Roof ventilation in post and beam construction


#1

Can anyone HELP???
We added a new roof over a post and beam roof to create a cathedral ceiling over an addition. We just installed soffit vents, pink rafter vents and a ridge vent and fiberglass insulation. But now its raining inside. the roof sheathing, wall sheathing and new wooden windows are covered with mold. We have been running a dehumidifer and fans for about a month now. the humidity levels were at 56% and are now down around 35%. The ridge vent was cut around a 4x4 ridge beam and there appears to be about an inch of sheathing removed. any ideas on what we should do next?

We have used clorox and removed the mold, bought an exhaust fan for the crawl space.


#2

Well, are there baffles between the insulation and roof deck? How big was the ridge vents cut opens up to. I see this about 5 times a year. If there are not baffles then you well tear up the roof or tear off the drywall. Since the insulation is wet thats not good anymore. WHen was this done?


#3

There are baffles and the airflow isn’t obstructed. The insulation guy thought the ridge vent wasn’t cut large enough. its about 1inch or less on the side of the cathedral and no sheathing was taken off on the post and beam side of the house since it doesn’t have soffit vents on that side.

The roofer that installed the roof thinks its moisture from the crawl space. :?: but said for a price that he could take the cap off cut a larger hole and add vent material on the side of the addition and have no gap on the other side. It seems to me that even if you cant cut the sheathing 1-2inches along the ridge beam on the post and beam side that you would still want the ridge strip on both sides of the ridge. he suggested that he would slice the ridge strip down the center use it only on the cathedral side. that way he would only have to buy half the materials. does this make sense?


#4

The post and beam homes I have worked on had cold roofs on them.
There was no way to vent them otherwise, the roof sheathing was a panel.
6" of foam insulation sandwiched between 2 pieces of osb.
They were a real joy to work on, nowhere to nail in roof jacks…


#5

Sounds like you have more of an inside humidity problem that roof ventilation alone will not be able to handle.
I would look at the crawl space and any other sources of excessive moisture inside the house.


#6

Thanks for your help.

I have ordered crawlspace ventilation fans, and am running the dehumidifier. I really want to close in the ceiling, but i am afraid the moisture and mold will come back.

Right now i have pink insulation with paper backing on the ceiling.

Should we cover it with plastic for an extra vapor barrier? someone told me that you shouldn’t put plastic on ceilings. I have tongue and groove pine bead board that i want to use on the ceiling.

thanks!


#7

Is this a post and beam constructed home with traditional rafter/truss roof framing?

You are not describing any post and beam construction I have run into yet.

I am not positive but I think that faced insulation is for exterior walls only, not attics/ceilings.
You don’t want a vapor barrier in your ceiling unless your home was designed for it.
This usually involves radiant heating instead of the more common forced air heating, and a filtration system for air inside the home.
It can get rather involved…


#8

Take some pics and post them here so we can see what you have.


#9

In this photo you can see the old roof and post and beam framing. ***The other side of the roof is still post and beam. There is no ventilation on the other side. And there is a ridge beam that made cutting the ridge vent difficult.

I think we want to add more ventilation on the ridge, but i want to buy a cap that will look good on a 200 year old cape. thanks for any suggestions!

http://www.roofing.com/images/default.jpg%between%


#10

for some reason i cant get the photos to upload. Lee


#11

Hi,

The ridge vent cannot be at the ridge. Put it a foot or so down. Air can not flow through to the peak.


#12

when he originally installed it he went down about 6inches and cut a 1inch opening.

He said if he goes any lower hes not sure how to cover the opening. Apparently normal shingles arent large enough.

I looked online and i saw some caps that might be wide enough, but i am not sure how you cover them with shingles?


#13

Hi,

Here is what you use. It is called Smart Vent. You can install it anywhere you need it.

http://home-and-garden.webshots.com/photo/2281653480054447052EyFnyM


#14

Hi,

Here are pictures of Smart Vent installed in the middle of the roof. I needed intake at this point.

http://home-and-garden.webshots.com/photo/1402398684054447052JJwVCi


#15

Lefty-
thanks for the photos. Is the smart vent that dark line i see half way down the roof? Lee


#16

PHOTO

www2.snapfish.com/shareeloginsu … /otsi=SALB

I think this link will take you to a photo of the new roof. If you look carefully you should be able to see the post and beam roof that is still under the new roof.
Lee


#17

Hi Lee,

Yes, that is the Smart Vent.


#18

Lefty-

thanks…fyi we are up to about 6 inches of snow…so we will probably wait a few days before we do anything!


#19

That is the Smart Vent, yes.

As to your photo(s), I suggest you get a PhotoBucket account & upload to their site. They host the picture & once the image is on their site, you click the block next to IMG code & it will automatically copy the URL to your PC.

Then, in your bbs post, click where you want the photo & either press “ctrl+v” or R click & use “paste”.

Left, I’d like to see that same photo but from the ground level.


#20

Lefty thanks-

What did you mean on you last post when you said that you needed intake at this point? I thought the smart vent acted as an exhaust point for air that travels from the soffit vents and up thru the rafter vents?

thanks Lee

Also my insulation is damp, do you think we can dry it and reuse it?