Roof insulation

[peter_nap]

I am going to use a metal roof on 2x4 perlins.
I'd like to leave the rafters exposed if possible but I doubt I can.

I am thinking about installing this:
http://www.radiantguard.com/index.asp?PageAction=VIEWPROD&ProdID=37

between the perlins and rafters with no sheathing. Has anyone used it? any comments about it or suggestions?

[glenn-k]

I haven't used it but have used sandwiched insulation on metal buildings.  

I think it looks like a very good product and well suited for the way you want to use it, although I don't think it can meet your total insulation requirements if you have any codes to meet.  I can't remember your complete situation.

[peter_nap]

No codes at all Glenn.

The place is a pole barn using Johns roof system with collar ties and beams and John's post foundation for the floor. Iknow that's confusing. The pole barn is self supporting and intended for a dirt floor or slab. I have jack posts on the exterior poles that hold the ledger for the floor joists.

There is a series of posts inside the perimeter with beams across that support the floor joists and prevent any bounce. These are placed every 6'.

The roof is 20' X 52' over the lofts. It has a shed roof to either side over the rest of the building.



There is a solar chimney and earth tube system to cool the main part of the house during summer.

Everything is open except the bedroom and bath.

All power is solar, hydro and wind and there is a composting septic system.

That's pretty much it in a nutshell.

[peter_nap]

OH...I forgot Glenn,

There's a backup generator using a diesel Lister engine with a 5K generator for when my wife has to run the AC  
I'm running it of a mixture of burned motor oil, kitchen grease and farm diesel.

Nice and quiet and only 680 rpm's

[jraabe]

Peter:

Radiant barrier insulations such as foil faced bubble plastic sheets have a checkered past. They do very little to slow conductive heat flow (what normal insulation does by trapping thousands of tiny dead air pockets - this has only one or two).

The only study I know of that found a place for radiant barrier insulation such as this was one done by the Florida Solar Energy Center and it involves a reduction in cooling costs in a hot climate.

http://www.fsec.ucf.edu/en/publications/html/FSEC-EN-15/#available

This material would not normally be used as the only attic insulation (just as a reflector of radiant heat from the roof above) and would not be used at all in walls or floors.

[peter_nap]

Thanks John!
I guess I'll pass on it then since it's a little pricey anyway.
Any suggestions?

[jraabe]

The insulation details in my plans (in general fiberglass batts and good air sealing) are the most cost-effective and time-proven techniques. However, you can have special conditions (read problems) doing this in a pole building. In general pole buildings are best left uninsulated (or insulated lightly and heated occasionally such as a shop or storage building). When used as a residence these buildings can have some nasty problems with condensation in cold climates, especially when they have metal siding and roofs.

The problem is that it is almost impossible to control air leakage and this moist warm interior air loves to make water on the cold inside of the metal. The best solution is to build a well insulated and sealed interior wall. To do this inexpensively you will probably use wood framed studs. Once you do that however, you might as well throw the poles away since the wall you just built is plenty strong enough for the structural loads the posts were carrying.

Which is why the only pole structures I design anymore are cut off a foot or two above the ground and support a beam and standard framed floor, wall and roof systems above. In other words, a pole foundation (also called post and pier or pier and beam).

For a barn or utility building a full height pole structure works fine.

[peter_nap]

Thanks John. This has your post and pier foundation in addition to the poles. The floor is 36" above grade.

The Perlins on the roof are 2X4's and my thinking was that by using the vapor barrier or sheathing under the perlins, would allow enough ventilation to avoid condensation.

The real advantage to it being a pole building in this case is that I don't need a permit and am code exempt.

[peter_nap]

I re-read your post and I see that you are talking about air infiltration everywhere. The poles are on 8 fiit centers now and I have a membrane that covers the girds as well as seals under the eves.

Air infiltration isn't a problem in the walls.

The space where the joists meet the walls is getting a good dose of tiger foam and the subfloor has 30# felt.

It should be tight.

The roof is still a problem though.

[glenn-k]

There is a solar chimney and earth tube system to cool the main part of the house during summer.  

Everything is open except the bedroom and bath.

All power is solar, hydro and wind and there is a composting septic system.

OH...I forgot Glenn,

There's a backup generator using a diesel Lister engine with a 5K generator for when my wife has to run the AC  
I'm running it of a mixture of burned motor oil, kitchen grease and farm diesel.

Nice and quiet and only 680 rpm's

Sassy mentioned that I missed replying to this part, which I meant to do but got busy and forgot.

Is that one of the new Listeroids, or a real Lister?  Both great.  Also is the rest of this in or planned at this time - I'd like to know more.  We are off grid with a 1KW Bergey Wind Generator and about 2KW of solar panels.  Is your Hydro in operation - information on it?

...and you mentioned you are an electrical engineer - as is Okie BoB. Comes in handy, eh?  I had 2 years of electronics in HS.  Yep - I was considered a nerd.  Seems I even had a pocket protector a time or two, in fact -- I could really use one of those. Haven't seen one in years. :-/

Thanks

[peter_nap]

Geeze, is there anything your not up on Glenn?

It's a listeroid (all 1100 pounds of it) You should have seen me getting that on the trailer for the trip up my as yet unfinished, road! Thank the lord for front end loaders and winches!

The hydro is still being built. It;s a Turgo and I have finished welding the frame and making the box but haven't gotten the spoons for it yet. This weekend I measured the flow and head and it's better than I hoped.  The head is 37 feet where I had guessed 20 and the flow is 25 GPM and we're in a drought.

Right now I'm running a little over 1 K of solar at the camper and a Wind Generator putting out 2 amps in a 15 mph breeze. I have a bigger 3 phase unit on the bench and am almost finished with the mods for it.

Needless to say, the hydro is going to be the big producer for the place.

[peter_nap]

Here's my small ginny Glenn. It's made from a servo motor out of an elevator. (.50 at a yardsale)

[glenn-k]

I learn quite a bit about quite a few things as I get bored kind of easily.   :-/

That's cool, Peter.  I got the Poor Mans guide to Wind Power -- lots of info in it for building one.  I am a Bergey dealer but won't sell to someone who thinks it's a cure all for power so haven't sold others. We're in a marginal wind area but it helps.

I think I will build one some day -- using a PM motor of some sort for a generator.

Knight Foundry near here in Sutter Creek made a wheel they claimed was an improvement over the Pelton wheel.

Also Victor Schauberger made a water turbine that was claimed to be much more efficient thatn the Knight or Pelton wheels.

http://www.frank.germano.com/vs_waterconduit_patent.htm

[MountainDon]

Seems I even had a pocket protector a time or two, in fact -- I could really use one of those. Haven't seen one in years. :-/

I saw some at Staples last week. Almost bought one for old times sake! That and a leather cased slip-stick on yer belt and you were all set to go, back a ways.

[glenn-k]

You probably had a better slipstick...  I only had one of the cheap plastic Sterling ones.

[MountainDon]

HP and real leather.

One of my profs had an oldie with engraved ivory scales.

[peter_nap]

Well, since I started this thread, I guess we can move to the right as much as we like

One of the things I like about this site is that there are a lot of people who have a vision of a better life. I was with the states utility  commission for more years than I like to remember. I've seen the transition from the house I was born in which did not have power for several years after I was born, through the Gold Medallion homes of the 60's and the gas crisis of the 70's to the current energy dependent homes today.

I laugh when I see news stories about people having cold fusion reactors in their back yards in the near future....My feeling is, not in my lifetime.

What I do see is Half the homes having perhaps 20% supplemental solar. A much larger segment generating 50% of their power needs with wind and solar and a small but growing group that is 100% independent.

The big step that people have to make is accepting the fact that this is NOT primitive living. I do everything pff grid that I do on, ,,,,,,,,,Just differently.

I use the example of some of the guns I build. This is the last muzzleloader I built.


Did I make it using primitive technology....NO

I used a trip hammer which I built, a gas forge which I built, three belt grinders 2 of which I built. a spokeshave, a band saw, chisels most of which I built...so and so on.

The point is to make it and use alternative technology but technology that I can build and control myself.

[John_C]

" That and a leather cased slip-stick on yer belt and you were all set to go, back a ways".

You guys are dating yourselves.  No one today knows what a slide rule/slip stick was.   My daughter is a chemistry major.  She has a very cool graphing calculator.  Looks at me kinda funny when I tell her how it was done in the old days, before they invented the abacus.

[peter_nap]

I didn't have to put batteries in my slide rule either

[glenn-k]

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