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Old 12-10-2008, 09:24 PM   #1
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Need Attic ventilation advice


I had a new roof and siding done about 7 years ago but it looks like I may have been the victim of some poor ventilation advice. I was a new home owner and didn't know anything. The exterior company (yes, not going to a "roofer" was probably my first mistake) told me ridge venting is not good because water and bugs get in. The salesman actually talked me out of it! But he sold me a power vent for 100$. I must have gotten their lame sales guy because I would have easily paid him whatever to get the ventillation right. Plus, they did not cut out the soffit wood to maximize intake through the perforated vinyl soffit. They did enlarge a few existing vent holes but I had to force the polish installers to do it and I think they only did it when I was watching them. I live in a typical tri-level 2000 sqft house with 2 roofs over living space and 1 over the garage. The living area roofs are approx 30'x25' and 25'x25'. I had Pro-pink fiberglass installation blown in to R49 (about 22") and baffles installed. The larger roof area has a power vent (approx 1000cfm) and 3 mushrooms and 2 gable vents. The smaller area has 2 mushrooms and a gable (only has 1 gable area). I am sure you pros already see alot wrong with this picture. I want to get things right before next summer. Or at least the best I can without completely redoing the roof. Here are my questions. I am pretty good arround the house but am also smart enough to know when to call in pros.

1) Should I open up the soffit area and cut out the soffit wood? The way the siding was done it does not "look" like it would be too difficult to get at the soffit wood. I would consider doing this myself on all but the 2 story soffit. Just do not feel comfortable that long on a ladder.

2) What should I do with the exhaust venting? I was considering installing ridge venting. Is this a "pro only" job?

3) The insullation contractor installed baffles every other truss space. Was this acceptable or was he just cutting corners save on a few 75cent foam bafles? The contract did not specify how many. It just said "install proper baffling". I imagine I could slip more up if I open up the soffit area.


Last edited by beerdog; 12-10-2008 at 09:27 PM. Reason: typo
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Old 12-10-2008, 10:29 PM   #2
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Need Attic ventilation advice


It seems like you have more than enough attic vents. That fact leads me to believe that the previous workers had reason to be concerned about condensation damage. It is rather easy to tell if you are still having problems, just go up there in cold weather and look for the telltale signs of condensation. The old condensation will have stained the wood black. Newer growth of mold will tend to be white. Rot can be discovered by poking with a nail or a pocket knife. Roofing paper gets crinkly and bleached when it has been exposed to moisture repeatedly. You will be able to feel and touch the moisture in the air and on the wood. If things seem relatively dry then they probably are. The insulation contractor should have checked the integrity of the ceiling vapor barrier and recommended remedial measures if signs of air leakage were discovered. Adding insulation will make vapor leakage problems worse. if you have a ceiling access to the attic, make sure it is thoroughly sealed and insulation in place when you come back down. Leave your soffit wood alone unless it is rotting. Every other truss space for ventilation channels is standard treatment unless you are having air leakage problems. With your mask on, look under some of the insulation take a look at the vapor barrier. Has it been punctured by sloppy sub trades? Are your ceiling electrical boxes installed with seals in place. Pay particular attention to bathroom ceilings. There is no such thing as fast rules in attic ventilation it depends on the style of roof construction, type of heating system etc.. Find out if you are having a problem first and then act sensibly.

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Old 12-10-2008, 11:03 PM   #3
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Need Attic ventilation advice


1) I do not think I have any leakage issue. No ceiling stains, etc.
2) I have been up there a few times recently and did not notice any condensation issues, mold growth, etc.
2) I did notice some darkness in the sheathing down by the soffits, but i did not crawl down to it. Could have been shadows. Was hesitant to squeeze down there. No dampness on the framing.
3) I only had about 2 inches of insullation so I used to get some really big ICE dams. I imagine that was causing some moisture intrusion. Maybe this will get better with the added insullation.
4) The attic access doors are well insullated now. The contractor made sure of that.
5) The house was built in 1972. There is no vapor barrier. Just the back of the sheetrock. It did look OK since it was very easy to see with only 2 inches of insullation.
6) Need to check the ceiling fixtures for seals. Can these be purchased? I gues I should check any wall outlets since warm air will escpe into the walls and then the attic.
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Old 12-11-2008, 07:54 AM   #4
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Need Attic ventilation advice


beerdog,
We have pioneered the concept of continuous roof top intake ventilation since 1999. Ridge vent technology has been out there for 40 to 50 years. No other major company has addressed the intake arena quite as well as DCI Products. Our technology is spinning heads and some major shingle and ventilation companies are quite embarrassed that DCI has developed this US Patented product instead of their people. Nonetheless, we continue to educate the roofing world on how to ventilate attic spaces making sure continuous intake ventilation is addressed. You have a major 'SHORT CIRCUIT'. Think this way. The exhaust wants to suck hot, moist, stale attic air from your attic like a straw. When you suck on a straw with your finger covering the bottom hole you get nothing. If you poke holes in the straw near the top (where your mouth would be) you will get air coming in those poked holes and nothing from the opening at the bottom, even if you move your lower finger away (air flow with the least resistance will be drawn). Do you now understand the 'straw' concept? Your attic vents are the same. That is why continuous ridge vents are the choice of most industry experts. Now is where DCI Products comes to the plate and hits not only a homerun, it is a Grand Slam in the World Series of Roofing! We have brought down attic temperatures (40*) and humidity levels (to ambient conditions) using our SmartVent Technology. Easy install, continuous intake without regard to the existing conditions of your soffit (can be installed under any course of shingles). Because of our strong patents, I would be very leary using copy-cat products, as their day will come to answer our questions.

To correct your situation, you need continuous intake, not spotted intake (rated at 9NFA). You also need to install a continuous ridge vent (SmartRidge-rated at 18NFA) available at most major supply yards. Block off ALL other exhaust vents and turbines, etc. You want a ridge vent (SmartRidge) and continuous soffit intake (either SmartVent or remove perforated soffit, cut out ALL under soffit wood and install highly efficient perforated soffit material). All rafter bays MUST have baffles if insulation is blocking the air flow. DCI Products has other vent products for cathedral ceilings as well. Call us to discuss at 1-800-622-4455 or visit www.dciproducts.com GOOD LUCK!
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Old 12-11-2008, 04:32 PM   #5
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Need Attic ventilation advice


Your exterior salesman and installers were very ventilation challenged.

Only 1/2 of the rafters have the baffle vent chutes, so did they ensure that they were positioned only in the rafter spacings that were directly above the soffit vents?

Also, your soffit intake is greatly compromised and very suspicious as to how much they allowed for in the first place.

I have studied ventilation as well or more than the majority of leading advisors and I personally recommend a 100% continuous intake ventilation scenario.

The Smart Vent, as mentioned by DCI Prodocts, Inc. has been my personal choice with resounding results for the past 7 + years.

A 100% Intake along witha balanced equal amount of exhaust would provide the greatest efficiency.

I highly doubt that your instalers cut out the areas when you were not making sure that they did, and even the ones that they cut out, were not cut out to the full amount of soffit wood it sounds like.

Therefor, the vented soffit panels are restricted by the amount that the hole cut out was reduced to.

Ed
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Old 12-11-2008, 05:36 PM   #6
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Need Attic ventilation advice


The installers cut out the soffit vents considerably, but not completely. Looks like I will plan on accessing the soffit wood and cutting a continuous opening. Would it make sense to completly remove the soffit (underside of the eave) plywood completly if possible?

Regarding the exhaust vents if I install ridge venting. Is it acceptable to block the mushroom vents and the power vent from the attic side or do they need to be removed?

Ed, since you are locate in my immediate area, what is the typical cost to have ridge venting and smart venting installed. I guess I would have approximatly 75ft of ridge and 150ft of intake spread over 3 roofs? Is something pros would complete in a day?
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Old 12-11-2008, 07:51 PM   #7
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Need Attic ventilation advice


Quote:
Originally Posted by beerdog View Post
The installers cut out the soffit vents considerably, but not completely. Looks like I will plan on accessing the soffit wood and cutting a continuous opening. Would it make sense to completly remove the soffit (underside of the eave) plywood completly if possible?

The Intake Ventilation needs to be at Least 50% but more preferably 60% of the total NFVA equation. Complete, uninhibited air flow is the best prospect for lowering the internal temperatures and humidity levels.

Regarding the exhaust vents if I install ridge venting. Is it acceptable to block the mushroom vents and the power vent from the attic side or do they need to be removed?

You could block the vents off from the underside, but make sure that the PAV, Powered Attic Ventilator Fan, has the electrical service turned off, otherwise it will switch on from the thermostat and cause a potential electrical overload from not being able to draw in air from the attic.


Ed, since you are locate in my immediate area, what is the typical cost to have ridge venting and smart venting installed. I guess I would have approximatly 75ft of ridge and 150ft of intake spread over 3 roofs? Is something pros would complete in a day?

You can click on my profile and send me an e-mail with your name and address and any other pertinent information. I will repond promtly to you by the folowing day, if not sooner. My shop is located in Carpentersvile and I service the entire surrounding area.
Since you already have 2 roofs on the house sections, it will depend on the brittleness of the shingles if the Smart Vent can e instaled as a retro-fit application without considering to do a complete roof tear-off.

How old is the top layer of roofing shingles now?

Ed
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Old 12-11-2008, 11:11 PM   #8
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Need Attic ventilation advice


When the roof was done 8 years ago it was tear-off. There is one layer of a high quality architectual shingles. They gave me several option on shingle grades and I went their best option. I think they were 30yr Tamco(?). I still have an extra package in the garage.
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Old 12-12-2008, 12:10 AM   #9
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Need Attic ventilation advice


If it was 8 years ago, those Tamko Shingles were just labeled as a 25 year warranty then.

Same shingle now, but the paperwork states 30 year warranty instead,

That is a good brand and quality of shingle in our neck of the woods.

Also, I got the impression that you did NOT have a tear-off done, due to this statement in your orignial post:
Quote:
"I live in a typical tri-level 2000 sqft house with 2 roofs over living space and 1 over the garage."

Ed
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Old 12-12-2008, 08:48 PM   #10
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Need Attic ventilation advice


beerdog,

I think it would be sensible to have Ed stop by and assess your situation.

DCI product guy,

Quote:
We have pioneered the concept of continuous roof top intake ventilation since 1999. Ridge vent technology has been out there for 40 to 50 years.


1. How is an attic like a straw?
2. How is it that small holes are less restrictive than large holes?
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Old 12-15-2008, 09:36 PM   #11
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Need Attic ventilation advice


Beerdog,
Wow, the vent salesman have gotten to you.Sorry I couldn't get back to sooner. You would be well advised to ignor basically everything they have said. I had to reread your original post. it is hard to believe that an legit insulation contractor would install 22 inches of blown in glass fiber on a ceiling that had no vapor barrier and no seals on the ceiling light boxes. R49 is classified as super insulation and brings with it enormous water vapor and condensation problems which must be addressed before insulation is installed. Prior to the new insulation you were basically heating Chicago with your totally inadequate 2 in fiberglass. Odd though, the only reason your roof didn't rot away is , you were creating such a torrent of warm air through your attic that the moisture never had time to condense on wood that was being heated from the passing gale. Are you quite sure the insulation guys did not apply vapor retardant paint on the ceiling and there is no foam seal or poly seals on your light boxes? That may be your only option now. It will be hard to fit vapor barrier and seals under a 22in pile of glass fiber. Make sure you fill all cracks in your ceiling, before applying vapor retardant sealing paint. You likely have wiring holes in the top plates of partitions and outside walls that will leak warm moist air into the attic space.Seal as many of them as you can with expanding foam by digging from the top side. it is possible to seal your electrical boxes from the inside with a gasket though it is not as effective as the poly boots that are installed around the top of the box. Be careful not to seal the top side of pot lights or other lights that require ventilation to keep them cool, Use cooler flourescent low wattage bulbs in these fixtures. Next time you are up there look for signs of moisture that is condensing in your fiber glass layer and causing it to compress. That is what will happen if warm moist air is allowed to get through the ceiling. Retrofit baffles into all soffit joist spaces, now that we know you are having a problem or soon will. Make sure none of the blown in has fallen down to block your soffit vents. Barriers should have been installed to prevent this. good luck, you can do it. Sawyered
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Old 12-15-2008, 11:37 PM   #12
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Quote:
it is hard to believe that an legit insulation contractor would install 22 inches of blown in glass fiber on a ceiling that had no vapor barrier and no seals on the ceiling light boxes. R49 is classified as super insulation and brings with it enormous water vapor and condensation problems which must be addressed before insulation is installed.
Without this v.b., will 16" of blown-in cellulose on top of R-19 fiberglass batt create the water vapor and condensation problem you are talking about? The batts aren't stapled to the 2x4's anymore and big pieces of the paper backing are missing, so there is no v.b. now.

Is a vapor barrier in the attic still worthwhile if it can't be placed and sealed over tight spots that can't be reached (like down where the bottom of the baffles meet the opening to the soffit)? Is vapor barrier an all-or-nothing type of thing or is it still effective when it's used here-and-there?

Sorry about all the dumb questions, but reading the info in this post makes me wonder if I'm really ready to have the blown-in added yet, or if I need to go back up there and do some more swearing .
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Old 12-16-2008, 02:32 AM   #13
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gma@rjc
The only dumb questions are the ones not asked. The problem of super insulated walls involves a good bit of physics. Beerdogs trouble was that a complete vapor barrier with octagonal box seals could have been and should have been easily installed when he had only 2 in batts in place. Now he has 19 inches of blown in to get out of the way to do the same job. There is no place to put it in the restricted attic space especially near the soffits. If you have R19 batts most of them will be 4 feet long and can be easily lifted and then replaced after the vapor barrier is installed or repaired. You will have to keep track of where cut batts have been fitted and batts must be carefully fitted so they don't crush or bend when installed. Working with fiberglass or mineral wool batts is nasty business and you must wear a respirator that fits your face or hire pros. Insulation contractors should be able to get close to your DIY cost. They pay much less for materials and screw ups than you will. The VB in your climate , usually 6 mil poly, should be installed as a continuous sheet against the inside of the wall studs and against the bottom of the ceiling joists. The two are overlapped and sealed with tech tape and all staple punctures and services entrances sealed. It is difficult to get a continuous VB on a retrofit with out removing the interior wall finish, so you do the best you can without too much demolition. People do this on older buildings but most buildings built since 1970 have some kind of vapor barrier or vapor retarder (paper or foil) in the wall. Your Michigan air is relatively dry most of the year and you should not have the additional complication of vapor penetration from the outside toward the inside in summer. The polystyrene baffles keep the insulation from filling up the joist space so air can travel unimpeded from the soffits to the attic vents. The area of the vents should be larger than the total area of the soffit intakes. Don't forget to vent moisture from wet vehicles in the garage directly to outside and not into the attic of the living space. Code in most places.
good luck.
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Old 12-16-2008, 01:52 PM   #14
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Thanks sawyerEd -

Are the octagonal box seals for putting around pipes that come up through the floor of the attic?

I've been working on sealing the attic for a little over a month now and thought I was almost done but I guess I'm not . I stapled a baffle to the roof sheathing between all of the 2x4's, except for the ones that have vent pipes going up through the roof because I didn't want to try to cut the baffle to go around the pipe.

I've also sealed all of the penetrations into the attic, except for one that is 8 in. x 10 feet long.

I bought the tape and the 6mil poly to use for a vapor barrier on the 'floor' up there, under the batts. I just didn't know if it made sense to put a vapor barrier up there at all if I can't reach it into the corners and far edges where the space is too tight to be able to reach. Is it still worth doing if only 80% of the space can be v.b.'ed?

You said to make sure to place the batts back so they're not crushed or bent. Should I remove the sections that don't look or feel right, like the piece that the bathroom ceiling fan was vented into? It's partially black and has a different feel to it than the rest of the batts.

Thanks again for all your help!
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'Succes has many fathers, failure is a mother' - Jeanne Phillips
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Old 12-16-2008, 02:37 PM   #15
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Didn't mean to be vaque. Octagonal boxes are frequently used to house the wiring connections for the lighting on the ceiling but electricians have other styles of box they can use. point is these are notorious places for air leakage into the attic insulation. Could you post a picture here of your mildewed bathroom fan ? I want the guys here to see what happens when these are not done right. Just lay the 6mil in the joist space and let the insulation press it down. Cut it so it stops just a bit past the interior wall finish. Do not allow cold air to touch the vapor barrier, instant condensation. Feel free to slot your baffles to get them around vent stacks etc. the insulation should not be pressing on them very hard. they need to be there. Seal the stacks with expanding foam, easy and very effective. Wear gloves and plan the work so you can continue to apply until the can is done. When you say batts don't feel right, you mean they have already absorbed enough moisture to render them useless? Make friends with your building supply guy, they often know their stuff.

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