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Discussion Starter #1 (Edited)
Okay, I've been through a few houses and done my share of reading about construction and the importance of attic ventilation. I had my roof done professionally 5 years ago on my 2 story colonial built in 1928 (one of few projects I've not had done as DIY). When they put in the roof, they did ridge vent and I believe they put in the kind of edge ventilation that goes between shingles and sheathing along the bottom row of shingles. (I can't actually see the edge from the ground because of the gutters)


So I'm into the ceiling on the second floor with my current bathroom project and it occurs to me... If the edge vents are intended to provide intake ventilation, I don't think it's working because my eaves extend about a foot past the exterior wall and the cavity in the rafters is blocked off from air flowing into the attic.


My roof structurally is supported with 2x4 rafters. I have put in batt fiberglass insulation in the attic and put baffles into the rafter cavities, but with a section of ceiling demolished I now see that the bottom of the cavities above the exterior wall is blocked with 2x4.


Should I add ventilation holes to the 2x4 blocking while I'm able to access it?


ETA: What I do know is the company that did my roof failed to properly flash 1 of 2 plumbing vent penetrations. They just cut shingles close and used tar to seal up to the pipe. This didn't last as I found that it was leaking into the wall cavity when I opened the wall for a first floor project. I also know this has caused the bottom of the eaves to sag, and we have had birds nesting inside the eaves because of this. So my guess is that if I put vent holes in I probably also should secure screening to prevent critters from intruding into the attic...
 

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retired framer
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So you have a vented soffit with no holes into the attic,
It sounds like you have a vented drip edge. Checking that that is really there would be my first step.

So to modify those blocks can be done from the attic, from the soffit or thru the ceiling from below.

I have taken a 2x4 into the attic that would reach the center of the attic when against the 2x4 block and beat the other end with a 10 pound sludge and just knocked them out, Just left the odd one in so they can still hold the rafters straight up.
 

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Discussion Starter #3
cut a hole with a hole saw in my wall so I could see into the soffit cavity and I was able to see that there is drip edge venting

Having seen that I hit the blocking a few times with a hammer to see if I could knock it out which I didn't succeed but I did hear some birds rustling around when I did that inside the soffit.
 

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retired framer
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cut a hole with a hole saw in my wall so I could see into the soffit cavity and I was able to see that there is drip edge venting

Having seen that I hit the blocking a few times with a hammer to see if I could knock it out which I didn't succeed but I did hear some birds rustling around when I did that inside the soffit.
So you have holes in the soffits somewhere, might be bats.
 

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retired framer
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cut a hole with a hole saw in my wall so I could see into the soffit cavity and I was able to see that there is drip edge venting

Having seen that I hit the blocking a few times with a hammer to see if I could knock it out which I didn't succeed but I did hear some birds rustling around when I did that inside the soffit.
With the slope of the roof and if they are tight they won't hammer out, you would have hit it right at the bottom and get lucky.
 

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Discussion Starter #6
So you have holes in the soffits somewhere, might be bats.
What I know to have happened is that the board on the bottom of the soffit is rotted, the aluminum soffit trim is sagging and that's where the birds enter and exit. This happened below the point where the roof leaked at the vent pipe due to not having flashing installed. I don't have any signs of anything but spider webs in the attic itself.


I've seen sparrows coming in and out of the gap at the bottom of the soffit.


At any rate, that's a separate issue and it's on the to-do list, but a very necessary list of ingredients I don't have is warmer weather, budget to rent a lift and a solid block of time. And I'm not convinced this is higher priority than building a garage.




Regarding the blocking, I was thinking maybe if I spade bit drill a 1" hole then Sawzall the block in half it should get a lot easier to knock out. Given the bird situation, I'm going to staple screen door material across the opening. I have 6 cavities I can access from the project area.
 
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If you have a garage to build keep your eyes open for some used staging, before temps warm up. Often you can buy it at a reasonable price and then sell it when done. it would help with the current soffit issues and be great for the garage.

I never sold mine, just kept buying :).

Bud
 

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My roof structurally is supported with 2x4 rafters. I have put in batt fiberglass insulation in the attic and put baffles into the rafter cavities, but with a section of ceiling demolished I now see that the bottom of the cavities above the exterior wall is blocked with 2x4.



Are you converting unheated attic space to living space?
 

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Discussion Starter #9
No, my attic only gets up to 6' at the peak. I just want it properly ventilated, especially considering the fact I'm gradually transforming the house to something more closely resembling modern tight construction.


Also, I've been taking on the effort to remove old lath & plaster before drywalling, and on exterior walls with 2x4 studs I'm furring the studs out with 2x2 to get approximately enough wall cavity to use R21 insulation for 2x6 wall cavities. Hauling bags of plaster out is getting a bit old, so I might eventually start to just drywall over plaster on interior walls, but I do intend to get through the entire house with demo and R21 insulation on exterior walls.
 
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Just curious why the R13 on the rafters. Do you have insulation at the attic floor level? R13 is light for ceiling or upper envelope. I get concerned about condensation under the roof deck when I see insulation up tight.


Regarding the lathe and plaster. It is a hassle, but the more of it you get out the better IMHO. If you try to wall board over it, it will likely start to crumble, possibly pushing the wall board out over time.
 

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Discussion Starter #12
Just curious why the R13 on the rafters. Do you have insulation at the attic floor level? R13 is light for ceiling or upper envelope. I get concerned about condensation under the roof deck when I see insulation up tight.


Regarding the lathe and plaster. It is a hassle, but the more of it you get out the better IMHO. If you try to wall board over it, it will likely start to crumble, possibly pushing the wall board out over time.
I don't recall having mentioned R13 at all... I am installing R21 in the walls. As purchased the house came with a layer of faced R11 in the attic (I think, it is for 2x4 wall cavities and older stuff.). This was laid perpendicular to the joists. Over that I've added R30. But I'm not stuffing anything into the rafter cavities except baffles to maintain ventilation airflow.


As far as the demo of lath and plaster... I generally tend to agree, where time and money is not a consideration. But my kids are 11 and 12 and I have projects I want to be able to include them in before they are leaving for college, and for that I need a garage and probably the next 5 years.
 

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I don't recall having mentioned R13 at all... I am installing R21 in the walls. As purchased the house came with a layer of faced R11 in the attic (I think, it is for 2x4 wall cavities and older stuff.). This was laid perpendicular to the joists. Over that I've added R30. But I'm not stuffing anything into the rafter cavities except baffles to maintain ventilation airflow.

You didn't mention R13, but spoke of installing bat insulation in a 2x4 rafter cavity, which is typically R13,



My roof structurally is supported with 2x4 rafters. I have put in batt fiberglass insulation in the attic and put baffles into the rafter cavities, but with a section of ceiling demolished I now see that the bottom of the cavities above the exterior wall is blocked with 2x4.

I must have misunderstood something?
 

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Discussion Starter #14
I described the rafters but fiberglass in the attic meant on the ceiling joists below the rafters. I did cut some of the old R11 to lay IN the joist cavities, but I could only take so much of that so I haven't done the whole attic.


At the time I was adding the R30 on top of the R11 I don't think I comprehended that the exterior soffits were beyond the blocking, so now I'm recognizing that it's there and it's blocking the intake side of the attic ventilation system from allowing airflow through the attic to the exhaust at the ridge.
 
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