Moisture Getting Inside Walls

[Invader21]

Not sure if this is a framing and foundation topic, or belongs elsewhere. Apologies if I’m in the wrong forum.

My son has a new (2 years old) construction ranch walk-out that has a curious problem.

From his unfinished basement, you can access the ‘bottom’ of the outside walls where they sit on the poured basement walls. The house is brick on the front, and sided on sides and back. The basement extends well above the grade (well past 6”) all around.

He has found that the external wall sheathing and some of the insulation on that sheathing, is wet. This is happening on all of the sides where there is siding (sides and back).

Nothing looks amiss outside - again, the basement extends well above the grade. And the siding (I’m no expert) all looks to be in good shape all around. Any thoughts on how the moisture is getting in?

 

[user 4883]

Is there any house wrap installed?
Might be moisture trying to leave but getting trapped inside.

 

[Invader21]

There is, kok328, but unsure what kind/brand. I can try to get a better look - we haven’t tried to pull any siding or anything to this point. Not exactly my forte. Just trying to rationalize possible sources (such as you noted). It’s just strange (to me) that it would be on all of these walls. Logically, that would seem to point to some non-external source? If it’s external it would have to be pervasive - I mean ever exterior wall with an issue.

Or am I not thinking this logically?

 

[billshack]

You should have a vapour barrier on the inside just behind the drywall. the outside wall should breath . See if you can find a place to see if there is a vapour barrier, I am guessing no.

 

[Invader21]

Thanks billshack…I will check on that. I can see ‘open’ insulation (non backed - just the pink fiberglass) down in the basement…now I think I need to determine if my son put that in in the basement area, or if it was already like that…and therefore, I’m assuming if it was the builder and no vapor barrier, we have BIG trouble if like that all over?

 

[oldognewtrick]

Is there a flashing on the siding wall that extends over and down the outside foundation wall?

 

[Sparky617]

What is the siding? Hardi-Plank (fiber cement), vinyl, something else?

 

[Invader21]

Sparky, the siding is vinyl.

Ol Dog, I’ll have to get my son to take a picture - he lives 30 minutes away, so I cannot just go outside and look. Do you have any photos or examples of what you’re talking about so I know what to look for?

 

[oldognewtrick]

Proper flashing detail at the base.

 

[Invader21]

Okay…got it. I’ll get a picture or get out there and confirm what I find. Thank you!

 

[Sparky617]

Vinyl is pretty leaky, the flashing details old dog posted mitigate this by directing the water away from the inside.

 

[Invader21]

Thanks, Sparky. I tried to guide my son away from this house when he bought it, as I found a few red flags with the builder’s handling of the lot, overall drainage of the lot, and some other concerns. Sadly, he did not listen to me. We are still trying to determine overall lot draining issue resolution.

However, this leaking/middle-wall moisture issue is more concerning. The poured basement walls extend well above the grade line, so I don’t think that can be at issue. And while I know next to nothing about siding, I didn’t see anything that looked particularly shoddy when I briefly looked this past weekend. But I didn’t know about the flashing, and/or recall what its situation was. So, hopefully my son will get me some pictures later today, and I will share here on the post.

I appreciate the help….thanks so much!

 

[oldognewtrick]

Here's another image of how to flash a wall.

 

[Invader21]

Okay guys. Finally got a pic from my son. Please see attached.

 

[BvilleBound]

Thanks for the photo, which might explain your problem. It appears that the building installed housewrap over the sheathing; it appears to be sticking out on the side and was not trimmed back properly. It also appears that he may have installed black poly over the sheathing, which appears to be sticking out at the bottom. Could you please confirm whether this is poly, and if it appears to be attached under the housewrap?

If so, also check to see if there is a poly vapor barrier on the inside. Contrary to one of the posts above, modern building science shows that poly vapor barriers should NEVER be installed on walls - on the inside or outside. See:

What Happens When You Put a Plastic Vapor Barrier in Your Wall? - Energy Vanguard

https://www.buildingscience.com/documents/digests/bsd-106-understanding-vapor-barriers
Poly barriers prevent the wall from drying. If you have poly barriers on both sides of the wall, then it becomes a 'diaper wall' that cannot dry in either direction..

I hope this is helpful.

 

[Invader21]

Thanks, Bville. Not sure how to tell if it is poly or not In the formal sense. My son says it is similar to a trash bag material - so assuming it is. I do know there is no poly INSIDE….raw insulation visible at the bottom of those walls on the interior.

Here’s another picture of the outside, and it’s odd/strange. Another material that seems to be placed over the black/poly material.

Bottom line, I have no idea how to proceed here to alleviate the moisture issue. Thoughts?

 

[Sparky617]

Thanks, Bville. Not sure how to tell if it is poly or not In the formal sense. My son says it is similar to a trash bag material - so assuming it is. I do know there is no poly INSIDE….raw insulation visible at the bottom of those walls on the interior.

Here’s another picture of the outside, and it’s odd/strange. Another material that seems to be placed over the black/poly material.

Bottom line, I have no idea how to proceed here to alleviate the moisture issue. Thoughts?

View attachment 27437

The white woven material with the blue printing is house wrap and goes on the outside. The poly mentioned earlier is what appears to be black plastic at the bottom of the siding. Any idea where that goes? It could just be between the sill plate and the foundation, or it could be covering the wall behind the siding, hopefully it isn't doing that.

 

[Invader21]

My son says it’s on the outside side of the sheathing, and only at the bottom…two feet at the most, and maybe not that much. So it is not covering the whole wall behind the siding.

 

[BvilleBound]

Dear Invader: Thanks for the second closeup photo. As Sparky noted, the white woven material is housewrap, apparently installed over unnecessary and troublesome black poly vapor barrier. So... two questions / suggestions:

1. Moisture level in your basement area: What is the humidity level in your basement? Do you also live in an area with cold winters, particularly if the outdoor temp drops below freezing? If the humidity level is high, this could lead to condensation on the sheathing and dampness in the insulation. You could reduce this problem by installing a dehumidifier in the basement, sized to match the square footage of the room..
   
   If your sheathing is OSB, this would be an important step - because OSB is much more vulnerable to moisture and rot, compared to plywood.
   
   
2. Moisture in upper levels: Do you have a location where you could check the moisture level higher up in the wall, to see if this problem is limited to the basement? You could drill a small hole in the sheetrock and insert a standard garden moisture meter, if there isn't a spot with open access. (Hold the moisture meter against the sheathing for a while; it won't provide the amount of contact that wet soil does.) Hopefully this problem is limited to the basement. If it affects upper floors, however, your only option would be to remove the vinyl siding and remove the black plastic vapor barrier. If you work carefully, you should be able to preserve the siding and reinstall it.
   
   Note: A 'rainscreen' with 1x4" PT lumber furring strips should be installed over the housewrap, with the vinyl siding mounted on the furring strips. This creates a 3/4" air gap between the sheathing and siding, to help the wall dry. 'OldDogNewTrick' included a diagram (above) that shows this. The furring strips also need to circle the perimeter of windows and doors, as the mounting surface for the trim. See a photo below of furring strips mounted on a recent project, over pink XPS foam board.
   
   If your son lives in an area with cold winters and/or hot summers, removing the vinyl siding would also give you the opportunity to 'wrap' the house with 2" thick foam board - like the photo shown below. If you have the budget, this will significantly improve the insulation (+R10), reduce heating and HVAC costs, break all of the 'thermal bridges' created by the (previously) exposed wood framing, help to air-seal the wall and prevent water infiltration, and help to keep the sheathing warm to avoid condensation. Note: the foam board must be 2" thick in many areas of the country, to avoid condensation on the sheathing. See the chart below.
   
   Finally, if there is no rainscreen or you decide to 'wrap' the house with foam board, you will need to install new trim around windows and doors. I highly recommend using cellular PVC instead of wood. It never rots, cracks or needs to be painted, and is easy to install. FastenMaster Cortex screws and caps are best to secure the trim; the matching caps make the screws disappear. You can use standard PVC cement to close corners. If you decide to take this step, post another question for more installation tips. A photo is included below of our beach house where all of the trim is cellular PVC.

I hope this is helpful.

BvilleBound

 

[BvilleBound]

You noted that the sheathing and some of the insulation were wet. This made it sound like the dampness was on the inside surface of the wall. If it is on the exterior surface, (a) how could he tell if the sheathing is wet, if if is covered by the vinyl siding, housewrap and black poly vapor barrier? And (b) what type of insulation is installed on the exterior surface? Standard foam board should not absorb moisture, unless the building used polyisocyanurate foam board and did not seal the edge. Polyiso foam board absorbs water like a sponge, and must be VERY carefully install if used in exterior applications. That's why we typically use XPS foam board on the exterior, because XPS does not absorb water.