Retro Insulating : maybe walls and slab needed?


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Old 01-10-22, 07:25 PM
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Retro Insulating : maybe walls and slab needed?

Previous owner of my house put on a two-story extension that sits atop a new concrete slab. The first floor is a family room and the second floor is the master bathroom.

Both of these rooms lose heat so much quicker than the rest of the house. I have scanned both rooms of FLIR guns and couldn't find any obvious cold spots.

I suspect the walls are under-insulated. I also suspect the floor in the family room isn't properly insulated from the slab.

What are my options here short of opening all the walls? What can I do regarding the slab (I already have a heavy rug down on 90% of the wood floor in the family room)?

Right now, the family room is on its own hydro air zone. The house is unoccupied and set to 58F. The thermostat delta is 2F. This zone calls for heat every 1-2 hours, killing my gas bill. Its probably costing me 100$ / month alone with how much it cycles the boiler.

Below is a screenshot of my thermostat run time (top being the main zone in the house, bottom being the extension zone that cycles often). You can see in the charts how much more often the extension is cycling.


 
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Old 01-10-22, 10:23 PM
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Really can't answer with the information provided - no obvious loss detected and we have no idea what's in the walls or how many and what kind of windows or anything like that.
 
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Old 01-10-22, 11:44 PM
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Insulation, think up, out, then down when it comes to efficiency.

Ceilings are usually easy to add/increase insulation to. Walls are harder, foam and cellulose can be added but it's intrusive. Slab, nothing your going to be able to do.
 
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Old 01-11-22, 09:58 AM
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Thanks guys. Here is all the info I can think of right now:

The houes is on the shoreline of CT.

In question is a two story extension on slab that was done around 2000. I am attaching schematics I drew with approximate dimensions and rough window/door locations.

The family room has two external walls. The third wall is shared with a semi-condition utility closet. The fourth wall is the main house. The bathroom has three external walls. The fourth wall is shared with the main house. In the drawings, all the walls (colored yellow) are insulated with fiberglass and a separate vapor barrier sheets. I do now know the rating of it, however. The ceiling between the two floors is also insulated. I do not know if the vaulted ceiling in the bathroom is insulated but i imagine it is (its covered in shiplap).

All of the windows and the sliding door are modern (circa 2000) and double paned. The family room is hardwood that sits on a plywood subfloor that i suspect, sits nearly on top of the slab. I may be able to explore a bit at the shared wall in the utility closet, which has the slab as it floor. The wood floor never feels warm but also doesn't particularly feel cold (heat is HVAC ducting in the ceiling).

I have scaned both rooms with a FLIR I borrowed and didn't find any obvious cold spots. I still can't figure out why this room loses heat so quickly when the rest of my house, which is 1930's structure with original windows, doesn't (as show in the data I put in the first post).

Knowing the walls are insulated and not finding any significant cold leaks makes me think the slab is acting as a cold sink and pulling heat right out of the room into the ground. That doesn't quite explain why the 2nd floor bathroom is also extremely cold, though.

Or maybe, even though they dont feel that cold, they didn't insulate well around the windows and I should

Any thoughts?




 
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Old 01-11-22, 10:18 AM
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Just to add to may last post: I just checked my ecobee (I am away from the house until tomorrow); outside dipped below 20F last night and my family room HVAC called for heat every 30 minutes.

My other zones in the house called for heat maybe every 2 hours.

Could this be less an insulating issue and more a horribly designed HVAC issue? The heating for the family room is terribly designed; its a 1.5ton unit just for that room with a hydro air coil. It comes on, blasts hot air for 10-15 minutes, gets to temp and the shuts off. Sine the vents are all in the ceiling and clearly oversized, maybe its only heating the air in the room and not the objects in the room itself so there is nothing to really hold the heat and thus, it dissipates quickly?
 

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Old 01-11-22, 11:59 AM
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the slab is acting as a cold sink and pulling heat right out of the room
As noted your biggest heat loss is the ceiling, slabs do not "suck" heat out of a room, heat loss moves out of a conditioned space and downward is the least of your concerns, not that there is much your even going to be able to do anything about it.

You still have not stated what the ceiling insulation situation is, that is absolutely the first thing to check and address!
 
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Old 01-11-22, 12:22 PM
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I don't know what the R value is but I do know there is fiberglass insulation between the ceiling and the floor. I will see if I can pull down a recessed can this weekend and find a rating on it. If that doesn't work, I will probably have to cut into the ceiling, which the wife won't be happy about. (she complains about the heat bill but then doesn't want me to spend time/money trying to fix...)

Also, if heat was escaping through the ceiling, wouldn't it just go into the upstairs bathroom above it? That room gets just as cold.
 
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Old 01-11-22, 02:58 PM
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if heat was escaping through the ceiling, wouldn't it just go into the upstairs bathroom above it? That room gets just as cold.
It's escaping the conditioned space which is the first and second floor, that is why the upstairs rooms are cold.
​​​​​​​
You typ would not have insulation between floors, only on the top floor!
 
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Old 01-11-22, 03:04 PM
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You typ would not have insulation between floors, only on the top floor!
yeah; I am not sure who did their construction but I've noticed a lot of peculiar things as I've done work on the house.
 
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Old 01-14-22, 11:52 AM
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So I discovered I could actually lower my blower speed down, so now the room heats on the lowest speed. I am hoping this will give more "thermal mass" (if that makes sense to say) to the room by allowing furniture to warm up and hold temp instead of just the air.

I am using an infrared thermometer to check temps around the room. the room is set to 63 at night and 66F 9am-7pm and 69 to 7pm-12am.

I checked temps today around noon when the room was set at 66 and outside is windy 41F. Here are the temps:

1) Air temp: 66
2) rug on floor: 67
2) Couch: 68
3) External wall baseboard: 61F
4) Wood floor near baseboard on external wall: 59F
5) Wood floor 1ft in from external wall: 63F
6) wood floor 2ft in from external wall: 65F
7) wood floor 3ft in external wall: 66F
8) wood floor near intenral wall: 66F

So 1) furniture is holding heat. 2) baseboards are cold. 3) floor next to external baseboards are even colder 4) floors more center in room at not cold 5) internal baseboards and floor are not cold

Reminder, heat is hydro air with registers on the ceiling only.

It looks like there may be insulation issues along the bottom of my walls. Here are some pics of the inside and outside. Any tips? Anything I can do inside or outside? I see some small gaps between the plywood under the siding in a few spots but for the most part, the shingles are tight to the concrete




 
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Old 01-14-22, 01:57 PM
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It's hard to say without opening up walls/ceilings. Insulation is about the R-value of the insulation, but it also assumes it's installed correctly. I have a sunroom which is 'insulated', but when installing an electrical box, it was quickly clear that while there is insulation, it's so compressed in spots, and gaps in others, it might as well have been excluded completely.

Connections areas are notorious for being difficult to insulate properly. Along the rim joist, it's possible the wall insulation doesn't go down all the way, or maybe there wasn't anything between the concrete foundation and the rim joist, or who knows what else. I don't know how to further troubleshoot without removing the bottom 6-12" of drywall... which may or may not provide additional indications.

There's nothing painfully obvious from looking at the pictures. You need to decide how much you want to start digging.
 
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Old 01-14-22, 10:38 PM
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Thanks, Zorfdt. Would insulating the outside wall with rigid foam help at all? Probably would have to dig down a bit?
 
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Old 01-15-22, 04:08 AM
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And the ceiling insulation is?

Your making a science project out running around the house taking temperatures of everything with some assumption that this is going to be of some use. Your inquiring about foam insulation on the walls but you still have not done the basic investigation of figuring out what type, the amount, or even if you have any insulation in the room.

 
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Old 01-15-22, 07:55 AM
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Marq1 your commentary is a bit off but thanks, nonetheless.

The foundation is accessible. The ceiling is not. I am well aware that heat rises and that ceiling insulation is paramount. I know there's insulation in the ceiling and that it doesn't have any labeling. Simply asking if people insulate the foundation isn't making a science project out of things.

Will more insulation in the ceiling stop the draft and cold sink I feel along the baseboards? Nope. So I think a question about people insulating exposed foundation is pretty logical here and Z's response prior to that was actual helpful.
 
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Old 01-15-22, 09:02 AM
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I have tried to explain that a majority of your heat loss is possibly going through the roof which by the way is one of the easiest and most effective projects you could do to improve your overall heat loss

If there isn't R60 up there that is the first project to tackle. You could go to all the trouble to tear out the walls to reinsulate, maybe making a slight improvement and still not make any where as much improvement at that one weekend project of adding insulation to the roof areas.
 
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Old 01-15-22, 09:48 AM
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"easiest project" is a bad assumption. the second floor room has a 15 foot arched ceiling that is shiplap. It has no attic above; just roof. I am certain its under insulated. That entire room will be insulated with spray foam when I have time to remodel the bathroom. I am certain it doesn't have the joist space for R60. For now, I am trying to tackle any other things that currently are accessible and low time commitment and might slow down heat loss. The construction on this extension was shoddy at best...
 
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Old 01-16-22, 05:47 AM
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the second floor room has a 15 foot arched ceiling that is shiplap. It has no attic above; just roof.
Wow, 16 posts and we finally get some valuable information.

So that changes everything.

Your ceiling and walls are pretty much as they are. The cost of fixing either of them is probably not worth the effort just to gain a small increase in R-value. Unless your willing to tear out the interior, or exterior, walls about the only other option is foam injection. But, that process works best when there is little or none insulation, moderately to well insulated walls can block the foam.
 
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Old 01-19-22, 08:25 AM
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Alright, so moving on from that.

I had some time to walk the exterior perimeter for this leaky room this morning. I noticed a few things...

1) There is no sill flashing.
2) In some areas the last row of cedar shingles overlaps the foundation wall, in others it abuts the top of it
3) In some spots I can see the sill plate if I gently pull the last row of shingles back.

It looks like I have several areas that are susceptible to water and cold air infiltration. I spray foamed the couple of large gaps, however, many small openings still remain. I am going to look into other flashing/insulating options. I would appreciate any suggestions.
 
 

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