Does Insulation Cause Humidity Problems?

Many people are retrofitting older homes and buildings with insulation to improve thermal comfort and reduce the runtime of their HVAC systems, whether for heating in cold climates or air conditioning in warm climates. However, it's important to consider that insulation can sometimes lead to indoor humidity issues and moisture problems. While insulation helps slow down the flow of energy or heat, it can also reduce the operational time of HVAC systems and diminish the building's ability to dry out. In this video, we discuss the potential negative effects of insulating existing buildings and what steps can be taken to prevent future moisture issues.

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License code: EFZCWNUSWZIWI67I

[jeffreycollier]

I live in South Florida in a 100 year old kit house that is up on concrete piers and a large attic space. After my inspection at the time I purchased the house, I realized how minimal the insulation is and why these old houses have lasted so long in such a hostile climate. Homes today are way over insulated which creates a terrible indoor air quality and severely reduces the lifespan of the structure.
Last year we had 130mph sustained winds with a direct eyewall hit from hurricane Milton. Thank God that we all survived and the house held up great under the extreme conditions. I noticed that many newer homes had severe damage. My neighbor's on slabs all had flooding while mine, an older house on piers, stayed high and dry.
There's something to be said about the older, simpler ways of building.

My 50 year old house in North Georgia has stood up well over the decades as well. Still has it's original wooden windows. Sure, it's a bit drafty in the winter and maybe a bit warmer in the summer, but the structure is sound.

[Obtuse]

The reason I love these ASIRI videos is that they really do focus on a lot of the things that are critical in retrofitting our housing stock. There isn't a way the US (or really probably any other nation) is going to solve any sort of housing problems without maintaining and upgrading our current housing stocks. We still need new builds as well of course, but one of the legs of this problem will be upgrading and maintaining.

[kylekyle]

I must say you’ve been so helpful. I purchased your water management pdf and applied everything I could to my diy retrofit. Water membranes, below grade drainage/seals, continuous internal foam boards with drainage runs. Next I’m adding a framed wall and insulation there as well. Truly changed how I approach my home build

[snugglyjeff]

A lot of issues come from poor uses of thermal breaks, which isn't always the insulation. If you have a house with plastic sheeting directly behind the drywall, you likely are causing moisture to build up inside the drywall and causing mold problems. Your vapor barrier should always be on the outside of the building, not the inside of the exterior walls. Even then, that vapor barrier should not be plastic sheeting, and instead should be Tyvec or an equivalent that still breathes but significantly slows airflow from the exterior, while allowing moisture from the inside to dissipate.
One of the common incorrect things I see is plastic sheeting on the insulated stud walls hung before drywall in basements, and all this does is trap moisture on both sides of the wall and causes mold in both your insulation and drywall. Instead use foam sheeting glued directly to the block foundation, with an airgap behind it. This will keep the moisture at the block, and away from your fiberglass insulation, framing, and drywall.

[crabkilla]

Another reason to have a dedicated dehum appliance /ERV inline with the AC. You can run the AC much less if you can control the humidity and fresh air precisely.

[michaelrodgers]

In short. If you insulate and air seal you need to take your mechanicals into consideration (most of the time upgrade). If you air seal and insulate, you need to add an erv (for ventilation) and a whole home dehumidifier or an HVAC system with built in dehumidification separate of the cooling.

[Gallowaylights]

Now I have more questions than when I started this video. 😢

[theprojectbasedlifestyle]

I have a really simple question on the complicated subject of vapor. The vapor moves primarily through air movement, air leakage. Why not simply use an air barrier on the interior, Tyvek, Typar, whatever, and make sure that this air barrier is tight????

Sure, moisture will diffuse through this air barrier, but in a damaging amount? Have another air barrier, again quite permeable to vapor, wrapping the house. In other words, put all of the effort into stopping air flow but allow the vapor to diffuse, especially if there is a drainage plane behind the cladding. The mold problems seem to be primarily the result of overly retarding vapor flow.

The current system, as i understand it, is that the code specifies some sort of vapor retarder, let's say it is the paint on the drywall, but really most of the vapor is actually moving through air leakage, penetrations in the drywall, cracks, whatever. So wouldn't it work better to give up on vapor retarding but do a really, really good job, interioe and exterior, on restricting air flow?

[nolongeramused]

Install an attic vent fan for under a $1000 and your humidity problems are solved. Honestly, every home should come with active attic venting for heat and humidity.

[demetriusgallitzin]

The areas where people live without frost heave or humidity have so little to concern about in home or building construction. :P

[EnduroPromotions]

Waiting for cities to focus on insulating values instead on if a house has solar.

[scottfrommaine]

Could you make a video about insulating a floor system for a tiny house on posts?

[pcatful]

You show moisture coming into the house in both cooling and heating modes. Isn't there a differential that water vapor always flows one way or the other based on temperature?

[aXeL]

Im doing new construction home 100% closed cell throught basement, 1st, 2nd and attic. + R5 rigid polyiso on exterior. Im adding an erv fantech 150cfm. Do you see any issue with this?

[pcatful]

We live in the Bay Area California so it's mostly on the cooler side but rarely freezing. We have very little air conditioning use in our house. Sometimes we run the (minisplit) in the upstairs for a few hours. Downstairs is always cool. We use natural ventilation more than half the year. The house has been blower tested when we upgraded windows, and has some leaks that they said was OK--within the limits that they had to work to (I guess). We know the air is relatively dry, though we have high soil moisture in our crawl space and we have fog. How do we judge the best practices in this borderline climate zone? For example the floor was never insulated, so what might happen if we do insulate it?

[CMCraftsman]

I have an HRV in VT and this was my first winter with it. It was uncomfortably dry so no I either need to add a humidifier in winter or swap it out for an ERV and see if it’s more comfortable.

[rehmsmeyer]

DAMNED if you do; DAMNED if you don't.

[Ariccio]

Wait you mean it's a *bad* idea to tremendously reduce cooling and heating load without doing anything to improve that "50 CFM" bath fan that sounds like an 18 wheeler but only moves like 10 CFM?

😉

[MarkO-H-tg]

I don't necessarily like the message of "blaming" insulation. True building efficiency is an insulation + mechanicals process, just like framing a house is a wood + nails process. If a house failed because of inappropriate nailing, would you blame the nails?

[foresttaylor]

Sounds like we should build using stone instead of paper and mud