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Robert Lamoureux: Sandblasting is not the right fix

Your Home Improvements

Posted: October 6, 2012 2:00 a.m.
Updated: October 6, 2012 2:00 a.m.

Hi Robert,

When I bought my house, the pool was dirty and I couldn’t check out the condition. Now that I’ve got it cleaned I can see that there is plaster that is coming up off of the bottom.

Some are small pieces about the size of a quarter and other areas I can peel off the size of a grapefruit. The weird thing is it looks like there is plaster under the plaster that is coming off.

Why is this happening and what do I need to do to fix it? Thank you,

Evan T.


Hi Evan,

It sounds like the previous homeowner had the pool sandblasted and plastered over which is not the right way to do it.

What you should do is have all the plaster chiseled down to the gunite.

This leaves a very course surface. Then you have the pool re-plastered.

A lot of guys will take shortcuts thinking that sandblasting will provide a good bonding surface. It will hold for a while, but not long.

At this point you need to remove all of the plaster.

You can call a plasterer and they will come out with pneumatic chipping hammers, get it all out and haul it away.

Do it once, do it right.

The new plaster doesn’t have to be white.

Blue or gray bottoms are good options. Whatever your color preference is, different colors make for good looking pools.

Now is the time to have your tiles redone if necessary. Bite the bullet, get it all taken care of at once and you’ll be good for another eight to 10 years.



Being a Do-It-Yourselfer, I want you to know that I really enjoy your column. I’ve got a carport with 4-inch-by-4-inch support posts that are rotted where they were set in the concrete.

I know that it’s all of the exposure to water over the years that is causing them to rot.

The bottom line is do I need to take the carport down and start from scratch or would it be better to jack it up and then replace the posts?

Any secrets or recommendations you could provide would be great. Thank you very much for your time,

Rick S.

Hi Rick,

What you can do is get some bottle jacks. I don’t know the size or weight of your carport, but put the bottle jacks, or a one-and-one-half-ton floor jack down on a piece of 4-inch-by-6-inch-by-2-inch to help transfer the load of the carport.

Take a long enough 4-inch-by-4-inch and place the top end against a 1-inch-by-4-inch against the roof for protection.

If the roof is pitched, you can nail the 1-inch-by-4-inch in place, angle the top of the 4-inch-by-4-inch as needed and toenail into the 1-inch-by-4-inch.

Purchase a metal stand-off bracket with a 1-inch rise. This will keep the bottom of the post elevated off of the surface by 1-inch preventing water from wicking up into the post and causing rot.

Jack up the roof and remove the post. Use a concrete saw, cut an approximately 2-inch square, about 18-inch deep and demo.

Repour concrete and using a plumb-bob, set the standoff bracket exactly where it needs to be and leveled.

Let the concrete dry for three days, come back and install the new 4-inch-by-4-inch post, primed and painted on all six sides, on top of the new bracket. Bolt into place.


Hi Robert,

Our air conditioner outside finally died on us. The A/C company came out and told me they had to change the part outside and the furnace inside the house because of the new refrigerant laws. This I know is the law and I don’t have a choice.

My question to you is now that we’re doing that what do you think about taking a complete unit with the heater and A/C together and putting that on the roof?

Casey D.


Hi Casey,

My first choice is stay with the split system or package unit and put it on the ground.

I am totally against putting any mechanical devices on a residential roof. You start incurring roof damage with the vibrations from the compressor kicking on and cycling and service people getting up on the roof.

Many people do opt to go with a roof-mounted system. To lessen the damages you would want to mount it on pitch pockets, free standing off of the roof and built by a roofer.

Pitch pockets are flashing boots. Once the mounting bracket is placed in the center of the flashing, a rubberized membrane is poured within the confines of that boot and the flashing is tied into the roof.

This is the proper method. I’ve seen some installers that will peel back the roof and smear roofing mastic around the brackets.


Hello Robert,

Congrats on five years!

We have a two story office building that is painted white on the top and brown on the bottom.

We have noticed in the last couple of months that we have white streaking down on the lower brown section.

Do you know what this is? We thought it might be the paint maybe melting from the heat and running down but that doesn’t make sense because it didn’t happen last summer. We’re stumped!

Thank you,

Ava N.

Hi Ava,

It’s not really melting but the top coat of your white paint has given way. The white pigment has released and rolls down with rain or heavy dew.

For the repair, get the upper portion pressure washed and re-painted. Have the painters pressure wash the lower elevation to see if the white streaks will come out, but it may have to be re-painted also.

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, after that contractor has made a thorough visual inspection. Send your questions to


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