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Robert Lamoureux: Compact sand for clean patio finish

Your Home Improvements

Posted: September 17, 2010 9:45 p.m.
Updated: September 18, 2010 4:55 a.m.

Hi Robert,
I built an 80-square-foot flagstone patio in my back yard. I excavated and put in a 2”-3” sand base, set the flagstone, made a mortar mix of one part Portland cement and five parts sand, the mix was blended in a trough with a hoe then was swept into the joints, tamped down with a 1” x 2” and refilled.

The patio was then watered and covered with plastic for two days. The problem is that some of the mortar is hard and some is still sandy and you can push a finger into it.

Where did I go wrong? My guesses are that the sand out of the plastic bag was damp, which kept the Portland cement from mixing properly — or that I put too much water on after completion. What do I do now?
Doug E.

Hi Doug,
There are a few ways you could proceed with this project. First, if you’ve decided to go with a mortar, mix the sand and mortar, 1 to 4, with water. Put it in a baker bag — a mortar bag — then squeeze the mixture between each of the flagstones. It’s much more time consuming than spraying the top with water, but for something as permanent as a flagstone patio, I’d do it once, do it right. 

It sounds like what you have now is a sand grout, which is fine. You can just keep sweeping sand in until it all settles down. 

As for where you went wrong, did you compact the 2” or 3” of sand base? You should first use a vibroplate to ensure the sand gets compacted. Use plaster wash sand, not silica sand, because the plaster wash sand compresses more and provides a better base than the silica. 

To use a vibroplate, just walk it back and forth over the base until the sand is well packed. You want to build a border, then set your stones inside. Since you’re not using mortar to hold them together, this will prevent them from spreading and walking. 

Instead of mortar, sweep sand in between the stones after the stones are set. The vibroplate is fairly heavy and it can damage the stone’s surface if you’re not careful. One trick is to cover all of the stones in a layer of sand, which acts as a buffer.

The vibroplate will also shake more sand down into the spaces and will tamp down the stones as well. Then, sweep up the excess sand. It is also possible to put down a sheet of masonite and walk the vibroplate over that so the bottom of the machine won’t score or scratch the stone. 

If you don’t want to rip it all out and start over with mortar, I would go with a vibroplate, available at the local rental yard.

Build a border to keep the stones where you want them, then get it all compacted with plenty of plaster wash sand.  

Mr. Lamoureux,
I live in a five-story condominium complex. I’ve had enough.  Once or twice a year, I get sewage backed up in my kitchen sink. It happened again recently and flooded my unit. I’m tired of it. What can be done, besides moving? I will forward your response to management. Sincerely,
Dr. R.

Hi Dr,
At the garage level, at every entry point to your unit, install a one-way check valve on every waste line.

These are now code. If any of the horizontal pipes in your garage back up, instead of backing up into your unit, the spring-loaded flapper inside the check valve closes and will not allow a backup. 

This is not to say that the check valves are 100-percent failsafe, because they’re not, but they are required on all new construction because they will prevent many problems from occurring. 

If, for example, your horizontal line is blocked, and your upstairs neighbor keeps dumping more water down the line, then the check valve would be under water, which would flow out through your drains. 

If, however, your adjoining units have ongoing problems, and they’re sharing your main line, your unit will be safe. You’re isolating your surrounding neighbors, not your stack, to prevent backups. 

The valves themselves are expensive and the job is labor intensive.  All of the cast iron pipes need to be cut and configured, but in the long run, it’s a small price to pay as opposed to sewage in your home, potential mold, as well as flooring and drywall repair. 

I have been reading your column regularly for some time now, not realizing that I would soon need your advice.

We are the original owners of our nearly nine-year-old home, and we are having huge problems with our windows.

The builder, now bankrupt, used some no-name brand of dual-pane vinyl windows (we have more than 40), and I am beside myself with what to do. 

Our insurance agent has told us this is not covered under our homeowners’ insurance, and one neighbor (no, we are not alone with this problem) received one bid in excess of $40,000 to replace his windows. Is there anything we can do?
We are not in a position to undergo such a huge renovation on such a new home (the reason we bought “new” in the first place). Thank you.
Evelyn B.

Hi Evelyn,

First of all, there is a 10-year statute of limitations. You’ve lived there nine years already. If you are considering legal action, you will want to move on this quickly. Going through an attorney, find out if the developer had insurance at the time your home was constructed. It then would be possible to sue the insurance company. 

I’m not a big advocate of litigation. I’m an expert witness but lawsuits are something I do not enjoy. Everybody is suing everybody these days. 

However, if you and your neighbors are having the same problems, it could be grounds for a class-action suit against the carrier that insured the developer during the construction phase of that property. 

Your attorney would also be looking into the manufacturer of the windows. 

Keep in mind even if you “win,” you will typically receive only pennies on the dollar after the attorneys take their percentages and fees. Most lawsuits only pay for a small fragment of what’s needed, but for most, something is better than nothing. 

Often the insurance carrier will not go to court. If it’s a lose-lose deal, especially in a class action, they will decide to give you a certain amount of dollars to drop the case. 

If you want to pursue legal action, it can take up to five years to settle. During those five years, you cannot touch your windows.

All damages have to be proven in discovery. The minute you touch or alter the windows, you own them.

You have to be prepared to leave them alone for five years. That’s living with bad windows for potentially five rainy seasons. 

If you are having water intrusion issues, cover the windows with plastic. We usually apply an adhesive on the frame, and then tape with plastic. 

We have designed a custom, full-color The Signal/Your Home Improvements T-shirt we will give you if we answer your question. The T-shirt is available to be picked up at our office.

Robert Lamoureux has 25 years experience as a general contractor, with separate licenses in electrical and plumbing contacting. He owns IMS Construction Inc. in Valencia. His opinions are his own, and not necessarily those of The Signal. Opinions expressed in this column are not meant to replace the recommendations of a qualified contractor. Send your questions to


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