Circa 1872


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Old 03-30-13, 05:25 PM
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Circa 1872

I'm the proud owner of an old house in Mass. Albet well over 100 years old.

Its a story and a half, so the second floor has knee walls about 5 feet tall and a slanted ceiling about 7 feet in length.

Being an old house, gable vents, never mind soffit vents were not an option in 1872.
Plans are being made to bring the attic up to, I believe R-30.

Now, my issue is with the slanted ceiling section of the house. The top intersection, slant to ceiling has a 2x4 between the roof rafters, which are also
2x4. The house is mostly horsehair and plaster and the 2 by 4s between the rafters have lathes nailed to them.

When I redid one bedroom a few years ago I installed R-13 insulation in each of the slanted bays. the 2x4s are full width which leaves an air gap between the insulation and the roof.

This Spring when I will be adding insulation to the attic I will be adding gable vents. ( no vents with no insulation)

Was insulating the slanted wall a bad idea? There aren't any soffit vents and I'm almost willing to bet that there 2x4s crossing at the bottom of the slanted wall...ie road block on both ends.

If I do get insulation blown into the rest of the house, slanted walls included, will soffit vents need to somehow be installed? Or will the gable end vents serve their purpose of venting moisture out of the attic (along with heat in the summer)

I was thinking of adding a humidistat to control a fan to exhaust the attic.

Any input is appreciated.

Thanks!
 
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Old 03-30-13, 05:57 PM
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Hi reef, you have your hands full. And I would assume you are like many Americans and not made of gold . The projects you have listed and your proposed solutions are falling way short of what you need in MA. Here are some of the concerns.
1. Gable vents by themselves do very little.
2. High and low venting need an air path inbetween, but more like 2" and not the fuzzy side of the insulation and 1/2".
3. Any air flow over the top of fiberglass insulation significantly reduces its insulation value. Baffles work, but still don't provide the 2" desired.
4. If you have side attics, you need to decide where your internal envelope will be, following the rafters or across the floor and up the kneewall.
5. The attic should be closer to R-50 and air sealing should be done before everything is buried.
6. Gable or ridge vents will work for high venting, and for low, when you do not have soffits, they make fascia vents or under shingle vents.

Now, before you address all of the above, consider a "hot roof" configuration. More frequently used down south to enclose the attic where they install the hvac, it can be used up here and it eliminates all venting. I personally have little experience in the process, but with the new energy codes involving duct leakage in attics, we will be seeing it a lot more. They are called unvented attics or a hot roof.

That will get you started, but be prepared to dig deep.
Bud
 
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Old 03-30-13, 07:23 PM
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Hey, its only money....

I got in touch with local gas company and they will foot the bill 75% for blown in insulation and leak sealing as well.

As for the soffit, its there but built like a ship...lol Trying to make a path for air to circulate in a 2x4 section of rafter will be a challenge. Theres no way to achieve the 2 inches you mention when there is only a 4" tall space.

That leads me to the next question. Am I just trying to get air in the attic or am I trying to get air movement along the roof itself? If its just air movement, what about just opening up several bays from soffit to the attic? Instead of 2 inch soffit vent holes, put in say, 4x12 inch vents? PVC Pipes?

Can the slanted section of 7 feet not be treated like a wall and just be insulated like older homes built in the 70's? That's how my parents house was built in 1972
I understand in 1972 they didn't have the perception we have now.

I have half of the downstairs insulated as I have installed new sheet rock and new electric along the way. half the upstairs is insulated as well.


The attic itself is small, like the house. The attic is 26 feet long by about 14 feet wide and about 4-5 feet tall at the peak.

Are soffit vents worth the trouble? Without destroying the 2x4 cross blocking on both ends which have horsehair lathes nailed to them in the bedrooms where the ceiling goes from slanted to horizontal. I don't want to reinvent the wheel trying to vent from the soffit if there is another means of doing so.

This is a basic roof line, no side attics.

The only other thing I can think of is ridge vent and gable vents together to control moisture. Soffit vents are doable in a typical house (with 2x6 or 2x8rafters) so a minimum R-13 insulation can be used, which I'm limited to now with full 2"x4" rafters. The least amount of insulation leaves me no space. That leads me back to using PVC pipe as a duct and blowing in insulation around it. Then again, will it sweat?

I want to do this right but in the process I don't want to rebuild my house...lol
 
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Old 03-30-13, 07:30 PM
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[QUOTE If you have side attics, you need to decide where your internal envelope will be, following the rafters or across the floor and up the kneewall.

Read more: http://www.doityourself.com/forum/in...ixzz2P53DDRX3][/QUOTE]

The knee wall is in the living space on the second floor...my bedroom
 
 

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