Archived from the Tools In Action forum (Woodworking). This thread is read-only.
I have 2 stairwells in this house I have been fixing up for almost a year. I painstakingly caulked these steps because many of them were not flush with the wall. And then I painted, to line them perfectly. I used dap dynaflex 230 because I was told by more than one person that it was ultra flexible, paintable and all around perfect for what I was trying to do. Things looked great for about 2-3 months. But I noticed this week this happened on multiple steps!!!!!!
Caulk usually fail because of moisture/humidity, temperature, poor adhesion (area not clean), and movement. Because high end silicone caulking doesn’t shrink and the stairs didn’t move in 3 months. Question: Was the caulk just pumped on? Try lining the areas with masking tape on both sides leaving 1/8″-1/4″ space and press the caulk to fill all gaps using your finger to ensure the caulk fills the entire gap to the bottom.
yes, I taped the stairs and smoothed it out. It was a very painstaking process but it came out great. Until now.
The humidity does go from 70% to 28% from summer to winter in PA.
In UK I use a caulk from a brand called Polyfilla, I think you can find it in Amazon.co.uk. It is the best I have ever used, it is quite thick therefore it does not shrink too much, but because of that it is not so easy to use, you need to wash your fingers a few times while using it. But as RT29 mentioned movement is one of the reasons and I think the main reason, other reasons he mentioned would not be the case I think as stairs move a lot because you step on them all the time. What I normally do with stairs is to enforce them with proper screws to the wall if you have access under the stairs, in the past a lot of guys have used only nail to fix stairs and nails are the worst thing for this purpose. There are some paintable silicones as well that you can use, I have used it once, and I was impressed with the result.
mgmartino wrote:
On 12/6/2024 at 8:47 AM, mgmartino said:yes, I taped the stairs and smoothed it out. It was a very painstaking process but it came out great. Until now.
The humidity does go from 70% to 28% from summer to winter in PA.
Looks like caulk shrinkage to me. I would not use the 230 again. Dak products I question. I’m not a big fan. Most of their caulks take forever to dry, and once I bought Almond and the caulk was white inside.
I use to like Dak but I am with you. Over the years I have had more issues with the products.
After talking to people at DAP and others I think one of the big issues is bead size, because I noticed other places where I used the Dynaflex 230 (in white and brown). Where the bead size is technically lower than their minimal bead size of 3/16 inch.
And it cracked or separated..So does anyone know of a caulk that can handle this tine seems really well? It would be much appreciated
Looks like bead is too small on most of the photos. And if humidity or movement is an issue try Dap Extreme stretch (their most flexible sealant. https://www.amazon.com/DAP-7079818714-Extreme-Elastonumeric-Limestone/dp/B08CYRTNJN/ref=asc_df_B08CYRTNJN?mcid=75aa0ae9f44c3a46824b26b4ffa7650f&hvocijid=4003399086304926914-B08CYRTNJN-&hvexpln=73&tag=tooinact-20&linkCode=df0&hvadid=721245378154&hvpos=&hvnetw=g&hvrand=4003399086304926914&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9021532&hvtargid=pla-2281435177818&psc=1