Hi. Hope all's well.
Now, I'd really appreciate your help ... I'm stumped. Greg V. of Bob Vila's site suggested I post this. Questions:
Do humidity levels rise and fall in the winter months ? e.g. up to 60 to 70 % then down ...
What is the proper level ?
Is it a mistake Not to have a vapour barrier ? It's an old house. Attic square footage is approx. 1000 sq ft.
Bear with me. Forgive me if I repeat items. Here's what I've done ...
Background: my house was built in the 1920's. I had insulation blown in after the attic was supposedly sealed to an approx. R35. The
installer suggested not to add a vapour barrier given the age of the house. He added 2" round, button type vents between the eave blocks
as there were no intake vents.
And I know humidity readings in the attic will rise and fall obviously without a vapour barrier in place. But what's normal ? Will they go
up to the 70's for a few winter days then drop ? Trouble is I have to
wait for winter to test ...
The first winter after the insulation job I noticed water dripping from the nail tips. Reason given: not enough intake venting. Add more vents 4 x 14 (3 X 12 actual opening). No difference. Humidity level 80 to 100 +
Problem @ the Ridge Vent. Reason given: poor ridge vent product & blockage. Replace entire roof for the 2nd time and install new continuous ridge vent manufactured by Lomanco. Better. But the humidity level still too high for my liking - 70ish.
So you know .... I did have a blower test performed and it did expose a # voids into the attic. Fed up with excuses by insulation installer. I removed the entire blown in insulation. I found 12 + knob & tube holes that weren't sealed. There was a 2 " gap in places around the chimney. None of the plumbing vent stacks were gasketed or sealed ... The smoke test really showed where the leaks were.
I read that sealing was more important than a vapour barrier given the age of the house ... I read this over and over ... so I sealed all the voids I could see with spray foam.
I made certain the intake vents were open and positioned the shoots so that they're right down to the edge of attic for good airflow. I laid R12 batts between the joists. Re-spread all the loose fibreglass insulation on top of R12's. Approx. 16 inches of insulation R-40ish rating.
I've replaced all the 2" button type vents on both sides of the house with 4x16 grilles.
*** Here's what I found and measured for the intake/eave vents:
32 Grill Type Vents with a 3 3/4" X 16" size with actual intake
opening/venting @ 3" X 16". They're placed as 1 unit - 1 hole cut-out @ the eaves.
DO I HAVE TOO MANY INTAKE VENTS ?
I think I've got a intake/outlet venting ratio of 150 to 1 as the 1 to 300 ratio didn't seem to cut it.
There's also 36 foot length of Continuous Ridge Vent Outlet over the living
space. New Lomanco Product. Attic square footage is approx. 1000 sq ft.
Now, here are what I think may be my options:
- As there's No Vapour Barrier, Add more batt insulation on top of existing insulation in cross hatch pattern ? I was thinking to add
R20 or R35 batts to slow the heat rise ... takes it to a R50ish + range. Waste of money ? Or ... is a layer of blown cellulose a better option ?
- Add Gable vents to create a cross flow ? I've read NOT to mix vent systems.
- Do Vapour Barrier type paints in the ceilings work ?
... I'm at a loss as to what else to do. I just don't want to have to lift everything again & add a 6 mil poly vapour barrier ...
I think I've done all I can and I really tried to seal all the possible air holes that I could find. All my fans - kitchen & bathroom - are directly vented to the outside and we use them.
The only other thing I can come up with for the humidity issue, is a humid basement. I've placed a de-humidifier in the basement and that lowers the hygrometer readings significantly. I know we contribute to the humidity - breathing, showers, cooking ... etc. But " the moisture source " ... the extra humidity from the basement could be it. The only thing to cure that is to re-do the perimeter drainage and spray a sealant on the concrete basement floor.
So ... that's where I'm at. I guess I'll have to wait for winter. I know humidity levels go up and down. I measured the attic this morning it was 71.
Thanks ... if you can give me your angle I'd appreciate it. Take care. Cheers for now.
P.S. For the time & money I've spent maybe I just should have had the attic spray foamed ....
J. K. (D.A.S., D.CDN.S., B.A., M.A.)
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