Results of improper attic / roof venting.

[PEG688]

 Poor photo but here's what happens when you don't vent your attic / roof properly.

12 to 15 year old house , OSB sheathing , soffit vents but NO ridge and or roof jack venting.

Shingle are shot so is the non H clipped OSB , makes for a MORE expensive roof re-shingle.

Make me, and others like me ,  money so I highly recommend  no venting

 

The top two courses are black , soft , and at least those two rows will need replaced.

[peternap]

Looks to me like the whole thing needs replacing PEG. I see lots of curl.

[PEG688]

  Could be I left the job site about 10 minutes after I took the photo , the roofers where going to finish stripping the roof when I left . I hope there's no structural damage , but we'll find that out today when the old stuff gets ripped off.


I only posted this photo to show what can happen , folks aways want to ask about short cuts , think this or that will never happen. There are reasons why houses are built a certain way , short cuts seldom work. 

The over all process isn't hard , if you follow the right steps , in the right sequence.

[glenn kangiser]

Sorry, PEG.  I thought all that moss was just normal in Washington.

[NM_Shooter]

OK... so this has me thinking.

I've never built a structure with a "cut" roof before, where 2X8 roof rafters join up with the ridge and insulation is placed in between the rafters.  Seems like I recall that there is blocking down between the rafters down low.  With all that insulation between the rafters, and blocking between the rafters at the tails, how do you vent something like that?  I don't think I've ever noticed any sort of soffit vents on small cabins that I've seen.

What's the solution ??

[MountainDon]

Here's one way. Info taken from HERE



image modified, ridge vent note added: MD

[PEG688]

Mtn. D's detail is pretty good , although ot does not show the ridge vent to let the air out. That's what the house pictured lacked , it had every thing BUT the continous ridge vent. Which is sold under a few different names , we mostly use "Core vent" around here.

It can get a little tricky to vent trapped rafter bays above and below skylight,  we bore 2" holes to vent those spaces / bays.

[MountainDon]

   I tried to find a picture that included the roof vent.
Then I thought of making a note about it.
Then I forgot. 
It's good to have PEG around to keep me on the straight and narrow. 

[mvk]

Thanks for the info Peg and Don.

As far as the insulation detail that Don posted. Is there a product that you use to get that 2" air space in the roof detail in the picture?  I remember a product (foam?) back about 20 years ago that you put in between rafters. Sized for 2' spacing's and you broke it in half for 16" spacing's. Kind of flimsy to work with, I think it was to keep fiberglass in ceiling from touching your roof sheathing at the eve and blocking the soffit vents. That only had about 1" air space? It also only filled part of the bay. I have installed foam or plywood on wood cleats before, that would work but a lot of work to do. R-30 cellulose works out to 8-9" thick so you would be talking about 2x12" rafters or building up smaller rafters. I'm sure that there was a lot of thought involved in this system.

With metal roofs how would you do it? Sheathing, felt, 2" vertical nailers, purloins, metal?  This seems to be more straight forward to vent. Guess you could just use purloins and vent east to west as Glen suggested in another post. That kind of gives you a dam every two feet or so though.

There are folks advocating dense pack cellulose with no vapor barrier and no venting? This would sure simplify the roofing detail. I guess that the theory is no air movement no vapor problem. John says this to, though he wasn't speaking of this case in particular just about vapor barriers. I saw this on a fine home building site, so I would think that there are people who are thinking about it kind of seriously. Might still be wrong though?  Anybody explore this. Think you would still use foam to prevent thermal bridging?
 
Cellulose or fiberglass or?? I'm still trying to figure this out. Does anyone know if dense pack and wet pack are the same? I installed cellulose in my old house about 30 years ago. I like how it seals. I guess that settling can be a problem. With fiberglass I think you have to really stop the air movement and I wonder how it would perform in the roof pictured. I think it is on the wrong side of the foam not sure though.  Another thing  I'm not real gung ho on this but if it was all the same I would like to build without any plywood ,osb, or foam at all though I probably won't.

Anyone else out there planning a bigger small house as a primary residence in a cold place and trying to figure out insulation.
Did I hi jack this thread?     
Mike

[FrankInWI]

what to do about insulating is a HUGE concern of mine too.  I have LP for heat and the $$$ is getting scary.  Better to invest now than to leak more money than I have to every day!   After I got done with the wiring, I am even less keen on doing just fiberglass in the lower garage.  There I might go with celulose and since I have 10' ceilings I can have a 8' vertical panel and then a removable 2' panel on top of that that I could remove in later years to check for settling.  With celulose though is there dry blow vs. wet spray?  Some seems loose, and I look at others that seem to be blown in wetish and sticks together.  Feedback ?

I like the idea of foam, but so exensive I understand.  I still get confused about what material fills the whole cavity, and what is used to just give you a few inches (with the benefit of super sealing) with fiberglass on top of that. 
Where I might splurge and go all out is the ceiling.  It's semi-cathedral and there I am talking with a contractor to come look at it and give me a price on foam filling the whole thing.  Even after that I might still put 1//2 or 1" insul sheeting on top of that to stop the thermal transfer through the rafters.  That may be a bit excessive...feedback?

Oooops, there IS an insulation thread.... should have posted this there?

[PEG688]

No worries about thread drift Glenn taught me long ago that as long as the main  question, if there is one , get answered thread drift is a good thing. Something we bounce around in someones mind and a solution will be revealed .

And this thread really had no purpose except to show what happens when you don't vent properly.

The good news is only 15 sheets where bad on the side pictured , the other side was fine. What happened was the fart fan duct never got hooked up , or some how got disconnected , there was a duct pipe it just wasn't hooked to the fan. So on top of no cross / out the ridge venting a whole load of hot exhaust air was added .   

  We have used the spray foam Icynene  (sp)stuff , I've never remodeled a place that used it , BUT They say it doesn't require venting and that's the way we use it . On remodels to get the max R value that's the way to go.

On a new build , depending on where you live , getting a R-38 is hard with lumber rafters , we have used TJI's for the added depth they f give you , so the air space can be maintained.

[Okie_Bob]

Peg, as Glenn knows, I am one of the biggest proponents of Icynene having used it in my house and non-vent attic or ceiling. This is my first winter with it but, so far no problems at all.
I understand there are a couple of new companies out now that compete with Icynene and hopefully that will drive the cost down. It is truly expensive and I just hope it's a good investment. One thing it does for certain is to seal the house better than anything else I've ever seen.
And if I'm drifting, beat me!!!
Okie Bob

[glenn kangiser]

We can't stop you from sharing your Icynene experiences, BoB.  We already tried. 

No -- we don't want to stop you -- thanks for posting about it and helping others.

[Willy]

We can't stop you from sharing your Icynene experiences, BoB.  We already tried. 

No -- we don't want to stop you -- thanks for posting about it and helping others.

I live in a real dry area in Eastern Washington. Now we get lots of snow and wind! Being that it is dry our snow is like fine powder and can blow into the vents and ridge vent!! In 1996 a lot of ceilings caved in because of this happening. I blocked my ridge vent to keep snow that blows up the metal roof and into the vent. On the north side of the buildings I had to put tempory covers on the screened holes on the bird blocks. I remove them after winter. No problems in 12 years now but I do check the attic during the winter. I have insulation on my ceiling not on the roof side of the trusses. We use a baffle to allow the air to flow thru the eve vents that keeps the ceiling insulation from blocking the holes. The building ridge is missing about 1 1/2 inches of plywood the full lenght and this allows the air to flow out thru the ridge cap that has a gap in it. This is the gap I stuff insulation into to keep the snow from blowing into. I had over a foot of snow in my attic below the ride before I saw it! I had to bag it up and remove it before it melted and was lucky I saw it!!Mark H.

[glenn kangiser]

Mark, that's way too cold.  I don't care for snow, let alone mis-behaving snow.

[Woodswalker]

My cabin is 100 or so miles NE of Willy's place.  Used a continuous ridge vent, but asphalt shingles - not metal.  See the pics and description in my thread (Cabin Build in N-Central WA by one person) for how I solved the venting issue.  My approach gives the added benefit of reflextive foil below the vent cavity to send much of that hot summer sun back from whence it came.  No problems last winter, and cabin stayed comfortable in very warm afternoon direct sun last summer.  A friend over there just sent some pics today, and it looks like about 1.5' of snow over everything.  I'm more concerned about the roof of my travel trailer than the cabin.


ED: made working link to woodswalker website - MD

[Willy]

My cabin is 100 or so miles NE of Willy's place.  Used a continuous ridge vent, but asphalt shingles - not metal.  See the pics and description in my thread (Cabin Build in N-Central WA by one person) for how I solved the venting issue.  My approach gives the added benefit of reflextive foil below the vent cavity to send much of that hot summer sun back from whence it came.  No problems last winter, and cabin stayed comfortable in very warm afternoon direct sun last summer.  A friend over there just sent some pics today, and it looks like about 1.5' of snow over everything.  I'm more concerned about the roof of my travel trailer than the cabin.


ED: made working link to woodswalker website - MD

The snow level is one reason my floor will sit 2 ft off the ground on my cabin. That way I don't have to worry about shoveing snow there in the winter. I am going to look for a better ridge vent for this cabin one that is upside down to let the air flow but not vented in a way the blowing snow can get into it sliding up the metal in the high winds. We have around 2 ft on the ground still so that is about right for the area. I know my building site is not ready yet for the pier/post foundation to go in! I bet at least 12+ inches of dirt is frozen solid in the ground still. The deep snow ground cover will help keep the frost from going to deep. Mark H.

[glenn kangiser]

Wonder if these would work, Mark?

[MountainDon]

Wonder if these would work, Mark?

[glenn kangiser]

Wonder if these would work, Mark?

Dude -- I meant these.

http://www.coravent.com/ventilation-products.cfm

My computer forgot to paste the link.

[Willy]

Wonder if these would work, Mark?

Dude -- I meant these.

http://www.coravent.com/ventilation-products.cfm

My computer forgot to paste the link.

Hey that X5 looks like the ticket to stop that problem from happening! I will check into getting it from my supplier or just ordering it direct. I save a link to the site in my favorites. Thanks, Mark

[Erin]

We have a friend that built a garage last spring with the "living space" trusses in the attic.  They didn't vent the roof though!

Consequently, when they stored their plastic lawn furniture in the attic this summer it melted !

[PEG688]

Looks to me like the whole thing needs replacing PEG. I see lots of curl.

Peter I was taking about the OSB , yes all the shingles are being  / have been replaced.

[PEG688]

Hey that X5 looks like the ticket to stop that problem from happening! I will check into getting it from my supplier or just ordering it direct. I save a link to the site in my favorites. Thanks, Mark

There ya go  some good did come out of this thread!

[glenn kangiser]

See, I told you.