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Black Mildew on white wood


LorLee
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It'd be surprising not to have insulation at all but there could be some missing or could simply be inadequate and the absence of vapor barrier is quite possible also.

She said it's built in the 1800s. Why are you surprised there's no insulation? Of course there's no vapor barrier! Do you know anything about how buildings were built before you were born?

The walls, ceilings, floors and roof of a house are what we call the envelope. Those components have to meet minimum construction standards. If the envelope is compromised in any way or does not meet minimum standards, that can lead to problems.
It was built in the 1800s! There's no requirement to meet current "construction standards"`. In many cases the construction methods and materials are far superior to current "minimum requirements". I can't keep count how many times retrofitting insulation and vapor barriers have caused moisture/condensation issues and paint failures where none ever existed before.

You're sending her on an expensive trip down a path that has nothing to do with a little algae on the siding.

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you know Bill, you're absolutely right. who am I to simply suggest the services of an expert. I was wrong all along. I should not have given her that advice (and I thought that was our job,silly me). I'll let you guys take the role of the expert. I don't have that need to feel that I'm right by talking other colleague's opinion down. have a good one.

Good luck Lorlee

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Stephen

You indignation might be justified if you had stopped to consider the age of the home and made your recommendation in the context of the house.

Before tossing out a recommendation for someone to consult an envelope specialist you need to ask yourself why an un-insulated house built in the 1880's, which would be perfectly normal for a house that old, would go 120+ years without an issue and then this issue develops.

A building envelope specialist deals with stuff like detailing a building envelope to ensure it stays dry. With a house that's 120+ years old where the homeowner says the house has been dry and there haven't been any infiltration issues, what benefit does the homeowner derive by spending money on a guy who is a specialist in detailing current construction?

I think the issue is under the paint - not on top of it. It's an un-insulated house cozy little house, which probably means the builder was not a wealthy person and wouldn't have bothered to spend the extra money to back prime all of that siding. In fact, I doubt anyone in the 1880's was back priming siding anyway.

It has decades of layers of paint on it without an issue and then modern paint is used and it starts to develop fungi. I think the new paint has done such a good job of sealing that siding that the wall is trapping moisture. Interior water vapor that's been migrating outward has been condensing on the backside of that siding. The moisture has caused fungi to develop on the backside of the siding and the stuff has been migrating to the outside of the building envelope.

It's happening on the sunny side because that side gets warm enough during the day for the spore to propagate, but not so hot that the moisture feeding the spore evaporates or the heat kills the spore. It's not happening on the other sides because they are staying cold enough during the day that spore count remains so low that the spore is dying off more quickly than it can spread.

They clean the exterior every year and by summer the issue goes away because the summer sun warms the siding to the point where the siding gets so hot that it evaporates so much moisture that there is nothing to sustain the spore. The issue then goes away until next year.

Take a sample of the fungi down to a local testing lab and have them identify it. Pull one or two clapboards at the area where it's occurring and take a tape lift sample from the backside of the wood and get that tested to see if the same stuff growing on the outside is on the backside of the siding.

If it were me, I'd try an old school solution. I'd get some painters siding wedges and wedge the siding on that side of the house so moisture could more easily flow to the outside and dry outside air could flow to the inside of that wall cavity and help dry up the spore.

If what I think could be happening is happening; adding insulation might help if blown-in cellulose with a high borate-content is used because borate is a fungicide. Cells works great to prevent air movement through wall cavities. Insulate those walls with blown-in cells and the borate in the cells will probably kill the spore on contact and the cells will either greatly slow down or stop air movement through those walls and keep the wall cavity warmer and help to reduce vapor diffusion that led to the moisture accumulating on the backside of the siding. The wedges will aid in drying the cells out if any minor infiltration occurs.

It's a theory. One I'm not married to.

ONE TEAM - ONE FIGHT!!!

Mike

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Holy smokes. Did I ignite a debate here?

Hopefully something to be learned here ... I truly appreciate your impassioned thoughts.

However, gentlemen, it seems some of you may have made an assumption (and you know what that means, etc etc)... Yes, the house is ca. 1850 but it was re-done in some fashion in the late '80s (well before we came along).

I believe my husband was told that they did not do insulation and wished they had... and when we purchased, ten years ago, it might be something to consider. They put a new roof on, painted, made some cosmetic changes inside, added a little deck, that sort of thing, but the main structure was not really messed with. No replacement windows, either.

Old houses often have insulation added later, no? That sort of seems natural.

I am pestering my husband to try to confirm the insulation story. In the meantime, I find it super helpful to suggest we take down a piece of clapboard or two and see what is behind. I have also called a local green builder, who does energy and insulation and building, he seems to be highly regarded. He may be able to give us more info. I don't know of a lab around here, but he might.

I am going to post here about our adventure.

Now, let's all be nice to each other! Life is too short!

peace,

LorLee

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Holy smokes. Did I ignite a debate here?

Hopefully something to be learned here ... I truly appreciate your impassioned thoughts.

However, gentlemen, it seems some of you may have made an assumption (and you know what that means, etc etc)... Yes, the house is ca. 1850 but it was re-done in some fashion in the late '80s (well before we came along).

I believe my husband was told that they did not do insulation and wished they had... and when we purchased, ten years ago, it might be something to consider. They put a new roof on, painted, made some cosmetic changes inside, added a little deck, that sort of thing, but the main structure was not really messed with. No replacement windows, either.

Old houses often have insulation added later, no? That sort of seems natural.

I am pestering my husband to try to confirm the insulation story. In the meantime, I find it super helpful to suggest we take down a piece of clapboard or two and see what is behind. I have also called a local green builder, who does energy and insulation and building, he seems to be highly regarded. He may be able to give us more info. I don't know of a lab around here, but he might.

I am going to post here about our adventure.

Now, let's all be nice to each other! Life is too short!

peace,

LorLee

Don't worry. This debate you see is what pries the truth out from it's hiding place into the open where everyone can see it and learn. Works very well. Sure, it gets heated sometimes but heck, it's the manure that makes the roses grow, ehhh?

Marc

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No debate, just the usual day at the office.

Regarding old houses, Kibbel's right. Getting an "envelope specialist", or a local "green builder that's highly regarded", may not get you the right answer. Everyone is well intended, but that doesn't guarantee right answers.

We all have businesses because of the dearth of accurate information about houses in all their forms.

Talk to a lot of people, see what everyone says, and weigh the information as best as you might.

Then, come here and tell us what you've found. The answer is somewhere in between all the ideas.

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Wow. You guys are philosophers, too!

[;)]

I will definitely keep you informed. I agree, I'm taking everything in and filtering and weighing... my husband is a bit out of the loop due to work right now, but I hope to help steer us in the right direction.

Feel like I need a pithy quote for my signature... You guys have some great ones.

L

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