Opinions on DAP Dynaflex Ultra

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creativepart

Active member
Joined
Jul 6, 2014
Posts
42
Location
Hill Country, TX
Windows don't generally need much resealing, but if yours do then maybe. But it can't be a proper all around replacement for Dicor, NuFlex311, and other approved RV sealants.

Look at the Specifications on the link from Lowers - not for use on roofs, gutters, or in Kitchens and Baths:

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Gary RV_Wizard

Site Team
Joined
Feb 2, 2005
Posts
74,316
Location
At our Silver Springs FL home
It's a fine product, as good but no better than a dozen similar ones. However, it's probably not what you want for RV windows. Most RV windows are mounted in metal frames that clamp to the sidewalls like a sandwich. The proper seal is to use butyl tape or caulk between the metal frame and the sidewall before clamping the two halves of the frame down tight. That's the primary water barrier and it works quite well, waterproof yet stays soft enough that the window can be removed again if needed. Then you put a slim bead of caulk (usually clear silicone) around the top and sides (not bottom) of the metal frame, just for extra insurance so that water doesn't accumulate behind the edge of the frame.

So, for your windows get yourself a roll of butyl ribbon caulk and a tube of silicone instead of this product. However, If you have a wall or corner seam that needs sealing, this Dap should work fine.
 

Tiercel

Well-known member
Joined
Jul 20, 2021
Posts
154
Location
Pennsylvania
Gary, I just put my front overhang window in with XFasten Butyl tape. I love how it sticks and squeezes out as the window frame is tightened down. It was also relatively easy to trim with just a plastic putty knife and using a glob of butyl tape to help lift it. I am impressed by the stuff.

I have heard several say stay away from silicone. I was thinking about the Dynaflex Ultra to do that final little bead around the window frames. I saw an RV shop on YouTube demonstrate it for that and to patch a small gap in rubber glazing.
 

Gary RV_Wizard

Site Team
Joined
Feb 2, 2005
Posts
74,316
Location
At our Silver Springs FL home
I have heard several say stay away from silicone.
Those opinions are often exaggerated and misinformed. Pure silicone should not be used on roof seams and openings because they frequently require re-caulking and you can't layer over silicone. It's also generally not a great choice for major vertical seams, again because of the difficulty of removing old sealant. However, Silicone has great properties for around window frames because they rarely if ever get recoated and the thin bead is easily peeled if needed. Some major RV factories use pure silicone on the windows frames and a few other places. It's a matter of choosing the right sealant for each job, not whether silicone is good or bad.

But if you have an aversion to pure silicone, try Geocel Proflex RV Clear or Lexel
 
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