Installing beautiful solid wood flooring can transform a home, adding warmth, luxury, and value. But choosing the right installation method is crucial, especially when laying wood floors over concrete. While floating floors are common for laminates and engineered wood, gluing down is best for solid wood planks. With proper preparation and materials, you can create a smooth, secure bond between wood and concrete.
Why Choose Glue Down for Solid Wood on Concrete?
Gluing down involves securely adhering wood planks directly to the concrete substrate using the appropriate flexible flooring adhesive. This method provides a range of benefits:
Superior Bond
When done properly, the glue forms a tenacious, resilient connection between the wood and concrete. This prevents gaps, squeaking, and movement of planks for the long term.
Improved Acoustics
With the planks firmly bonded, there is less hollow noise or echo when walking across the floor. Glue down delivers excellent sound absorption.
Enhanced Heat Transfer
Concrete makes an ideal thermal mass, absorbing warmth from radiant heating systems. Gluing the wood directly to the slab allows this warmth to conduct efficiently upwards through the flooring.
Versatile Subfloor Options
Glue down allows solid wood installation over any structurally sound and properly prepared concrete, whether above, on, or below grade. Even radiant heated slabs are suitable.
Works with Wide Planks
Gluing enables wide plank flooring 6 inches or greater to be securely fastened without movement or hollow spots. Nailing or stapling down wide planks often results in instability.
Sleek Appearance
With no nails, staples, or fasteners visible, a glued down floor has a smooth, seamless look. The planks sit flush to the subfloor for a clean aesthetic.
Key Considerations for Glue Down on Concrete
While offering fantastic benefits, gluing solid wood on concrete also comes with a few special considerations:
Concrete Moisture
Excess moisture from the slab can damage wood flooring. Concrete must be properly cured and tested prior to installation.
Precise Work
Glue down requires meticulous floor preparation, careful adhesive selection and application for success.
Permanent Installation
Unlike floating floors, glued down wood can’t easily be removed or replaced. The bond is designed to last the lifetime of the flooring.
Potential for Squeaks
Any imperfections in the subfloor or adhesive application may still allow minor squeaks or movement.
Higher Labor Costs
Professional installation is recommended, adding cost. Gluing takes more time compared to other methods.
How to Prepare a Concrete Slab for Gluing Down Solid Wood
Preparing the concrete slab properly is the most vital step for a successful glue down floor. Follow these key guidelines:
Make Sure Concrete is Fully Cured
Concrete must cure for at least 60 days prior to wood flooring installation. This allows moisture levels to stabilize and shrinkage to complete.
Check for Level
Use a straightedge and level to ensure the slab is flat within 3/16 inches over 10 feet. Grind down any high spots. Fill low areas with approved patching compounds.
Conduct Moisture Testing
Use a concrete moisture meter to check moisture vapor emission levels. For glue down, levels should be below 3 lbs per 1,000 sq ft over 24 hours. High moisture can damage wood.
pH Testing
Check pH levels, which should be between 5 and 9 for proper adhesive curing. Rinse the slab if outside this range.
Remove Surface Contaminants
Clean slab thoroughly to remove any oil, wax, paint, dust, sealers, curing compounds, adhesives or other chemicals which can block adhesive bonding.
Fill Cracks and Holes
Use hydraulic cement or epoxy filler to patch any cracks, control joints, grooves, holes, and other imperfections for a smooth surface.
With the slab fully prepped, you’re ready to begin gluing!
Choosing the Best Adhesive for Concrete and Wood
Selecting the proper adhesive is crucial for durable glue down installation. The adhesive must remain flexible over time while keeping planks firmly attached to the concrete. Look for these essential features:
Flexible Bonding
The adhesive must allow slight movement of the wood while still adhering tenaciously to form a moisture- and alkali-resistant bond to concrete.
Non-Water Based
Water-based adhesives can re-emulsify, degrading the bond. Opt for urethane or epoxy-based formulas.
Moisture Barrier Properties
Adhesives with vapor barrier benefits help protect wood from moisture evaporating through the concrete slab.
Low VOC and Solvent Free
Choose low odor, environmentally friendly adhesives without harmful solvents or VOCs.
Popular adhesive options include Bostik’s GreenForce wood flooring adhesive, SikaBond flexible wood flooring adhesive, and Mapei Ultrabond ECO 811. Consult the flooring manufacturer for recommended products.
Step-By-Step Guide for Gluing Solid Wood Flooring to Concrete
Once you have prepped the slab and selected adhesive, follow these steps for flawless glue down installation:
1. Acclimate the Hardwood
Let the wood flooring planks acclimate in the installation area for 72 hours to adjust to indoor temperature and humidity levels.
2. Dry Fit the Planks
Lay out planks without adhesive to test layout, pattern, and fit. Check for gaps, alignment, and grain pattern flow.
3. Apply Adhesive
Use the appropriate trowel to spread adhesive evenly across the slab, following the product’s open time and coverage guidelines. Work in sections.
4. Install Flooring into Adhesive
Carefully lay planks into the adhesive, pressing down firmly to ensure full adhesive transfer and no gaps between flooring and concrete. Use a tapping block if needed.
5. Roll Installed Flooring
Use a 100-150 lb roller across the flooring surface once the area is fully glued to further embed planks into the adhesive for a tight bond.
6. Clean Up Adhesive
As you work, immediately wipe up any excess adhesive from the flooring surface with the recommended cleaner and clean rags before it cures.
7. Add Trim and Transitions
Install wall base trim, thresholds, transitions, and reducers with adhesive or nails to provide a finished look and protect flooring edges.
With each step done correctly, you can rest assured your solid hardwood flooring will remain securely bonded to the concrete for decades.
Tips for Preventing Callbacks on Concrete Glue Down Installations
Gluing wood flooring requires precision. Follow these pro tips to help avoid callbacks or complaints:
Allow Proper Open Time
Let adhesive become tacky before placing flooring according to manufacturer guidelines for best results. Too little open time can compromise adhesion.
Use Notched Trowels Properly
Hold trowels at a 45° angle to ensure consistent depth of adhesive left behind. Worn trowels should be replaced.
Factor in Ambient Conditions
High humidity can shorten open times for glue. Adjust work speed accordingly.
Work Clean
Changing adhesive buckets and tools often helps keep wet glue from drying on trowels or contaminating unused adhesive.
Check Bond Periodically
Inspect areas as you work to ensure adhesive is transferring 100% to the back of the planks.
Roll Thoroughly
Make multiple passes across each section with the roller to fully adhere every inch of flooring to the concrete.
Troubleshooting Common Problems Gluing Solid Wood on Concrete
Though rare with proper installation, here are some potential issues and fixes:
Hollow Spots or Popping
This means adhesive didn’t fully bond wood to concrete. Re-glue problem areas.
Cupping or Warping Planks
Indicates moisture-related issues. Ensure concrete was dry enough and apply sealant to wood.
Discoloration or Dark Streaks
Adhesive may have seeped between planks. Wipe promptly before drying or replace affected boards.
Floor Squeaking
Some adhesive may have set before placing planks. Refasten loose areas with trim screws.
Gaps Between Boards
This typically results from not pressing planks into adhesive firmly enough before it cured. Refill small gaps with wood putty.
Maintaining Glued Down Solid Hardwood Floors
Once installed, be sure to care for your glue down wood floors properly:
- Sweep and vacuum regularly to remove abrasive dirt and dust
- Use felt pads under furniture legs to prevent scratches
- Avoid excessive moisture from spills or wet mopping
- Keep indoor humidity between 30-50% year-round
- Refinish floors when worn using compatible low-VOC finishes
With proper maintenance, your glue down wood floors can continue looking beautiful for decades of enjoyment.
Gluing Down Solid Wood: The Healthy, Durable Choice for Concrete
Gluing solid hardwood planks delivers a rock-solid, long-lasting wood flooring installation over concrete substrates. Taking the time to correctly prep the slab, select premium adhesive, and carefully install planks results in a smooth, even floor that feels great underfoot and looks stunning for years to come.
While the process requires more skill and labor compared to floating floors, the end result is well worth the effort and investment. The peace of mind from a permanently bonded wood floor that resists moisture, lasts a lifetime, and increases your home’s value makes glue down the best choice for solid wood over concrete.