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Exclusive Hardwood Floor Preparation for Concrete and wood Sub-floors

Bush Beans Engineered Hardwood floors


Free hardwood floor preparation steps to properly prepare a subfloor that will be clean, dry, level and structurally sound. 

 From a Knoxville,TN. based Commercial Flooring Installation Contractor Since 1975.



The engineered Hardwood floors installed in the image above was in the lobby of Bush Beans Product development center Knoxville, Tn.

There was a very large hump (10' X 15') in the middle of this concrete floor.

We ground down about 1'' with a rented scarafier, then applied about 3 applications of Ardex Feather Finish to smooth the substrate.

After the Feather Finish had sufficient cure time, it was sanded with a 16 grit sandpaper attached to a floor buffer.

Note: If you give Feather Finish a long curing time it will not sand easily, it wants to just polish, even with 16 grit sandpaper.

Bush Beans was probably the most demanding commercial flooring installation this flooring contractor has had.

We had to provide a mock-up area and wait for approval, for every type of flooring we installed.

  • We had to post a safety form listing what we were installing
  • What tools we were using 
  • List what types of accident or injury could occur
  • List what we were going to do to insure no accidents or injures would occur

 Then it had to get approval and a signature from the safety inspector.   

We were had to provide floor preparation before...

  • installing Carpet with a Border
  • Installing Welded Sheet Vinyl Flooring 
  • Installing Engineered Hardwood Flooring
  • Installing Rubber Stair Treads and matching Rubber Tile
  • Installing Ceramic Wall Tile and Ceramic Floor Tile installation  

All the crew with had to wear Hardhats, Safety Glasses, Steel toe shoes, and proper work clothes. Plus we were required to have a weekly safety meeting.

We walked this job 5 years after the installation with a potential subcontractor supplying flooring and granite counter tops to the general contractor for Springhill Suites By Marriott and Homewood Suites By Hilton (same Owners).

Not a single floor covering issue, the floors all  still looked awesome.


The project above was a 6,600 square foot Engineered Hardwood Floor Installation, provided to a general contractor, in West Town Mall, Knoxville, TN.

This was a difficult installation because it was comprised of Three different retail locations with each having different types of flooring, requiring different Hardwood floor Preparation requirements.

We rented a scarifying machine and spent a week grinding the adhesives, mortar, etc. left after the existing flooring was removed.

After sweeping and vacuuming the substrate a primer was applied and a Self Leveling Compound was installed to level and smooth the surface.

The hardwood floor preparation solution chosen (Self Leveling Compound) for this retail environment, was a perfect fit. 

A client supplied Engineered Hardwood Floor from Armstrong (Black Pattern Plus) was installed on the newly leveled sub-floor using a glue down method.

This hardwood installation did not have a single item on the Architect/Owners punch list, and we were invited by the GC to install there next Sephora build-out in California

The Steps Acufloorz Use For Hardwood Floor Preparation On Concrete

Hardwood floor preparation, first step if it concrete...

Leaving out the moisture testing requirements because I consider it part of Hardwood Floor Installation process.

  • Broom sweep the entire area
  • Vacuum the surface

Sand the entire surface with 16 grit Sandpaper or a 25 grit concrete prep tool attached to a Floor Buffer

We often use the 25 or 100 grit Concrete prep tool for abrading the surface to create a superior bond with adhesives.

Especially helpful if the concrete has been slick troweled by the concrete contractor.

The tool can prepare slick, old, worn, dirty, concrete substrates using standard cleaning equipment such as automatic scrubbers or floor buffers.


Second Step 

Once the substrate is clean use a long straight edge to check the floor for levelness.

If you have access to a laser light, map the floor, marking the high spots and low spots.

We would typically use chalk to mark the areas to fix with a - or + , for example (1/4'' +). That would indicate that that area would need to be Ground down 1/4''.

Other tools to check the levelness of the substrate...

  • Long straightedge or level
  • Long and Straight 2 X 4
  • Chalk line

For glue down installations, Sub floors must be flat to within...

  • 1/8" in 6 feet 
  • 3/16" in 10 feet

Third step

If I had to grind high spots 1/8'' or more I would recommend using something aggressive like a scarifier to remove the high spots. 

Using a grinding tool like the Edco which uses a concrete stone would provide a smoother grind, but will not be time friendly.

Forth step

For low areas or to fill ground areas we use a flat trowel to apply a smooth layer of cementitious floor patch to level the floor.

Usually it takes more than One coat of patch.

Fifth step

Once installed and cured it gets sanded smooth with a floor buffer, with a 16 or 20 grit sandpaper attached.

Sixth step

All adhesive installation specs specify a dust free surface. This is very difficult to get.

Our approach is Broom sweep, Vacuum, then using a wet mop, clean the remaining dust and let dry.  Still have dust, wet mop again

The Steps Acufloorz Use For Hardwood Floor Preparation On Wood Substrates

Hardwood floor preparation First step for wood substrates...

If it's a remodel with a carpet tear out and has a wood substrate, after carpet and pad removal...



 

  • Remove pad staples
  • Broom sweep the entire area
  • Vacuum the surface

This is a good time to check the floor for squeaks and loose sheets. We often use Screws, although ring-shank nails will also work.

It's also a good time to determine the thickness of the subfloor and the type, to determine if the subfloor is an acceptable subfloor for hardwood flooring.

You can determine the thickness by removing the floor registers or drilling a small hole in the subfloor.

The following are general guidelines from NWFA's Installation Guidelines

Thickness: Plywood (CDX grade & exposure 1) and OSB panels are acceptable subfloors for hardwood flooring as long as they are the proper thickness.

Generally, the minimum thickness for plywood is 5/8 inch; for OSB it's 23/32 inch.

However, as joist spacing increases, the subfloors need to be thicker.

For joist spacing of more than 16 inches up to 19.2 inches on center, the minimum thickness for both plywood and OSB is 3/4 inch.

For joists spaced more than 19.2 inches on center, the minimum thickness for plywood is 7/8 inch and for OSB, 1 inch.

Keep in mind that for mechanically fastened floors, OSB doesn't hold fasteners as well as plywood, so you may need to use a thicker material to get the same holding power.




Second Step 

Once the substrate is clean and free of squeaks use a straight edge to check the floor for levelness.



If you have access to a laser light, map the floor, marking the high spots and low spots. We would typically use chalk to mark the areas to fix with a - or + , for example (1/4'' +). That would indicate that that area would need to be sanded down 1/4''.

Other tools to check the levelness of the substrate...

  • Long straightedge
  • Straight and long 2X4
  • Chalk line

For glue down installations, Sub floors must be flat to within...

  • 1/8" in 6 feet 
  • 3/16" in 10 feet




Using a belt sander or use a edger like in the image (36 grit sandpaper will work), sand the seams in the plywood that are high.

These sanders are more powerful than a belt sander and can be rented from the big box store or from most Tool rental centers.


If I have a Hardwood Installation requiring a mechanical fastening system on wooden subfloor, some times I will build up the low areas of  the subfloor with roofing Shingles or #15 building Felt.

I Don't use a cementitious floor patch because the fasteners may not penetrate, can also crack and break when penetrated by mechanical fasteners. 

In some cases, I may pull the existing wooden substrate, shim up, plane down, or sand down the floor joists, then reinstall the substrate.

If i'm installing a glue down system I use a cementitious floor patch with a flat patching trowel to level the substrate and fill the seams. After curing, sand with a 16 or 25 grit sandpaper to smooth and level the patch.



Third step...

Using a hand saw cut the door casings, door frames, etc. using the hardwood to Gage the depth of the cut.

All the Hardwood flooring cuts need to extend under the casings, door frames, etc.

 There are 2 sided door casing Handsaws and mechanical saws that will make these cuts. 

  

All the doors that need to be cut also need to be marked before removal or cut in place with a mechanicall saw designed for this.

This jam Saw can be rented  from Home Depot. It's basically a side grinder with the adjustable attachments for making adjustable cuts on door jams and doors.

Note: On hollow core doors we would recommend you remove the door.  Use painters tape on the side of the doors the blade will be exiting to control splintering, then very slowly and carefully remove the tape at a 90 degree angle after cutting.


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