest of this article will help you learn more about a chase in construction, including:
- What you need to know about chases
- How to chase cables and pipes into a wall
- Chase cutting
- Putting pipe or cable in a chase
- Filling the chase
What Is a Chase? All You Need to Know
A chase is drilled in a concrete floor construction or wall and helps accommodate features like cables and pipes. The width of chase often varies depending on the type or the number of services it will enclose. However, in most cases, the width of a chase will not exceed 3.9 inches (100mm). At times, larger chases are necessary to accommodate features like sewage or rainwater pipes.
Contractors can cut chases in plaster, brick, or concrete block walls. They can also cut chases in concrete floors if there was no provision for cables and pipes during the design stage. At times, an unforeseen requirement for chasing may arise.
After securing the required cable or pipe into the chase, contractors conceal the chase using cement mortar, plaster, or any other surface finish. It is important to house features such as power cables in protective tubing before placing the plaster or other concealment materials.
In the case of drywall, stud, or other hollow constructions, builders can pass the cables and pipes inside the void in the wall or the partition, but this is not chasing.
How to Chase Cables and Pipes Into a Wall
When you run pipes or cables up or along a wall, the neatest way to conceal the cables is by burying them or chasing them in the wall surface. You have to follow several guidelines when you are chasing pipes or cables into walls:
- You should avoid cutting a chase at an angle between the start and the finish of a wall. Instead, a chase cut-out should always be horizontal or vertical between the start and the wall’s finish.
- If you are making a vertical chase, the chase should not be deeper than 1/3 of the wall’s thickness. If you have standard 3.9in (100mm) blocks or bricks, the chase should not be deeper than 1.3in (33mm). This depth is adequate for the installation of piping and cables, not allowing for the plaster coating.
- If you are making a horizontal chase, the chase should not be deeper than 1/6 of the wall thickness. Therefore, if you have 3.9in (100mm) blocks or bricks, the horizontal chase depth should be 0.6in (16mm). This is sufficient to install the piping or the cables, not allowing for the plaster coating.
- If you are cutting chases on the opposite sides of the walls, you must ensure that the chases are not in line. This means that the chases should not be back to back.
By adhering to the requirements that cables and pipes should only be chased vertically or horizontally, you reduce the likelihood of the person driving a nail into the wires or pipes. Cutting a chase in a masonry wall weakens the wall structure. A horizontal cut weakens the wall structure more than a vertical cut.
Cutting a Chase in a Wall
What do professional builders use when cutting a chase in a wall? Usually, professional builders have special chase tools, typically an angle grinder. An angle grinder contains two parallel cutting discs that have a certain depth cutting. The builder must first set the depth gauge before running the grinder up and down for a vertical chase or across the wall while making a horizontal chase.
The grinder makes two parallel cuts on the wall. The builders then knock out the wastes between the cuts using a cold chisel. Most of the chase cutting machines come fitted with dust extraction. However, they still produce a sizable amount of dust. Therefore, while chasing a wall, certain precautions are important to protect both the builder and the property.
If you intend to do the work yourself, you will most likely have to rent out a chase-cutting tool. You may also consider using a normal angle grinder fitted with a cutting disc. You can use the grinder to cut reasonable parallel cuts on the wall and then use a cold chisel to cut out the waste between the parallel lines. You may mark the sides of a chase on the wall and use a power drill to cut the waste by drilling several holes.
After drilling holes on the wall using a power drill, you can then use a cold chisel and a hammer to remove the concrete and trim the chase’s edges. It is important to inspect the wall and locate pipes and cables already chased in it.
Ensure that you use protective clothing, including a mask and goggles, to protect the face and eyes. Only use a power cutter with a dust collection system to avoid being covered by dust.
Putting Pipes and Cables Into the Chase
You should ensure that you run the cable in a conduit. You may go for a metal or a plastic conduit. However, a plastic conduit is favorable because it is narrow and will sit well in the chase’s shallow depth. Using a plastic conduit also helps you avoid the need for an earth bond, as in a metal conduit. It is easier to run the cables through the conduit before you fix the conduit in place.
You should use nails on either side of the conduit to hold the tube in place. PVC channeling is the alternative to a pipe. You can also go for metal channeling, but it has to be earthed. While using channeling, you start by laying the cable in the chase and then position the channeling above it. Ensure that you nail the channeling side flanges to the back of the chase.
If you are laying copper pipework, you do not have to use a conduit. Copper pipework is rigid enough. You only need to lay it in the chase and secure it using some large-headed nails on either side.
How to Fill the Chase
After placing the cable or the pipe in place, you should use a clean paintbrush to brush the back and chase sides using clean water. Ensure that you apply a clean coat of PVA and adhesive on the back and sides of the chase and the conduit.
This will help enhance the adhesion of the filler. The filler or the plaster may sag if applied to a deep chase. To prevent this, the plaster or the filler should be in layers.
Final Thoughts
The number of chases necessary for your home will vary depending on the number of floors or rooms. The number of chases required will also depend on your home’s wiring needs.
It’s important to know where chases are located before beginning any renovation work on your walls. You can usually get this information from your home designer or from the drawings of your home if you have them available.
Sources
- Frank Betz Associates: Chase
- DIY Data: Chasing Cables and Pipes into Walls
- Professional Electrician & Installer: Chasing and placing accessories: Top Tips
- Asking Lot: What is a chase in a brick wall?
- Family Handyman: How to Use an Angle Grinder
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