When renovating, be sure to properly upgrade insulation

Q. We have a family room, originally a porch, that we now use year-round. It is a 3½-inch step down from our kitchen. We have baseboard heating. The room is 12-by-16 feet. There is 12 feet of baseboard heat on one side and 10 feet on another. We had the room insulated from underneath, but the floor is cold when it gets below zero.

We have five large wooden Marvin windows about 3-by-5 feet that are about 25 years old. There are two on the north side, three together on the western side, a Marvin wood sliding door and a small window on the south side. We are thinking of raising the floor to be even with the kitchen, having insulation sprayed in, installing a subfloor and hardwood floor, and putting in high-efficiency baseboard heat. We seem to have heat loss from the windows. None of the seals are broken. Can windows that old be made more efficient in any way? The sliding door is only two or three years old. Thanks for your help.

A. The cold floor may be because the insulation between the floor joists from under the porch may not have been installed tightly to the subfloor, leaving an air space between the floor and the top of the insulation.

Unless there is a solid covering material on the bottom of the joists to seal in the insulation, and you used fiberglass, the effectiveness of the fiberglass may be compromised. And it also may become damaged by animals seeking shelter.

Since the room was originally a porch, is its floor flat or sloping slightly to the outside?

To avoid heat loss through the framing, you may want to consider applying 1-inch-thick rigid insulation on the floor and fastening furring strips of the right thickness over the rigid insulation, tapering the furring strips to accommodate any slope in the floor, if necessary. But make sure you allow space to fasten the new subfloor and hardwood flooring onto the wood strips in order to end up even with the kitchen floor.

Alternately, if the bottom of the joists is not sealed with plywood or another suitable material, you could fasten the rigid insulation to the bottom of the joists and cover it with plywood.

Twenty-five-year-old windows are obviously not as efficient as modern windows. Contact a Marvin dealer to assess your windows and suggest any improvements, if warranted.

Q. Great column and advice in the Daily Herald. Our raised ranch in Northern Illinois has two bedrooms over the garage, both of which have cold floors. I'd like to insulate (an inspection hole reveals minimal insulation exists) the garage ceiling by removing the wallboard and adding R-25 batts (8-inch joists), including over the 2-foot overhang, and installing new wallboard. The garage has a heat vent but is generally unheated.

Two questions that get different answers from local home repair dealers involve the vapor barrier with faced batts: Should it go up toward the bedrooms or down toward the garage? The bedrooms have hardwood floors, which means there is a tar-paper-like material between underlayment and hardwood - is that sufficient for a vapor barrier so I can use unfaced batts? With unfaced batts, could I just staple a vapor barrier either at the bedroom or garage side? With the overhang, I would use faced batts with vapor barrier up toward the heated bedrooms. With the 2-by-4 sidewalls, I would reuse the existing ceiling insulation and add a vapor barrier, if unfaced, on the garage side before putting up the wallboard.

A. To save yourself a lot of labor, you can have either cellulose blown in or closed-cell foam injected in the joist cavities. In either case, this will be done through a few holes in the gypsum board garage ceiling, which I assume is fire-rated.

If the ceiling board is not fire-rated, your plan is best so you can replace it with fire-code drywall. But if you opt for blown-in or injected insulation, you can simply add a layer of fire-code gyp board to the existing after the insulation job.

It is best to use unfaced fiberglass, and there is no need for a vapor retarder. The plywood that is very likely to be the subfloor under the hardwood floor is an effective vapor retarder and all you need. It is far better than any rosin or felt paper between the subfloor and the finish floor.

Both cellulose and foam would give you better insulation than fiberglass. But of course, these involve outside contractors at a higher cost than if you do the job yourself.

In any case, consider adding a layer of 1-inch-thick rigid insulation to the bottom of the joists before installing the new fire-code gyp board to block the heat loss through the joists.

The vapor retarder on the 2-by-4-inch sidewall should be facing the heated side - the living spaces - of the wall.

Two coats of paint on the drywall will provide a good enough vapor retarder.

Q. Just recently, I found that in our attic the hose from the range hood had become disconnected at the roof vent. This allowed the moisture from the range hood to go onto the underside of the roof sheathing. Now there is an area of black mold on the sheathing. It looks like this has been going on for a while. I have reconnected the hose to direct the exhaust outside.

Once the sheathing dries out, I was thinking of putting some KILZ paint over the mold to seal it. Would this be acceptable, or is there something different that you would recommend? Since taking the sheathing out really isn't an option, I was hoping that I could seal off the mold and be all set.

A. There is no need to apply KILZ. You may either let the mold dry over the summer heat and die, or, if it would make you feel better, spray the mold with a mixture of equal parts bleach and water, and let it dry over the summer.

Q. I would greatly appreciate your advice on a maintenance project that is needed at my home.

A previous owner added a 2½-car garage with a lovely terrace above it, which is accessed via French doors in the living room.

There is a black aluminum railing around the entire space and down a set of wooden stairs to the backyard. This railing has been needing maintenance (painting) ever since I purchased the house seven years ago, and is showing more age at this time. The railing gets a lot of sun exposure.

What procedure and materials would you use for this project? My handyman is very interested in your input.

Please include the specific names of materials you recommend and businesses that sell those.

A. All loose paint needs to be removed from the railing. Then it should be sanded as needed to remove any other substance that is adhering weakly to the metal. This should be followed by a wash with a mixture of one cup TSP-PF to three quarts of warm water. A cup of bleach may be added to the solution if there are signs of mildew.

When dry, paint the railing with a paint specially designed for this type of project, such as DTM Acrylic, which is self-priming. Applying two coats would be best.

Sherwin-Williams paint stores sell DTM acrylic paint. Good luck with the project.

Q. I am still struggling with my upstairs windows. These are sliding windows. There are two windows in each set and they each slide up and down. Right now it is 15 degrees out and the inside of the storm window on the upper half of each set of windows is pretty much frosted up, though the lower part is not.

It turns out our storm windows weren't caulked at all so we carefully caulked them on the sides and top but not on the bottoms. That does help with heat loss. I could see open spaces along the sides of the storm windows.

I also tried putting trays of desiccants at the bottom of the window ledge, between the regular windows and the storms. They seem to absorb moisture, but not enough to do much good.

I don't know if there is a way to put weatherstripping on windows that slide up and down. I only open one or two of the five windows, so it wouldn't matter if they opened or not. I have had some window experts here, and they first thought I could put felt along the sides of the primary windows, but then they changed their minds. Maybe there is nothing that can be done. I do have plants in front of two of the windows and that could cause problems, but the windows where there are no plants have moisture on the inside of the storms, too.

A. There are many different types of weatherstripping for double-hung windows that can be used as a retrofit. I am surprised that the window experts could not find a suitable one for your windows. How old are your windows?

Caulking the top and sides is standard practice, and you are only experiencing frosting on the upper part of the storms because the bottom part is slightly ventilated by the bottom not being caulked.

You may want to try using a rope caulk, such as Mortite, around the perimeter of your interior windows and at the mid-rail where the two sashes meet. Press it in for a good fit. This may help. In the spring, you can peel it off and roll it back in the box for use next winter.

• Henri de Marne was a remodeling contractor in Washington, D.C., for many years, and is now a consultant. His book, "About the House," is available at www.upperaccess.com. His website is www.henridemarne.com. Email questions to henridemarne@gmavt.net, or mail First Aid for the Ailing House, Universal Uclick, 1130 Walnut St., Kansas City, MO 64106.

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