What kind of insulation do I need for this?

[jeromedawg]

Hey guys,

Just had some drywall cut behind the kitchen sink and dishwasher areas (this was done due to a bad persistent rat infestation the prior owners had going on before we did fumigation). Fortunately no major activity or dead rats from what I could see where they cut. They did pull out the old insulation from the areas that were cut because it just looked a little gross. Now I'll need to pickup some more so they can fill it back in.




The old insulation was the yellow fiberglass batt type I think.

Will this stuff do?:
https://www.homedepot.com/p/Johns-Manville-R-7-Small-Project-Unfaced-Fiberglass-Insulation-Roll-16-in-x-4-ft-B777CT40/206116325

[feelingroovy]

Yes, that looks like the right size.

Others may have opinions on faced vs unfaced. Based on the lack of staple holes in the studs, it looks like you already had unfaced.

[jeromedawg]

Yes, that looks like the right size.

Others may have opinions on faced vs unfaced. Based on the lack of staple holes in the studs, it looks like you already had unfaced.

Faced is where the fiberglass/insulation is covered with something right? Whereas unfaced it looks like cotton candy? hahaha... The guy just pulled it out as is. Looked a lot like the pink stuff just yellow.

[nereo]

Hey guys,

Just had some drywall cut behind the kitchen sink and dishwasher areas (this was done due to a bad persistent rat infestation the prior owners had going on before we did fumigation). Fortunately no major activity or dead rats from what I could see where they cut. They did pull out the old insulation from the areas that were cut because it just looked a little gross. Now I'll need to pickup some more so they can fill it back in.

Well you can add “inadequate insulation and air-sealing” to your list of home projects.  Please tell me this is in a mild climate?
Insulation gets “a little gross” when there’s a lot of air filtration - basically the batts act like a filter, trapping all the air particles and turning the insulation brown/black in spots.  Unfortunately, fiberglass is very ineffective as an insulator when there’s a lot of air moving around.

I assume this is an exterior wall, though it’s a bit concerning to see pipes running that close to an exterior wall with that poor insulation.  Again, please tell me this is in an area where it never, ever freezes?
It looks like there’s felt on the other side, and 2x4 framing - what’s on the exterior side?  What is the cladding?

[feelingroovy]

Yes, facing is usually some sort of sheeting that extends beyond the sides of the fiberglass so you can staple it to the studs and it doesn't slip down over the years.

I wouldn't think slipping would be an issue since you're filling in at the top and bottom of the stud cavity.

It's been a while since I've insulated, but iirc, the facing can double as a vapor barrier. A vapor barrier is important in cold climates, but you're in southern California, right? I'm guessing it's not so important there, but I don't know.

The most important thing with fiberglass is to wear an n95 mask as you don't want to breathe fiberglass fibers. Wear gloves. Second most important is to not pack it down. It needs to stay fluffy to work.

[jeromedawg]

Yep, I'm in SoCal - it doesn't get super cold here. In fact, it's quite warm outside right now probably in the 80s yet the house is like 70-75 hahaha.

[jeromedawg]

Hey guys,

Just had some drywall cut behind the kitchen sink and dishwasher areas (this was done due to a bad persistent rat infestation the prior owners had going on before we did fumigation). Fortunately no major activity or dead rats from what I could see where they cut. They did pull out the old insulation from the areas that were cut because it just looked a little gross. Now I'll need to pickup some more so they can fill it back in.

Well you can add “inadequate insulation and air-sealing” to your list of home projects.  Please tell me this is in a mild climate?
Insulation gets “a little gross” when there’s a lot of air filtration - basically the batts act like a filter, trapping all the air particles and turning the insulation brown/black in spots.  Unfortunately, fiberglass is very ineffective as an insulator when there’s a lot of air moving around.

I assume this is an exterior wall, though it’s a bit concerning to see pipes running that close to an exterior wall with that poor insulation.  Again, please tell me this is in an area where it never, ever freezes?
It looks like there’s felt on the other side, and 2x4 framing - what’s on the exterior side?  What is the cladding?

The pieces of the batts that he removed were black/brown in various places. The climate here is quite mild. This home was built in 1980 so I'd imagine the insulation is from then. We've only cut small sections of drywall out and he pulled the insulation that was visible, so we're not replacing larger pieces here. I believe the black is the vapor barrier? And yes, it's an exterior wall.

[nereo]

Hey guys,

Just had some drywall cut behind the kitchen sink and dishwasher areas (this was done due to a bad persistent rat infestation the prior owners had going on before we did fumigation). Fortunately no major activity or dead rats from what I could see where they cut. They did pull out the old insulation from the areas that were cut because it just looked a little gross. Now I'll need to pickup some more so they can fill it back in.

Well you can add “inadequate insulation and air-sealing” to your list of home projects.  Please tell me this is in a mild climate?
Insulation gets “a little gross” when there’s a lot of air filtration - basically the batts act like a filter, trapping all the air particles and turning the insulation brown/black in spots.  Unfortunately, fiberglass is very ineffective as an insulator when there’s a lot of air moving around.

I assume this is an exterior wall, though it’s a bit concerning to see pipes running that close to an exterior wall with that poor insulation.  Again, please tell me this is in an area where it never, ever freezes?
It looks like there’s felt on the other side, and 2x4 framing - what’s on the exterior side?  What is the cladding?

The pieces of the batts that he removed were black/brown in various places. The climate here is quite mild. This home was built in 1980 so I'd imagine the insulation is from then. We've only cut small sections of drywall out and he pulled the insulation that was visible, so we're not replacing larger pieces here. I believe the black is the vapor barrier? And yes, it's an exterior wall.

A bit difficult to tell from the photos, but the black looks like tar paper, which was and continues to be a fine house-wrap.  It is NOT a vapor barrier (nor do you need a vapor barrier in a SoCal climate).  The term “vapor-barrier” is perhaps the most misused and misunderstood term in building. A vapor barrier is designed to completely stop water vapor from passing through (technically it’s something with a “perm rating” of < 0.1).  About the only true vapor barriers are plastic sheeting 6+mm thick, and their correct use is generally limited to under slabs and in very cold climates. Tar paper is not there to stop water vapor - it’s there to help water (rain and condensation) travel down and out, and to let your walls dry out.  Vapor will always get into your walls… as dew point, during rain events, and as humidity from the interior (e.g. cooking or a steamy shower).

What tar paper does very poorly is serve as an air barrier. Which is why your insulation as stained black in places… that’s areas where air was moving more or less un-impeded through your wall and into your home. And in those places fiberglass batts are basically useless as an insulative material.

Good to know you are in SoCal - that at least reduces the chances that those pipes will freeze (though there are freak occasional cold snaps even in San Diego - we got snow one year I was living there). If you really want to improve your home’s energy efficiency you need to find a way of stopping all that air infiltration - i can basically guarantee that if those batts showed a lot of air infiltration the rest of your walls are probably similar. Or you can just accept this is a poorly insulated home and move on.  But of course insulation isn’t just about keeping a home warm - it can be even more important with A/C; something that’s becoming more and more important in SoCal each year.

This of course is getting beyond the scope of your original question, but as is often the case with homes, once you open a wall you discover other things that need (or should) be redone.

[jeromedawg]

Hey guys,

Just had some drywall cut behind the kitchen sink and dishwasher areas (this was done due to a bad persistent rat infestation the prior owners had going on before we did fumigation). Fortunately no major activity or dead rats from what I could see where they cut. They did pull out the old insulation from the areas that were cut because it just looked a little gross. Now I'll need to pickup some more so they can fill it back in.

Well you can add “inadequate insulation and air-sealing” to your list of home projects.  Please tell me this is in a mild climate?
Insulation gets “a little gross” when there’s a lot of air filtration - basically the batts act like a filter, trapping all the air particles and turning the insulation brown/black in spots.  Unfortunately, fiberglass is very ineffective as an insulator when there’s a lot of air moving around.

I assume this is an exterior wall, though it’s a bit concerning to see pipes running that close to an exterior wall with that poor insulation.  Again, please tell me this is in an area where it never, ever freezes?
It looks like there’s felt on the other side, and 2x4 framing - what’s on the exterior side?  What is the cladding?

The pieces of the batts that he removed were black/brown in various places. The climate here is quite mild. This home was built in 1980 so I'd imagine the insulation is from then. We've only cut small sections of drywall out and he pulled the insulation that was visible, so we're not replacing larger pieces here. I believe the black is the vapor barrier? And yes, it's an exterior wall.

A bit difficult to tell from the photos, but the black looks like tar paper, which was and continues to be a fine house-wrap.  It is NOT a vapor barrier (nor do you need a vapor barrier in a SoCal climate).  The term “vapor-barrier” is perhaps the most misused and misunderstood term in building. A vapor barrier is designed to completely stop water vapor from passing through (technically it’s something with a “perm rating” of < 0.1).  About the only true vapor barriers are plastic sheeting 6+mm thick, and their correct use is generally limited to under slabs and in very cold climates. Tar paper is not there to stop water vapor - it’s there to help water (rain and condensation) travel down and out, and to let your walls dry out.  Vapor will always get into your walls… as dew point, during rain events, and as humidity from the interior (e.g. cooking or a steamy shower).

What tar paper does very poorly is serve as an air barrier. Which is why your insulation as stained black in places… that’s areas where air was moving more or less un-impeded through your wall and into your home. And in those places fiberglass batts are basically useless as an insulative material.

Good to know you are in SoCal - that at least reduces the chances that those pipes will freeze (though there are freak occasional cold snaps even in San Diego - we got snow one year I was living there). If you really want to improve your home’s energy efficiency you need to find a way of stopping all that air infiltration - i can basically guarantee that if those batts showed a lot of air infiltration the rest of your walls are probably similar. Or you can just accept this is a poorly insulated home and move on.  But of course insulation isn’t just about keeping a home warm - it can be even more important with A/C; something that’s becoming more and more important in SoCal each year.

This of course is getting beyond the scope of your original question, but as is often the case with homes, once you open a wall you discover other things that need (or should) be redone.

Ahh, ok good to know. You're probably right that it's tar paper then, and especially in explaining why there were black/brown spots here and there on the insulation.

So for something like this what would you even suggest as far as filling those gaps? Should I even bother?

For energy efficiency, it seems like we'd have to do a full kitchen and home remodel and rip all the drywall off then install new insulation?

I don't know that it's worth it at least right now... I checked the temps earlier and the inside temps were 72 while the outside temp was 80 which IMO seems pretty good. Of course, this is coming from living in a tiny 2nd floor apartment that could very easily get to 5-10 degrees above the outside temps :O

Anyway, the downstairs stays pretty cool throughout the day - it's also tile down there so maybe that is a factor. We have spanish clay tile roofs so that too could very well be a factor.

The only drawback is that when it gets cold outside, it gets pretty cold inside. But it's also been colder lately too in general now that we're into the fall season

[nereo]

So for something like this what would you even suggest as far as filling those gaps? Should I even bother?

Oh definitely replace the areas removed and fill the gaps.  As you linked earlier you can buy 3.5” fiberglass batts and gently push them into place (wearing gloves, long sleeves and a mask of course).  That will put your walls into about same state as before. 

SLightly better for your situation would be mineral wool batts (often called by the manufacturing name ‘Rockwool’). Mineral wool can be swapped out for fiberglass, is slightly denser, completely impervious to flames and water, and performs better when there’s lots of air movement.  It’s a bit more expensive, but given the relatively small amount you’d need (one bag) it’s what I would do.’

As for improving the home’s insulation overall, that’s another rabbit-hole.  Finding out where and how air is moving through is a big first step, and a blower-door test would help and is the gold standard to know how ‘leaky’ your home is.  If you have siding that’s relatively easy to remove and replace (like vinyl siding) you could take it off and replace it with a much better house-wrap (there are dozens, and which one to use is another whole point of discussion - but almost any would be a marked improvement).  But  if you have something like stucco ont he exterior (which I suspect given the location and the clay tile roofing) that isn’t an option, and you’d probably have to address it from the interior, and it probably wouldn’t be worth it economically.

It is still a very good idea to chase down any and all sources of air-leakage, and seal them up.  While it takes some time and effort, the materials are incredibly cheap - Caulk and Great-Stuff (foam in a can) are your best tools.  Check every penetration (windows, vents, cable-routing) and ensure they are sealed (most probably aren’t).

[jeromedawg]

So for something like this what would you even suggest as far as filling those gaps? Should I even bother?

Oh definitely replace the areas removed and fill the gaps.  As you linked earlier you can buy 3.5” fiberglass batts and gently push them into place (wearing gloves, long sleeves and a mask of course).  That will put your walls into about same state as before. 

SLightly better for your situation would be mineral wool batts (often called by the manufacturing name ‘Rockwool’). Mineral wool can be swapped out for fiberglass, is slightly denser, completely impervious to flames and water, and performs better when there’s lots of air movement.  It’s a bit more expensive, but given the relatively small amount you’d need (one bag) it’s what I would do.’

As for improving the home’s insulation overall, that’s another rabbit-hole.  Finding out where and how air is moving through is a big first step, and a blower-door test would help and is the gold standard to know how ‘leaky’ your home is.  If you have siding that’s relatively easy to remove and replace (like vinyl siding) you could take it off and replace it with a much better house-wrap (there are dozens, and which one to use is another whole point of discussion - but almost any would be a marked improvement).  But  if you have something like stucco ont he exterior (which I suspect given the location and the clay tile roofing) that isn’t an option, and you’d probably have to address it from the interior, and it probably wouldn’t be worth it economically.

It is still a very good idea to chase down any and all sources of air-leakage, and seal them up.  While it takes some time and effort, the materials are incredibly cheap - Caulk and Great-Stuff (foam in a can) are your best tools.  Check every penetration (windows, vents, cable-routing) and ensure they are sealed (most probably aren’t).

Ughhh, the batts I got are only 2" thick. Is it OK to just double them up?

I did just buy a can of the Great Stuff foam because I was initially planning to use it to seal up holes for exclusions of rodents but have been hearing it's really not the best stuff to be using. I figure it'll come in handy for sealing cracks/air-leakage in this case though :)

[nereo]

So for something like this what would you even suggest as far as filling those gaps? Should I even bother?

Oh definitely replace the areas removed and fill the gaps.  As you linked earlier you can buy 3.5” fiberglass batts and gently push them into place (wearing gloves, long sleeves and a mask of course).  That will put your walls into about same state as before. 

SLightly better for your situation would be mineral wool batts (often called by the manufacturing name ‘Rockwool’). Mineral wool can be swapped out for fiberglass, is slightly denser, completely impervious to flames and water, and performs better when there’s lots of air movement.  It’s a bit more expensive, but given the relatively small amount you’d need (one bag) it’s what I would do.’

As for improving the home’s insulation overall, that’s another rabbit-hole.  Finding out where and how air is moving through is a big first step, and a blower-door test would help and is the gold standard to know how ‘leaky’ your home is.  If you have siding that’s relatively easy to remove and replace (like vinyl siding) you could take it off and replace it with a much better house-wrap (there are dozens, and which one to use is another whole point of discussion - but almost any would be a marked improvement).  But  if you have something like stucco ont he exterior (which I suspect given the location and the clay tile roofing) that isn’t an option, and you’d probably have to address it from the interior, and it probably wouldn’t be worth it economically.

It is still a very good idea to chase down any and all sources of air-leakage, and seal them up.  While it takes some time and effort, the materials are incredibly cheap - Caulk and Great-Stuff (foam in a can) are your best tools.  Check every penetration (windows, vents, cable-routing) and ensure they are sealed (most probably aren’t).

Ughhh, the batts I got are only 2" thick. Is it OK to just double them up?

I did just buy a can of the Great Stuff foam because I was initially planning to use it to seal up holes for exclusions of rodents but have been hearing it's really not the best stuff to be using. I figure it'll come in handy for sealing cracks/air-leakage in this case though :)

You want to avoid compressing batts as they lose their effectiveness.  For a 2x4 wall you should use 3.5” thick batts (the thickness of the width of a 2x4).

Rats can chew through Great Stuff if motivated, but it’s great to seal up any cracks that are >1/‘4” in diameter (for smaller cracks caulk typically works better). Of course motivated rats can chew through wood, particle board, rigid foam and plywood as well.  THey love to nest in fiberglass batts as well, which is another reason I dislike the stuff.  Mineral wool and cellulose aren’t perfect deterrents but they do seem to be less inviting to rodents than fiberglass.