My second story of my house is 'unfinished'. It has everything but drywall. The house is basically a ranch style house in the shape of a rectangle...literally.

So...the upstairs has a kneewall about 4-5' high and then goes up to a 8 foot cieling. Everything is insulated.

My question is...is it enough and how do I calculate it? All of my walls are insulated to R13...and the second story floor is insulated to R19 I think...all batting. None of that can be changed and doesnt matter. But the second story cieling has R13 or so...and then there is batting between teh roof joists that is R19...I think.

So... is this enough? Do you simply add the cieling and the roof to get the value or does the roof need a much higher value on its own? its a metal galvalume roof on tech shield radiant barrier decking, if that matters. Im asking because NOW is the time to consider adding more or redoing with closed cell spray in...which I am a huge fan, but im not interested if its not necessary.

Also...my downstairs has all 9 or 10 foot cielings. Is if customary for an upstairs to have 8 foot cielings instead of 10' to match the first floor?

I need to check my R-values when I get home, but my questions still are valid mostly.

[This message has been edited by BrazosDog02 (edited 1/10/2012 2:57p).]

R-13 in walls and R-19 in what's called a "Cold ceiling" is minimum code in TX.

If I'm understanding you right, the second story of your house goes right up to the roofline and there's no attic whatsoever.

Unfortunately, if you want to put more than R-19 in, even with spray foam, it depends on the size of your rafters. There just isn't space between 2x6s for more than R-19 unless you compress it, in which case you lose most of the insulating ability. Open-cell spray foam or flash-and-batt techniques can't deliver a higher value, either, and god forbid you ever try to trace a roof leak if you spray foam right on the underside of the roof deck.

If you have any attic space at all, or have 2x10 rafters, you should be putting in at least R-30. If you have a big open attic like most houses in TX, you should be putting in R-50 or so of blow-in, or R-30 batts with another couple inches of blow-in on top of it.

It's up to you to do the math on the return on investment. If I had to do it over again, I would fir out a cold ceiling using a resilient metal channel that'd be attached crosswise to the rafters, which would not only allow me to completely thermally break the drywall from the roof surface, but would provide an extra couple of critical inches for insulation.

[This message has been edited by superspeck (edited 1/10/2012 9:03p).]

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Also...my downstairs has all 9 or 10 foot cielings. Is if customary for an upstairs to have 8 foot cielings instead of 10' to match the first floor?

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Yeah, it is. The 10 foot ceilings are intended to be used in the areas of the house that are for show or where you spend most of your time living, and the 8' ceilings are intended for 'private' family areas or for sleeping/utility use only.

OK...here we go with a piss poor cross sectional drawing. This is what the house looks like from end to end aside from a few true dormers, but those arent an issue. Blue is where R11 is between rafters and Red is where R19 is.



This should at least help with what I mean. I do have a pretty sizable area that is 2x10 roof joists and then roof....as you can see. How do I address this to get the proper or best R-value? Its the area that is highlighted in orange with a "?". Would closed cell spray insulation be OK or would you recommend against it in just this portion (in regards to roof leak tracing, all metal roof on top, if that matters).

As for the actual area that has attic space in the top, how is the best way to get it properly insulated? Big fat ass batting rolled across the cieling? This area is pretty much a space to run large gauge and wires that go to the other side of the house. Theres a big bundle in the middle and decking to walk.

AS I said, this upstairs is unfinished, so I have a chance to make it right or do it.

Why r30 was not used in the rafters I don't know. It should be noted that since they didn't, there is a small space between the deck and insulation which allows air to flow from the soffits to the ridge vents. Filling those roof rafters and the area highlighted will cut off any air flow to the ridge vents. Where that little attic space will draw air from once it's finished off, I don't know. Dormer soffits I supp

[This message has been edited by Brazosdog02 (edited 1/11/2012 12:03a).]

[This message has been edited by Brazosdog02 (edited 1/11/2012 12:04a).]

[This message has been edited by Brazosdog02 (edited 1/11/2012 12:05a).]

Thanks! A picture's really worth a thousand words.

In return...



You've got a bunch of insulation in places you don't need, and not enough in places where you really do need it. I don't understand the logic of putting insulation in the space over the porch. There should be no need if that's actually attic. I also don't understand why your roof deck is insulated. This also makes no sense and can actually actively harm your roof surface... there should be air flowing along the bottom of your roof deck to help cool it.

One big thing you need to pay attention to with this design is ventilation. You MUST ventilate all of the attic spaces. If you don't, you bring the insulation up to the ambient temperature of the attic and it is less effective... Careful to keep the air coming in from one direction, though, and venting out the top. If you put loose fill or R-30 in, definitely install baffles. I like the Berger Accuvent the best.

[This message has been edited by superspeck (edited 1/11/2012 9:55a).]

I dont think the porch area is actually insulated..i just kinda drew it out.

The roof rafters are...why, I have no clue whatsoever. Now, I could take all of that down and put it on the cieling, its just stapled in place.

I am going to probably have insulation bown in, will a regular insulation company be knowledgable enough to tell me where I should REMOVE insulation and ADD more like you have done?

The way they put in insulation, as in R19, there is a very clear and open 'path' between the insulation and roof decking, since they are 2x10. That creates an air flow channel, and that may be why they did not use heavier insulation. You still get air moving beneath the roof, but there is a thermal break via insulation...i dunno. The rest of the attic is vented through the ridge vent and the dormer soffits...so that's OK.

Looks like all I really need to do is simply add more to the ceiling.

Now, my living room on the first floor is about in the center of this 'rectangle house' and it goes all the way to the roofline through the second story. That area has to be insulated, but its literally drywall, insulation, decking, metal roof. the cieling is the roof rafter. As I understand, its done the same way, 2x10 but with R19 insulation, creating some insulation, but also air flow to the ridge vent.

From what I can tell, with 2x10, and the cieling being the roofline, there is not solution to having proper R-value AND airflow, like I have now.

However, several sites and science studies recommend that my living room cavity between the drywall and decking be completely and densely filled, cutting off all airflow to properly insulate it.

For my area with the question mark, I think I will take that short section out, install a decking vent baffle type thing, and then pack that cavity with R-30 or better. That will allow the most insulation and still adequate venting between the two open cavities of the porch and actual attic.

[This message has been edited by BrazosDog02 (edited 1/11/2012 11:24a).]

Yeah. That area in your living room, and the area I labeled R-19 on top of the 2nd floor where the walls and the roof meets, are what's called a "cold ceiling" and it's allowed / supposed to be that way. You don't want to densely pack it, but you should have more than R-19 if it's 2x10. R-19 is the code minimum, but R-25 or R-30 is preferable in those areas if you have the space.

But from what I understand, your cold ceiling in your living room is vented at the peak and probably also at the soffits. This isn't ideal to have just R-19 in there and no protective channel... It's probably fine, don't change it, but you'd need something similar to the Berger Accuvents in there to form an actual channel and it'd be better to have an actual thermal break between the rafters and the ceiling. If you notice that room being cold in winter or warm in summer and it really bugs you, I'd do something about it. If you *just* have the peak vented and not the soffits, you have a problem. If you *just* have the soffits vented and not the peak, you have a problem. With both vented and just R-19, it's OK, just not ideal.

There's absolutely no reason to insulate the roof deck in the attic where there's no drywall. Really. No reason. It can screw a lot of stuff up if the house isn't designed for it, and it sounds like you've got a conventional design. It forms a separate zone that isn't conditioned, that has a vapor barrier, and where the air doesn't circulate. Tear it down...

The other thing is, note the place where I put R-30 on the walls of the 2nd story. That really should get done.

Yeah, a company that does insulation professionally would be able to tell you this, although I'd be concerned if they don't follow what I've said above. I DIY everything, and I've spent a lot of time studying websites and back issues of Fine Homebuilding and JLC to be able to answer questions like this in my own homes, and to be able to spot things like this in friends' homes.

[This message has been edited by superspeck (edited 1/11/2012 11:36a).]

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There's absolutely no reason to insulate the roof deck in the attic where there's no drywall. Really. No reason. It can screw a lot of stuff up if the house isn't designed for it, and it sounds like you've got a conventional design. It forms a separate zone that isn't conditioned, that has a vapor barrier, and where the air doesn't circulate. Tear it down...

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I assume you mean the attic space....which is between the second floor cieling and the roof...air space between two sets of insulation. If so, this area DOES circulate air to the ridge vent because there are dormers in the second story, big ones, that have soffit vents. I don't mind tearing down insulation, but not if I don't have to.

If you mean the area directly under the decking, that air is circulated by soffits on the porch and an air space...just like the cathedral cieling.

EDIT: thanks for the pic. At work it doesnt show up, so I didnt realize it was there. Im looking at it on my phone now.

Based on your drawing, the R19 sections on the second story cieling need to be R30...thats fine, I can do that myself, but the problem is, filling those cavities will cut off air flow from the continuous soffits on the porch and up those cavities all the way to the ridge. So, in just that section, I was thinking to put some waffle board they sell on the site you linked and THEN pack that thing full of R30. This way, I get my decking airflow without tearing all my insulation down. And since I havent shown the dormer setup or any other stuff, im concerned im leaving out a key item that may justify it...maybe not. Im concerned with tearing it out between the roof rafters...is there any design at all you can think of that justify its being there? Its a lot of expense and effort to go through if it wasnt needed and im worried they knew something I dont.

BTW, what program are you using to draw that image. If its handy, I could whip up a much better and more accurate drawing. I think yours is pretty close to illustrating what you mean though. I just want to make sure im addressing everything.

My downstairs exterior walls are 12" poured concrete faced and backed with styrofoam forms and a limestome.

I too will be DIY nearly the whole project except signing off on electrical and HVAC installation. I have only started to research the insulation issue and everything you have said makes complete sense. and my initial thoughts to some of the insulation was "why the f--- did they do that?" but i wanted to check here in case there was something I am not aware of....which is the case for the cold ceiling, but not the roof rafter cavities. My other time will be spent researching proper framing techniques and carpentry.

[This message has been edited by BrazosDog02 (edited 1/11/2012 12:03p).]

[This message has been edited by BrazosDog02 (edited 1/11/2012 12:07p).]

The way you have me doing it, taking it out of the roof rafters, saves me money. I'm going to take the facing off and put the fiberglass in the ceiling.

I think they did it for noise insulation though. Metal roofs are loud.

Superspeck....would it be inappropriate to use something like this:

http://www.homedepot.com/Building-Materials-Insulation-Sheathings/h_d1/N-5yc1vZbaxx/R-100317820/h_d2/ProductDisplay?langId=-1&storeId=10051&catalogId=10053

Id actually like to use it on the inside of my knee wall, OR the bottom of the roof rafters in that kneewall area. It would allow for air flow if attached to the rafters. But...is it acceptable?

Sorry I didn't see your responses earlier.

The program I used was OmniGraffle; it's a basic drawing/diagramming program similar to Microsoft Visio but for the Mac.

Re: insulation on the roof decking -- My thinking is that they did it for sound, just like you pointed out. The noise is one reason I wouldn't do uncoated metal roofing for my own home, despite all the maintenance and energy benefits. Then again, there are a lot of people that really think that insulating the underside of your decking keeps the roof cooler. I disgaree with that, and I did a bunch of my learning from http://www.buildingscience.com/index_html ... a lot of their info is focused on colder climates than ours, but I think insulation and ventilation are just as important down here even if we don't have to deal with ice dams as much. Anyway. No, I can't see a specific use for attaching insulation to the roof deck besides sound muffling.

Careful when you're packing in the stuff where I have R-19 labeled that you don't compress the insulation. Insulation needs to be fluffy. If you are compressing it, you will reduce the R value. How much space do you have after the baffle? this handy chart shows you average insulation values by material.

I don't have a qualified opinion on the polyiso foam. It's not a product that I've used before or considered using in an attic application. I have considered using it to form a thermal break over sheathing but before siding, but decided not to since I couldn't do it around the entire house.

[This message has been edited by BrazosDog02 (edited 1/11/2013 11:33a).]

Ok superspeck, I'm going with your suggestion but have an additional question. I have attached a better more correct layout.



Part A and B is what I am doing based on your recommendation. Now. I'm still confused about this cold cieling (top portion of part C). I NEED R30 according to you and the code. I have R19. It is a 2x10 rafter, and it abosolutely requires air space behind the insulation for air flow from the soffits out on the porches. You suggested firring it out to make it a little thicker, I can do this, but is there something I can ADD to the R19 already there, because it already has baffling behind it, and I dont want to remove it. Is there something I can add to my setup here to get to R30. Keep in mind I have metal roofing and tech shield decking if that matters.

What about for the lower arrow of part C? That probably needs to be R30 as well, with air flow requirements too. On top of that, I want to make Part D my storage space with access from within the rooms. How should I tackle that? Make it unairconditioned? Condition it? What about the insulation? Its probably going to hold items that I normally would put in an attic.

The porches have a continuous soffitt vent.


Sorry again for the frustration. Like I said before, Ive had spray foam guys out, ive had a few standard insulation and attic ventilation guys out and I have gotten everything from 'what you have is more than adequate' to 'you should spray foam and remove all this stuff' to 'finish it off like it is, and we can come out with a heat gun and see how it performs and add if we need'. Im pretty sure that spray foam is going to be a complete and total waste of money here, but it sure sounded nice. I think I can spend a LITTLE money here with adding insulation to what I have and save all the cost of spray foam and replace 3 pairs of leaky french doors downstairs for efficiency. Probably be a far better use of that money.

[This message has been edited by BrazosDog02 (edited 1/11/2013 11:38a).]

You need a minimum 1.5 inches between the rafters and insulation for venting up to the ridge vent.
R30 is 10.25 inches deep. What is often done is the rafter are furred out 1.5 inches with ripped 2x4 to gain airflow clearance. In your case it would only give to 10.75 inches of clearance and only 1/2 inch for airflow with r30 in the rafters so not a good idea. I have never seen anyone put r30 in the knee walls. It could not hurt anything but will hang out the back 5-7 inches and give the mice something to chew on. What is usually done is if they are 2x4 you put in r13 or r19 if 2x6 and then on the backside of the wall you install the foil celotex like you posted a link to above and then tape all of the seams with foil tape. 3/4 inch celotex will add an additional r4 to whatever r value is in the wall. For the 2x8 ceiling I would put in minimum r30 but be careful where the ceiling joists meets the rafters so that you are maintaining 1.5 inches for air to flow through.

[This message has been edited by JP76 (edited 1/11/2013 1:37p).]

[This message has been edited by JP76 (edited 1/11/2013 1:39p).]

Wait, for the cold ceiling part, they are 2x10 joists. So, what you said basically says I can't get R30 in there, even if I fir it out as you described since I need the clearance for airflow..... So what is the solution? This is the area noted as 'C' on my drawing. Its a 2x10 roof rafter with decking. It is the roofline. Im confused still as to how to get R30 requirement while maintaining enough clearance for air flow.

Maybe im being really dense here.

Also:

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You need a minimum 1.5 inches between the rafters and insulation for venting up to the ridge vent.

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Did you mean this or did you mean between the DECKING and the insulation?

[This message has been edited by BrazosDog02 (edited 1/11/2013 2:12p).]

Is the existing decking techshield with foil on the inside ? If so then r19 will be fine and it will give you about 3 inches of clearance to pull the outside air through the soffit vents. If you fur it out 1.5 inches and put 30 you will gain r value but kill your airflow and basically render the soffit/ridge vents useless which will then make the attic area above the 2x8 joists even hotter.

1.5 inches between the back of the insulation fully expanded and the underside of the decking on the angled ceiling part.

Yes, teh existing decking is techshield with foil inside. Then there is an airgap, then R19 insulation.

So, for my angled ceiling, im back to doing nothing? With tech shield, and R19, with an air space for air flow to the soffits....its good enough?

I think I will carry that vaulted cieling down over that storage space so that I can essentially get that storage space into the 'air conditioned' side. Will be better for storage, and on the other side of the house, the HVAC is in that space....and that will be good too.

[This message has been edited by BrazosDog02 (edited 1/11/2013 2:41p).]

In the angled ceiling portion you really can't do much unless you want to rip the drywall down sister some additional rafters on the side to make a larger area than the 2x6 rafters and shove more insulation in. The cheapest to do in that section is to simply add 2 layers of foam board to the rafters and add the sheetrock back on.

Yeah, I dunno. There is a lot to remove or add to. I may just leave it R19 with the airflow behind it and call it good. R19 to R30 on a metal roof and radiant barrier is probably not going to result in ANY gain for what it will cost.

If I go with hard foamboard, I will need to remove the facing on my insulation before attaching foamboard to the joists and drywalling it.

[This message has been edited by BrazosDog02 (edited 1/15/2013 3:01p).]