Inman

What to do about that mushy subfloor

Q: I have pulled up the carpet in my condo, and found a couple of areas of subfloor that seem mushy underfoot, as well as some areas with raised ridges where the two pieces of plywood meet. How is this properly taken care of, and who is the best person to contact to do the work? –Katherine D.

A: It’s unusual for this type of ridging to occur in plywood unless it has been wet. My first concern would be to check for any signs of moisture in this area, such as dry rot or staining on the surface of the wood. If you suspect moisture, you need to contact an insurance restoration contractor or a flooring contractor who has the proper type of moisture meters to probe and check the moisture levels in the floor. Be sure to do this before installing new flooring.

The subfloor itself is best repaired by cutting out the soft area, installing blocking between the joists so that all four edges of the new plywood are supported, and then installing a new piece of plywood using screws and subfloor adhesive. If there are any other minor high spots in the subfloor, these can be taken care of with a belt sander prior to installing the new carpet. These repairs can be handled easily by any licensed general contractor, or the condo association may have a recommendation for a licensed handyman that does this type of work.

One final thing: Before undertaking any structural repairs to your unit, you need to contact the condo association. In many condo bylaws, you own the carpet and can do what you want with it, but you may be limited to what you can do with the structural shell of the building. Be sure you clarify your rights and responsibilities prior to doing the work.

Q: Is it OK to use MDF moldings in a bathroom? Is the glue resistant to moisture, and what would happen if it got wet where it abuts the shower — would it swell like particleboard? –Lucy D.

A: MDF stands for medium density fiberboard, and is a composite material made up of fine wood fibers bonded together with resin and pressed up under heat and pressure to form moldings and other items used in construction and furniture making. While MDF has no structural value, it does make a great trim material for painted applications.

In normal usage, MDF is moisture resistant and is used extensively for trim and even cabinets in bathrooms. As to the second part of your question, if it gets wet and stays wet for any length of time — as opposed to just being exposed to high humidity in the bathroom — it definitely can absorb water and swell.

Two things you might consider: You can find a number of common molding patterns in both MDF and solid wood, so you might want to install a solid wood piece where it butts up to the shower. Otherwise, seal the back, bottom and ends of the MDF moldings with a good primer prior to installation in any areas that might be subject to water, which will help minimize absorption.

Q: We are buying a house that’s constructed of concrete blocks with a stucco coating on the outside, and we want to install a new outside door. How do you cut an opening in concrete blocks? What type of contractor should we hire for this and what kind of experience should they have? –Diane S.

A: Cutting a hole in concrete block is a relatively straightforward operation, but it does require specialized equipment — typically a rail-mounted masonry saw with a water-cooled diamond blade. You can check the Yellow Pages under “Concrete-Break, Cut, Saw” for companies in your area that do this type of work. The contractor should provide you with his or her license and bonding information, as well as a list of references from previous jobs.

If you want someone to install the door and repair the stucco as well, you may instead want to consider a licensed general contractor with experience in remodeling who can take care of the entire project for you. Here again, check out both the license and the references.

Remodeling and repair questions? E-mail Paul at paul2887@hughes.net.