# Reliable Ext/Int Paintable Caulk that's redially available



## BrushPro (Nov 15, 2018)

What's your go to? I have a lot of Hardiboard houses where all the butt joints need to be done so I'm looking for something that wont fail in a month (ie Alex plus). Also want something that can handle Interior trim as well and is water clean up etc. Dynaflex 230 is my first thought, what are your recommendations? SW is the store I use most, and a home Depot is near by.


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## RH (Sep 7, 2010)

Tower Tech 2 has been my go to for some time now. Think I read here that there is now a newer version (3?) available?


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## SemiproJohn (Jul 29, 2013)

I have had good experiences with Tower tech 2 and Sherwin Williams Shermax. As far as caulking the butt joints of Hardie siding (not recommended by James Hardie by the way), I don't care what caulk you use, those joints will become a maintenance issue over time. I just finished an exterior of Hardie siding and the owner insisted that I caulk the butt joints. I used Shermax and told them it would not hold up and those joints would have to be recaulked in a couple years max. There should be joint flashing installed behind the butt joints instead of caulking between them, but there wasn't.


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## BrushPro (Nov 15, 2018)

SemiproJohn said:


> I have had good experiences with Tower tech 2 and Sherwin Williams Shermax. As far as caulking the butt joints of Hardie siding (not recommended by James Hardie by the way), I don't care what caulk you use, those joints will become a maintenance issue over time. I just finished an exterior of Hardie siding and the owner insisted that I caulk the butt joints. I used Shermax and told them it would not hold up and those joints would have to be recaulked in a couple years max. There should be joint flashing installed behind the butt joints instead of caulking between them, but there wasn't.


Good to know. Would that joint flashing prevent moisture getting into the ends of the Hardie? I'll look closer next time for this. Is it generally not recommended to Caulk the butt joints or just a general "flaw" of having Hardie?


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## SemiproJohn (Jul 29, 2013)

BrushPro said:


> Good to know. Would that joint flashing prevent moisture getting into the ends of the Hardie? I'll look closer next time for this. Is it generally not recommended to Caulk the butt joints or just a general "flaw" of having Hardie?



The joint flashing serves as a moisture barrier behind the butt joints, it's really nothing more than 6'' by 6'' squares (or so) of a material similar to Tyvek that is installed to overlap the siding directly behind the butt joints. Originally, many years back, Hardie recommended caulking the butt joints (but the joints had to be a certain minimum width to allow enough caulking to actually get fully between the joints). He later ditched that recommendation and switched to joint flashing rather than caulking.


I think many people dislike the look of uncaulked butt joints, but they are a pain to caulk, especially if the joints are an eight of an inch or less, and will need future attention. I always "educate" the customer regarding this. If they know that joint flashing was installed, they can be rather easily swayed into nixing the caulkiing idea.


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## Woodco (Nov 19, 2016)

I've never seen joint flashing used.

When I caulk new hardy, I just get the best, and most elastomeric caulk the store has to offer. Big stretch, or Shermax PPG's Top Gun 400 or whatever. Each company will have something similar.


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## PNW Painter (Sep 5, 2013)

Elastomeric caulks such as Tower Tech II and Shermax are great indoor/outdoor products. My one complaint is that they tend to shrink quite a bit. 

You’ll typically on see them on exteriors, but I’ve had great results with products such as Tremco Dymonic FC and OSI Quad. These products handle more movement, shrink less and can be used in wider joints compared to elastomeric caulks. The biggest drawback is that they need about 5 days to cure before they can be painted and you have to clean up with mineral spirits.

You might want to check out the Dymonic FC data sheets. It’s got a lot of good info.
http://www.tremcosealants.com/inc/pdf_merge.ashx


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## Mr Smith (Mar 11, 2016)

For interiors I still use Dap. Either regular or with silicone.

For exteriors I use Big Stretch or Sikaflex Polyurethane Sealant caulk for wider cracks on stucco or wood.

I also use Mor-Flexx to repair crumbly mortar & cracked stucco.

I also use Dap with silicone for smaller cracks.

https://www.sashco.com/products/mor-flexx/

https://www.sashco.com/products/mor-flexx/

https://www.sashco.com/products/big-stretch/


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## DEK Painting inc. (Dec 31, 2016)

My go to is Sherwin Powerhouse or Shermax. Alex plus is cheap junk !


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## woodcoyote (Dec 30, 2012)

Shermax. Done.


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## jr.sr. painting (Dec 6, 2013)

Powers house exterior Shermax interior 


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## BrushPro (Nov 15, 2018)

Shermax it is cheers!


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## Wildbill7145 (Apr 30, 2014)

Dap has gone way down hill over the years. I used to use it exclusively until about 5 years ago when it became so runny it was useless.


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## Holland (Feb 18, 2011)

BrushPro said:


> What's your go to? I have a lot of Hardiboard houses where all the butt joints need to be done so I'm looking for something that wont fail in a month (ie Alex plus). Also want something that can handle Interior trim as well and is water clean up etc. Dynaflex 230 is my first thought, what are your recommendations? SW is the store I use most, and a home Depot is near by.



I thought HardiBoard butt joints were not to be caulked? can cause buckling. At least that’s what carpenters and lumber sales guys are telling me...?


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## Wintersun (Apr 14, 2019)

I have used various brands of GE Supreme Stretch Siliconized Acrylic sealant and it is very easy to work with and can be painted in 30 minutes. Dunne Edwards sells a GE acrylic urethane caulk that is cheap, comes in a green tube, and is a stretch caulk that is very easy to work with as well. Far better than any DAP product I have used.


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## BhamPainter (Mar 6, 2013)

Holland said:


> I thought HardiBoard butt joints were not to be caulked? can cause buckling. At least that’s what carpenters and lumber sales guys are telling me...?


HardieBoard expands and contacts more than wood siding does, so the caulk won't last. That's my understanding of why it is not supposed to be caulked. Of course, if the last guy caulked it (and in my area, he often did) then you're sorta stuck. Use OSI Quad or QuadMAX of you absolutely have to--I'm pretty sure it's the only product spec'ed for Hardie brand, though it's supposed to be used only for joints between siding and trim.


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## Woodco (Nov 19, 2016)

It doesnt matter if its supposed to be caulked or not, no GC will hire you if you dont...


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## BrushPro (Nov 15, 2018)

I've used quad but don't like the stickiness and the fact it's not easily wiped with water. It seems to flash as well, I know it's good stuff though for what it is intended for.


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