oh and why are these used?

I am seeing different $hit everyday… why would these vents be installed? they are located at the second floor framing levels and just below some of the window sills… 1940’s dutch colonial…

i realize they are some type of vent… but why? what was the theory behind adding these buggers in? venting insulation?



It does appear to be a vent. I’ve never seen holes like that on siding. There’s no need to ventilate insulation in walls.


i have no idea… i’ve racked my brain… maybe someone here has seen them before… we’ll see…


They installed them after blowing in insulation to help vent the moisture in the wall cavity because back then a vapor barrier was not used…didn’t work that well.

large installation photo



I agree with Larry on this one. I have seen in many older homes(plank houses) in my area that tried to insulte have these vents. I am not sure how well they actually work b/c usually they are painted right over after a few years.

I have seen larger versions… but did not think they would be able to insultate through these… but makes sense to me.

thanks all.


Who’s the beautiful broad?

This is a test!!!

In early research into condensation moisture in walls, it was thought that venting might be the solution. In some of the houses, venting increased the moisture in the walls (and some attics also)…why??

They just didn’t have the proper solid plastic plugs. These are “vents” for undereaves…but they are so small with not much “net free area” that cracks around soffit and fascia materials will give much more venting than the vents. As for using them with wall insulation… in wind driven rain areas, they will let in more bulk moisture (rain) than they will ever allow out by evaporation.

I have seen (many times) 3" versions of this undereave vent used to try and vent a bathroom fan!! Firstly, if the fan has a 3" discharge outlet, it’s too small and weak; that particular fan cannot push water downhill. Secondly, most residential ventilation that I see is at the lower end of the quality scale in equipment, design and installation.

That’s a good thing!

Temperature differential between exterior dewpoint & interior = condensation

The venting increases the flow of moisture laden air into & thru the building & condensation builds.

Am I close?

Are you sure the house hasn’t been insulated with UFFI?

She’s a hard working lady that runs circles around most of her male associates and competition.

My personal experience is the women that choose manual type labor professions including our own have much better attitudes and work ethics than a lot of the men I know.

Many even whine less :mrgreen:

UFFI? Foam? I suppose it is possible but these look pretty old… been there a while… I saw no other indications of foam.

Dense pack cellulose has long been available for retrofit usage.

If I’m not mistaken it was first introduced in the 1950’s

Those little ‘vents’ were used in Canada in the early 70’s when people were having UFFI sprayed into their walls. The vents helped with the off-gassing and supposedly helped vent the walls. (I never understood that part)

If the UFFI is still in there, it’s likely shrunk and hard to find.

Bill Mullen

In 1980, just before I started my insulation business, I visited a local cellulose manufacturing plant to inspect their quality control procedures as I was trying to decide whose product of 3 competitors I would install*. In the plant office was a picture of a horse drawn insulation blower supposedly taken in Philadelphia in the 1930’s.

*(Note: They were very surprised…no other insulation contractor had ever done this before. Ended up being taken to dinner by the plant owner to discuss the industry. He actually made me an offer to manage the plant as he lost his manager the week before!)

Dense pack cellulose would be blown through 2-3 inch holes as it takes much larger equipment to get the higher densities to do the top airsealing job. The one inch holes would be for those using the smaller electric powered blowers. These units can get the densities needed to prevent settling, if the holes are spaced appropriately. Air leakage is reduced at these densities also but not as much. In 2 two storey houses, I have measured air leakage reduction by just blowing at the lower densities and found 39% and 34% reductions in total house air leakage.
NOTE: Don’t replace windows for air leakage reduction and energy savings only…it’s a long payback. Window/ door air leakage in houses is uusally 10-15% of total leakage…work on the worst areas, of which the attic is #1 or 2.