Tyvek Under 1/4in Foam For Vinyl Siding?

Ranzan

Exactly my point Tom

Guys are going to use what they want and so be it as far as I`m concerned

I myself think a house is wrapped to tight nowadays no breathing ... but some will dissagree and that`s okay by me as well

easy sider

Your local Permit Center would have some one available to answer any question about what product is acceptable to use in your area for a barrier under the siding to be used. As a building professional you should know what product is being used in your area.

Foam sheathings have little R value but do help reduce thermal bridging and are commonly applied over barrier wraps.

kansas-builder

Absolutely, however that thermal bridging effect may be greater you might think. Look at the differences between 2x4 w/R11 and 2x6 24" OC
foam-tech.com/theory/whole_wall_rvalue.htm and
building.dow.com/europe/mk/applications/tmlbridges/index.htm
I am also interested in trying the product (or similar) from these folks - thermablok.com but I think that the labor/benefit may offset use - although I do like the idea for internal sound reduction - there are some stud clips to minimize sound xfer through interior walls, this product may do same and work more easily.

I do not wish to cast all building code folks in a negative light but they are looking at "does the car have 4 wheels" ? Yep .. its good to go and not ask if I plan on driving in snow/ice/road race/offroad.

Want to call your local building code people and ask them about radiant barriers in the attic ? Or even OSB w/foil attached.
There is a difference between meeting code and being best practices. They do not always align or even come close. When my city was adopting ( and the cities around here as well ) the 2006 ICC Building Code do you know who was the strongest opponent of it ? The Kansas City Home Builders Association. Huh - Wonder why ? In a public meeting they even denied knowledge or existence of LEED certification in residential construction.

When _I_ build it _I_ want it built the way _I_ would want to live in it for the next 20 or 40 years. It only takes a 5 minute trip to any other construction site in my city to see the differences that I am talking about. I especially like showing houses that are being built with the walls standing up - how are you going to get that straight/plumb and well wrapped standing up ?

When you put in a tankless hot water heater do you also add a small high efficiency electric heater like the Fine Home Building article a few years ago talks about ? Code guy was concerned about having a drip pan around the heater - not if it was insulated with 1" of foam or 3" and if the tankless was variable gas flow or just off/on or if the hot water lines were run with foam insulation to minimize heat loss in an unfinished basement.

How about ridge venting on new roofs versus turtle vents ?
Both are code but which one less likely to leak ? Which one is easier to repair after 10 years ? Which one is easier to install ? ( I don't like holes in my roofs ).

easy sider

Thicker vinyl sidings, .046 and greater, usally don't have a problem with thermal bridging, with or without foam under layment.

Worknguy

The main thing to consider with foam board on the exterior side of the sheathing is proper thickness for the climate zone you are building in. I live in Massachusetts and the minimum r-value for this zone is R 5. Considering that the majority of foam board products are approx. R 3.6 per inch, We would need to use 1.5 inch foam here in Mass to meet the standard. The danger of of using foam that is too thin is that the wall is not kept warm enough to offset the detrimental effect of the now reduced ability of the sheathing to dry to the exterior due to the low permeability of the foam. Warm air leakage from inside the heated home during the winter months into the wall cavity will form frost when it reaches the freezing cold sheathing. This moisture will collect (in the form of frost) over the winter and then be drawn out during the summer months and usually (emphasis on usually!) does not do much harm, unless it CAN'T be drawn out due to the layer of foam. So unless the foam is thick enough to prevent the interior side of the sheathing from becoming freezing cold, don't bother installing it, you'll do more harm than good. Although I agree that 1/4" fanfold does a nice nice job of hiding irregularities when installing vinyl over existing surfaces it is a very bad practice in colder climates. My humble opinion.

Willy is

Great thread thank you all. -W