Go Back  DoItYourself.com Community Forums > Interior Improvement Center > Basements, Attics and Crawl Spaces
Reload this Page >

Installing baffles in a attic where the insulation has already been installed

Installing baffles in a attic where the insulation has already been installed

Reply

  #1  
Old 03-04-13, 07:15 PM
Member
Thread Starter
Join Date: Jul 2011
Location: USA
Posts: 28
Installing baffles in a attic where the insulation has already been installed

I have someone blow in insulation in my attic about 2 years ago. They did not install any baffles. What is the recommended way for me to get the baffles in there?
 
Sponsored Links
  #2  
Old 03-04-13, 08:22 PM
Nashkat1's Avatar
Member
Join Date: Mar 2012
Location: USA
Posts: 8,470
Likes Received: 1
I have someone blow in insulation in my attic about 2 years ago. They did not install any baffles. What is the recommended way for me to get the baffles in there?
If you mean you need to install material to keep the insulation out of your roof overhangs and allow your soffit vents to work properly, the least expensive and most efficient way is probably to lay some plywood over the insulation and joists and lie down on it.

You do have a continuous soffit vent, right? And a ridge vent?
 
  #3  
Old 03-05-13, 05:15 AM
Member
Join Date: Feb 2006
Location: USA
Posts: 6,531
Likes Received: 3
Baffles

Baffles can be installed from the outside by removing the soffit.
 
  #4  
Old 03-05-13, 05:33 AM
Member
Thread Starter
Join Date: Jul 2011
Location: USA
Posts: 28
Yes, I would like to install the baffles for proper venting. I do have a continuous soffit vent but not sure about the ridge vents. I will have to check when I get home.

After the insulation was blown in the contractor nailed down plywood over the joists so that we could use the attic for storage. I am afraid that the soffit vents are blocked by the insulation. If I shove a baffle down the there wouldn't I be just compacting the insulation more?

As a side note-I have a whole house and attic fan in the attic that vent outside. The temperature in the attic seams to be almost the same temperature as the outside. Am I being worried for nothing?
 
  #5  
Old 03-05-13, 06:09 AM
Group Moderator
Join Date: Oct 2004
Location: WI/MN
Posts: 19,221
Likes Received: 34
Yep, you have to dig out the insulation if it's blocking the soffit vents.
 
  #6  
Old 03-05-13, 10:27 PM
Nashkat1's Avatar
Member
Join Date: Mar 2012
Location: USA
Posts: 8,470
Likes Received: 1
I am afraid that the soffit vents are blocked by the insulation. If I shove a baffle down the there wouldn't I be just compacting the insulation more?
Baffles shouldn't be shoved down into the overhang. All insulation should be removed from the overhang. A baffle, if needed, starts at the top plate of the exterior wall. It provides a space for the entering ventilation air to pass above the insulation, and it prevents the insulation from getting into the overhang.

As a side note-I have a whole house and attic fan in the attic that vent outside. The temperature in the attic seams to be almost the same temperature as the outside. Am I being worried for nothing?
A whole house fan removes heat from the living, or conditioned, space. An attic fan is a waste of material and energy, especially if it is controlled by a thermostat. It needs to be removed.

The purpose of attic ventilation is not to lower or otherwise control the temperature in your attic. It's to remove moisture and keep the insulation dry and effective. Heat, up to a very high level, just drives the ventilation system.

The most effective and efficient ventilation system for most roofs combines continuous soffit intake vents with a ridge vent for the exhaust.
 
  #7  
Old 03-06-13, 07:27 AM
Member
Join Date: Nov 2007
Location: MI
Posts: 2,608
I have a whole house and attic fan in the attic that vent outside.
You have both types?

@Nash--I've never heard that an attic fan (roof or gable mounted) is a waste of energy. I thought the purpose of such a thermostatically-controlled unit was to remove excess heat in the summer so the "heat load" isn't bearing down on your ceiling.
 
  #8  
Old 03-06-13, 05:16 PM
Nashkat1's Avatar
Member
Join Date: Mar 2012
Location: USA
Posts: 8,470
Likes Received: 1
I've never heard that an attic fan (roof or gable mounted) is a waste of energy. I thought the purpose of such a thermostatically-controlled unit was to remove excess heat in the summer so the "heat load" isn't bearing down on your ceiling.
Yes, that's what the sales people say. Since doing that not only doesn't add to the effectiveness of the attic ventilation but can interfere with it, the best thing to do with one that is already in place is to remove it. That way the materials can be recycled and the energy cost is eliminated.
 
  #9  
Old 03-06-13, 07:30 PM
Member
Join Date: Nov 2007
Location: MI
Posts: 2,608
Cut to the chase. They dont cool an attic in the summer? I have never had one but was considering one for my cottage where I'm way more concerned about comfort than energy costs.
 
  #10  
Old 03-06-13, 09:45 PM
Nashkat1's Avatar
Member
Join Date: Mar 2012
Location: USA
Posts: 8,470
Likes Received: 1
Cut to the chase. They dont cool an attic in the summer? I have never had one but was considering one for my cottage where I'm way more concerned about comfort than energy costs.
OK, here's the chase: An attic exhaust fan controlled by a thermostat may lower the temperature in your attic. In addition to costing you money to install, maintain and operate the fan, that is more than likely to do less than nothing toward making the conditioned space more comfortable.

If you feel the cottage could be more comfortable than it is now, then there are probably some effective and efficient improvements you could make. Where is your cottage? What type of roof does it have? What is the existing condition of the insulation and ventilation? How many ceiling fans do you have there and how do you use them? Do you have a whole-house fan in the cottage?
 
  #11  
Old 03-07-13, 05:51 AM
Member
Thread Starter
Join Date: Jul 2011
Location: USA
Posts: 28
Nashkat, whats the best way to removed the insulation from the overhang?
 
  #12  
Old 03-07-13, 06:45 AM
Nashkat1's Avatar
Member
Join Date: Mar 2012
Location: USA
Posts: 8,470
Likes Received: 1
whats the best way to removed the insulation from the overhang?
I just reach in and pull it out.
 
  #13  
Old 03-09-13, 04:31 AM
Member
Join Date: Feb 2008
Location: Lake Wales, FL
Posts: 463
Hot attic?

Buy a weather station and place the remote sensor in the attic.
Connect to your computer and see the temperature in the attic 24/7.
Compare the temperature outside, with that in the attic with the fan running and not running.
Know exactly what is happening in your attic.

Keep in mind that having a ventilated attic, the running fan is pulling hot air into your home through the floors and walls. When the fan is not running the passing wind creates a low pressure area above the roof and down wind to your home that also pulls hot air into your home.

In winter it pulls in cold air.

Having an over ventilated roof is not a good idea, unless you are positive that all the holes and cracks in your home have been blocked and the air inside your comfort zone cannot be removed.
 
  #14  
Old 03-10-13, 09:00 PM
Nashkat1's Avatar
Member
Join Date: Mar 2012
Location: USA
Posts: 8,470
Likes Received: 1
Xsheesh, with all the questions I asked you earlier, I forgot to ask the most important ones! Do you use the cottage year-round or just in the summer? Are you interested in conserving heat or just in the most efficient and effective way to keep it cool in hot weather?
 
  #15  
Old 03-10-13, 09:03 PM
Nashkat1's Avatar
Member
Join Date: Mar 2012
Location: USA
Posts: 8,470
Likes Received: 1
Buy a weather station and place the remote sensor in the attic.
Connect to your computer and see the temperature in the attic 24/7.
Compare the temperature outside, with that in the attic with the fan running and not running.
Know exactly what is happening in your attic.
Why, so long as you have the right amount of ventilation, more-or-less?
 
  #16  
Old 03-11-13, 10:49 AM
Member
Join Date: Feb 2008
Location: Lake Wales, FL
Posts: 463
The right amount of ventilation!

The problem is....that it is impossible to discover the right amount of ventilation.
When you have a hole, or a number of holes. You are entirely at the mercy of the wind. This relates to how exposed you are to the weather, how high the roof is, the general geography of the area. One day there is no wind, the next it may be blowing a gale...your ventilation will vary depending on the force of the wind and its direction.

Wind wash in attics is a real problem, pulling heat from a home or delivering more heat than you want.

A hole, or holes that may work satisfactory when a building is surrounded by other buildings, trees, hills.....will not work satisfactorily in an exposed location.

The only way to judge if the ventilation system is working is, are you happy with the amount of money you are paying for your heating and cooling.
If you are happy fine. If you think your bills could be lower....then you need the facts.
 
  #17  
Old 03-11-13, 03:14 PM
Nashkat1's Avatar
Member
Join Date: Mar 2012
Location: USA
Posts: 8,470
Likes Received: 1
The problem is....that it is impossible to discover the right amount of ventilation.
Why do you say that? Here's just one resource on the topic, for example:

Calculate Proper Attic Ventilation In 5 Easy Steps

Wind wash in attics is a real problem, pulling heat from a home or delivering more heat than you want.
It can be, if too much opening is created, if the openings are concentrated rather than spread out as continuously as possible, or if the openings are not provided with adequate screening or grilles. If those conditions are met, wind wash and wind scour should not be a problem.
 

Last edited by Nashkat1; 03-11-13 at 03:30 PM.
  #18  
Old 03-12-13, 03:17 AM
Member
Join Date: Feb 2008
Location: Lake Wales, FL
Posts: 463
Roof ventilation

As I wrote earlier, the fit all solution offered, does not allow for the geography of the area or the style of house.
You may well agree that most people are not aware what happens in their attic and have no idea how much over ventilation is costing them in comfort, noise and heating and cooling bills.
 
  #19  
Old 03-12-13, 12:16 PM
Member
Join Date: Nov 2007
Location: MI
Posts: 2,608
I stepped back from the discussion because I didn't want to hijack the thread...but it looks like that's happened anyways.
For my cottage at one time there was no ceiling, judging by the age of the materials. Pretty common up there in seasonal cottages and especially in log cabins. Then insulation was stapled up in the rafters to keep it cooler in the summer & warmer during the 2 weeks of deer hunting. THEN a ceiling was added by notching 2x4 joists to fit over the top of the log walls, and another layer of foil-faced batts was dropped into the bays and covered by 1/4" paneling (ceiling) to hold it up and look somewhat acceptable for the lower expectations of the 1960's.

So that's what I have now--an unventilated formerly-conditioned attic now closed off from the conditioning. Not exactly what you find in the textbooks. Heating costs aren't a big concern because I plan to only use the place 2-3 weekends per winter. It's on a lake so I don't think it will ever get uncomfortable in the summer (great breezes there). AC will never be installed here.

Bottom line--I don't know what, if anything, to do. My old shingle roof hasn't suffered from the lack of ventilation. There's no moisture or water issues. Should I leave it alone?

My previous cottage (just a block away) had no insulation at all and my annual gas bill came to about $300--and most of that was a flat-rate monthly "gas availability" charge, not actual gas consumed.
 
  #20  
Old 03-12-13, 02:36 PM
Nashkat1's Avatar
Member
Join Date: Mar 2012
Location: USA
Posts: 8,470
Likes Received: 1
I stepped back from the discussion because I didn't want to hijack the thread...but it looks like that's happened anyways.
Thanks, and you're right. I just looked back through the posts for a way to make some separate threads out of them, and I didn't see a way to do that easily. So I guess we'll just keep rolling for now.

I did see where I addressed one question for you to another member But you've answered it anyway, so that's OK. (It was the one about the seasonal use of your cottage.)

So that's what I have now--an unventilated formerly-conditioned attic now closed off from the conditioning. Not exactly what you find in the textbooks. Heating costs aren't a big concern because I plan to only use the place 2-3 weekends per winter. It's on a lake so I don't think it will ever get uncomfortable in the summer (great breezes there). AC will never be installed here.

Bottom line--I don't know what, if anything, to do. My old shingle roof hasn't suffered from the lack of ventilation. There's no moisture or water issues. Should I leave it alone?

My previous cottage (just a block away) had no insulation at all and my annual gas bill came to about $300--and most of that was a flat-rate monthly "gas availability" charge, not actual gas consumed.
It's a good question. Here's the thing, though. Attic ventilation is needed to keep the insulation dry and effective. By extension, it's needed to keep the attic dry. With your closed attic, you almost certainly have some condensation forming. The effect on the insulation may not be much, at least not that you can feel, or see in your energy bills. But that's partly due to the way you use the cottage.

Without access to the attic, you can't really judge how much condensation there might be, or what it's doing. But it could be helping mold to grow there. It could be feeding rot in the ceiling joists or other wood. And you wouldn't know that, at least at first.

If it were mine, I would look for a way to inexpensively add some intake at the overhangs, and I would put a ridge vent on for exhaust, and call it good. No powered equipment. That should keep everything dry, and that should help the cottage, and you, hold up longer.
 
  #21  
Old 03-12-13, 07:21 PM
Member
Join Date: Nov 2007
Location: MI
Posts: 2,608
Without access to the attic, you can't really judge how much condensation there might be, or what it's doing. But it could be helping mold to grow there. It could be feeding rot in the ceiling joists or other wood. And you wouldn't know that, at least at first.
But I do have access and it's dry, no musty smell, no mold/rot/staining or any evidence there ever has been. The insulation has excellent loft and isn't soiled. That's why I'm on the fence between doing what I always read is suggested (albeit to year-round inhabited homes), and "if it aint broke don't fix it".

The soffits, facia and roof are in decent shape and not at the top of my TO DO list. When I do get to them I certainly will cut in vents but I don't see any reason to rush into that. I'm considering the (slight) possibility I might retire to this place some day so as the work progresses I will be trying to move in the direction of energy efficiency. If I don't retire here, these things can only help sell the place. I just don't want to do something wrong that will require tear-out down the road.
 
  #22  
Old 03-12-13, 08:13 PM
Nashkat1's Avatar
Member
Join Date: Mar 2012
Location: USA
Posts: 8,470
Likes Received: 1
I didn't realize you had access. From your description it sounds like everything is OK so far.

The condensation problems really only become acute if and when we're heating the interior and driving a bunch of vapor into an unheated attic. Then it can condense on the underside of the roof or in the insulation and wreak havoc if there isn't adequate ventilation.

One reason everything seems to be OK so far, I suspect, is that you say you've only heated the place for a few weekends each winter. If you retire there, or if you start spending longer periods in the cottage during heating season, that could change the conditions dramatically. And that's probably soon enough to address the whole insulation and ventilation question, as you suggest.

I don't think "if it ain't broke don't fix it," for now, is likely to lead to tear-out down the road.
 
  #23  
Old 03-13-13, 04:59 AM
Member
Join Date: Feb 2008
Location: Lake Wales, FL
Posts: 463
Water vapor/condensation.

When your cabin is empty, it will be dry.
We put water vapor into buildings by cooking, washing, breathing, sweating.
As you are only there for a short time, the 14 cubic feet of water vapor you add to the cabin every 24 hours you are there by breathing and the vapor added by cooking and washing will be minimal.
Untreated wood absorbs water vapor without problem, as the year progresses the amount of water vapor in the air is in constant change, the summer sun dries it, your staying there adds a bit. Nothing to worry about.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes