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Penetrating sealer is preferred for protecting concrete

Q. Hello, I am a faithful reader of your column in the Daily Herald in the Northwest suburbs of Chicago. In the next couple of weeks, I am having new concrete front steps and two sidewalk pads replaced in the front of my house. The contractor says as part of the job he will seal the concrete, not with permanent sealer, but with one that needs to be redone every couple of years.

Is this sufficient, or can I apply the permanent sealer over the top of this so I don't have to redo it all the time? Our home faces northeast, so I do need to use de-icer many times during the winter season. Also, what kind of de-icer is safe to use so it won't damage the new concrete?

A. At this point, you have two choices. Ask the concrete contractor how much he would charge you to switch to the penetrating sealer, if you trust him to do so, or let him apply the topical sealer and wait a couple of years to apply the penetrating sealer. Nothing is lost going this route.

Applying penetrating sealer over performing topical sealer is a waste of money and effort, as the former would not be able to penetrate the latter as long as it is effective.

To make sure that the penetrating sealer will penetrate into the concrete when the time comes, sprinkle water on it. If the water beads anywhere on the surface, the time is not ripe for applying the penetrating sealer. Wait another year until water is absorbed into the concrete.

Meanwhile, de-icers should not be used during the first year of new concrete, as it is especially vulnerable until it has aged. Instead, shovel the snow and use a broom to remove remnants down to bare concrete as soon as you can after it has stopped falling and before anyone walks on it. This strategy works very well in preventing ice formation. It is the old standby in New England.

The concrete industry changed its de-icing recommendation a few years ago. Now we are back to sodium chloride as less harmful than calcium chloride, but neither is advisable long term. Moreover, both are harmful to vegetation and corrode metals.

It is best to use coarse sand or cat litter for traction.

Q. I have a farmhouse that is well over 100 years old. When the house was first built it was constructed on cedar posts. At a later date, basement walls were poured without removing the cedar posts.

Over the last 100 years, with the posts going through freeze-thaw cycles, the posts have shattered the basement walls. Additionally, the sill plate and rim joist are rotted out.

All of this damage is on the parallel side, rather than the joist end of the house. My question is: How do I best support the house while I repour the wall and replace the sill plate and rim joist? The house is two stories with a footprint of 20-by-24 feet. Thank you for your time.

A. Not knowing the layout of the cedar posts and the concrete, which is causing the posts to shatter it, the best advice I can give you is to hire a contractor experienced in such work to perform the repair. Too much is at stake.

Even though this is the type of work I performed many times during my active construction career, it would be irresponsible of me, without seeing the site conditions, to attempt to give you instructions for a job that requires structural know-how.

An alternative, if you insist on doing the work yourself, is to retain the services of a structural engineer to guide you.

Q. I would like to use the crack sealer that is available from Asphalt Seal Coating Direct as you have recommended.

My concern is whether I can use Latex-ite Optimum as the final driveway coating after filling the cracks with the Asphalt Seal Coating Direct product.

A. I can see no reason why you can't use Latex-ite Optimum driveway sealer on your asphalt driveway once you have filled in the cracks.

But to achieve success in the application of any sealer, the driveway surface must be prepared thoroughly. It should be swept and cleaned with a cleaner/degreaser, and any oil spots removed. This can be done by sprinkling TSP-PF crystals on any problem spots and sprinkling hot water on the crystals. Scrub the surface with a stiff brush. Wait 20 to 30 minutes and scrub again.

Rinse well with your garden hose, but be aware that TSP-PF can damage vegetation.

Q. I have a couple of questions for you:

First, will products such as Round Up or other such weed killers be effective against moss or algae growing on roofs? I know there are many other solutions, such as copper strips or roof cleaning companies. Also, does the sun get rid of moss on roofs? I noticed a few spots on my roof, but after the sun came out, they seemed to disappear.

Second, can I use products such as Flex Seal to seal driveways effectively where cracking exists? I've used different caulking products. They work for a while, but the cracking seems to come back in the spring months. I've often wondered why commercials for such products as Flex Seal never show concrete being sealed.

A. An extensive exposure to the sun is a good deterrent to the formation of algae and the growth of moss or lichen on any surface. But on surfaces receiving little or moderate sun exposure, the sun is not likely to get rid of any growth that has developed.

To get rid of moss and algae, try Wet & Forget Outdoor. Check out Wet & Forget's website at www.wetandforget.com, click on "Store Locator" on the right and enter your city to find the nearest store selling the product.

Flex Seal is marketed as "rubber in a can." I have had no experience with it, but it seems to me that it is only a surface coating film. I can see no use for it on a concrete driveway.

There are several concrete crack sealers sold in hardware and big-box stores. The kind to use depends on how deep the cracks are and their shape.

If the cracks are very small, such as shrinkage cracks, and your concern is aesthetics, you can make a slurry with Portland cement or a vinyl-reinforced concrete repair product and work it into the cracks.

For successful repairs of larger cracks, widen small cracks to one-quarter inch wide, using a cold chisel and a hammer. The cracks should have vertical sides or, better yet, inverted V sides.

Remove any loose pieces of concrete from the cracks and thoroughly clean the cracks with a steel brush.

For cracks no wider than one-quarter inch, you can use Quikcrete Concrete Repair, a flexible repair product that can stand small movements in the concrete. It comes in tubes for use with a caulking gun. Apply it to the cracks, and tool it with a putty knife.

For cracks wider than one-quarter inch and up to one-half inch, use Quikcrete Concrete Crack Seal, which comes in its own pressurized container.

Overfill the cracks with the product to allow for settlement during curing, which takes about 24 hours.

If the cracks are deeper and wider than one-quarter inch, you will need to apply several "lifts," allowing 24 hours between each.

Be sure to follow the directions for a satisfactory result.

Q. Our concrete driveway is about 50 years old. The expansion joints are breaking down. I bought a bottle of Quickrete blacktop crack sealer.

I filled up the cracks with dry sand. Then I used the Quickrete as a sealer. Before I do any more joints, is this the right thing to do? Is there another product I should be using? Will doing nothing cause harm to the driveway? The driveway is in good shape otherwise.

A. The only potential problem with doing nothing is water filling the joints, freezing and damaging the concrete. But this is only conjecture, as original expansion joints are not waterproof anyway.

The method you are using is acceptable, but consider the following for a more durable solution: Remove as much of the failing expansion joint as you can.

Insert a backer rod of the correct size into the crack, pushing it gently to the bottom of the crack with a blunt tool or stick to avoid breaking its fragile skin.

The object is to have a caulking space shallower than wide, so you may need to put some sand down to leave enough space to top the sand with the backer rod.

Backer rods ensure that the caulking compound only adheres to the opposite sides of the surfaces to be joined because, for elastomeric caulking to perform as intended, it must not adhere to a third surface - the bottom of the crack.

Get as many oversized tubes of Sika Pro Select concrete crack flex sealant as you'll need to caulk the cracks. You can buy Sika products in construction-specialty stores, some big-box stores or through A.H. Harris's stores or website: www.ahharris.com. Backer rods can be purchased in the same outlets.

Be sure to follow the directions for a satisfactory result.

• 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.

© 2016, United Feature Syndicate Inc.

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