Insulating walls, ceilings and/or roofs???

[Rumi in Hawaii]

Are folks having any problems with insects or mold or dampness or rodents in fiberglass batts? What R factors are recommended, say in Mountain View elevation, for insulation? Anyone perfer radiant barrier insulation for the roof? Any problems with that? Anyone recommending single wall construction over double wall, and pros and cons????? Seems like I've heard that, altho electric lines are visible in single wall construction, that it eliminates the above mentioned possible problems, i.e., termites being undetected, mold going unnoticed...??? We're still in the planning stages here, so open to suggestions. Mahalo, and hope your day is lovely - we're staying in Ainaloa, and it's cloudy, but wonderful...

Katie and David

Wherever you go, there you are.

[Kapohocat]

Might also want to check with your insurance company about insuring single wall construction. I think that as of last summer most companies are declining insurance on single wall.

The radient barrier has gotten some good review other than cost. Also **Rob Tucker's** company has some insulated roofing that seems to do a very good job.

Catherine Dumond
Blue Water Project Management
808 217-7578
http://bluewaterpm.125mb.com/index.html
"We help make building your dream home a reality"

[oink]

I have radiant barrier, in addition to fiberglass in my attic. The radiant barrier works very well (worked) and keeps the attic temperature down in the attic. The barrier I have is a fiber reinforced foil coated paper that must work in conjunction with adequate soffit vents and ridge or peak ventilation. Mine is 18 YOA and although there has probably been improvements, my experience was that high cyclone winds can force enough wind through the attic to rip out much of the radiant barrier.

S. FL Islander to be

Edited by - oink on 02/09/2007 09:08:02

[Rose C]

Our daughter's insurance company told them that if they dropped their hurricane insurance they could not get it back if their house was single wall construction or built prior to 1983. This only applied to the hurricane insurance.



Rose C

[kyosan]

I'm not living in Hawaii yet but am thinking about how to build there like you. My property is just below Mountain View at just over 1300 ft.If you're building in Mountain View you probably want to have a fair amount of insulation because it can get cold there. At my elevation it can drop down into the low 50's on cold winter nights.

Unfaced fiberglass batt is good in the respect that it has high water vapor permeance; that will help the walls dry out inside. Foam insulation board isn't nearly as breathable so if you have thick foam on the outside of the frame the walls won't dry to the outside as well.

I think that if you do use fiberglass you'd have to cover both sides of the wall because you wouldn't want the fiberglass exposed.

I'm thinking about making my house with R18 (that may be more than I need). I don't intend to have any heating or cooling systems. Here's my current plan for my walls (from inside to outside):

* 1/4" fibercement panels (viroc) plastered on the inside
* 2x4 heavy duty steel studs with fiberglass insulation in the spaces (R13)
* 1/2" fibercement panels (viroc) as sheathing
* Tyvek housewrap as drainage plane
* 1" medium density EPS sheathing (R4)
* 1x4 vertical furring strips for spacing rain screen
* Fibercement clading waterproofed with penetrating (breathable) sealer on all sides
* Cover the drainage space and exposed area of EPS with aluminum screening to prevent termites/rodents/bugs from getting in.

[kyosan]

I just thought of something else. When fiberglass batts get wet they loose their ability to insulate, but rock wool batts don't (so I read). And rock wool is a better sound insulator. So rock wool sounds like a better product to use. I'm wondering if it's available on the big Island and how expensive is it compared to fiberglass.

[David M]

Kyosan
You might want to check out the ProTec product at www.castleblock.com.

It's concrete panels, foam insulation layer, metal channel structure - in an R20 package. Used it for our house and love it. Pics at: http://community.webshots.com/album/468915553RbjdnV

David

Ninole Resident

[kyosan]

Thanks David for the suggestion. I've looked into the Protec SIPS. It's nice that the wall construction is simple using them but I like my way better. I see that they use XPS (extruded polystyrene), probably 4 inches thick. XPS has a permeability of about 1.1 perms/inch which would make the permeance for 4 inches about 0.275 perms. That's not very breathable and it only counts the insulation; it doesn't count the cladding.

I plan to use medium density EPS (expanded polystyrene) which breaths better and use only an inch. One inch of medium density EPS has a permeance of about 3.5 perms. I did some calculations and expect the total permeance of my wall assembly to be just over 1 perm which is probably about 3 times more breathable than using the SIPS.

Also my assembly has more barriers to prevent water infiltration from the outside. And there's a scenario I see happening with the SIPs that I don't like (this is a wellknown problem that happens in wall assemblies):

* It rains
* The walls get wet and the concrete cladding soaks up some of the water
* The sun comes out and heats up the walls and produce water vapor
* Since the walls are warmer than the inside of the house, water vapor migrates into the walls and into the house. Much of it would be stopped by the XPS though, since it doesn't breath very well, but some of it will make it through and make the house more humid inside and some of it might condense inside the walls.

The same thing can happen with my assembly also but using back-ventilation (rain screen) and waterproofing the cladding helps prevent it from happening. It might look like I'm overdoing things but the average rainfall in Mountain View is around 200 inches/year; I don't want to have problems.

[Carey]

We are renovating a 1970's aluminum framed SIP building in Keaau that was built with fiberglass insulation. We didn't expect the amount of things that live in fiberglass here when we bought. Everything that you can think of that lives outside built nests in our walls. In the kitchen & bath walls there was mold on the facing & throughout the batting.
We do not have heating to worry about, so we have removed every bit of fiberglass, cleaned all of the framing to remove mold & detrius, placed Reflex radiant barriers on the upper ceiling (it was amazing how well that works on the sun heat...we could actually feel the difference as we were installing it). We are adding Reflex insulation to the ceiling & walls mainly for radient & sound barrier. We are also replacing the masonite sheathing with the concrete Hardi Panels, to reduce moisture damage potentials.
Aloha, Carey