Enough of COVID...what are you doing to the house?

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Here’s one I’m doing this week. The foil backed insulation is on the drywall side of the roof. IMG_1582.jpeg

If you’re doing a basement, you foam behind studs to break the bridge. One I did a few weeks ago.
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If your doing an attic, you go over the joist or rafter ends
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No idea. However, if the ceiling void is completely filled with closed cell spray foam then my understanding is there's no cavity for moist humid air to enter at all. I'll ask them about the thermal break.
 
JC99 said:
No idea. However, if the ceiling void is completely filled with closed cell spray foam then my understanding is there's no cavity for moist humid air to enter at all. I'll ask them about the thermal break.
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Doesn’t work like that. The joist gets cold and works like a cold beer bottle does on humidity. If that’s in contact with your drywall and condensation happens on both sides of the Vapor barrier.

In some houses you’ll see light ghost marks on the drywall where it’s fixed to the joist, telltales there is no thermal break — that’s caused by moisture from the inside the house. Another clue is when you paint over the area, blisters often appear in the paint.
 
None of the issues I've had currently have come from where the drywall is connected to anything above it. Paint blistering and stains are in void areas. I've asked them the question though. Also, there are zero issues in the winter, only the summer and only for a few days where the dew point is a bit odd.

This is a pretty big company, not a fly by night so I assume they know what they are doing.

Cover the beer bottle outside with a waterproof shield to stop humid air touching the glass and there won’t be any condensation there. Look at foam bottle cosies.
 
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JC99 said:
None of the issues I've had currently have come from where the drywall is connected to anything above it. Paint blistering and stains are in void areas. I've asked them the question though. Also, there are zero issues in the winter, only the summer and only for a few days where the dew point is a bit odd.

This is a pretty big company, not a fly by night so I assume they know what they are doing.

Cover the beer bottle outside with a waterproof shield to stop humid air touching the glass and there won’t be any condensation there. Look at foam bottle cosies.
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While foam in the cavity evicts the humid air, it does nothing to the joist temp. Joist between plywood and drywall has no vapor barrier and no thermal break. I wouldnt be surprised if drywall gets some moisture there and that attracts dirt over time. To Mike's point, adding a thermal break below the joists kills this potential disappointment.

All of the above may not be a big deal if your ceiling joists are not solid lumber to the roof deck. Some are short trusses which gives you the break over most of the span. You'll find out what you have after the ceiling drops.
 
GreyGhost said:
While foam in the cavity evicts the humid air, it does nothing to the joist temp. Joist between plywood and drywall has no vapor barrier and no thermal break. I wouldnt be surprised if drywall gets some moisture there and that attracts dirt over time. To Mike's point, adding a thermal break below the joists kills this potential disappointment.

All of the above may not be a big deal if your ceiling joists are not solid lumber to the roof deck. Some are short trusses which gives you the break over most of the span. You'll find out what you have after the ceiling drops.
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If this was an issue now I'd be seeing the condensation along the joist lines but that's not and never has been the case. Got a response that this isn't going to be an issue with 5+ inches of foam in that cavity. Will see a bit more anyway when they tear down the ceiling.
 
JC99 said:
If this was an issue now I'd be seeing the condensation along the joist lines but that's not and never has been the case. Got a response that this isn't going to be an issue with 5+ inches of foam in that cavity. Will see a bit more anyway when they tear down the ceiling.
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It's all orders of magnitude. Right now, the cavity is the big issue. Fixing the cavity means the next weakest link tries to find a way to piss you off. Whether that link is a big problem or a non-issue is hard to predict ahead of time.
 
JC99 said:
None of the issues I've had currently have come from where the drywall is connected to anything above it. Paint blistering and stains are in void areas. I've asked them the question though. Also, there are zero issues in the winter, only the summer and only for a few days where the dew point is a bit odd.
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In the winter the issues can be tougher to detect as condensation freezes and the relative humidity is far lower above the ceiling. But the lumber does suck up moisture and that’s why you sometimes see mold or ghost lines on the ceiling.

In the summer, there is humid air on both sides.
JC99 said:
This is a pretty big company, not a fly by night so I assume they know what they are doing.

Cover the beer bottle outside with a waterproof shield to stop humid air touching the glass and there won’t be any condensation there. Look at foam bottle cosies.
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Exactly the point. That cozy is the thermal break.

If you don’t have a cozy around the joist….
 
GreyGhost said:
It's all orders of magnitude. Right now, the cavity is the big issue. Fixing the cavity means the next weakest link tries to find a way to piss you off. Whether that link is a big problem or a non-issue is hard to predict ahead of time.
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I'll chat to them when they are here. If it's an issue (they see wet joists in the ceiling say) then they can add some materials and labour to the last part of the job which is the drywalling.
 
The wood rafters actually have an R value of (give or take) about R1 per inch. If you have say 2X8... ~7.5, if 2X6... ~5.5 for R value for the rafters, but they also have thermal mass so it is not as simple as straight up R value. Unless there is other nonsense going on (extreme humidity inside in winter), etc. I doubt thermal bridging is going to be the cause of the problems but it can be enough to cause ghosting if you are a smoker or have a wood fire place (or a fire)... If you think about it.... houses have stood for decades with batt insulation nothing more than vapour barriers between the rafters/joists and drywall.

But if you are concerned--as an example... what I did for my 1940s 2X4 roof above my loft. I left 1.5" of air gap under the sheeting. I placed 2" EPS foil backed foam boards (very tight fit) to fill the rest of the cavity. I then strapped the rafters perpendicular with 1X and filled the gaps between the straps with 3/4 inch foam boards (which are also perpendicular to the rafters). Then under that I did 1" 4X8 EPS sheets for a full thermal break and as vapour barrier (taped). Spray foam any gaps along the way. Drywall under that with long #8 drywall screws.

I use a combo of 1X3 and 1X4 strapping so it is easier to hit the strapping with the drywall screws, always do when I strap a ceiling.
 
backmarkerducati said:
The wood rafters have an R value of (give or take) about R1 per inch. If you have say 2X8... ~7.5, if 2X6... ~5.5 for R value for the rafters, but they also have thermal mass so it is not as simple as straight up R value. Unless there is other nonsense going on (extreme humidity inside in winter), etc. I doubt thermal bridging is going to be the cause of the problems but it can be enough to cause ghosting if you are a smoker or have a wood fire place (or a fire)... If you think about it.... houses have stood for decades with batt insulation nothing more than vapour barriers between the rafters/joists and drywall.

But if you are concerned--as an example... what I did for my 1940s 2X4 roof above my loft. I left 1.5" of air gap under the sheeting. I placed 2" EPS foil backed foam boards (very tight fit) to fill the rest of the cavity. I then strapped the rafters perpendicular with 1X and filled the gaps between the straps with 3/4 inch foam boards (which are also perpendicular to the rafters). Then under that I did 1" 4X8 EPS sheets for a full thermal break and as vapour barrier (taped). Spray foam any gaps along the way. Drywall under that with long #8 drywall screws.

I use a combo of 1X3 and 1X4 strapping so it is easier to hit the strapping with the drywall screws, always do when I strap a ceiling.
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Thanks.

Have to have an asbestos test carried out apparently. $200. Not worried about that. This roof has been replaced 3 times and the ceiling done about the same. I know what's up there and none of it is from the 60s anymore. My word won't count for any safety issues though.

The only problems with this ceiling are in the summer and never in the winter. It's only an issue in the summer when the humidity conditions are just right. Unfortunately that's been a bit more this summer than previous ones. Previous summers the condensation issue might just be over one week, this one it's been a few weeks. For instance, it seems to have stopped right now. I suspect that's because the evenings are a little warmer maybe.
 
JC99 said:
Thanks.

Have to have an asbestos test carried out apparently. $200. Not worried about that. This roof has been replaced 3 times and the ceiling done about the same. I know what's up there and none of it is from the 60s anymore. My word won't count for any safety issues though.

The only problems with this ceiling are in the summer and never in the winter. It's only an issue in the summer when the humidity conditions are just right. Unfortunately that's been a bit more this summer than previous ones. Previous summers the condensation issue might just be over one week, this one it's been a few weeks. For instance, it seems to have stopped right now. I suspect that's because the evenings are a little warmer maybe.
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I am a little concerned that this is a summer only issue and not winter. While summer air will typically hold more moisture (humidity...) the temperature differential inside to outside will be much more extreme in winter.
 
backmarkerducati said:
I am a little concerned that this is a summer only issue and not winter. While summer air will typically hold more moisture (humidity...) the temperature differential inside to outside will be much more extreme in winter.
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The AC system does a very good job of removing humidity in the main house in the winter and in the winter any external air in the ceiling gap is going to have low humidity anyway so there's nothing to condense in that ceiling gap. The room under the flat roof has ceiling fans etc in too which moves air quite a bit as opposed to the ceiling gap with no air movement. I'd actually be more concerned if this was an all seasons issue. One thing we did this year that was different to other years is we fitted a window AC unit in the upstairs room above the garage as that always got hot. That's worked so well that it makes the upstairs quite cool exaggerating the humidity differential in the other upstairs room with the flat roof in the summer.

It doesn't help that our upstairs is actually a combination of the older original house (with pitched roof) with a newer tacked on addition (flat roof) and then a bunch of assorted compromises with return air registers and ductwork for the HVAC.

Put it this way, if we knew then when we bought the house what we know now we'd probably have walked away! Bit by bit issues are getting resolved though. The flat roof is finally watertight. This insulation should solve the condensation issue and as for the room above the garage we are considering putting in a mini-split AC/ heat pump unit to balance out the downstairs ductwork which has no issues with the upstairs ductwork that needs a bit of help.
 
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So, the next project after this then is probably that mini-split. It's either that or heated floors in that bedroom but that doesn't help with cooling in the summer of course. Price wise I was quite surprised that a small unit wasn't too pricey. A 9000 BTU combined ac and heat pump unit is about $1300 from Costco then installation would be another 1k I think. We have spare capacity for the dedicated circuit as we removed some baseboard heaters years ago from another room and those circuits have been unused so just need a connection.

The bedroom is at the end of the HVAC run and above an unheated garage so it's a fight to control temps in that one. Over the years we tried a few things (booster fan in the ductwork didn’t help and sounded like a plane taking off) but they are all compromises such as the window AC unit and a separate heater in the winter. So, sealing off that ductwork and basically having two zones with the minisplit as one of them seems like it may be a neater solution.
 
JC99 said:
So, the next project after this then is probably that mini-split. It's either that or heated floors in that bedroom but that doesn't help with cooling in the summer of course. Price wise I was quite surprised that a small unit wasn't too pricey. A 9000 BTU combined ac and heat pump unit is about $1300 from Costco then installation would be another 1k I think. We have spare capacity for the dedicated circuit as we removed some baseboard heaters years ago from another room and those circuits have been unused so just need a connection.

The bedroom is at the end of the HVAC run and above an unheated garage so it's a fight to control temps in that one. Over the years we tried a few things (booster fan in the ductwork didn’t help and sounded like a plane taking off) but they are all compromises such as the window AC unit and a separate heater in the winter. So, sealing off that ductwork and basically having two zones with the minisplit as one of them seems like it may be a neater solution.
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I had exactly the same issue at my sons house, his living room was above an unheated garage - colder than the house in winter, hotter in summer.

He put in an 18k btu dual zone heat pump/ac mini split. He put one zone in the garage, the other in the great room above. It cost $400 more than a single zone, but now he has hvac in his garage too. He put in a Senville 18000, I have a 24k for my garage … haven’t installed it yet.

The modern ones are cheaper to run, and can make heat down to -30c. Energy cost for heat is better than gas when outside temp in zero or above.
 
Mad Mike said:
I had exactly the same issue at my sons house, his living room was above an unheated garage - colder than the house in winter, hotter in summer.

He put in an 18k btu dual zone heat pump/ac mini split. He put one zone in the garage, the other in the great room above. It cost $400 more than a single zone, but now he has hvac in his garage too. He put in a Senville 18000, I have a 24k for my garage … haven’t installed it yet.

The modern ones are cheaper to run, and can make heat down to -30c. Energy cost for heat is better than gas when outside temp in zero or above.
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I didn't even know that was an option. I'll take a look. The issue is the garage is storage, no room to swing a cat so it's not used as a workshop often.
 
backmarkerducati said:
Which ones did you have put on, we are looking?

We had a guy that would come every November and clean them for $50, he didn't come by last year... fate unknown.
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My parents had gutter guards installed 3 years ago (no idea what brand). That winter they had massive ice damming and 8 ft long icicles dangling over the entry door for the first time in 35 years at that house. They removed the guards and sold them to someone local on marketplace for about 20% of the purchase price. About a year later they ran into the guy in a store and he told them that he'd had ice damming problems with the guards and sold them to someone else after 1 winter. I guess whether they are effective or not depends on the precise situation (guard shape, roof slope, type/amount of debris, etc).

FWIW, my 75 year old dad now uses a long hooked wand for the pressure washer to blast out the gutters on their 2 story house every fall. Messy but fun, apparently. And no ladders, which is a plus.
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