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Discussion Starter · #1 ·
Any suggestions to cool down a attic that's been converted to a second floor?

Attic is converted and roughed in for a second floor. It gets to be about 140 degrees in the summer. There still are two turbines on the ceiling one, on each end of the second floor. Second floor is about 600 square feet, with A frame ceilings extending up to about 12'.

Walls have been furred out at about 5'. There is a 3 ton unit cooling the downstairs. Am in the process of connecting the downstairs central air ducting with the upstairs to not have to buy another central unit for the upstairs. The central air unit, and the plenum are directly downstairs from where the location is of the upstairs. So I've cut holes in the plenum and added 10" hardpipe ducting for upstairs. Once upstairs, the 10" piping is converted to 7". Everything is still in works so changes can be made. It costs a lot to run the air to keep both floors cool, when usually only the top floor or the bottom floor needs to be heated or cooled. Also I'm in the South. A lot of humidity and moisture. I am underneath a 100' tree.

What type of attic fan do I need, or ceiling fan should I install. Also the electrical is in the process of being upgraded from a 100amp to a 200 amp system, so it is all changeable at this time.

Any suggestions to cool down a attic that's been converted to a second floor?

A couple of heating and air specialists said another central air unit is needed to cool the upstairs due to the size of the square footage of the ceiling space. Dollars don't make this possible.


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A mini split would have been the way to go.

How well did the 3 ton cool before you finnished and added this area.
It may not be big enough.

I doubt reducing to 7" was a good thing to do.
When you find out it doesn't cool right. It will be a bit too late to increae it again.

I'd run the 10" all the way.
Its easier to close down a damper if the 10" is too big. The to reopen things later.
 

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You might want to consider reflective film inside the roof sheathing before you insulate. And double check that the insulation ventillation is appropriate (doesn't sound like it will be - should should have a roof vent and vent sleeves). On the upside, an undersized system will remove the humidity nicely!
 

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Discussion Starter · #5 ·
Attic converted to be second floor A frame shape

Where are you located?
How much insulation did you/are you installing?
No ridge vent ?, what about soffit vents?
Thanks, for the response, am much appreciative for all suggestions. I'm in Hot Springs, Arkansas where it's really hot and humid in the summer and wet and cold in the winter.
The attic with an A frame, on both ends, has walls that are roughed in and furred to be 5' on each side. Where the walls have been furrred out that is where the hard pipe is lying on the floor which connects the upstairs to the downstairs central air. There are two turbines, one on each end. The rafters are original and true 2 x 4s. I've not put any insulation, or sheet rock upstairs, until the heating solution is found. When I redid the roof, I put white cedar for the soffits, but didn't put any soffit vents..., which I'll probably will put in? Every so two feet or so right?
 

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Discussion Starter · #6 ·
A mini split would have been the way to go.

How well did the 3 ton cool before you finnished and added this area.
It may not be big enough.

I doubt reducing to 7" was a good thing to do.
When you find out it doesn't cool right. It will be a bit too late to increae it again.

I'd run the 10" all the way.
Its easier to close down a damper if the 10" is too big. The to reopen things later.[/quote

The upstairs was never finished as far as the insulation and sheetrock. When the air ran, in the summer when it was really hot, it didn't seem to cool the upstairs down. Although, downstairs it did feel cool.
 

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Discussion Starter · #7 ·
Rafters are true 2 x 4s... cant use reflective film not enough room for insulation

You might want to consider reflective film inside the roof sheathing before you insulate. And double check that the insulation ventillation is appropriate (doesn't sound like it will be - should should have a roof vent and vent sleeves). On the upside, an undersized system will remove the humidity nicely!
I believe I can't use reflective film because the rafters are true 2 x 4s and after putting the insulation and sheetrock, there will not be enough air space, which needs to be 1/2" to 3/4" space where the insulation sits. That's what top foil said, that there needs to be an air space.
 

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I believe I can't use reflective film because the rafters are true 2 x 4s and after putting the insulation and sheetrock, there will not be enough air space, which needs to be 1/2" to 3/4" space where the insulation sits. That's what top foil said, that there needs to be an air space.
Yes, that's what the vent sleves are for. They go between the roof/reflective film and the insulation to provide about a 1" space. They're usually made out of a plastic material with a cross sectional shape as follows:
_______ Roofing

\_____/ Sleve
======
====== Insulation
 

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I would have built out from those 2x4 rafters to allow more insulation. I have R30 & R38 in my cathedral ceilings
Heatig & cooling will be effected by how much (or how little) insulation is installed

Rafter vents:

 

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Discussion Starter · #10 ·
putting about two inches of insulation with 5/8" sheet rock

In finishing the second floor, which was a attic and now is a living space with two turbines, cathedral ceilings, and rafters that are true 2 x4s. A friend suggested to just put insulation between the rafters, and use a thicker sheetrock of 5/8" to help insulated it. He also said to cover the two turbines with sheet rock. Hard pipe pipe is run which attaches to the central air unit downstairs. It is 10" running up, and then get downsized to 7". Any suggestions for helping with the hot summer months in the humid south?




I would have built out from those 2x4 rafters to allow more insulation. I have R30 & R38 in my cathedral ceilings
Heatig & cooling will be effected by how much (or how little) insulation is installed

Rafter vents:

 

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Discussion Starter · #11 ·
Hi there,

Nice shots, I understand now. I'll try and take some pictures today of mine..., and will post them this afternoon, but my cathedral ceilings are the actual ceiling. There is a lot of space on top above where the can lights are positioned. Are you suggesting to put 2 x 6s next to the ceiling rafters 2 x 4s, in order to fur it out to have more room to put the reflective stuff allowing dead air space with that plastic stuff you're showing in the picture and r30 insulation?
 

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Discussion Starter · #13 ·
Attic converted to living space how to insulate

Attached are some pictures of the converted attic to second floor. Two rooms about 600 square feet, walls have been furred out to be five feet.

I would have built out from those 2x4 rafters to allow more insulation. I have R30 & R38 in my cathedral ceilings
Heatig & cooling will be effected by how much (or how little) insulation is installed

Rafter vents:

 

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Does R13 in a 2x4 roof meet remodelling codes? What about the 2x4 rafters, do they meet code? Sistering the 2x6 or 2x8s to the existing 2x4 rafters souds like a great idea but I think it should have been done before the knee walls went in :(
 

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R13 meets code for walls, not for ceilings
I put R19 in my walls, R30 or R38 in the ceiling
Heating/cooling costs are not going down
Pay now & do it right, or pay every year

2x4's meeting code:
Depends upon the span they cover
ANd how far apart they are - 16" OC, 24" OC or ?
 

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Discussion Starter · #16 ·
Attic converted to living space cooling problem

I'm a bit confused... Dave: Your saying, you put in R19 insulation for the walls, and R30 & R 38 in the ceiling, and your energy bills did not go down?

Wow, I was only going to put insulation thick of about 4" thick, the width of the true 2 x 4 rafters. I'll look and see how thick the R30 is, and will measure the rafters, but Dave you're saying it didn't help, with keeping the temperature more moderate? Dave what are suggesting to do it right? It's hard because of the shape of the rooms with the cathedral ceilings, because the wider you fur out the studs, the more head room your losing, and since the walls have been furred out the code of 5' the closer you get to the walls you head space is affected. More on the smaller room than the larger.

sktn77a has interesting comments. Can't do anything about the knee walls, there alrealy built. I were to sister the 2 x 4s to 2 x 6s or 2 x 8s, maybe I could do it, just on the upper part of the structure about 6' to allow for the head space?

R13 meets code for walls, not for ceilings
I put R19 in my walls, R30 or R38 in the ceiling
Heating/cooling costs are not going down
Pay now & do it right, or pay every year

2x4's meeting code:
Depends upon the span they cover
ANd how far apart they are - 16" OC, 24" OC or ?
 

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I think what Dave was saying is that in general, the costs of heating/cooling will never go down, so by insulating properly now, you will save in the long run.

I can see why you thought his costs did not drop, but I am sure his insulation efforts will more than pay for themselves.

Rebuilder Girl, just a comment regarding your project. I know your original question was regarding HVAC. Be patient and get the structure and insulation done properly first as the guys have indicated. I know it may take longer and cost a bit more money up front. But in the long run you will save yourself tons of money over trying to air condition a space that is really like an oven.

Keep us posted on your project.
 

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Discussion Starter · #18 ·
How to sister fur out 2 x 4 rafters to 2x8s with roof caps blocking

Alright drtbk4ever...thanks for the input always appreciative. I understood what Dave said, or okay now I get it, Dave would have like it better had he put more insulation in, because the energy costs are not going down.

It's such a hardship because the cathedral ceilings are at 8'8" with the walls being furred out to 5.' And in the other room, the ceiling is only about 6.' I'm thinking of how to fur out the true 2 x4s as I was in the oven today, and noticed nails and roofing nails that hold down the roofing felt paper are poking through the ceiling sheathing on the inside. If I try to sister fur out the 2x4 stud so it's wider, some nails & roofing caps about 1/2"to 1/4" will be in the way. I'm sure it would be possible to force the new stud next to it, but it will most likely push the nails back towards the outside of the roof where the shingles are and would cause problems with the new roof. Not all new decking, just where it was rotted out, but all new felt paper and architectural shingles. Any suggestions for this stump in the road?

I think what Dave was saying is that in general, the costs of heating/cooling will never go down, so by insulating properly now, you will save in the long run.

I can see why you thought his costs did not drop, but I am sure his insulation efforts will more than pay for themselves.

Rebuilder Girl, just a comment regarding your project. I know your original question was regarding HVAC. Be patient and get the structure and insulation done properly first as the guys have indicated. I know it may take longer and cost a bit more money up front. But in the long run you will save yourself tons of money over trying to air condition a space that is really like an oven.

Keep us posted on your project.
 

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Rebuilder Girl,

I am not an expert so take my advice with a grain of salt.

Assuming the 2X4 rafters are sounds structurally, instead of sistering the rafters, could you put furring strip either along the 2X4 rafters or across the rafters. This will give you a little extra space for the insulation and rafter vents. Yes you will lose a little more head room. But what good is head room if you can live in the space.

Here is a link on Furring strips in the How to section.
http://www.diychatroom.com/f98/hows-whys-furring-strips-part-1-a-44090/

Perhaps an expert can weigh in as to the validity of my suggestions.
 

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It's such a hardship
If you're going to move [within the average 7 years] to a new house, it may be worth it not to insulate.
Paybacks longer than 10 years are probably impractical.

Run some numbers based on current heat loss vs. what you could be getting in the future by expending XX time and labor and money in the present.
The economic term is "present value of an annuity" the annuity being what you won't spend on cooling a lossy space.
 
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