Repairing a garage floor

Q. My garage floor is pitted in some areas. You mentioned a penetrating sealer in today's column. Is there a certain brand you would recommend? Would this work if applied just to the pitted areas? The original floor was troweled and the unbitted areas are fine. I recently had an estimate to refinish the whole floor ($2,500) but a less expensive solution would certainly be most cost effective.

A. The pitted areas should be repaired and, depending on how many there are and their severity, it shouldn't cost anywhere as much as redoing the whole floor. A mason or concrete contractor, or a very handy person is the one to call. There are many special products on the market for repairing concrete; you'll find them in building specialty, big box and hardware stores.

As mentioned in the previous column you are referring to, a hard troweled slab is unlikely to be a candidate for a penetrating sealer unless water sprinkled on it penetrates the surface. If water beads on the surface, a penetrating sealer would be a waste of money and effort.

A topical sealer would be a better option and, being in a garage, it should last a lot longer than if it were outdoors.

Q. Hello, this blog post (sewer gas smell permeating my home when the furnace runs) describes the situation I am experiencing almost exactly. I also notice the smell after the furnace has stopped running. I moved into an older home in September and have called a plumber and two different HVAC contractors, each looked at me like I'm crazy and told me they have never heard of this issue and to pour water into the floor drain in the basement (which I have done repeatedly but still experience this issue). Do you happen to know any contractors in the Chicagoland area that you could recommend that are familiar with assessing and correcting this type of issue? Any assistance you can provide would be greatly appreciated.

A. Sorry, I do not reside in the Chicago area and can't help you on that score.

If the furnace in your older home does not have a fresh air intake, when it comes on it draws makeup air from any place it can get it, and that may be one of your toilets.

Ask a plumber to check the wax seal on all your toilets, and if he or she finds any failing seals, ask that they be replaced with the newer type of seals that are permanent.

Q. Some time ago, we were planning to have oak flooring over a grade-level concrete slab. My wife wrote to you saying our contractor plans on putting the moisture barrier over the subflooring. Your reply was to put the vapor retarder directly on the concrete. Sorry, the contractor did it his way. The boards are slightly concave; could the placement of the moisture barrier be a reason the boards are cupped?

A, It could indeed. The moisture should be controlled at its source and concrete is porous to some extent, varying on its density when finished.

Applying the vapor retarder (VR) over the subfloor allows any moisture permeating from the concrete to remain below the VR where it can work its way to the finish flooring, as plastic film is not a total vapor retarder.

Moreover, the finish flooring is in contact with the VR and has no way to breeze, whereas the subfloor and the framing supporting it are very good at tempering these fluctuations.

That being said, there is always a risk at laying a wood floor over concrete.

The following Q&A is a reprint from his column in 2015.

Q. Henri, I give your book out to people who just bought a house. It's such a great book and has helped me much in the past. Thanks!

We just bought a house that was built in the 1920s that has phenomenal attic living/play space/man cave potential, but I am reluctant to finish it at all because of the unreliable slate roof. As you know, it lasts 100-plus years but leaks every year. I only plan on being in the house about seven to eight years. Even though we've had it checked twice in the last six months, we still got a new leak, but a minor one. If I were staying there for 10-plus years, I'd consider tearing it off and putting in a new modern roof. The roof is a pseudo hot design with fiberglass batts on the underside and they are falling down.

The only thought I've had so far is to put up plastic sheeting that would encapsulate the fiberglass and still make it easy to access leaks. The plastic on the plus side creates a vapor barrier. On the minor side, it would trap water from the leaky roof. With the plastic sheeting, I could feel more comfortable minimizing water damage and sealing the fiberglass somewhat for better air quality. Then I could put in Ping-Pong table, etc., but the space will still be rather raw.

Any other suggestions beyond the plastic sheeting would be most appreciated on how to deal with leaks proactively and smart ways to make the space less raw given the leaks.

A. I would urge you to find another roofer, one very experienced with slate roofs, to do a thorough check of your slates.

Some types of slates can last 100-plus years, but some other types do not have such longevity. It depends on where they were quarried. Slate roofs often need frequent attention, fasteners can rust and slates can crack or fall off. Snow and ice can be rough on them.

Ensuring a complete repair is not only healthier all around, but as you undoubtedly know as a professional, when resale time comes, you may experience difficulty selling your house. And you'll have to disclose the roof leaks.

Depending on the type of slates you have, the expert slate roofer may advise you that repairs are no longer worth it and you should consider a total replacement, a shame, really, as long-lasting slates in good shape add value to any house. Replacement can be done with other than slates.

Capturing leakage, however minor it may be, between the roof sheathing and the plastic you are planning on installing, may lead to the development of mold and the degradation of the R-factor of the insulation as it gets, and stays, wet. But the worst scenario is the possible rotting of the rafters and roof sheathing over time.

Resolving the slate leakage issue will also allow you to finish the attic into a more pleasant space to be enjoyed for the number of years you plan on living in the house, and make it more valuable and salable.

• Henri de Marne, a former remodeling contractor turned columnist and consultant, is the author of "About the House with Henri de Marne" (Upper Access Publishing). He continues to take questions from readers for this column and his website, www.henridemarne.com. Email questions to aboutthehouse@gmavt.net.