I am trying ascertain the source of moisture and in some places water behind the bubbled paint on the north wall. The house was built around 1960, the roof has no overhang to speak of, the basement is dry, and the other walls in the house seem fine.
It seems to me that the lack of an over hang isn’t great, but that the painted clapboards should still be able to shed water. The fact that the moisture is getting captured behind the paint makes me think that it’s coming from the interior of the house and some how condensing below the surface of the paint and causing it to buble. I have not taken any thing apart so I don’t know what the wall assembly is, but given the age of the house I assume that it has plywood sheathing and fiber glass insulation. Probably no interior vapor barrier and tar paper between the sheathing and the clapboards.
Has anyone come across this, do you know what might be going on here? Thanks.
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Greetings awlright,
This post, in response to your question, will bump the thread through the 'recent discussion' listing again which will increase it's viewing.
Perhaps it will catch someone's attention that can help you with advice.
Cheers
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Is there a bathroom on the other side of the wall?
No, it's a 2nd floor bedroom with an attic, maybe only a crawlspace above.
Are you in a heating climate? Houses often have a weak point in the insulation where the top of the wall meets the roof. Warm air escaping from inside will condense there and lead to moisture issues.
Yes, I am in Massachusetts. If there is heat escsaping at that juncture do you think it would cause enough moisture to cause the paint to bubble with entrapped water over the entire height of the wall surface? Do you think that it would be more concentrated the higher up on the wall?
>>>Probably no interior vapor barrier and tar paper between the sheathing and the clapboards.
That, combined with the fact that the North side is coolest, therefore most likely to condense migrating moisture, might be the problem.
Scott.
Always remember those first immortal words that Adam said to Eve, “You’d better stand back, I don’t know how big this thing’s going to get.”
I think that might be the issue. I guess the next step may be to do a little disecting to see what the actual wall assembly is. Thanks.
I have a similar problem with a 2-story, 1989 addition on my house in eastern Mass. There is the possibility of interior moisture of course but 2 things convinced me that it's from a different cuase.
#1 - I had the house painted last fall and after hard rains during the winter I saw brown stains on clapboards. It was obvious that water was leaking out from behind the clapboards in spots.
#2 - I had some doors and windows replaced on the ground floor last fall. The contractor discovered that there was no house wrap, no tar paper, nothing, under the clapboards. Clapboards were nailed directly over plywood sheathing.
The conclusion is that the lack of house wrap makes it impossible to properly flash around openings. Water seeps in and runs under clapboards until it finds a place to leak out, often appearing as much as several feet away (laterally) from the opening. Sometimes the paint seals the bottoms of the clapboards well and the water can't escape so the clapboards soak it up and emit it by pushing the paint off the wall.
Final bit of evidence: the contractor replacing doors & windows demo'ed clapboards for the entire first floor of the addition, properly wrapped and flashed everything and replaced clapboards. The new areas have no apparent problems (so far). We're re-siding the rest of the addition this spring.
Maybe your house was as badly built as my addition? Is bubbling paint generally found within several feet of an opening and always below the top of the opening? Do you know or can you find out if openings are properly flashed?
Thanks for your response. I will have to do a little detective work in order to determine if there is missing flashing. The house pre-dates house-wrap, but perhaps they never put any barrier for shedding water. Thanks again.
Glad to help but I hope your problem is something simpler (and cheaper to fix).
Sounds like you have it pretty well figured out from the start. The combination of north wall ( colder surfaces) and interior moisture condensing is a common problem in older homes in colder climates. Combine that with the fact that insulation of that era was woeful.
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OK so if it is warm air migrating through the wall, and becoming trapped and condensing below the paint, some air sealing would be the ticket along with some better insulation. All of that seems like it would require a lot of deconstruction so I wonder what you might recommend to be as certain as possible that that is in fact what's causing the problem. Any ideas there?
that is the answer in new construction. But sometimes there are other ways to deal with it from the outside. Better of course, to prevent from interior, butcan tackle the symptom outside.For instance if the clap boards are going bad and need replacement, be sure to backprime with oil and use Rainslicker under them - or other rainscreen methods. If not replacing them, strip them to bare wood and use latex going back on. Oil paint seals to stop moisture, so when moisture boils up behind it, it will blister the paint right off. But latex allows moisture to move through it, so a good latex firmly attached to good wood has a chance. The oil sealer backpriming the same board keeps the moisture from betting into the wood, but moving through the seams instead. Also, never caulk the horizontal joints in claps.
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I've tried googling Rainslicker - can't isolate it. Is it a housewrap? If so, do you prefer it to tyvek or typar?
I think this is what Piffin meant:
http://www.homeslicker.com/
Another option is this:
http://tyvek.com.mx/Tyvek_Construction/en_US/products/residential/products/drainwrap.html
Both promote drainage behind the clapboard.
Thanks! (To both Mike and Piffin.) I'll see if it's available in my area and ask my contractor what he thinks of using it on my house.