Attic Venting

duckmansheba · Sun Oct 05, 2014 8:34 pm

I own a 2005 Double-wide Fleetwood Mfg home with open (beamed) ceilings throughout. I always assumed that there was no space between the ceiling beams and the roof, however there is about a four foot high factory installed duct through the roof near the marriage line to the the ceiling in the living room for the evap. cooler. The ceiling isn't two feet thick, nor is the roof, so do I have some space above the ceiling? The reason that I am asking is that there are no roof vents, no side vents on the side of the house near the roof. Shouldn't this be vented? Was this some option form the factory? During the summer, I can feel heat radiating from the ceiling. Any help/advice would be appreciated

JD · Wed Oct 08, 2014 11:02 am

The best way to find out is to get your head up there and take a look. You can make an access panel in a closet. The older vaulted ceilings were a problem because they put roof sheathing on top and sheetrock on the bottom of 2x6's with no venting at all. After many law suits and repairs, they started using ridgecap and eave edge venting. I don't work on may newer homes, I imagine because they are newer and fewer. I did install a skylight in a 2004 though and was amazed to see a full 18" gap between the roof sheathing and ceiling sheetrock. They use engineered trusses, where there is wood at the top and bottom, with "W" patterned metal bracing in the middle. This made the roof quite breathable. Thia roof also incorporated ridge and eave vents. No whirlybirds or gable vents.

ponch37300 · Fri Oct 10, 2014 9:06 am

"Attics" should always be vented. Even if you have insulation all the way up to the roof sheathing you need to use those foam spacers to leave a space and allow air to flow from the eaves to the ridge. If you don't have any venting hot moist air forms in the attic and will cause moisture issues and damage. At a bare minimum without seeing the actual home installing a ridge vent i pretty simple and will at least allow the majority of the hot air to escape at the peak. Then if you can create some "intakes" in the gable or at the eaves this will help with circulating the air.

duckmansheba · Fri Oct 24, 2014 3:23 pm

Thanks Everyone for your help. I am having trouble understanding how Fleetwood could manufacture a home in their Riverside factory (California)in 2005 and not be required to vent the attic.
I am a realtor and see hundreds of mobile/manufactured homes that are older than mine, and many of them have what appear to be factory installed gable and ridge-line vents. I didn't think that energy efficiency and mold prevention were a factory option

JD · Sun Oct 26, 2014 1:27 pm

Many manufacturers built mobile homes this way in the '80s. I worked on a few jobs where Fleetwood paid contractors to repair damage and retrofit edge and ridge vents. The damage was dry rotted marriage beams and the ends of the rafters. Law suits and voluntary repairs probably changed their building practices. This was a problem with vaulted ceilings where a single row of 2x6's were sandwiched between the ceiling and roof sheathing. Gable vents were not an option on those roofs.

thatswhoiam · Wed Oct 29, 2014 11:01 pm

there is a lot of information on attic venting on this site http://www.buildingscience.com/document ... going/view

the article i linked is just one of several, there are more on the subject to the right of the page

ponch37300 · Thu Oct 30, 2014 8:31 am

Venting topics and the various facts and opinions that go with them are always interesting to me. Like I've said before on here it seems everyone has there own opinion on venting. Then there are those of us that have had to fix damage directly caused by not venting. JD posted one example about real world damage that lack of venting caused. I've seen many issues also. There is not one manufacturer of shingles, roof sheathing, insulation, etc that I have ever seen recommend no venting. Last time we had a venting thread it just went in circles about if venting was good or not. So I have learned to agree to disagree with those that have opinions that have been proven wrong by real world examples. But I will say there are a few of us on here that have seen first hand the damage the lack of venting can do.

My mom for example bought a house that someone had finished the attic in. They used the roof rafters as part of the ceiling framing and put insulation in the rafter cavities tight to the roof ceiling(no venting) and then screwed drywall to the rafters. Then they put a 3' or so knee wall and then had a 6' or so spot where the ceiling was flat. She had all sorts of issues with moisture problems from this lack of venting. I had to rip the whole thing out and redo it. All because someone didn't vent the attic. Not one problem since it's been done and she did notice a drop in the heating and electrical costs. So I can tell you that venting is a good thing in unconditioned areas.

Mark440 · Sat Nov 01, 2014 5:50 am

The proof for venting is an easy experiment.

Fill a jar with about 1/8" of water. Screw on the top. Set it out in the sun. After a couple hours, un-screw the lid and look at the bottom side of the lid. Yep - water.

Washers, dishwashers, showers, toilets - we have all kinds of 'water' devices inside the house. Now add the normal humidity for your geography. Water is in the air....everywhere.

Roof vents give it a way out.

duckmansheba · Thu Feb 12, 2015 8:00 pm

I am having trouble understanding how a home built in 2005 could come from the factory without any venting. Based on the comments here, it seems like this violates all kinds of common sense rules. I notice new manufactured homes have gable vents, roof vents, and vents in the overhang too.
Thanks for all your help