Cite | Pool Surfacing and Repair, Satellite Beach, Brevard County, Florida. Among the many causes of surface failure and reasons pool interior finishes require resurfacing is de- lamination, also called “hollow spots” or “pop- offs”. When surfaces do fail, there is a tendency for all parties to finger- point and deflect blame. In this case, the failure of the finish to stick to the substrate is, without a doubt, the applicators fault. There are various conditions that can cause hollow spots and all are within control of the contractors and subcontractors. The reason finishes don’t stick is relatively simple to understand once you realize all cement surfaces are porous to some degree. They absorb moisture at different rates depending on the density of the material. The “softer” the material, such as old pool plaster, the more water it sucks up. When a newly applied wet cement finish is applied over an old cement surface, the old surface absorbs the moist cement content of this material at the place of contact. This cement forms the bond between the two materials. If the old surface draws out too much of the cement at this contact area, the bond is compromised. There will not be enough cement in place to form a tight bond. In areas of de- lamination, usually varying between six inches and a couple of feet wide, the finish will pull away from the old surface about a quarter to a half- inch. Sometimes hollow spots are not detected when the pool is full. If the finish is applied thick and dense, water cannot get behind the spot and lift it further away. Sometimes, simply the weight and pressure of the water will keep a hollow spot from lifting. Replastering Guide Preparation. A saw cut. The pool is checked for loose plaster by sounding. While bond coat is the preferable way to prep your pool for. When hollow spots lift away further, they tend to crack allowing water to fill the void. This water gets saturated with calcium and calcium salts will form along the crack. That’s what I look for when I bid on a resurfacing job. Although it is more common to find hollow spots on previously resurfaced pools, I come across lots of new pools with that problem. The record number of hollow spots is 4. Did you check out those pictures in the disaster files? Among some of the other reasons for hollow spots in new pools are dirty surfaces and “hot spots” on the concrete shell. These are areas that have a higher sand content at the surface. Gunite pool shells are very porous and spotty. I anticipate lots of work in the future due to bond failures in new gunite pools in this area. So how do I prevent hollow spots from occurring? First of all, all my pools get a thorough cleaning. This will allow a good surface for an application of an acrylic- based bond- coating surface. This bonding surface has sealing properties that will prevent too much cement to be drawn out of the newly applied finish, thus providing excellent adhesion. Before this bond- coating was used, pools were either acid- washed or sandblasted. Just because a surface is rough doesn’t mean something will stick to it! Bond- coating a sandblasted pool may seem redundant, but I learned the hard way and it cost! Hollow-sounding tiles may signal installation problems. that sounds hollow. Notice if the hollow-sounding tiles are grouped together or are the spread out. Again it is now sounding hollow when i tap it as if it has not adhered properly. it doesnt matter how hard you slam your doors the plaster shouldnt crack and fall of. Swimming Pool Plaster or Whitecoat. you will hear a hollow sound. plaster, vinyl and fiberglass. Swimming Pool Crack Repair. Pool Plaster Crack Hollow Sounding RodOf course, right before a new finish is applied, everybody knows you’re supposed to hose down the pool walls and floor to cool them down and moisturize. This will allow adequate bonding, right? Let me tell you a secret. The subcontractors that apply pool finishes, whether they are new pools or re- dos, get paid by the job, not hourly. So, if they can get the pool done in less time, do you think they will try? Of course! The first thing the finishers will do is NOT wet down the pool surface. This easily knocks an hour or so off the drying time. Aren’t these guys compromising the bonding? Yup. What do the contractors do about it? They point the finger. What do I do about it? I’m in every pool I do, and I’m the one who guarantees it for five years. So I make quite sure everything is proper and as good as it can get. Cracks In New Pool PlasterIt is common knowledge that one of the popular subcontracting firms in my area never wets the pool down before they apply the finish. I’m looking at a lot of work in the future thanks to these guys. Pro- Cite is located in southern Brevard County Florida which includes the communities of Melbourne, Palm Bay, Viera, Suntree, Satellite Beach, Indian Harbour Beach, Indialantic, Melbourne Beach, Eau Gallie, West Melbourne, Malabar, and most of the Space Coast. Investigation of Exterior Veneer Porcelain Tile Falling Off. A 2. 0 x 3. 6 inch glazed porcelain tile was installed over the plaster substrate on the exterior walls of a 4 story condominium project. After about 9. 0 days someone carrying a ladder bumped into the tile on the wall and the tile fell off. The Problem. Investigation of Porcelain Tile Falling From Exterior Veneer of Building. A 2. 0 x 3. 6 inch glazed porcelain tile was installed over the plaster substrate on the exterior walls of a 4 story condominium project. After about 9. 0 days someone carrying a ladder bumped into the tile on the wall and the tile fell off. CTa. SC was retained to investigate the cause of the tile falling from the building and to determine if it was an isolated problem or if there was a systemic problem that could be a life safety issue. Request: CTa. SC was asked to investigate and inspect the exterior veneer tile installation to determine the cause of the tile debonding, to determine the extent of the problems, to determine if the installation met industry standards, and to determine how best to remediate the problems. The Solution. Inspection Findings: I inspected the areas where there were missing tiles. We could see the trowel ridges of the thin- set mortar adhesive and most them were not collapsed. There were a limited number of areas where the tile had been bonded. The thin- set on the wall and on the back of the tile seemed very hard and well bonded to those respective surfaces. I then randomly tapped other tiles and found that some tiles sounded well bonded, but many tiles had hollow sounds that covered from 2. I gently pulled on some tiles and detected the tile moving, which was another indication the tiles were not well bonded. Tensile Pull Testing: We cut out 6x. When we removed the hollow sounding tiles they fell from the wall by themselves, thus their tensile bond strength was zero. In some cases the tile was back- buttered with a thin coat of thin- set and some cases there was no thin- set. In each case the thin- set mortar was applied to the plaster wall with a 3/4" marble loop trowel, but it wasn't applied thick enough to reach the back of the tile due to the plaster substrate not being flat and within plane tolerances of 1/8" in 1. Tiles that sounded solid were tested and their tensile bond strength ranged from 1. Destructive Testing: I found a tile that sounded fully hollow. We cut the grout joints out around the perimeter of the tile and as we did the tile came completely loose and there was no thin- set on the back of the tile. The plaster substrate had thick marble trowel ridges of thin- set mortar adhered to it. There was a continuous vertical crack in the thin- set mortar. When the thin- set was removed we discovered that they had installed the tile over a plaster control joint, which is against industry standards. The control joint should have continued through the tile and filled with a flexible sealant. Conclusions: It was determined that the hollow portions of the tile were not bonded at all, but the solid sounding portions of the tile were bonded well. We found that most of the tiles were excessively hollow and not safely attached to the wall. The plaster substrate was not properly plumb and flat within industry standards, so the tile installer should have corrected it before installing the tiles. Even though the tile installer used a lot of thin- set mortar, he didn't use enough for the thin- set to make full contact to both the plaster substrate and the tile. Industry standards requires 9. If the installer had pull tiles as they were being installed, as industry standards require, to verify he was achieving adequate thin- set contact, he would have realized he wasn't and could have corrected the problem. Compounding the problem was that the tile was installed over plaster control joints and the tile did not have any movement joints as industry standards require movement joints every 8 to 1. Recommendations: Before I left the job site, I did tell client that I thought leaving the tile on the building could be a hazard. If there were an earthquake, I would expect that a substantial amount of the tile would shear off the building. It was my recommendation that all tiles on the exterior veneer be removed and replaced. During the new installation the substrate needs to be properly prepared and repaired as needed. A high strength latex or polymer modified thin- set should be used to install the new tile. The tile should be back- buttered and should substantially achieve 9. Movement (Expansion) joints in the substrate should continue through the tile and overall expansion joints should be installed every 8’ to 1. TCNA method EJ1. 71. There should be a quality control plan in place during the re- installation to assure a quality and a substantial installation. This entry was posted in Case Studies, Exterior Veneers, Hollow Sounding Tiles, Tile Debonding. Bookmark the permalink. Donato Pompo Donato Pompo, CTC CMR CSI CDT MBA, is the leading tile and stone forensic expert and consultant in North America, and he is a National Tile Contractors Association Recognized Consultant. Donato is the founder of CTa.
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