# Caulking laps of siding



## BigDogPainting (Apr 13, 2011)

I had a customer tell me the other day that the guy that painted her home originally gave her the option of caulking each lap on her lap siding. I imagine thats a terrible idea because any moisture that does get in there needs to escape through those laps, right? Has anyone ever seen this and what exactly happens?


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## DeanV (Apr 18, 2007)

Besides trapping moisture, wood movement may pull the caulk in areas as well. If she has that caulked, she may be destined to some combination of horrible peeling and looking siding.


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## TheRogueBristle (Mar 19, 2010)

BigDogPainting said:


> what exactly happens?



The customer ends up replacing all of their siding.


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## One Coat Coverage (Oct 4, 2009)

It looks fantastic when its fresh and new, but you are right, it's a fast track to horrible peeling.


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## b2dap1 (Mar 18, 2009)

Ive had to vent the underneath of a house where the previous painter caulked all the siding. My rule is never caulk a way for the water to get out.


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## RCP (Apr 18, 2007)

This site has some good explanations and videos, and I have heard some guys swear by the ridgevents. We don't see much of that in the desert!


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## BigDogPainting (Apr 13, 2011)

What do you mean "vent the underneath?" You mean you had to install vents in the foundation or something?


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## pacificpainters.com (May 5, 2011)

Do you have cavities behind the weatherboard (what you call siding)? Another thing, what about the sealer? What sealer are they using there?

I have never seen any of these problems here, I wonder why you are getting it there? I have never seen acrylic paint peel on weather board, only old alkyd paints.

I don't see a big problem with caulking laps as long as the caulking is flexible. Mind you we don't use a lot of cedar on the exterior of houses unless we want a stain finish.


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## mpminter (Mar 21, 2011)

The guy I used to work for caulked every lap. The caulk did separate after a while, but he got lucky and I don't remember any of our jobs ever peeling. As was stated earlier, it does look awesome right after you finish! Personally, I don't caulk the bottom edge, only the butt ends and where the siding meets window/door trim or corner boards.


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## Schmidt & Co. (Nov 6, 2008)

BigDogPainting said:


> What do you mean "vent the underneath?" You mean you had to install vents in the foundation or something?


This product, and the reason for it. Also, go to the home page and watch the video.

http://www.wedgevent.com/cause.htm


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## b2dap1 (Mar 18, 2009)

Schmidt & Co. said:


> This product, and the reason for it. Also, go to the home page and watch the video.
> 
> http://www.wedgevent.com/cause.htm


I dont think the ones I used were that name brand but the same concept. Worked great by the way. Infact, he is having me back this year to take care of the 40+ peeling windows.


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## damianjwalker (Feb 17, 2009)

At the beach, we caulk every bit of the hardie siding, every lap, butt, joint, it is pretty common practice here and encouraged by the windstorm engineers.

After the last hurricane, of the houses that were still standing, the homes that had laps caulked did not lose siding from wind, but ones that did not caulk laps had blown off siding.


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## Contractor Jeff (Apr 8, 2011)

Moisture problems causing lap siding to peel could be an external problem of moisture getting up under each uncaulked plank, in which case caulking each lap joint will remedy the problem. It could also be a moisture barrier problem with the house interior moisture not having a proper means of escape.


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## BigDogPainting (Apr 13, 2011)

So if the siding has no other means of ventilation don't caulk. If the building is in a hurricane prone area caulk 'em because peeling paint on a siding is better than no siding after a storm. Got it.


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## BreatheEasyHP (Apr 24, 2011)

Siding vents can help prevent vapor from being pulled through siding. 

Also, I had a job where I was going to use the Wedgevent. The potential client got nervous; others cautioned against it. In the end, I'm still not sure if they're a good product. 

The house I was working on had bridging of multiple layers of paint, the bottom of which appeared to be oil by their brittleness (and lead on the bottom, as tested). She had places where you'd pull off a slightly-bulging area of paint and a cup or two of water would fall out.

It was the smooth face of cedar lap. I wonder if fiber cement board wouldn't have the same problem since cement isn't vapor permeable like wood? In which case you could caulk it without that same problem? (But possibly other problems...)


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## Contractor Jeff (Apr 8, 2011)

BigDogPainting said:


> So if the siding has no other means of ventilation don't caulk. If the building is in a hurricane prone area caulk 'em because peeling paint on a siding is better than no siding after a storm. Got it.


If that ancient house lap siding has no other means of ventilation, make some. There are plugs you can buy to vent older houses where renovations has messed with proper moisture ventilation.


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## BigDogPainting (Apr 13, 2011)

link?


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## Contractor Jeff (Apr 8, 2011)

Here are some:
http://www.cgm-inc.com/catalog/cableglands/14_59.cspx


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## BigDogPainting (Apr 13, 2011)

Oh, wow. Thanks.


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## Tino (Nov 7, 2020)

damianjwalker said:


> At the beach, we caulk every bit of the hardie siding, every lap, butt, joint, it is pretty common practice here and encouraged by the windstorm engineers.
> 
> After the last hurricane, of the houses that were still standing, the homes that had laps caulked did not lose siding from wind, but ones that did not caulk laps had blown off siding.


That's what we did in the FL Keys, everyone seems to bash it, let yet outside leak so the inside can breathe toss up uh


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## Masterwork (Sep 13, 2020)

What's with the influx of new members digging up these ancient posts?


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