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We seem to be having some condensation in our attic. We had a new roof put on about a year ago (one layer) and added a couple of roof vents. Does anyone know what else we can do to alleviate this problem? Thanks!
In some areas of the country, I've seen various vents terminating in the open attic. In other areas, that's a big no-no. So, are any of your vents terminating in there, like the one from the bath or maybe the kitchen? If the answer is, yes, you would need to extend them through the roof.
If your answer is, no, then I'm afraid we'll both have to wait for other answers.
No other vents terminate in the attic. I'm wondering if my house humidifier is set too high, although there's no moisture on my windows. Thanks for your response.
Just having vents does not mean there is an air interchange of the attic air volume. Basically you have to have some means of air flowing in to replace the air being vented from the attic.
In mine, I built an under roof air path way that brings cool air from the gutter eaves area and that passes under the roof and vents into an upper attic volume which vents out the roof ridge vent.
If you have only a static trapped air volume with no replacement air for that vented, there will only be venting on expansion while heated. You might start seeing condensation from the trapped volume on cooler days.
The best systems have an actual system of air flow from the outside, thru the attic area and out some type of venting ports. Doesn't need any fans, just natural circulation works well if properly constructed.
Just having a few vents does not mean there is much air flow or volume interchange in the attic if some type of replacement air is not available. See the problem a lot in hip roof designs. Difficult to set up good air flow paths, get good vents installed, find sources of fresh air for all the separate trapped volumes of air.
Hey Cosmic, hope your doing OK, haven't read a post from you in awhile.
Many homes get attic ventilation problems when the attic insulation blocks up those vent openings around the gutter eaves. That can really happen fast with blown in insulation. I like those plastic "U shaped" ventilation troughs that are several feet long that can be installed in between the roof joists in the attic around the lower vents by the eaves. It that what you are referring to Cosmic?
When I lived for a few years down in the very hot and humid southeast, my house had a ridge vent across the entire top length of the roof ridge, with the U shaped ventilation troughs allowing lots of air flow up from the eaves. Worked great for natural bottom to top air flow under the entire surface of the roof, not just the sides or where a few vents on the roof were located as in many homes.
Appreciate all the feedback. I should add that the insulation is probably the original (house is 50 yrs old!). We're here 12 years and never replaced it. We may have a lot of heat escaping into the attic space. This is the first time we've had this problem.
Look carefully at your eave vents. I have a friend who discovered the seeming vented eaves actually had a plywood installation that blocked all airflow. The builder then put the vented aluminum things on the outside. Amazing what stupid things some builders do.
I also replaced the u-shaped troughs to ensure the insulation doesn't block the airflow in my attic last summer. The old ones were a foot wide trough that had collapsed so most of them were no longer holding the insulation down. The new ones have a v in the middle for more strength against the insulation. The attic is noticeably cooler even on really hot days now.
Hey Cosmic, hope your doing OK, haven't read a post from you in awhile.
Many homes get attic ventilation problems when the attic insulation blocks up those vent openings around the gutter eaves. That can really happen fast with blown in insulation. I like those plastic "U shaped" ventilation troughs that are several feet long that can be installed in between the roof joists in the attic around the lower vents by the eaves. It that what you are referring to Cosmic?
When I lived for a few years down in the very hot and humid southeast, my house had a ridge vent across the entire top length of the roof ridge, with the U shaped ventilation troughs allowing lots of air flow up from the eaves. Worked great for natural bottom to top air flow under the entire surface of the roof, not just the sides or where a few vents on the roof were located as in many homes.
Recycled, I built my own custom system using that stuff called Reflectix, which is like a bubble wrap membrane with aluminum foil on both sides. The air flow system was also part of the insulation. The Reflectix is rated to 160F and I installed it about 1/2" gap between the roof boards. It needs a small gap on either side but within about a one inch distance will give up to R-18 value. I just had standard 2 x 4 depth (old style 2 x 4) in the roof rafters. Yep, skinny but I needed to get the insulation value way up. That Reflectix gets installed tight like a drum head over two spacers on each side, I stapled it in. The gap between the roof and it acts like the air flow system in my house. The gap is open at the eaves and attic volume to allow air to flow naturally. This method gives a lot of volume in the air pathway compared to those trough thingees.
Those ventilation troughs probably work but I like my design a lot better. Mine would require more labor and it probably most expensive but that gets some credit on the need to install less insulation over top it. In this design the insulation is in the roof, not the attic floor. My attic is more like a crawl space, very little actual volume up there. Most of the roof runs as slanted walls over living / storage space. Works like a charm and normally I have no need for A/C in summer. Before you could not stand to be in the upstairs area. Old boy before me slept down in the dining room in summer.
Yep, insure the builder actually provided a source of air. Those high paid clowns are well known to do strange things in the name of progress. A good design actually has screen ports under the eaves in new houses to provide a bug free cool air supply. Same old deal, one sub contractor is known to mess up another's work. The supply ports might be blocked up insulation but they should have been designed to have a physical barrier against that happening.
A good under roof air flow system will solve a lot of problems. Also can make the attic volume more useable, better storage area, etc. You can design it to be a heated area without actually providing any, if you do a little work to close in the attic peak and make that the vented volume only. The air flow system dumps into that area and then would vent out a ridge vent. Will make the house so much cooler in the summer.
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Maybe it is a lack of air flow
