Swimming Pool Tips
EXPANSION JOINT CAULKING
It used to be that all pools built had the expansion joint between the perimeter coping and the pool deck caulked or filled with elastomeric sealant 30 days after the concrete was poured. This was holding up the checks to the builders, I was told, so they sort of stopped mentioning it.
It is well worth mentioning. The expansion joint is an important interface between the pool and the deck. These two independent structures need to remain independent. Keeping debris out of the joint ensures that the joint is "true" and the two structures are not in contact with each other. When they do come in contact, the pool may develop a crack in the tile, which is usually an indication that the "beam" has cracked all the way through. The beam is defined as the top 6 or 8 inches of the pool wall which holds the tile & coping. Beam damage gets worse with time, eventually crumbling, requiring beam reconstruction. To avoid this costly expense, caulk those joints! Caulking also keeps out water which can freeze and expand. This can damage the coping, beam and eventually, the tile.
A good caulk job starts with good surface prep. The sides of the joint must be clean, dry, rough and solid. Backer rod foam should be placed in the joint (don't use sand) to give the caulk something to sit on top of. The joint is taped off to keep things neat, and caulk is shot or troweled into the joint to a depth of 3/8-1/2". The caulk should be an elastomeric sealant, suitable for outdoor use. Deck-o-Seal and Vulkem are two popular brand names. Tape is removed before caulk sets. Replace or repair caulking annually if it cracks or pulls away from either side.
Prices for professional expansion joint caulking run $3.50-5.00 per linear foot. Add up the perimeter of the pool to figure your price. The variance depends on the width of the joint, which is usually 1/2"-1" or regional diferences. Price includes full prep, backer rod, caulking and finishing.
The "beam" is the top six or eight inches of the pool wall where the tile attaches to the front and the coping sits on top. The width of the pool wall, coming up from the floor is generally 4-6". The beam is where the width of the wall rapidly increases to 10-12" to accommodate the width of the coping and to provide structural strength and integrity in this sensitive area.
The beam is not visible to you, and you may never know it's there until it's time to repair it. Water, aka nature's slow jackhammer, is the largest cause of beam damage. Water entering the voids of the gunite from either tile side or expansion joint side can spoil the gunite, or can freeze and expand, breaking it apart. Water can also sit in an uncaulked expansion joint, freezing with enormous lateral pressure.
An expansion joint that is filled with debris such as pebbles, sand, concrete, dirt, etc., will allow the pool and deck to contact each other, and when one moves, they both move :-(. Similarly, if the original deck work was sloppy, they may pour the deck right on top of the pool, or allow areas of contact between pool and deck.
Since you are unable to see the beam, you will look for signs of damage in the tile and coping. Tapping the coping stones with a metal rod determines their bonding. A hollow sound indicates that the stone is no longer bonded properly, and also could indicate a cracked or crumbling beam. Tile that is falling off provides another clue. If there is a crack in the beam behind the tile that has fallen off; it is likely that it extends back all the way through the beam, and is not just a surface crack. If you notice any evidence of these types, contact a professional contractor to ameliorate this progression, and put things back right.
Because it's under the coping and behind the tile, beam repair is done in conjunction with tile and coping replacement. The tile and coping is removed and transported to the landfill. The beam is chipped down to solid gunite (usually 2-3"). Forms are set, steel rebar is wired together, and a new beam of hydraulic cement is poured and leveled to the proper height. When this is cured, forms are removed and tile and coping is put on. Finally, the expansion joint is caulked to prevent this from occurring again :-). Prices will vary according to the extent of the perimeter damage, the depth of the beam damage (it can break below the tile), as well as other factors. Expect charges of around $60 per linear foot for tile, coping and beam.
Hallmark Pools and Spas is Houston's Premier Pool Builder and can you help you with beam repair.
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