Refinishing an old softwood floor

Q.  I have an old farmhouse that I’m slowly redoing. After removing 3 layers of Lauan and Formica on the kitchen floor, I found a softwood floor set interestingly diagonally to the walls. I would like to sand and finish this floor.

Softwood flooring
Unfinished wide-board flooring

I would use polyurethane on it if it was a hardwood but I’m afraid if I finish it that way and something is dropped on it, (silverware etc.) It would chip the polyurethane and eventually look bad. Do you know of a better finish I could use?  Would a boat-building epoxy be a good choice or would it crack between the floorboards? Is there an epoxy made that is non-yellowing?

A.    Formica on the kitchen floor? That’s a new one on me.

You may be down to the subfloor. Before the advent of plywood and particle board, all sheathing on floors and walls was installed diagonally to prevent them from wracking.

If the subflooring is in good enough shape to be used as the finish floor, go ahead and use polyurethane. It’s OK on soft wood. I used it on my pine floors nearly 30 years ago. An experienced paint store person can tell you which varnish they recommend that would not yellow.

The traffic areas will have to be re-coated every few years, but that also goes for hardwood floors. Softwood floors are more prone to denting from furniture, etc., but that’s part of their charm. And I don’t think any finish would prevent denting.

Insulating a cantilevered floor

Q.    I have a two-story colonial. The second floor extends two feet over the first floor on the front side of the house. The problem is heat loss. The section of floor  on the upper level that overhangs is often cold, especially when the wind blows.

What is the proper way to insulate this overhang? Currently the underside of the overhang has non-perforated aluminum. I believe fiberglass insulation is packed in between the floor joists and the insulation sits directly on top of  the aluminum. What would you recommend to improve this?

A.    Since the condition is worse when the wind blows, it tells me that the non-perforated aluminum is not tight, and the wind penetrates around its perimeter. One possibility is that  the entire depth of the projecting joists may not be filled with fiberglass insulation. Another possibility is that the band joist may not be fully insulated.

Since fiberglass is a porous filter that works in slowing down heat loss only when tightly enclosed, the wind robs it of that property and cold air circulates through it. The easiest solution is to remove the aluminum soffit, make sure that the entire joist depth is filled with fiberglass insulation (if not, add some or replace the existing insulation with the correct size) and install plywood, properly sealed, around all edges.

If there is enough room between the bottom of the joists and trim board at the base of the wall, add rigid insulation–as thick as will fit–fastened to the bottom of the joists. Then caulk the perimeter and cover it with the plywood.

Concrete scaling on basement floor

Q.    I need help. I have had my house from new. After four years, I used a good industrial oil-based floor paint on my cement basement floor. It was down for 20 years. Then I used water-based paint and it lasted 20 years. I wanted to get back to oil-based paint.I used as heavy-duty floor sander and took off much of the old paint.

Now the problem. In a few spots on the floor, by the cinderblock wall, the cement is scaling. It bubbles up; I scrape it and a white powder comes up. What can I put on it to stop the white powder from coming back and to make the paint stick to the floor?

A.    By the cement scaling, do you mean that it is breaking up or simply that the white powder is developing? The white powder is undoubtedly efflorescence. Moisture is dissolving the salts in the concrete and bringing them up. The moisture then evaporates, leaving the salts behind. It sounds to me that after 44 years you are suddenly having a mild moisture problem at the base of the walls — just enough to cause this new problem.

Check the grade around the house to see if there have been any changes that lead the water from the roof or gutters to pool against the foundation. If you find any anomalies, take care of them, and see if that solves your problem.

Restoring a pitted garage floor

Q.    My garage floor has become pitted from road salt over the years. I’m considering using one of those epoxy coatings to fill in the pitting and smooth it out and/or first using concrete restorer to fill in the pits and then the coating. What do you think of the possible outcome (looking decent) from this approach?

A.    Why not simply using a polymer-modified product such as Thorocrete or vinyl-reinforced TOP’N BOND? They are both one-step processes for repairing damaged concrete surfaces and should be easily available in building supply stores.

Just be sure that you remove all loose particles with a strong jet of water before applying the new mix and that you follow the instructions on the containers.

Engineered flooring for kitchen?

Q.    I need to replace the flooring in my kitchen and dining room area. What do you think of the laminates that simulate wood versus real wood versus engineered wood?  I would appreciate any advice you can share.

A.    Wood laminates such as Pergo are very popular but cannot be refinished if they’re damaged, as the laminate is either very thin or only photographed on a wood base. Engineered flooring is made of thin, real wood adhered to a wood core.

They come in two types: A floating floor that is laid over a foam pad, and individual pieces that are either glued or nailed to the subfloor and which can be refinished to a certain extent. Real wood is much thicker and solid throughout.

Of concern in a kitchen is that the additional thickness could affect the dishwasher and any other appliance set under counter tops, locking them in and making replacement a more difficult job (the counter tops may have to be removed).

Replacing tiles over old adhesive

Q.  I enjoy your column and blog, and hope you can provide information on my current situation. My laundry room had 2 layers of vinyl tiles on top of a concrete slab. After removing both layers, there is what looks to be a black mastic adhesive left on the concrete slab.

Tests were done and no asbestos was found. The vinyl was probably installed 30 years ago.

What do I have to do to prep the floor in order to install ceramic tiles, using a mortar mix to set the tiles? Does the adhesive have to be removed? And, if so, what with? Or can I tile directly over the adhesive?

A.    The 30-year-old black adhesive is most likely cut-back asphalt commonly used at that time. It cannot easily be removed chemically or mechanically. The only way may be by grinding or shot-blasting — a very messy method that few will be willing to tackle due to the small size of the project.

However, you may set tile with one of the specialty mortars made by Mapei, designed for use over cut-back mastic. Please keep in mind that the bond strength between the tiles and the concrete, in spite of the strength of the thinset mortar used, will only be as strong as the bond between the concrete and the cut-back adhesive.

Finding floor joists

Q.   Please enlighten me on how to find the floor joists especially through carpeting.

A.   Floor joists run perpendicular to the hardwood floorboards (although I have seen some aberrations where they ran parallel, but that is very unusual) or the long side of the plywood subfloor. Some electronic stud finders work with floors, so you may look for one in a hardware store, but make sure that it states that it works on floors. You can also find the floor joists the old-fashion way.

A skilled carpenter will use a hammer to locate the floor joists by sound, but that is not easy for a do-it-yourselfer, and it won’t work through carpeting anyway, so, you will need to pull the carpeting up along the long walls of your house. If you find that you have plywood or OSB subfloor, the nailing pattern of the subfloor will show you where the joists are.

But if you find hardwood floors, and there is a shoe mold, remove it where it is parallel to the hardwood floors on both opposite walls in each room with squeaky floors. (The shoe mold is the small molding at the joint of the floor and the baseboard). Use the smallest bit you have that can protrude a minimum of 2 inches from the drill’s chuck.

For 4-inch-thick exterior walls, measure approximately 12 inches from the exterior wall perpendicular to the run of the hardwood floor; that should be about where the first free joist is. For 6-inch exterior walls, measure 10 inches. At that point, drill a hole where the shoe mold was. If, after you have drilled approximately 1-1/2 inches deep, you hit empty space, you have not found the joist. Drill another hole about one half inch to either side until your drill bit hits solid wood all the way through.

Continue drilling about 1/4 inch to each side of the good hole until you hit empty space again. This will help you locate both sides of the joist. Put a small nail in the hole at the center of the joist. Do the same in the opposite wall. Run a string between the two nails. Joists are usually 16 inches on center. although some framing can be 24 inches on center, so the others should be easy to locate

Insulating the floor over garage

Q.    I live in a split-entry brick home. The garage is in the house. The back bedrooms are very cold. I have insulation between the joists with the vapor barrier up against the floor of the bedrooms. There is some heat in the garage but I don’t want it too hot because of the salt from the roads on the cars. Should the vapor barrier face the garage or should the insulation be unfaced?

A.    You did it right: the vapor retarder should always be on the winter warm side of the insulation but, in your case, the insulation should be tight against the floor above. The exception to this rule is in climates where air-conditioning is prevalent over heating — the deep South.

Keep in mind that the bedrooms (which I assume are over the garage) have an added exposure to the cold — their floor. In such cases, the insulation should completely fill the spaces between the joists. If the fiberglass batts are left exposed in your garage, they are subject to heat loss through air movement (fiberglass is a filter, after all). In that case, do whatever is needed to fill the spaces between the joists with more unfaced insulation, fasten 1-inch thick rigid insulation to the bottom of the joists and cover it with fire-rated gypsum board, making sure to tape the joints.

If there is already gypboard on the garage ceiling and the fiberglass insulation does not completely fill the spaces between the joists, your choices are to have dense-pack cellulose blown in or the gypboard removed and additional fiberglass put in. If the spaces between the joists are filled with fiberglass, consider adding 1-inch thick rigid insulation to the bottom of the joists, even if the ceiling is covered with gypboard, and cover it with another layer of fire-rated gypboard.

You don’t say what your heating system is but it may need to be better balanced. If your system is warm air, insulate any ducts in the garage space and balance the system to feed more warm air in the bedrooms. If you have a hydronic system, and the bedrooms are not on a separate zone, you may need to add radiation in each of them.