Is there some new revolutionary venting concept

[MOM]

Where the house is designed to NOT have any roof vents.........whether it be ridge, gable, or louvered?

This is a brand new house with aluminum vented soffit. The ONLY vents in the roof are for either plumbing/sewer, or bathroom exhaust. It's a hip roof.

My builder is BSing me and saying that the house is engineered to not need it. The attic doesn't have any special insulation other than upgraded blown in over attic floor (R30). This is a two-story house 4000 sq ft including garage.

Every single house model in the subidvision except for my model (which is soo brand new it's not even in the catalog) has either ridge vents, or the increasingly more-popular louvered vent (storm-proof type). I live in FL btw.

What's funny is that the elevation rendering shows 4 advanced off-ridge vents. I checked the prints and they don't show vents. I think it was an oversight and now the builder is trying to BS me with "We engineered it that way".

So someone tell me that the establishment has reversed its thinking and that attics no longer need ventilation. I am familiar with the new trend where the underside of the roof is insulated and not the attic floor...........this is not the case.

[RTF]

There are several varying opinions on this, that being said your builder is on target. If you insulate the area properly and close it up to any air penetration you are good to go, make sure an architect/engineer is behind the design.

[MOM]

So then that means that the underside of the roof itself needs insulation in addition to the blown-in attic floor right?

[RTF]

Just did a project where the attic was sprayed with Icynene insulation and closed up tight.Everything in the attic was covered. If you need ammo contact a Mechanical Engineer.

[MOM]

Sales rep just called me back and told me they are putting 2 off-ridge vents in the back first thing tommorrow in the AM.

[bighammer]

2 vents - what about an intake solution, exhaust is important, however, the other half of proper ventilation is intake. I realize you have vented soffit, enough? I also doubt that 2 roof pods (vents) are enough. Proper vents are another thing, if we vent thru the soffits, we will need something to allow air to flow to the ridge vents. Ventilation is so important - you do need both intake and exhaust - I would be worried about this and bring in a third party --- this cause mold and mildew issues and cause shingles to fall apart mush sooner than normal.

[MOM]

Just got back from the house, they're installing 4 vents, which is what was on the initial house rendering.

[bighammer]

so you have a two story house with 4000 total sq.ft.

so our roof area ia 2000 sq.ft. which means if they are using the 3 sided louvered stationary vents we would need 10 vents, however, if they are using the "whirlybird" type vents they can get by with 4 - make sure you are the correct vents - this ventilation is often overlooked

[MOM]

4 of these are being installed:
( put an hteeteepee://) in front of it, I don't have 15 posts yet so I can't post links.

images.lowes.com/product/736223/736223155837.jpg

[Rich]

That vent in particular is good for 212 sf of attic space. If you have 2000 sf of attic area - you will need at least 9 to meet code.

[Rich]

http://www.lowes.com/lowes/lkn?actio...-10065-RVG55BR
is actual link to product.

[MOM]

Thanks all, I found this on the prints:

TOTAL NET FREE VENTILATION AREA SHALL NOT BE LESS THAN 1/150 OF THE AREA OF SPACE VENTILATED. (FBCR 2004. SECTION R806.2

SOFFIT VENTILATION

ALSCO - QUAD 4 VENTED SOFFIT (16" WIDE = 26.1 SI/LF)
26.1 SI /1.34' = 19.5 SI/LF PER 12" WIDE SOFFIT

CALCULATIONS
2046 SF /150 = 13.64 SF VENTILATION REQUIRED

SOFFIT:

192 LF SOFFIT VENT @ 19.5 SI/LF = 3744 SI
3373.5 SI /144 SI PER SF = 23.42 SF ACTUAL

NOTE:

SOFFIT ALONE SATISFIES FBCR 2004. RIDGE AND OFF-RIDGE
VENTS SHOWN ON THE ELEVATION SHEET ARE TO BE INSTALLED
AND ACT AS INCREASED VENTILATION ABOVE AND BEYOND THE
CODE REQUIREMENTS

[Rich]

Here is the actual code reference
R806.2 Minimum area. The total net free ventilating area
shall not be less than 1/150 of the area of the space ventilated
except that reduction of the total area to 1/300 is permitted, provided
that at least 50 percent and not more than 80 percent of
the required ventilating area is provided by ventilators located
in the upper portion of the space to be ventilated at least 3 feet
(914 mm) above the eave or cornice vents with the balance of
the required ventilation provided by eave or cornice vents. As
an alternative, the net free cross-ventilation area may be
reduced to 1/300 when a vapor barrier having a transmission rate
not exceeding 1 perm (5.7 × 10-11 kg/s ⋅ m2 ⋅ Pa) is installed on
the warm-in-winter side of the ceiling.

[Rich]

I've always used the 1/150 of the area and split it between soffit and roof/ridge vents.

[MOM]

FCBR 2004 isn't referring to the year of the code is it?

[Rich]

Most likely the year they adopted them - it would've been the 2003 codes. Codes are updated every 3 years. 2003, 2006, 2009 is the most current but they probably won't be adopted for a couple years yet. Many places have just adopted the 2006 codes.

[MOM]

So how much am I lacking for exhaust here with just the 4 units. I'm guessing the only way they got away with just soffit for venting is crossflow?

OK, so I have 848 worth of exhaust and need 1023 (half of the total), So I'm only lacking 175, basically 1 vent.

With the intake being more than enough (soffit area) and the fact that it's a two-story house on a lake, with a constant breeze, I'm thinking I should be OK due to crossflow venting right? Add to the fact that that my hip roof has four sides and the sun should only be hitting 2 sides at any time?

The latest codes I'm showing at my County's website are 2007. I was told that my house had to conform to the latest ones, which is why I got screwed out of the arched windows my initial renderings had.

[Rich]

Hmmm... 2007 isn't a published code year. Unless it's the year they made amendments to it.

Either way, I don't believe the 1/150 ratio has changed in many years.

I'm not sure how you would get crossflow venting on a hip roof. Typically crossflow venting happens in gable ends with gable end vents. I would check with your local building inspector - they may have amended a code that may change the total area required. I know our local jurisdiction has amended many codes to include fire-wise construction. This wreaks havoc on our venting, because they do not allow soffit vents in fire-wise construction.

[Rich]

You lost arched windows due to a code? I don't believe they put stipulations on the shape of windows. Maybe the ratio of window area to floor area was too high for the IECC codes?

[MOM]

I believe it was some fire code, but your last statement sounds familiar.