Blocking behind walls is an important part of home construction and remodeling projects. Properly blocking walls allows you to mount items like cabinets, televisions, shelves, and more securely on your walls. With some basic carpentry skills and the right materials, blocking walls is an achievable DIY task.
In this comprehensive guide, we will cover everything you need to know about How to Block Behind Walls for your Generation NEXT home projects.
What is Blocking Behind Walls?
Blocking refers to the process of installing wood blocks within wall stud cavities to provide extra support and backing. Blocks create solid mounting surfaces for heavy items, prevent drywall damage, and improve the strength of your walls.
When a wall is framed with just studs, there is only support at the stud locations, usually every 16 inches. If you try to mount something heavy in between the studs, it will not be secure and may rip out.
Blocking gives you solid backing anywhere you need it along the wall by screwing wood blocks horizontally between studs. You can install blocking:
- Behind drywall where items will be mounted
- To support cabinets, railings and handrails
- For anchoring grab bars in bathrooms
- For securely mounting TVs and heavy shelving
- Anywhere else sturdy backing is needed
Adding blocking as you frame or remodel walls is the easiest way to build this extra support into your home.
Benefits of Proper Blocking
Installing blocking in your walls provides a number of important benefits:
- Creates solid mounting surfaces – Blocking provides secure attachment points for mounting heavy items on your walls.
- Prevents drywall damage – Sturdy blocking prevents screws and hangers from ripping through drywall when holding weight.
- Strengthens walls – Blocking makes walls more rigid and prevents movement when bearing heavy loads.
- Adds versatility – You can mount items anywhere on a wall, not just at stud locations, when blocking is installed.
- Saves time – It is much easier to add blocking during construction than to add it later.
- Enhances safety – Grab bars and railings mounted into blocking provide solid stability and prevent dangerous collapse.
Taking the time to block properly will make your walls much more functional, durable, and safer for years to come.
When Do You Need Blocking?
Any time you want to mount an item that is heavy, will be under stress, or needs extra stability, blocking should be added. Here are some common situations when blocking is highly recommended:
Mounting Cabinets and Shelving
Kitchen cabinets, bathroom vanities, entertainment centers and bookshelves should always be secured into wall blocking. Trying to anchor them just to drywall and studs may lead to collapse under weight. The top and bottom mounting points of tall objects especially require the extra support.
Hanging TVs
Modern flat screen TVs are large, heavy and require stable mounting surfaces. The best way to hang a TV securely is to use multiple lag bolts screwed into blocking between the studs. This distributes the weight and allows precise positioning.
Adding Grab Bars
Grab bars in bathrooms need to support hundreds of pounds of force. Attaching grab bars just to wallboard risks dangerous failure. Always locate and mount into blocking to safely hold weight over years of use.
Building Railings and Staircases
Any rails, banisters or handrails need the strongest mounting backing possible for safety. Always ensure newels and mounting points are anchored securely into blocking.
Installing Heavy Wall Decor
Solid wood shelves, plate collections, large artwork or mirrors require sturdy bases if they are heavy or jut out from the wall. Mounting these securely into wall blocking prevents rip out.
Creating Seismic Reinforcement
In earthquake prone areas, blocking between joists and rafters helps strengthen the building against lateral movement. Consult codes for your area.
Any time a heavy item, safety concern, or special requirement arises, plan ahead and add blocking.
How to Install Blocking Between Wall Studs
Adding blocking between studs is a relatively easy carpentry process:
Step 1: Plan Locations
- Mark intended mounting points for cabinets, TVs, rails and other items on the bare stud walls.
- Identify the stud bays where you need solid backing.
- Space blocking rows no more than 24 inches apart vertically for wall-mounted items.
Step 2: Cut Blocking Boards
- Use 2×4 or 2×6 lumber for most blocking projects.
- Cut boards to fit snugly between the wall studs horizontally.
Step 3: Install Blocking Rows
- Measure and mark blocking locations with a stud finder.
- Screw or nail blocking boards into studs with 3-4 fasteners at each end.
- Stagger seams if using multiple boards per bay.
- Leave 1/2” gaps between blocking ends and drywall for expansion.
Step 4: Add Additional Blocks
- Mount specialty blocks for cabinets, TV brackets, and other anchors.
- Double up blocking anywhere extra strength is needed.
That is the basic process. Always follow local codes and use common sense for safe installation.
Blocking Materials and Hardware
Blocking projects mainly utilize basic lumber and fasteners:
- Lumber – Use 2×4 or 2×6 boards for most residential blocking. 2x8s may be needed for heavy loads.
- Fasteners – Screws provide the strongest connections. Use 3-4 screws at each stud end.
- Adhesives – Construction adhesive bonds blocking for additional strength.
- Anchors – Lag screws, bolts, toggles, and sleeve anchors secure items into blocking.
Pressure treated lumber should be used anywhere blocking contacts concrete or masonry. Metro areas may require fire retardant treated wood. Some areas require stamped lumber.
Always check local codes and use corrosion resistant hardware. Stainless steel screws are ideal.
Tips for Solid Blocking
Follow these tips and methods for professional grade blocking installs:
- Cut blocking boards slightly short to allow for wood expansion and drywall. Leave 1/2″ gaps.
- Stagger blocking seams when spanning multiple stud bays.
- Screw into studs at both ends with 3-4 screws for maximum strength.
- Consider nailing + gluing + screwing for heavy loads and seismic areas.
- Double up 2x4s to create thicker 2×6 blocking when needed.
- Install dedicated cabinet blocking at all mounting points.
- Use rated horizontal blocking braces for handrails and guardrails.
- Add plywood panels for large mounting areas like baseboard heaters.
- Use solid blocking behind shower seats, benches, and bathroom accessories.
Put in the work during framing and you will have walls ready to mount and hold anything securely.
Mistakes to Avoid
While blocking walls is a straightforward task, inexperienced DIYers make some common mistakes:
- Not planning ahead – Failing to indicate blocking locations on plans makes installation much harder later.
- Ignoring codes – Building codes contain specific blocking requirements. Not following them risks citation.
- Forgetting firestops – Fireblocking must seal blocking cavities. Omitting firestops creates fire hazards.
- Mounting directly to drywall – Never secure heavy objects solely into drywall. Always hit wood blocking.
- Over-spacing blocking – Maximum 24″ spacing is recommended. Greater spacing compromises strength.
- Using inadequate fasteners – Always utilize the strongest recommended screw size and quantity.
- Not staggering seams – Failing to offset blocking seams concentrates stress in one spot.
Take the time to block thoroughly and correctly. Pull permits and have experienced carpenters review work if unsure. Proper blocking takes some labor upfront but prevents problems down the road.
Installing Blocking in Existing Walls
While it is ideal to add blocking during framing, you can also retrofit it into finished walls:
Locate Studs
Use a stud finder to identify stud locations and mark the bays needing backing. Confirm with small drill holes.
Cut Access Holes
Use a drywall saw to cut rectangular holes to access the stud bays. Make holes large enough to insert blocking.
Measure and Cut Blocking
Measure between studs and cut boards to fit tightly. You may need to angle pieces to insert through holes.
Screw Into Studs
Have a helper hold blocking in place while you screw into the studs with 3-4 screws at each end.
Patch Drywall
Replace any insulation, then use drywall patches to fill the access holes. Tape, mud, and refinish the patches.
With some careful measurements and cuts, retrofit blocking can be added to strengthen your existing walls. This is worthwhile for adding grab bars, railings, or securing wobbly cabinets and decor.
Blocking Codes and Permits
Building codes contain specific structural requirements for wall blocking. Key areas to address:
- Fireblocking – Firestops seal blocking cavities at 10 foot intervals vertically. This impedes fire spread.
- Seismic blocking – Special horizontal bracing is mandated in earthquake zones. Lag bolts anchor bands between studs.
- Load bearing walls – Heavier blocking at 24 inch intervals is often required.
- Shear walls – Braced wall panels along some exterior and interior walls may need blocking.
- Handrails – Extensive blocking rules apply to stair and loft handrails under the IRC code.
Any significant structural work likely requires permits from your local municipality. Always check the specific codes and regulations for your area. Consulting local building inspectors is wise to ensure you meet all requirements.
Hiring a Professional
If your blocking project is complex, a professional can help:
- Framing carpenters – Hire a crew experienced in rough framing to install blocking per plans.
- Finish carpenters – Retain detail-oriented pros to handle fussy retrofit blocking jobs.
- Handymen – Many handymen have skills to handle smaller blocking tasks.
- Builders and remodelers – Seek out licensed builders familiar with all local codes.
Avoid “ghost contractors” with no references or reviews. Verify any contractor’s licensing and insurance. Get a written contract for significant jobs.
For most simple blocking tasks, with proper planning, materials, and safety precautions, DIY installation is perfectly achievable. But know when to call a blocking expert to be safe and code compliant.
Conclusion
Blocking behind walls provides the invaluable benefit of allowing you to mount items securely anywhere. While blocking requires a little extra effort during construction, the long term strength and versatility it adds is well worth it.
Following the techniques outlined here will give you the confidence to tackle most standard blocking projects for your Generation NEXT home upgrades. Just be sure to always pull permits and comply with local building codes.
Properly blocked walls are stronger, safer, and built to last. So take the time to do it right and you will have a home constructed to the highest standards. The small investment will pay dividends every time you fearlessly hang that new flat screen TV or giant mirror precisely where you want it.
When it comes to How to Block Behind Walls like a professional, rely on the methods here and have fun with your next project!