Wednesday, July 15, 2015

DIY Inground Pool Repair: Part IV–Replacing Cracked Caulk in Expansion Joints

After doing repairs to the tile and coping, we had simply planned to fix some small cracked areas of caulk in the expansion joints of the pool deck, then repaint it. Upon closer inspection, however, all the caulk was clearly in need of replacing. This part of the process was as fun as it sounds, or maybe less, and my back was spasming for days from the effort. Still, well worth it. I have read of estimates that suggest you would pay someone $5-8 PER LINEAR FOOT to replace caulking. What?!?! We have about a million linear feet of this stuff, so even if I needed medical attention after this DIY, it was still going to save us big money.

Removing the caulk was time-consuming but not terribly difficult since it was in bad shape. Some pulled right out, other parts needed some help from a linoleum knife. I didn’t think to take pictures of this part, but you can use your imagination to visualize disturbed ants nests, dirt of all colors, and general filth and decay. One pool’s worth of old caulk and backer rod filled a 5 gallon poly bucket. I then swept out the areas so they would be clean and dry for putting in the new caulk. At this point, I wish I had sprayed all the cracks for ants… they love burrowing under the caulk, and they don’t mind eating through it if they have to. So, consider that if you have a multitude of anthills along your expansion joints.

Since I did my homework, I knew I needed paintable, elastomeric caulk, ideally with some silicone content for durability. This is not something you can find easily at the Blue or Orange stores. I looked around the interwebs, asked in some pool forums, and finally found that the stuff I was looking for was available at my local Sherwin-Williams*. I chose the Powerhouse Siliconized Acrylic Latex Sealant… the red tube. I bought it on sale and used a $10 off $50 coupon, so it came out to be about $1.59 per tube instead of $2.99. Which is great because this project required about 31 tubes of caulk. We bought 5 cases of 12 and returned what we didn’t need (they even recommended that we do that, and it was as easy as pie to return the unused tubes).


To properly repair expansion joints of this width (1/4”-1” in places), you need to first place foam backer rod into the crevice, leaving room for caulk on top. Backer rod looks like a long length of tiny pool noodle foam. It saves caulk by filling some volume, and prevents the caulk from adhering to the bottom of the trough. When you know the concrete slabs are going to move over time due to instability of the material beneath it (the definition of an expansion joint; in our northern climes it occurs due to slight erosion and/or frost heaving in winter), you want to create a bridge of caulk that spans from one side of the crack to the other, to keep out water that can freeze and cause problematic cracks in the concrete or induce the aforementioned erosion of the ground under the concrete. If the caulk is also adhered to the bottom of the joint, it can limit how the caulk can stretch and cause it to crack and fail prematurely. So, backer rod. Find it near the insulation area in any home improvement store. It might run you about $3-5 for 25 feet. We used about 5-6 packages of the stuff, in varying widths to fill whatever size gap you have. 31hGdh1LAgL

I then filled the gaps with backer rod, and proceeded to caulk the joints. I put a generous bead of caulk on each side of the rod to make good contact with the concrete sides, then used a very flexible putty knife to smooth the top level with the concrete. As it dried, it pulled down to form a concave trough. The excess wet caulk I scraped up I would then slop into a nearby deep area so as not to waste it, and I just moved along around the pool until I was back where I started. It took basically forever.


Now, in an ideal world, you’d have a week of dry weather both before and after caulking in order for it to cure the best. Here, it had rained a day before and then about 36 hours after, so it took a loooong time to cure properly, and a few lingering smooshy areas got a little mangled by little toes that needed to go swimming. I was feeling very pessimistic for a time, but eventually it all cured properly and there are precious few areas that I feel will need attention from me any time soon. We waited over a week before painting, but some of that waiting was due to more rain and other life happenings.


Next up is the painting (actually staining) of the concrete pool deck.

Here are the other pool repair topics I have already covered:

  • Safety
  • Replacing fallen tiles
  • Repairing crumbling pool coping

*This is my honest review of the product, which we purchased with our own money. I recommend it, and they had excellent customer service.

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