This article is actually a follow up to “Guide to installing a DIY Floating Wood Floor” that I published on Factoidz five months ago. Although a floating floor can be installed over almost any existing floor it shouldn’t be until any major defects in the existing floors are corrected. If you have creaking squeaky floors; floors that are buckling, cupping or warping; floors that move beneath your feet when you walk on them; floors that feel spongy in areas, or; floors that suffer from large cracks, you need to ascertain what the causes of those problems are before laying any type of new floor over them. In many case the problem will lie with a subfloor that has become deteriorated to the point where it can no longer provide adequate support to the flooring material covering it. It really doesn’t matter whether the deterioration was caused by water damage or insect infestation the subflooring will have to be replaced before laying a new floor. Of course it goes without saying that the cause of the deterioration, if still present, will have to be dealt with first. Checking the condition of the subfloor is relatively easy if it’s a floor locate on the first floor over an unfinished basement or over a crawl space. On the other hand, if it’s a floor located above a finished ceiling you will actually have to remove some of the old flooring to get to the subfloor, never the less it has to be done. While you’re inspecting the subflooring for damage also inspect the floor joists (beams) for damage as well. I will cover how to repair defective or damaged floor joists in the next article in this series.
Tools that you will need to inspect and replace the old subfloor
· Stanley 15” Super Wonder Pry Bar
· Disco 5 ½” wonder bar
· Disco 3” floor chisel
· Stanley 16oz claw hammer
· Stanley 48oz hand sledge
· Stanley chalk line w/blue chalk
· 3/8” drill/driver
· Swanson 16” X 24” aluminum carpenter’s square
· Swanson Speed™ square
· Black & Decker powered caulk gun or hand powered caulk gun
· Stanley 48” Box Beam level
· 7 ¼” Skill saw
· Saw horses
· Stanley nail set
· Stanley utility knife
· 4” scraper/putty knife
· 25 foot tape measure
· Safety goggles
· Work gloves
Material and supplies that you will need for this project
· subflooring adhesive
· ¾” Tongue & Groove plywood (Georgia Pacific DryPly® Plywood recommended because it’s moisture resistant) subflooring
· #8 X 2” deck screws for a single layer subfloor or #8 X 3” deck screws for a double layer subfloor
I never like to assume anything because assuming can do nasty thing to everyone involved but in this case I’m going to risk that and assume that your inspection has determined that the subfloor need to be replaced. For this instructional I’m also going to assume that the inspection showed that your floor joists were in good condition and didn’t need to be replaced or repaired.
Every project, no matter how big or how small, begins with the first step, so let’s get started.
Removing the old subfloor
· Begin by removing all the furniture from the room. There’s no way of getting around this step, so find yourself a helper and move everything into a spare bedroom, the garage or even the driveway if necessary. If you have to move everything into the yard or driveway make sure you keep it off the ground and covered with tarps just in case Mother Nature decides to play tricks with the weather
· Using the Stanley utility knife cut through the paint between the walls and the top of the baseboard
· Using the 4” putty knife/scraper create a space between the wall and the baseboard to insert the Dasco 5 ½” wonder bar
· Using the Dasco 5 ½” Wonder Bar carefully remove all the baseboards and any quarter round shoe moldings. Proceed carefully because if you have an older home the wood will be very dry and easily broken. You will want to use as much of the original trim as possible
· Strip off the old flooring material. If the original floor was tongue and groove hardwood flooring use the floor chisel to cut through the tongue and grove of the first strip allowing you to insert the pry bar. After prying the first strip up the rest should come up relatively easy.
· Next remove the old subflooring. If the old subflooring is 4 X 8 foot sheet good you may find it easier to remove if you cut it in strips. Since most subflooring is ¾” thick set your circular saw for a 7/8” cut depth. Making a plunge cut run the saw parallel to the floor joist. With a 7/8” cutting depth you should be relatively safe from hitting any wiring that may be concealed in the floor
· Remove all the old nails and/or screws from the floor joist as you remove the subflooring otherwise you will have to balance on the narrow edges of the joists or use a kneeling board to get the nails and screws out
Installing the new subfloor
· To calculate the number of sheets that you will calculate the area of the floor in square feet and then divide 32. Add 20 percent to this figure as a fudge factor.
· Any ¾” plywood can be used but Tongue & Groove plywood is recommended because it creates a more secure subfloor. Subfloors made with tongue & groove panels are less likely to squeak and they require no blocking where it spans gaps between joists.
· Install the panels so that the grain runs perpendicular to the direction of the joist
· If there aren’t two joists that are 96” o.c. (On Center) you will have to measure and trim each panel accordingly. If the joists are 16” o.c. which is standard there shoulb be 96” between each 6 joists.
· When placing the panels in place make sure to stagger the joints. This is accomplished by starting every other course with a 48” long piece
· Strike a centerline on each joist using the chalk line
· Allow 1/8” gaps between joints to allow for expansion and contraction
· For the most secure, trouble free subfloor apply a bead of floor adhesive to the top of the joist before placing the panel. Plug the tip of the adhesive cartridge with a large nail or screw between use so the adhesive from drying up
· Although many people use nail guns to secure subflooring the best results comes from using screws and a drill/driver or screw gun
· Using a block of wood and a hammer tap the tongue of the second course panels into the grooves of the first course panels. Make sure you leave the 1/8” gap for expansion and contraction
· If your eyesight is anything like mine you may want to snap a centerline down each joist on the panels to make placing the screws easier
· Recess each screw head below the surface of the panel.
· As a rule you should place the screws 6” to 8” apart but check with your local building codes department on the exact spacing required
Sources for tools and supplies
