Block walls are attachment points between wall studs that provide support for cabinets, shelves, or other heavy fixtures. Without blocking, cabinets can become loose, damage your walls, and even injure passersby. Read how to block behind walls for cabinets and fixtures in our step-by-step guide below, and watch the video above for tips from This Old House expert Tom Silva.
Why Blocking Behind Walls is Necessary
Mounted fixtures and cabinets can loosen over time if you don’t have adequate blocking behind your walls. This could damage your walls and even injure passersby in your home. Below are a few reasons contractors use blocking behind walls:
- Create support for heavy fixtures to prevent sagging
- Enhance overall stability of wall-mounted elements
- Minimize wall damage from items that don’t have proper support
- Provide fixed attachment points for cabinets so they don’t move
Pro Tip: Fitting lengths of 2x blocking between the studs is one of the most practical steps a builder can take. As This Old House Magazine notes, blocking “provides a solid base for attaching cabinets, towel bars, or other wall hardware in a bathroom or kitchen.” Without it, you’re relying on drywall alone to hold the weight — a recipe for failure.
When to Install Blocking
Below are the points at which you should install blocking:
- Before you install kitchen or bathroom cabinets
- Before you mount heavy fixtures, such as televisions or shelving units
- During new construction or gut renovations
- When you’re planning to add grab bars or other safety features
Pro Tip: As Norm Abram explained in This Old House Magazine: “If you hang a couple of wet towels on a rack screwed to the drywall alone, towels and rack will probably all end up on the floor one day. Towel racks, like handrail brackets, pedestal sinks, and a lot of other bathroom hardware, should always be screwed to something solid, like studs.” Unfortunately, there isn’t always a stud where you want it — that’s why installing 2×8 blocking (or wider) when framing new walls, or whenever you open a wall during remodeling, is so important. It gives you an easy target to hit with mounting screws, so you can secure something exactly where you want it.
When gutting a bathroom, take the opportunity to add 2×8 blocking between the studs wherever you plan to put towel bars, grab bars, and pedestal sinks. As noted in This Old House Magazine, blocking gives screws something solid to bite into and provides more area to work with than a stud edge alone. If you’re installing the blocking with a hammer, stiffen the studs with 1×3 strapping and 8d nails so they don’t bounce with every swing — drive the nails only partway so they’re easier to remove when you’re done. If you’re using a nail gun, the strapping isn’t needed.
Materials and Tools Needed for Blocking
Collect the items below before you start the blocking process:
- Drill and screws
- Level
- Lumber
- Measuring tape
- Pencil
- Safety glasses
- Saw
- Work gloves
Step-by-Step Blocking Process
Follow the steps below to install blocking between wall studs:
- Measure and mark: Use your cabinet plans to figure out where to place the blocks. Measure and mark your wall.
- Cut the lumber: Measure the distance between studs before making cuts.
- Position the blocking: Place the cut lumber horizontally between the heights you marked.
- Secure the blocking: Use screws to attach the blocking to the sides of the studs.
- Check for level: Confirm that the blocking is horizontal and level before you permanently attach it.
- Repeat as necessary: Install additional blocking as necessary.
Aim to measure low on the wall where stock is least likely to distort.
Pro Tip: Tom Silva, general contractor on This Old House, explains why blocking matters for cabinet installations: “You gotta think about the weight of the cabinet. What’s gonna go into those cabinets? You never know. Let’s say dishes. Well, that’s heavy.” His approach is to put blocking in between each stud cavity, spanning the full height of the cabinet area — from a little below the bottom to tight to the ceiling — so every fastener hits solid wood.
Tips for Effective Blocking
Follow the tips below to create a solid foundation for the wall-mounted items in your home:
- Add extra blocking for particularly heavy items to reinforce support.
- Consult local building codes so that you meet all of your municipality’s requirements.
- Install blocking at different heights to accommodate different types of fixtures.
- Use lumber that matches the thickness of the studs.
Pro Tip: Tom Silva, general contractor on This Old House, adds blocking to any wall more than 8 feet tall or one that bears a load. These short pieces of lumber, nailed between the studs about halfway up the wall, “help keep the studs straight, and so add integrity to the wall and make it stiffer.” For this structural purpose, he prefers herringbone blocking — so called because of its distinctive zigzag pattern — which he routinely uncovers in older houses.
Common Blocking Mistakes to Avoid
Even the most skilled contractor can make mistakes. Below are common issues you might encounter and tips on how to fix them.
- Misalignment issues: Carefully align your blocking with your fixture attachment points.
- Neglecting to level: Always make sure blocking is level.
- Overlooking existing utilities: Be conscious of the locations of electrical and plumbing fixtures to avoid complications.
Professional vs. DIY Block Wall Installation
Many homeowners can tackle this project by themselves, but certain situations call for professional services. Contact a pro if any of the following apply:
- You have multiple fixtures that are complex.
- You have an older home that might need expert handling.
- You have load-bearing walls that a professional should handle.
- You need to make extensive modifications and adjustments to existing walls.
