460 Ford Forum banner

1 - 18 of 18 Posts

·
Registered
Joined
·
2,021 Posts
Discussion Starter #1
I am building a metal building type house. It will be a traditional metal building (metal I-beam, purlin and r-panel sheeting- muellerinc or metalmart makes these) with a 2x4 wood frame built into that metal building "shell". I was thinking about insulation and was wonder what combination of radaint barrier and batt would work best. My idea is radiant barrier on the metal outer walls and then R13 batt in the 2x4 walls. I could swap the two around, but think the first way would be better. I live in Texas and the heat off the metal outer walls is huge in the summer. Would the radiant barrier work better next to the hot metal side or in the 2x4 wood wall? In my idea the 'layers' would look like this- (out to in)- metal sheet>radiant barrier>~4" air gap (purlin)>2x4 wall with batt insulation>interior. What do you think? How would I apply a vapor barrier with this setup?

thanks
stephen
 

·
Registered
Joined
·
2,221 Posts
up here in the cold thats how they generally do it. the foil in the steel and the fiber in the wood.
Vapour always as close to the warm area as possible (imagine the outside is cold)
new-ish product i really like is the spray foam but $$$$$ no vb, no leaks....
 

·
Registered
Joined
·
443 Posts
In your area the radiant barrier will be a great thing against the metal but I would not put in the 4 inch air space this allows to many air currents and negates your insulation. I would recommend having blown insulation(cellulose or fiberglass)blown in a 4 inch cavity against the radiant barrier use batts as an absolute last case scenario. also caulk and seal EVERY hole plumbing, electric, etc in the walls ceilings and floors as well as insulating under the slab if you have one. By the way I do have a little experience I am an energy advisor at the local electric co-op.
 

·
Registered
Joined
·
2,021 Posts
Discussion Starter #4
thanks for the replies.

I thought that dead air space was a 'good insulation'?

to blow in foam insulation in that area would add alot to the cost. If I did that it would be like:
1/4" radiant barrier
4" foam
R13 2x4 batt

That would be like a cooler! I know it would be very efficient.- but costly?

I am looking for the best way to do it, but keep the cost reasonable. If your advice is the way to go, I will do it in a heartbeat.

thanks again

stephen
 

·
Registered
Joined
·
443 Posts
Ok air spacs can act as an insulation but they have to be very very small. If to large they allow air currents which reduces r-value. The foam insulation is good but you need to be very careful about what type open cell(soft) has same basic value as blown cellulose(recycled newspaper) and blown fiberglass(dense pack). the closed cell(hard) is double the r-value. Around here either will cost three times what cellulose cost. My suggestion is blown cellulose with commercial glue in it to keep it from settleing and you have to loose that 4" space put you 2X4 wall against the radiant barrier it will all work better that way. Now waht are you doing in the ceiling/roof area?
 

·
Registered
Joined
·
2,021 Posts
Discussion Starter #6
Ok air spacs can act as an insulation but they have to be very very small. If to large they allow air currents which reduces r-value. The foam insulation is good but you need to be very careful about what type open cell(soft) has same basic value as blown cellulose(recycled newspaper) and blown fiberglass(dense pack). the closed cell(hard) is double the r-value. Around here either will cost three times what cellulose cost. My suggestion is blown cellulose with commercial glue in it to keep it from settleing and you have to loose that 4" space put you 2X4 wall against the radiant barrier it will all work better that way. Now waht are you doing in the ceiling/roof area?
R25??? (2x6) ceiling joists, ridge vent, gable vents, sofit vents, and radiant barrier on roof metal
 

·
Registered
Joined
·
112 Posts
I work for a urethane foamer and would HIGHLY suggest pricing a closed cell job. I have ripped out way too many "good" fiberglass and cellulose jobs that are either soaked with water or have been. The remaining mold always tells the truth. I know someone is going to say "moisture isn't a problem if the vapor barrier is installed right", but that is rare and almost impossible. Steel buildings are the worst for condensation and the hardest to seal up. Yes, it will cost more initially but with the reduction in air infiltration, it will pay for itself over time. A few years ago a developer built two identical houses next to each other, one fiberglassed and one foamed. The heating/ cooling bill was right at half for the foam house. Not to be a know it all or an ***, but I will never insulate anything w/out urethane. Oh yeah I forgot to mention if closed cell foam gets wet, it won't soak in and it meets permiable ratings (no vapor barrier needed) Just my experiences here in Minnesota. Good luck with the new house.
 

·
Registered
Joined
·
443 Posts
Ok I am guessing you will have a flat ceiling then, go with all the vents you stated but pay the most attention to the ridge and soffit as they will do 90% of the work. For insulation I would recommend at least an r-38 blown cellulose (10 to 12 inches). I would NOT use batt insulation in the attic it will not work properly as there is to much airflow thru the insulation. keep the radiant barrier against the roof.
 

·
Registered
Joined
·
456 Posts
Up north we have issues too. My shop is 2x6 stick with metal/plywood/barrier/insul/sheetrock. Right now, my shop is the most comfortable place I have. If I keep the doors closed-2 14x10s, 1 10x10 and 2 man doors. These are all insulated ,not the high dollar doors. Granted, we do not have summers like you. Winters, well I got you beat . The insulation is bats in walls and blown cellulose in the cap. I do have double sheet on the ceiling for the fire code. Tres...
 

·
Registered
Joined
·
2,221 Posts
if you have bat insulation you want the air space.. regardless of "currents" its meant to clear the moisture that can build up in between where the cold meets the hot.. There should be little to no currents on the inside anyways.
In your case the cold meets the hot on the back side of the 2x wall on your foil, therefore you dont want your bats touching that or they'll soak up moisture thus causing mold.
 

·
Registered
Joined
·
1,309 Posts
Here is a couple pages that I found when doing some metal building research. Maybe it will help some.



http://www.insulation4less.com/foil-fiberglass-vinyl.asp

http://www.insulation4less.com/install_methods.asp

Just out of curiosity have you looked at building a pole type building like Morton Buildings or Mallett buildings?

http://www.mortonbuildings.com
http://www.mallettbuildings.com

I have a buddy in Vidor that has a Mallet building and when Rita came right through his place it had no damage at all.
 

·
Registered
Joined
·
1,990 Posts
Stephen, when I built my shop I had it insulated with the spray in foam. Even though it was expensive, it was the best money I ever spent. I don't have heat or AC in it yet, but on the hottest summer Georgia days we have it could be 100* outside, and on my thermometer inside it will read about 80-82*. I wish I had this stuff in my house, it would cut my electric bill dramatically.





 

·
Registered
Joined
·
443 Posts
I agree that foam is your best option but cost sometimes outwieghs benifit, Doug that is one of the best foam jobs I have seen most around here spray it quick and you might have 1/4 inch and you might have 3 inch but the cavity isnt full. Batt insulation DOES NOT need an air space if you look at walls done this way with an inferred camera they look almost the same as a wall with no insulation. it is correct that there is a dew point when warm meets cold if the air currents allow that to be against the metal you have condensation and a problem, but that is why you are insulating the insulation keeps the cold in the home in your case skosler hot in the home for you northern guys not against the metal siding. Look at it this way take a berr out of the fridge and it condensates on the can but if you put a can hugger on it the only place it is condensating is where the air is getting to the can. and yes i know most beers are drank fast enough to not worry about this but it is a good example. another example is windows if you have single pane windows they will condensate even with storm windows during certain times of the year but install a double pane window and the condensation goes away yes there is an airspace there but it is vacuum sealed at the factory and sometimes it is filled with a gas (argon or krypton) to be an insulator also your better windows typically have no more than 1/4 inch between the panes.
 

·
Registered
Joined
·
2,221 Posts
i dont know about DIY kits, i was wiring a house last week, they spray foamed the basement, so i took it upon myself to ask many questions. As a result they'll be coming to do my basement (at least the joist spaces) this fall. They were frequently checking it with their stick, and will let the homeowner prawd away at his own discretion. The pro stuff was also r7 per inch, but the guy told me its actually R6.98. lol anyhoo. up here they charge $1.35 per inch/square foot. Now getting to the point of the DIY. The stuff seemed to be real finicky crap. They were frequently adjusting pressures and whatnot (that may have been due to 2 different guys spraying...different preferences) and also they had their gun apart a couple times in a 1200-1500 or so square foot house's basement.. The one guy (definitly knew his ****, other guy...knew his drugs) was saying it takes a bit of getting used to to spray, its easy to get uneven spray, not enough and too much all within a said joist space.
 

·
Registered
Joined
·
443 Posts
They work but get very expensive the big kit in that link only cover 1200 sq ft of wall 1 inch thick. that is a 28 x 50 with 8 ft walls and minimum windows so with no waste you would need at least 3 kits to fill the wall cavitys.
 

·
Registered
Joined
·
431 Posts
Yeah, the spray kits work. Just remember there is two types, expandable (yellow cap) and non expandable(blue cap) The blue is for around windows and doors.

X1000 on the spray urethane. Forget all the other methods.Vapor barriors are a disapointment. One leak and you have condensation then mold. GOTTA LOCK OUT THE AIR.
My shop is getting the foam when it goes up. Especially metal buildings. They just sweat horribly. A freind has his done and swears by it.

Nice building Doug. I put one of those brand of buildings up for a guy. Went up sweet.
Regards.
al
 

·
Registered
Joined
·
112 Posts
Yeah, the spray kits work. Just remember there is two types, expandable (yellow cap) and non expandable(blue cap) The blue is for around windows and doors.

X1000 on the spray urethane. Forget all the other methods.Vapor barriors are a disapointment. One leak and you have condensation then mold. GOTTA LOCK OUT THE AIR.
My shop is getting the foam when it goes up. Especially metal buildings. They just sweat horribly. A freind has his done and swears by it.

Nice building Doug. I put one of those brand of buildings up for a guy. Went up sweet.
Regards.
al
X2 on vapor barrior. Like I said in the first post it is more expensive but with fuel prices like we saw 2 years ago, and they still aren't cheap, it WILL pay for itself. The guy from canada said $1.35 per inch there. Shop around, most are .80-.85 around my area. There is pretty good mark-up in the stuff and competition keeps the price lower.
 
1 - 18 of 18 Posts
Top