Cables, Coffee, Cycles, and Cocktails

[Wardsweb]

I have a ridge vent that runs the full length of my house. It has always done a great job. Just have to make sure I don't push speaker boxes between the ceiling and roof, as not to block the vents.

[jason str]

^^^ If you ever have even a slight seepage penetration from the roof the moisture will mold everything up there eventually rotting the structure away.

[CECAA850]

 

 

A balanced system is desirable according to current thinking.

 

Correct.  You need the proper amount of soffit intake area to feed the ridge vents.  Normally if you use a powered vent, ridge vents aren't needed.  Using a powered vent and ridge vents together can actually suck rain in through the ridge vents as well.  It's odd that they're using both on a brand new install.

 

When I built my house back in 2010 I did a lot of research on attic assemblies. I finally went with a completely sealed attic. Spray foam insulation was applied to the underside of the roof and all gable ends. There are NO unsealed penetrations into the attic from the outside and no insulation between the attic floor and the ceilings in the living space. I had major fights with building officials in the county and finally had to have the manufacturers rep for the spray foam meet with the building officials. They finally saw the light and allowed this unconventional construction method. The fire officials love the fact that there are no penetrations(I live in high wildfire area). But what I like is when it is 110 degrees outside and 75 degrees inside the attic is only 85 to 90 degrees. Other attics in the area would be 130 degrees + on a 110 degree day.

 

 

 

I'm not disputing the results but having a hard time wrapping my little brain around how this works, especially the "no insulation between the attic floors and ceilings" part.

 

Do you have attic access?

[babadono]

Yes I have attic access in 2 areas of the house(3 if you include the garage). That's how I knew that when its 110 outside its only 90 in the attic. Also how I knew there is no way I can do an IB sub over the family room

 

 Google "sealed attic" or "semi-conditioned attic"

Edited May 25, 2016 by babadono

[babadono]

^^^ If you ever have even a slight seepage penetration from the roof the moisture will mold everything up there eventually rotting the structure away.

I'm not saying this is the way to go every where but in the Hot Dry climate (and high fire danger) area where I live it is suitable.

[Tarheel]

Sealed attics and crawl spaces stabilize air flow and reduce air leakage.  As babadono points out it depends on what part of the country you live in.  Foundation vents make perfect since in Minnesota or North Dakota but not in Louisiana, Mississippi, or Florida. 

 

In humid environments vents are counter productive.  Warm air always seeks cooler air.  So the air outside your house seeks cooler air such as in a crawlspace and then condenses.  What makes matters worse is if you have a vapor barrier on grade to keep the moisture from going into the ground you create a swimming pool.  AC ducts that leak aggravate the problem by providing additional conditioned air.

 

Speaking of air leakage check with your power company to see if they will do a power audit to include duct leakage.  It is possible to pinpoint sources of leaks by using a blower door and creating a negative pressure on the envelope of the structure.  Armed with that information you can go about sealing the leaks.  In my training while I was in the housing industry I quickly learned where most houses leak.  Any penetration through the structure is suspect. 

Go into a house under construction before the dry wall goes up and look at the size of the holes under a bathtub where the supply and drain come in

[dtel]

 

If there isn't any air moving outside, there won't be any air moving in that attic,

 

You should still have convection air movement but you're correct, the powered vent moves so much more air.

 

 

True but with powered you constantly pay for electricity and need replacing which easily offset cost of free convection if done correctly. With summer temps attic powered vents run almost nonstop even when set at high temperatures.

 

Ceptorman last time I installed a attic vent it was on my father in laws house, when I cut the hole to begin installing we had to step back, it was like a blast of hot air from the attic wanting to rise. That is what turns the old round spinning models, convection,  not the wind at all. 

 

But one downside to the spinning models is for a hurricane many people will put a garbage bag over and tied at the bottom so really high winds make the rpm's of the spinning destroy itself.

Edited May 25, 2016 by dtel

[CECAA850]

True but with powered you constantly pay for electricity and need replacing which easily offset cost of free convection if done correctly.

 

There's plusses and minuses to both.  The small amount of electricity the powered vent is more than made up with energy savings from the decreased load on the ac unit.  Attics are much cooler with powered vents vs convection, at least that's what I've read in the past.

 

My last one hung in there for 20+ years.

[CECAA850]

Yes I have attic access in 2 areas of the house(3 if you include the garage). That's how I knew that when its 110 outside its only 90 in the attic. Also how I knew there is no way I can do an IB sub over the family room

 

 Google "sealed attic" or "semi-conditioned attic"

 

Interesting.  I had never heard of this before.

 

[Ceptorman]

 

Yes I have attic access in 2 areas of the house(3 if you include the garage). That's how I knew that when its 110 outside its only 90 in the attic. Also how I knew there is no way I can do an IB sub over the family room

 

 Google "sealed attic" or "semi-conditioned attic"

 

Interesting.  I had never heard of this before.

 

 

That's the direction things are going around here for crawl spaces, they want it sealed and conditioned. It's not currently a code requirement, just a suggestion. 

[Ceptorman]

A company called Aeroseal can seal your ducts from the inside.

[babadono]

 

 

Yes I have attic access in 2 areas of the house(3 if you include the garage). That's how I knew that when its 110 outside its only 90 in the attic. Also how I knew there is no way I can do an IB sub over the family room

 

 Google "sealed attic" or "semi-conditioned attic"

 

Interesting.  I had never heard of this before.

 

 

That's the direction things are going around here for crawl spaces, they want it sealed and conditioned. It's not currently a code requirement, just a suggestion. 

 

Yes I'm >5 years in and all seems OK so far. I feel it will last longer than I do. Know what I mean?

[Ceptorman]

Yes I know exactly what you mean

[Wardsweb]

Now for something totally different. The lake house in Bodcaw AR.

 

[Ceptorman]

^^Great photo^^

[Wardsweb]

^^Great photo^^

 

I cannot take credit. That was taken by Kevin with his drone.

[Ceptorman]

 

^^Great photo^^

 

I cannot take credit. That was taken by Kevin with his drone.

 

I figured, unless you had a satellite camera

[Tarheel]

I've seen a lot of folks lay their attic insulation right up to the roof sheathing effectively making the soffit vents useless.  There must be a path for the air coming through the soffit to get to the attic.  Card board or Styrofoam baffles prevent the blockage if installed correctly.

 

Great photo Kevin via Luther.

[Ceptorman]

I've seen a lot of folks lay their attic insulation right up to the roof sheathing effectively making the soffit vents useless.  There must be a path for the air coming through the soffit to get to the attic.  Card board or Styrofoam baffles prevent the blockage if installed correctly.

 

Great photo Kevin via Luther.

That's probably the number one reason your attic doesn't vent properly.

 

I've recently noticed a rubber or plastic mesh system that goes over your black tar paper or ice and water shield on your roof, under your shingles, to allow air to circulate under the roofing. It's mandatory with cedar shakes.

[Rivervalleymgb]

The best way is to build with a knee wall in place to allow 12" of insulation over the wall/ceiling joint, AND proper ventilation over the insulation. I know it adds to the cost of new construction, but well worth it if you are building a house to live in for life. Most energy efficient designs on have a payback over a period of 30-40 years.