Repairing past sins – Floors – A Special for Med


I have been fixing other peoples problems for about 55 years. This includes everything from septic tanks to decks where the amateur installer overlooked the task of attaching same to house. Your problem is akin to several that I have seen over the years. Outdoor and porch problems used to fill my weekends. Here are my options which could well be wrong as I have not seen your situation.

Removing the plywood sub-floor would be the best way to start if it is nailed to joists or 2x2s. If this works, simply put down a new sub-floor. Check the joists for level if you do this. You can use one inch square shims cut from sheet vinyl (One can easily get a remnant or scrap piece from Home Depot or Lowes.) to place leveling pads about every foot along each joist.  Check between joists for level as well. Nail these with common carpet tacks. You should have a perfectly level surface on which to build a new floor on. Before nailing or screwing down the sub floor, glue a sheet of sheet plastic to its  bottom side. This will act as a moisture barrier. At this point, you will have a stable base for whatever finish you would want to apply. As a minimum, you should use ¾” B-C grade plywood; A-D will work just as well and is even better if you only plan to paint.

Scraping the sub-floor is the least expensive method. It also requires the most elbow grease. Use a scraper  to remove the bulk of the glue and carpet backing. For touch-up, a Surform tool is the cat’s meow. The Surform has an advantage as its blade is replaceable. Fill in any gouges (I use Epoxy paste (PC-7 is an example).) and then you are ready to apply your flooring. Befor actually laying down the new flooring, I would use an fungicide and a paint or stain from Behr, Thompsons or Cabots. The Cabot site is rich with suggestions for both the Do-It-Yourselfer as well as the professional, but I am not acting as an advocate for their products.

A final possibility is to use the vinyl shims, as above, to level and raise a new sub-floor over the old one. In this case, you can use ½ “ plywood as the maximum flex should be less than 1/32“.  Level as you would for the joists, but be sure to scrape any crap off where the shims are applied. The shims should be on 16-20” centers. Use the same vapor barrier technique as in the prior option. If this option is used, you run the risk of decay spreading from the original underlayment. A copper based fungicide (look in the garden center) should hold this at bay, but no guarantees. If you do this, keep kids and pets out of the area until the new underlayment is down. The vapor barrier should help with the fungus as well.


4 thoughts on “Repairing past sins – Floors – A Special for Med

  1. Walt, thanks for this post. You have learned lots in helping folks over the years and I appreciate the pointers. There are a few new ones that sound pretty good.

    I’m not going to remove the plywood. Its of good quality and in good shape. I tore up the carpet because the porch faces south and between traffic and sun it was wearing out. The path of least resistance is to clean the floor and lay down I/O carpeting again. (The stuff I took out was about 14 years old). But I don’t like carpet. It just collects dirt and with two dogs, one practically lives on the porch, I’m tired of rubber raking, vacuuming and Rug Doctoring.

    There is a slight pitch to the front of the porch but since the porch is enclosed, rain and snow isn’t an issue. I was thinking of removing the old glue and patching gouges. Usually I use Durham Rock Putty. It bounds well and is stable but due to the temperature changes, I’m thinking of checking out your Epoxy PC7.

    I have a roll of commercial grade vinyl flooring I’m thinking of using but its only 5′ wide. The porch is 98″ x 236″ so it means one long seam or 3 short ones. Pattern match shouldn’t be any problem as it is your basic sand pebble. I just don’t like seams, especially with the temperature changes.

    I’m thinking paint. I want to check out some of the new products they have for concrete that is sort of a mock terrazzo. If they aren’t compatible with wood I’ll use a floor paint and sprinkle mason sand in it to add some grit for traction. I can always use a rubber backed runner between the doors for winter.

    I do plan on getting my nephew and son to do the adhesive removal. I should have had them help with the carpet removal but the were busy and I was impatient. Any recommendations on the adhesive remover?

  2. Med,
    It was probably stuck down with mastic. I would go to a building supplies store and peruse the back of a container for suggestions. After 14 years, you may have a struggle. Paint remover may work best on old adhesive.
    Whenever using volatiles, be sure to keep the area well ventilated.

  3. Actually, Walt, I’m using Krud Kutter. The adhesive is breaking down from age. My son just soaked down a section, let it sit for about 15 minutes, hit it with a floor buffer and about 60% of it came up. Scraping is getting another bunch. A second soak/buff/scrape tomorrow will probably finish it.

  4. Med,
    Just be careful not to remove the top ply of the plywood. It sounds like you are on your way. Good luck!

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