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vented ridge cap

Started by yukon cornelius, March 21, 2015, 10:36:47 PM

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yukon cornelius

We have been battling condensation on our ceiling. we just have fiberglass between rafters and tried covering that with thick plastic. Our ceiling is still unfinished and will be for a while.  condensation remained after the plastic so we ended up adding this vented ridge today. This is not a total cure but a fix until I can spray foam insulate the whole ceiling.

Pretty simple install and not only made in USA but made a 20 miles from our old place.
It seems I am a coarse thread bolt in a world of fine threaded nuts!

Making a living with a manual mill can be done!

yukon cornelius

It seems I am a coarse thread bolt in a world of fine threaded nuts!

Making a living with a manual mill can be done!

yukon cornelius

 

  her is the only one I can get. basically just cut the sheathing back 3/4 inch on each side of the ridge. place ridged vent over it and place ridge shingles back over it. the moisture is already drying up and there is a lot of warm moist air exiting the vent area.

Success for now.
It seems I am a coarse thread bolt in a world of fine threaded nuts!

Making a living with a manual mill can be done!

POSTON WIDEHEAD

I don't get on ladders.  ;D
The older I get I wish my body could Re-Gen.

yukon cornelius

Bologna! goats can and will climb anything. ours were in a tree once! Im starting to think your not a real goat  ;D now a turtle on the other hand....they don't climb :D
It seems I am a coarse thread bolt in a world of fine threaded nuts!

Making a living with a manual mill can be done!

Brucer

Attic and roof venting has been more of a black art than a science (until recently). I've concluded that a really, really tight seal between the insulation and the heated room is absolutely essential. For venting, the ridge vent is the way to go.
Bruce    LT40HDG28 bandsaw
"Complex problems have simple, easy to understand wrong answers."

Peter Drouin

If you get snow the ridge vent will not work with snow on it. Also put in gable end vents, For me in NH they're the best.
A&P saw Mill LLC.
45' of Wood Mizer, cutting since 1987.
License NH softwood grader.

21incher

For those ridge vents to work there has to be unrestricted airflow between the insulation and the roof sheathing from ventilated eves up to the vent. They make a extruded vent pocket that you staple to the underside if your roof sheathing to make a path for the air before you put the insulation in place. Also if you add poly over faced insulation be sure to slash the vapor barrier on the insulation so moisture does not get trapped on the warm side and form mold.  :)
Hudson HFE-21 on a custom trailer, Deere 4100, Kubota BX 2360, Echo CS590 & CS310, home built wood splitter, home built log arch, a logrite cant hook and a bread machine. And a Kubota Sidekick with a Defective Subaru motor.

47sawdust

Unless you have a continuous air flow from vented soffit to the ridge a ridge vent alone will not work.Insulating the rafter bays is the least desirable method.It is much better to insulate the ceiling and install gable end vents and fully vented soffit.

Also cellulose ,say 18'',would be cheaper than comparable spray foam.Not knowing your construction details though,that is just a guess.
Mick
1997 WM Lt30 1999 WM twin blade edger Kubota L3750 Tajfun winchGood Health Work is my hobby.

Bruno of NH

Ridge vents work best in combination with soffit vents .
Is the ceiling vaulted ?
Jim/Bruno
Lt 40 wide with 38hp gas and command controls , F350 4x4 dump and lot of contracting tools

Autocar

On our place we have a 14/12 fall on the roof I had sawed 2x8's twenty four feet long and used six in insulation leaving a two inch air space between the roof and ceiling. With vents at the over hang and at to top of the ridge we have never had a issue with condensation.
Bill

yukon cornelius

We are fully vaulted ceiling as in the rafters are the ceiling. once I can afford the foam it will be a continuous  sealed area where the indoor air will never meet a cold or hot surface until then venting it is my only option. fiberglass insulation was never in the plan to begin with because I think it is one of the worst forms of insulating compared to the others available. this house is being built with cash in hand so I regrettably stepped downgraded to it. my situation now is to remove the moisture that is in it currently and work extra hard to buy the foam.
It seems I am a coarse thread bolt in a world of fine threaded nuts!

Making a living with a manual mill can be done!

Chuck White

My garage roof has a vented ridgecap and when it snow or rains with wind, the weather will end up in the garage.  It's a steel roof on perlins spaced at about 8 inches, no insullation.

Eventually I will be redoing the roof and it will be OSB covered with felt paper, then the steel, but the ridgecap will be sealed and I'll be putting attic vents on the gable ends of the building!
~Chuck~  Cooks Cat Claw sharpener and single tooth setter.  2018 Chevy Silverado and 2021 Subaru Ascent.
With basic mechanical skills and the ability to read you can maintain a Woodmizer  LT40!

sawguy21

Quote from: Peter Drouin on March 22, 2015, 07:30:21 AM
If you get snow the ridge vent will not work with snow on it. Also put in gable end vents, For me in NH they're the best.
That was my first question when I saw them, not much good in snow country. If you have gable vents why bother with the vented ridge cap?
old age and treachery will always overcome youth and enthusiasm

Peter Drouin

When you build A house you want to vent the roof all you can in the north with the cold.
A&P saw Mill LLC.
45' of Wood Mizer, cutting since 1987.
License NH softwood grader.

Gadrock

I have put up a bunch of this venting ridge row stuff in the past. We aimed at 6 to 8 complete airchanges per hour for the ceiling area.

Not likely to see me building any of that stuff up North, as I reserve that area for visiting only.

And I do not allow goats on my roof, even if they wanted to be there.

David G

carry on
LT40 G18,   bent Cresent wrench,   broken timing light
Prentice 280 loader, Prentice 2432 skidder, Deere 643J fellerbuncher, Deere 648H skidder, Deere 650H Dozer

Don_Papenburg

That turtlegoat might be OK up there though
Frick saw mill  '58   820 John Deere power. Diamond T trucks

Peter Drouin

Quote from: Chuck White on March 22, 2015, 07:34:42 PM
My garage roof has a vented ridgecap and when it snow or rains with wind, the weather will end up in the garage.  It's a steel roof on perlins spaced at about 8 inches, no insullation.

Eventually I will be redoing the roof and it will be OSB covered with felt paper, then the steel, but the ridgecap will be sealed and I'll be putting attic vents on the gable ends of the building!



I see a lot of guys do that . Add heat and it will rain inside when it's cold out.
A&P saw Mill LLC.
45' of Wood Mizer, cutting since 1987.
License NH softwood grader.

Chuck White

I have no ceiling in the garage, just strapping!
~Chuck~  Cooks Cat Claw sharpener and single tooth setter.  2018 Chevy Silverado and 2021 Subaru Ascent.
With basic mechanical skills and the ability to read you can maintain a Woodmizer  LT40!

Peter Drouin

Quote from: Chuck White on March 23, 2015, 07:47:09 AM
I have no ceiling in the garage, just strapping!



Had a farmer did that with a barn. I told him the board the roof F paper then tin. He just strap it then tin. And when he put the cows in it rained. Every one likes to skip a step with a roof.
An open shed is ok. But if you box it in, put on a real roof. And OSB will sag between the rafters over time. Go with CDX 5/8. Good luck
A&P saw Mill LLC.
45' of Wood Mizer, cutting since 1987.
License NH softwood grader.

Chuck White

Quote from: Peter Drouin on March 23, 2015, 08:40:25 AM
Quote from: Chuck White on March 23, 2015, 07:47:09 AM
I have no ceiling in the garage, just strapping!



Had a farmer did that with a barn. I told him the board the roof F paper then tin. He just strap it then tin. And when he put the cows in it rained. Every one likes to skip a step with a roof.
An open shed is ok. But if you box it in, put on a real roof. And OSB will sag between the rafters over time. Go with CDX 5/8. Good luck


My garage is unheated, so it doesn't rain in there, and when the reroofing is done, the roof will be solid boarded or OSB will be installed on the existing 1x6 perlins!
~Chuck~  Cooks Cat Claw sharpener and single tooth setter.  2018 Chevy Silverado and 2021 Subaru Ascent.
With basic mechanical skills and the ability to read you can maintain a Woodmizer  LT40!

thecfarm

Vents are VERY important is having a cold roof. The air in a vented roof should be almost the same as the outdoor temp,seem like only 10° difference?? Been over 25 years since I did all this.
Model 6020-20hp Manual Thomas bandsaw,TC40A 4wd 40 hp New Holland tractor, 450 Norse Winch, Heatmor 400 OWB,YCC 1978-79

Peter Drouin

Quote from: Chuck White on March 23, 2015, 08:54:11 AM
Quote from: Peter Drouin on March 23, 2015, 08:40:25 AM
Quote from: Chuck White on March 23, 2015, 07:47:09 AM
I have no ceiling in the garage, just strapping!



Had a farmer did that with a barn. I told him the board the roof F paper then tin. He just strap it then tin. And when he put the cows in it rained. Every one likes to skip a step with a roof.
An open shed is ok. But if you box it in, put on a real roof. And OSB will sag between the rafters over time. Go with CDX 5/8. Good luck


My garage is unheated, so it doesn't rain in there, and when the reroofing is done, the roof will be solid boarded or OSB will be installed on the existing 1x6 perlins!


You don't have to yell at me Chuck, I was just trying to help so you don't have to it a third time. :)
A&P saw Mill LLC.
45' of Wood Mizer, cutting since 1987.
License NH softwood grader.

Chuck White

Not yelling, by any means Peter.

Just letting you know my options!   smiley_peace
~Chuck~  Cooks Cat Claw sharpener and single tooth setter.  2018 Chevy Silverado and 2021 Subaru Ascent.
With basic mechanical skills and the ability to read you can maintain a Woodmizer  LT40!

Brucer

Some comments on other comments.

Venting is done for two purposes. One is to keep humidity from building up, or to evaporate moisture inside the roof. This prevents molds and fungus from building up, and keeps the wood from rotting.

The other purpose in the snowy north (where I live) is to keep the air beneath the roof surface from getting above freezing temperature. If the surface temperature gets too high, the snow starts to melt from the bottom, the water runs down to the eaves (which are cold), and then it freezes and forms ice dams. No amount of insulation will stop heat from flowing up into the roof spaces -- it only slows it down. Snow also acts as an insulator so it tends to push the temperatures of the roof spaces up above freezing.

Eave vents combined with gable vents do a decent job of keeping the humidity down. It's been my experience that this isn't enough for dealing with ice damming in snow country. The problem is this. As the air under the roof slowly warms up, it starts to rise. The rafters (or the top chords of trusses) form channels that conduct the warm air up to the peak, but prevent the air from moving sideways to vent out the gables.

If you just try to direct the warm air out the sides of ridge vents, they will get blocked by snow (as Peter points out), and may also let the weather in (as Chuck points out). The solution is to have a ridge vent that only discharges warm air out the ends. In other words, it acts like a duct above the tops of the rafters or truss chords and vents lets the warm air trapped there get out.

The vent will also have to be insulated on top (a half inch of insulation board will be plenty) to the warm air flowing out the vent doesn't melt the snow on top of it.

I have seen a commercial ridge vent that is insulated on top and open only on the ends. For long ridges these vents can be connected to a prefabricated chimney-like tower that extends well above the roof line (and hopefully above the snow line).

Two years ago a neighbour was doing renovations on his house and discovered a lot of rot in the roofing system, caused by inadequate ventilation (the house was built the same year I built mine). When the roof was being rebuilt, the owner had the contractors build an insulated ridge vent (about 8" high and two feet wide) that was vented only at the ends. The roof is 50' long. There has been absolutely no sign of ice damming or snow melt during the winter.

When I built my house, I put in 4 times the venting specified by the building codes. I still had ice damming. Fifteen years ago I increased the venting by another factor of 4. I still get a modest amount of ice damming. Next time the shingles need replacing, I'll be putting in a ridge vent.
Bruce    LT40HDG28 bandsaw
"Complex problems have simple, easy to understand wrong answers."

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