Whirlybird question

I was asked to inspect an attic because client was having moisture problems. There was moisture in the attic, a very low slope roof, blown in fiberglass insulation was blocking ventilation, plus there was whirlybird wind powered ventilator and excess humidity in the house. I am going to recommend that she controls the humidity problem with a bath exhaust to exterior and crank down the humidifier (was set at 30, it is off now), that she has someone take apart the soffits to make sure the insulation is cleared away from the trusses and inserts installed, (can’t access them from attic) And that she replaces the whirlybird with a static ventilator.

But I was wondering whether it would be OK to just prevent the whirly from whirling, put some screws in it or something, turning it into a static ventilator.

Any thoughts?



Not enough ventilation with the whirly bird or a static vent of the same size. I would recommend continuous ridge vent and insure that ALL soffit is unblocked.

There are also 6 static vents besides the whirly

I don’t recommend taking the soffits apart I recommend using a leaf blower at the soffit vents it removes the blown insulation very nicely

I think controlling the moisture and air sealing the attic is the first choice before anything else. In a cold climate the moisture will condense on the sheathing before the vents get to get all the moisture out.

Static upper roof vents will act as intakes for the whirlybird bird. Ventilation should enter at the soffit and exit at the ridge.

now that’s a pretty slick idea…

The whirlybird pulls intake air from the surrounding static vents instead of the soffit. This leaves stagnant air at the lower areas of the attic.
So, in this case it would be beneficial to turn the whirlybird into a static vent. However, you may still not have enough area for egress air.

I found many cases with the cyclone vents they have caused so much negative pressure they draw warm moist air from the home causing MOULD.

I am not a lover of them or power vents in our cold climate .

I think Natural air movement is best .

I agree with Roy because of the lack of control when it is really windy. Get those suckers pulling at full volume and you will not have enough soffit vents to keep up.
Get the picture!

Depends upon your climate. Rick wins, IMO. Turbine vents are worthless unless you have proper eave/soffit vents, and close off the other static roof-top vents.

Power blowers have many uses. Just ask a certain “vendor”.

Thanks all, love the leaf blower suggestion, I want to be there when they try it.

Leaf blowers are also fantastic for cleaning the gutter of trash.

So what did your report actually recommend? Because your language in reporting what you found and what you recommend… I don’t understand.

After seeing all the suggestions, I ended up recommending that she replace the turbine ventilator with a static ventilator, try using the leaf blower to clear the rafters at the soffits, inspect the attic to see if it worked, take apart the soffits to clear the rafters if it didn’t,

There were also some things to do inside the house to control excess humidity, a bath fan that had to be vented to exterior, setting the humidifier too high, etc.