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How to keep horizontal soffit vents clear when adding insulation

Posted by thebigad (My Page) on
Tue, Jul 10, 12 at 15:53

I'm about to blow some of that Atticat insulation into my attic to get up to standard. I have horizontal soffit vents around the perimeter of my roof. How do I make sure that I don't block these vents when blowing in the insulation? The baffles I have seen appear to be for rafter vents.

Also, I have two gables about 6X3 feet along the length of the roof. Does this affect anyone's advice? In other words, if I end up covering the soffit vents will the gables keep the air moving?

Thanks!


Follow-Up Postings:

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RE: How to keep horizontal soffit vents clear when adding insulat

Also, reading through the forum and one of my previous posts, is it essential to do all the air sealing tasks recommended by Energy Star? For example, where pipes, flues, wires are coming in to the attic, to remove insulation and seal those openings?


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RE: How to keep horizontal soffit vents clear when adding insulat

And looking at some diagrams, it looks like the baffles go in the rafters and keep insulation from entering the soffit vents. Am I right? So, does that mean I do need to buy one baffle for each soffit vent? More? Less?


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RE: How to keep horizontal soffit vents clear when adding insulat

not clearly understanding your soffit ventilation.
you have soffit vents and gable end vents??

air sealing is always recommended.
insulation only performs if air is not
moving through it. when you have a hole in
the attic floor and cover it with insulation,
you are only filtering the air thru the insulation.

seal electrical penetrations, plumbing penetrations
openings for bath vent fans, stove vents and supply
boxes for hvac should all be sealed.

do you have recessed lights?
any work in attic, even duct sealing should be
done prior to insulation being installed.
once insulation is installed it will be difficult
to access these areas again.

baffles are inserted into soffits where soffit
vents are located. then they are attached to
roof decking inside rafter bays.
I usually put two baffles in rafter bays
to bring air flow pathway higher up on roofline.
I use button cap nails to install the baffles.

be careful up there! don't
do this work when you are the only one home.

best of luck.


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RE: How to keep horizontal soffit vents clear when adding insulat

I have horizontal soffit vents around the perimeter. I also have semi-circular gables at two locations along the length of the roof on the rear of the house. The gables have wooden slats and allow air to move through.


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RE: How to keep horizontal soffit vents clear when adding insulat

Also, as I'm researching air sealing, it looks like I have a big job ahead of me. I went into the attic, but there are no markings on the recessed light fixtures to tell whether they are IC or non-IC. What to do?


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RE: How to keep horizontal soffit vents clear when adding insulat

turn on the recessed lights and go back into the
attic. do you see lights thru the holes in the
housing of the cans?
if so it is Insulation Contact..but not Air Tight.
there is a sticker inside the housing that
you would see when changing the bulb..but
the holes or lack of holes are visible
from inside the attic.

looking for light from inside the house into
the attic is one way to find air leakage sites.
not all will be visible though..just some areas.

you have options..remember that you need
to have a minimum of 4" clearance between
top & sides of recessed cans.
you can use a foam ice chest.
make a box out of sheetrock and seal the seams
and corners.
use a razor knife to notch the box so that
it fits tightly to attic floor around the
'legs' of the recessed cans.
then caulk the box to seal any leakage into
the box. you may need to set a brick or something
to hold the box while the caulk dries.

this will seal the leakage of the recessed cans.
you will need to use clf's in these lights from
here on out.

other places to look are cuts in sheetrock around
bath vent fans..remove cover from inside house.
stove vents ..anything that pentrates the ceiling
into the attic.

sealing cuts where hvac supply boxes is another
large leakage site. luckily you can seal
bath fans and supply boxes from inside the
house with the proper materials...

also tell me about your return air..in a
wall low to the floor or in the ceiling?
what type of ductwork do you have..flex
or hard pipe?

is this air sealing something you are willing
to do?

best of luck.


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RE: How to keep horizontal soffit vents clear when adding insulat

I want to do the air sealing....I just want to make sure it is something I can do right and safely....my understanding is that if I have an IC light, I can dump insulation on it and that I only need the box on top if it is non-IC -- right?

I don't have any HVAC ductwork in the attic, thankfully.

I have the HVAC exhaust vent coming out, and I'll have to somehow seal around that.

I have a brick chimney extending through the attic. The fireplace is natural gas, and rarely used. Do I need to flash the chimney or something or can I dump insulation around it.

I have numerous wires, light fixtures, wall cavities, etc.

I tried to see about putting in a baffle at the perimeter, but I have a ranch house with low sloping roofs. So, I can't get that far to attach the baffles to the rafters. What to do?

I have some ceiling speakers. Can insulation go on those?


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RE: How to keep horizontal soffit vents clear when adding insulat

If I understand what you mean by horizontal vents and baffles, then the baffles go between each rafter whether there is a vent there or not. You do not want the new insulation to touch the roof. The baffle should provide air circulation.

As to covering the ceiling speakers, I would treat them like a light can. Cover them with something before blowing the insulation on. That way you can take them down without loose insulation falling out.


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RE: How to keep horizontal soffit vents clear when adding insulat

I tried to see about putting in a baffle at the perimeter, but I have a ranch house with low sloping roofs. So, I can't get that far to attach the baffles to the rafters. What to do?

put two baffles together. overlap the baffles and
tape the two baffles together. push the baffle
into the soffit, attach the longer end of the
baffle to the roof deck.
not ideal, but I've done this in homes like
yours with low roof pitches. this will
maintain the air flow, and the baffle
will be held in place by areas you can
reach to attach to decking.

you can dump insulation on an IC can.
but it is the air leakage that will keep
the insulation from performing.
1 IC can is equal to 1 sq ft of uninsulated space.
this is due to air movement thru the insulation.

IC cans can have insulation next to and over
them. it is the air leakage that is a concern.
if each IC can lets 25 cfm of air into the
house. this air is attic air..hot in summer
cold in winter. usually laden with humidity
and insulation particles.
it is the air sealing that is the concern,
but it will also improve indoor air quality
and reduce amount of particulates entering the
house.

if you don't seal the IC cans, it doesn't
matter if you insulate them or not..it
doesn't address the air leakage.
insulation slows air movement..it doesn't stop it.

use same method for speakers in the ceilings.
both are leakage sites.

"I have a brick chimney extending through the attic. The fireplace is natural gas, and rarely used. Do I need to flash the chimney or something or can I dump insulation around it.
I have numerous wires, light fixtures, wall cavities, etc."

seal everything before adding insulation.
else it is a waste at the areas that leak
into the house.

best of luck.


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RE: How to keep horizontal soffit vents clear when adding insulat

I found out that I have some ic lights and some non ic lights. How do I air seal ic lights before I dump insulation on it? Just foam around the edges where it sits on the attic floor?

I see that I have to build an enclosure for non ic lights. But some non ic lights are at the very edge. I can't get there. How to seal those?

So I need an enclosure on the speaker too?


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RE: How to keep horizontal soffit vents clear when adding insulat

I found out that I have some ic lights and some non ic lights. How do I air seal ic lights before I dump insulation on it? Just foam around the edges where it sits on the attic floor?

I see that I have to build an enclosure for non ic lights. But some non ic lights are at the very edge. I can't get there. How to seal those?

So I need an enclosure on the speaker too?


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