Trying to re-insulate an attic/bedroom

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Old 04-30-12, 07:22 PM
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Trying to re-insulate an attic/bedroom

I have a story and a half. The top story is the attic with a bedroom built in. The walls and sloped part of the ceiling are knotty pine. The old insulation that is in the 2x6 rafters (behind the knotty pine) is R13. I can re-insulate with R19 but that doesn't get me to the preferred R38 minimum for my area.

What other options are there to get insulation in between the knotty pine and the roof?

Is it possible to cut rigid foam to size and slide it in? 6" would give me R39.

Am I just going to have to live with R19 in these areas?

Thanks
 
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Old 04-30-12, 07:31 PM
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Is it possible to cut rigid foam to size and slide it in? 6" would give me R39.
It is very difficult to get a good fit and get the full r-value with the walls open. It would be almost imposable to do it with the wall finished.

It's expensive but spray expanding foam is the best way to get the highest r-value. I suggest getting a few bids.
 
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Old 04-30-12, 07:43 PM
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Can spray foam be used behind the knotty pine? That is, can is be sprayed down into it while it is in place?

Also, I would need to put in air channels so I can get the proper venting. Can I put in those foam air channels and spray foam on it so I can keep air flow up to the attic vents?

I see that there are a lot do it yourself kits. How difficult to use are they?

I will get a quote. There is one place in my area that does spray foam. It is time to give them a call

Thanks
 
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Old 05-01-12, 06:33 AM
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Yes, they can spray behind a finished wall. They will know the right kind of spray to do.

I am not an insulation expert but I believe you can do what is called a "hot roof" without the venting. This is something you should ask your contractor.

The DIY kits do work, but can be messy and is better for walls that are open, IMO.
 

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Old 05-01-12, 06:34 PM
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I think I figured this all out.

I am going to take down the knotty pine. It appears as though it is sitting off the rafter by an inch. It is nearly an inch thick itself. I am going to place batts of 5.25" stonewool that is R23 (unfaced). Then I am going to place 2 inch R6.5 rigid foam over that (taped and sealed) then 1/2" drywall over that. The resulting angled ceiling height will be about the same as the knotty pine but I will be at about R36!

I think this setup will leave a small airgap between the insulation and roof so that air can flow up to the vents. There are three passive vents in the roof, near the peak, now. I am going to replace two of them with powered vents and plug the middle vent.

Then I need to create intake vents. Not sure how I am going to do that yet.

I am also looking at adding a radiant barrier as well but need to do more research as there needs to be an air gap between the barrier and the roof butI think there will be.

I am excited as my bedroom is always hot in the summer and in the winter, I am melting so much snow that I get icicles that run from the roof line to the ground.

I think this job will pay for itself in 2-3 years!
 
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Old 05-01-12, 07:55 PM
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Note: powered vents can be a bit noisy. Might not be ideal over a bedroom.
Any chance to do a continuous ridge vent?
 
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Old 05-02-12, 03:51 AM
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I agree wholeheartedly with Tolyn's comment on the ridge vent. You don't need holes in an otherwise non leaking roof. Powered vents fail.....regularly. They don't pull the hottest air (at the peak) leaving it to sit. A continuous ridge vent (remove and seal up the others) will give passive total flow from the soffit to the ridge.
 
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Old 05-02-12, 04:38 AM
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That is good to know. I am not sure I can add a ridge vent. The rafters meet at the peak with a 1x6 sandwiched in between at the peak.

I will have to look up ridge vents to get more info on the subject.

I also still need to figure out how I am going to do the low vents. The overhang of the roof is not inside the attic. It is just the underside of the roof. Does that make sense?

The last ceiling/floor joist in the attic looks like it is sitting on the wall bellow it. In order to get holes from the outside to the inside, I would have to drill holes or notch out a piece of that joist. Although, if it is sitting on the wall below, I don't think I would need to worry about weakening it?

Thanks
 
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Old 05-02-12, 05:43 AM
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Adding a ridge vent is fairly straight forward. Just snap a chalk line and run a circular saw with the blade set to just cut through the shingles and sheathing. (Remove the ridge cap shingles first) You will end up with about 4-5" gap at the ridge, depending on the ridge vent you buy.

On the other end of the roof, most cases you will add the vents to the underside of the soffits. The only time this won't work is if you have exposed rafter tails, and therefore, no soffit.
 
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Old 05-02-12, 07:20 AM
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I am not an expert on this, but have a similar situation with a room in my attic (third floor) and have discussed options with a buddy of mine that does spray foam insulation for a living.
For the space between the ceiling in my attic room and the roof, he suggested using a sprayfoam that can be injected. Looking at the quality of the drywall work on my room's ceiling, we agreeed that taking some down would make life easier for the insulation install and allow me to repair the "high quality" workmanship that was done by one of the previous owners. My spacing is approximately 4" between the drywall and the actual roof. The spray foam removes the need for ventalation and removes the headakes of fans if you choose that direction.

He did warn me it would not be cheap (even with his labor costing me a box of beer). My current attic room is insulated with injected blow-in insulation (a number of 2" holes cut to blow in).

For the rest of my attic, we agreed blow in insulation would be the most cost effective solution for the higher R value.
I would suggest talking to different local insulation exports and get their opinions.
 
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Old 05-02-12, 10:08 AM
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That is now my problem to work out, I have exposed rafter tails and therefore, no soffit. I need to find a way to vent.

I have just about ruled out spray foam for two reasons. 1) It will be very expensive. I am guessing > $5K for my attic and 2) The attic above the porch is part of my main attic and I would need to insulate that too.

I did get a quote, 5 years ago, for filling my walls with foam and that was >$3K. I ended up with cellulose for $800.

I also think I can get R36 minimum in my attic without spray foam. The downside is that I will have to vent.

From what I have read on the internet, passive venting only makes a 3-5 degree difference and that is why a powered vent or a just running a hot roof is the way to go. I wish this was easier :-)
 
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Old 05-02-12, 10:50 AM
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maximumpower,
Is this room your entire attic?

In my case, my bedroom makes up less then 1/3 of my attic, so I can spray foam where it's needed, and blow-in cellulose for the rest.
 
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Old 05-02-12, 12:07 PM
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Your only real options that I can think of is either just punch holes between the rafter tails to let in air and put some kind of cover to hide the holes or install a vented soffit on the rafter tails. You like will have to install a fascia too. You could do maintenance free soffit and fascia. Maybe somebody else will have other options.
 
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Old 05-02-12, 01:37 PM
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I will have to punch holes. Perhaps I can build a soffit. The two issues I think I am going to have is 1) Will I be punching through any load bearing structure and 2) on the inside of the attic, the path has to be clear of insulation.

I am sure I can figure this out but if anyone has experience I would love to hear about it.

My bedroom is about half the attic by square footage but most of it by volume.

I could use spray foam behind the sloped walls and I have thought of that but it still will cost more, I still need to let air flow behind it and I think I can still reach R36 without losing any more (or very little) of the head space I currently have.

Does anyone have opinions on 1) radiant barriers and 2) efficiency of ridge vents?

Thanks
 
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Old 05-02-12, 04:21 PM
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I'll assume that since you have exposed tails, that you have 2x4 rafters. That will give you 3 1/2" from the bottom side of the roof sheathing/boards down to the bottom edge of the rafter tail. The bottom of the tails sit on top of the walls top plate. It will be clear there with the possible exception of any plumbing pipes, or electrical pipes/cables.
 
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Old 05-02-12, 06:46 PM
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The rafters are 5 1/2". This gives me more room for insulation. In parts of the attic, the rafters look like they stop at the wall plate, that is, they are cut around the wall plate but then they continue on the outside as whole rafters. Plus, there is so much other pieces of wood (joists and other "stuff") that it is not clear what the path to the outside is. There is molding on the outside I can take off and see.

I have done a dangerous thing! I went off and did some web research about powered, vs passive type, vs ridge vents. There are a number of people claiming ridge vents do not work and have tested by going up in the attic with a smoke device (of some sort) and watching the flow.

My head is now spinning! lol

Thanks again for all the help.
 
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