One thing to point out is that yes, saving CO2 is grand, but this doesn't sell just how much more _comfortable_ decent insulation makes things.
I live in a '30s UK semi detached. It had an air brick , a blocked up fire place and blown double glazing in each room. (barring two that were replaced)
We had to re-render the place, as it was starting to fall off at the front, and the back was scarred from unfinished renovations.
We replaced the double glazing with triple (it was cheaper than double glazing at the time, so a no brainer. has a u-value of about 1.0)
We also put 90mm of external wall insulation round the outside as part of the re-render. This cost an extra £4k compared to just a normal re-render.
before the insulation, in summer the front room would reach 37 degrees C with the blinds down, and in winter with a 5kw wood burner and central heating on full we'd reach about 18 degrees c when outside was either windy or -3c
Now in summer the hottest we've had it is about 29, with the blinds open. In winter we reach 20 within 30 minutes of the heating coming on. ( no need for the wood burner)
I wish I had done that to my father's home last year when he was alive. I didn't realize how much heat can come into a home from the attic. The joists act as a heat bridge radiating heat down from the ceiling. I plan on installing fibre wool in two layers one in joist cavities and one perpendicular over the exposed wood frame.
My parents also have a door to the attic for storage and heat leaks up through the un-insulated edge of the pull-down stairs door.
On YouTube Matt Risinger is a great resource for home repair and information. He tends to like expensive products but overall he explains main concepts well.
Early on, Risinger did a bunch "building science" explainer videos. Challenging then conventional building practices. Like advanced framing (using 2x6 studs at 24" spacing). Like properly insulate attics to prevent condensation and heat loss (keep HVAC vents within the thermal envelope).
Those early explainers are the foundation (harhar) of subsequent product and project highlights. Alas, now they're hard to find (via YouTube's lame UX). Risinger should probably pin primers to the top of his playlist, linking into his archive.
> We also put 90mm of external wall insulation round the outside as part of the re-render. This cost an extra £4k compared to just a normal re-render.
Having insulation on the outside of your structure, and especially outside of your air/vapour barrier, is ideally where you want it (behind whatever cladding you're using):
For us it stopped our moisture problem. We had mold growing on the walls, because all the moist air would hit the wall and dump out water (proper drops).
Now the walls are 10 degrees warmer, none of that condensation is built up.
there is also thermal mass and junk, but not having to wipe down the walls every night is a big big win
This is going off-topic somewhat, but I am thoroughly confused by the article you link to. The author insists we should put the rain control layer inside of the insulation, even on roofs.
He does not go into much detail on roofs, but in his wall examples, the outer cladding and the drained cavity behind it appear to be a de-facto rain control barrier outside of the insulation layer (which could be, he says, rock wool or glass fiber, which are surely a big problem if they get wet, right?) If this is so, then what does it mean to say the insulation is outside of the rain control barrier? Furthermore, if we combine these diagrams with the one showing a roof-wall junction, there does not seem to be any barrier against rainwater reaching the wall insulation that way, and I cannot see how this is not a problem.
> If this is so, then what does it mean to say the insulation is outside of the rain control barrier?
Yes, the cladding is acting as a bulk water control layer, but there is still moisture in the air from humidity.
* In a cold climate the warmer/moister inside air will at some point reach the edge of the building: by having the insulation on the outside of the control layer(s), the air will be kept warm, and so there won't be a cold surface for it condense on. If the insulation was on the inside then the control layer would be cold, where the air would condense, possibly causing mold growth.
* In a hot/humid climate the humid outside may get by the insulation and hit the cooler control layer and condense, but will just roll off the control layer outside of the building (and not cause mold inside).
> Furthermore, if we combine these diagrams with the one showing a roof-wall junction, there does not seem to be any barrier against rainwater reaching the wall insulation that way.
This is probably regarding Figure 5. All the various layers are connected to each other, so what's on the inside cannot get out, and what's on the outside cannot get in.
The black line (air/vapour layers) is continuous up the wall, around the corner, and onto the roof. The light blue (insulation) goes continuous up the wall, around the corner, and onto the roof. And the cladding is also continuous so that bulk water and UV rays are also blocked continuously.
That is what I originally thought it might mean, but the article uses the term "rain control barrier", and has a separate item for vapor control.
With regard to their relative placement, see, for example, the caption to figure 2:
"Figure 2: "The Perfect Roof"—The perfect roof is sometime referred to as an “inverted roof” since the rainwater control layer is under the insulation and ballast." [my emphasis.]
The author also writes, in the caption to fig. 1: "The claddings function is principally to act as an ultra-violet screen", thus seeming to differentiate it from any of the control layers he listed at the start of the article.
In addition, the author also lists a separate item for air control, but later writes "What about this air control thing? Well air can carry a lot of water and water is bad for the structure" - further muddying the issue, as now he seems to be discussing water vapor.
I guess this could all be attributed to being sloppy about definitions, to the point of being unambiguously wrong when it comes to roofs.
> The author also writes, in the caption to fig. 1: "The claddings function is principally to act as an ultra-violet screen", thus seeming to differentiate it from any of the control layers he listed at the start of the article.
The cladding can not stop any water and, if the control layers beneath the insulation are properly installed, it won't make any difference. The fact that the cladding does help in blocking rain is just a nice bonus to its primary function.
In some locations it may be difficult for the cladding to do this: think of any place very foggy. There's no way to make the cladding air tight, so high humidity (100%) air will get behind it (stopped by the c. layers). Or if you have shingles on your roof that leak (or get blown off in a storm), they can still block UV, but there will be dripping. And that's why you want the control layer(s) further in.
Water can destroy a structure very quickly if you don't allow for easy/quick drying. Defense in depth.
> In addition, the author also lists a separate item for air control, but later writes "What about this air control thing? Well air can carry a lot of water and water is bad for the structure" - further muddying the issue, as now he seems to be discussing water vapor.
At the top of the article he lists the control layers in order of importance. Controlling for air is more important than control for vapour, as this video explains:
It's just if you control for air you also just happen to do a lot of controlling for vapour. There's can be a lot of moisture in air, i.e., humidity.
Further there can be some subtleties with moisture/vapour: in many case you want to stop any flow either in or out of the building; in other cases you want to control air but let moisture out:
> The cladding can not stop any water... The fact that the cladding does help in blocking rain...
Clearly you are using some words differently than I do, but it is not clear to me which ones.
>...blocking rain is just a nice bonus to its primary function.
In our house and our neighbor's houses, blocking rainwater is its primary function - we do not live in a desert.
> Or if you have shingles on your roof that leak (or get blown off in a storm), they can still block UV, but there will be dripping. And that's why you want the control layer(s) further in.
And that is when you need to fix your roof, regardless of what is underneath.
In your replies here, you seem to be trying to turn this into a discussion about water vapor, but I have made it very clear that a) my questions are about what the author has to say about rain and water, and b) the author himself makes a distinction between water and vapor control.
Tellingly, you have nothing to say about this quote from the article:
"Figure 2: "The Perfect Roof"—The perfect roof is sometime referred to as an “inverted roof” since the rainwater control layer is under the insulation and ballast." [my emphasis.]
> In our house and our neighbor's houses, blocking rainwater is its primary function - we do not live in a desert.
Wherever you live the sun shines, and UV damage can be extensive against materials that are not designed against it. Cladding is about physical protection to the layers underneath.
> And that is when you need to fix your roof, regardless of what is underneath.
Yes, when you notice it. The shingles may be leaking into the roof structure without you seeing it for a while. Then once the roof has disintegrated, the leakage may go into the attic, which most people don't visit/inspect very often.
So by the time it gets to the ceiling in the livable space, where it is actually noticeable, there could be a lot of damage done.
> "Figure 2: "The Perfect Roof"—The perfect roof is sometime referred to as an “inverted roof” since the rainwater control layer is under the insulation and ballast." [my emphasis.]
You can call the things Foo, Bar, Baz, or whatever you want. The important points are the principals in the design and the order in which the different layers are (ideally) put together.
>>>...blocking rain is just a nice bonus to its primary function.
>> In our house and our neighbor's houses, blocking rainwater is its primary function - we do not live in a desert.
> Wherever you live the sun shines, and UV damage can be extensive against materials that are not designed against it. Cladding is about physical protection to the layers underneath.
This is a non-sequitur on at least two levels. Firstly, regardless of the truth of your statement about UV, it does nothing to address the point I was making here. If our houses were stripped of their cladding, they would soon fail - from rainwater damage, long before UV took its toll. Secondly, it is yet another attempt to avoid the overall issue, which is the author's position on the placement of the rain (not vapor or UV) barrier.
You seem to think that you can make an argument by quoting out of context and then stating some vaguely related fact, but, unless that fact has relevance, it does not work. Your comment about roof repair is of the same type.
> You can call the things Foo, Bar, Baz, or whatever you want.
This is just ridiculous. You are not even trying to address the question.
> If you want to argue Joe Lstiburek, be my guest:
I am not arguing with Joe Lstiburek, I asked a question about something he wrote, and have ended up arguing with you about what you mistakenly think would work as answers to that question. Your replies make it clear that you are no Joe Lstiburek.
it seems these 'perfect' walls are really double walls, with an exterior wall and interior wall separated by a "control layer" that blocks air and moisture/vapor penetration, and reduces heat transfer.
the exterior wall features brick/stone cladding as a primary rain/UV barrier and thermal buffer, and a channel to wick away air, heat, and moisture on its interior, before hitting the "control layer".
the interior wall can be concrete block, steel frame, or wood frame, with only the latter insulated, and with a semi-permeable interior skin (gypsum board + latex paint).
both walls are designed to wick moisture away from the control layer to reduce mold and other problems.
the big downside to these perfect walls are that they're actually two walls, and as such, (roughly) twice the cost of regular stick-built walls, and they're twice as thick, which, given a fixed lot size, reduces interior square footage.
Specifically with insulation, have you had trouble with air exchange?
I keep hearing (to my naive/inexperienced/non-builder mind) contradictory advice about how insulated houses should be, and I've been trying to figure out how to square decreasing heating/cooling costs with keeping a house from feeling stuffy.
I guess for stuff like the triple glazing that's not really affecting air exchange in the first place, it's just preventing energy loss, since you're already not doing air exchange through your wall. And maybe getting better insulation in walls means you can crack open a window without it being as much of a problem?
Modern construction standards like Passive House call for an extremely well insulated and air tight building envelope. Because you're no longer losing conditioned air to drafts, they then use a system that constantly brings fresh air from outside, runs it through a heat exchanger to extract most of the heat (or cool, and in some cases moisture) from the conditioned air before it's exhausted. Generally you constantly pump fresh air into the living areas and bedrooms and exhaust air from the bathrooms and kitchen (places with lots of moisture and smells).
This is very important. But there’s a good solution (last paragraph).
Our old house, built in the 1920s had been basically sealed. Since it was only 1600 sqft and had no air ducts, the rooms were small and got terribly icky. Id crack the window open in the winter to get rid of the humidity (in PA, so hardly mild winter).
You have to realize that a lot of moisture from those those 8 tall glasses of water you’re supposed to drink leave your body as vapor. I think I’ve read half the water you expel is through your lungs [citation needed]?
If your house is sealed this water has no where to go. If there’s four of you it gets bad very quickly. This moisture eventually will escape through your drywall, into your insulation and finally through the cracks of tour siding; but that means materials that should be kept dry aren’t
Our new house is very drafty and I dont plan to fix that until I instal a heat exchanger. The air in the new house is much better, and despite being at least double in size our bills have only doubled (ie the added draftiness doesn’t seem to have had that big an effect)
The solution is a heat exchanger. This is a device that exhaust stale air and replacing it with fresh air while passing through a heat exchanger. You can have very large air flows with the outside almost free energetically.
As I understand it -- In a passive house you exchange air with an always-on air exchanger (HRV or ERV depending on your climate) which also has filters.
> Specifically with insulation, have you had trouble with air exchange?
I don't have empirical evidence, however I am pretty sure that we have reasonable air exchange. My evidence for this is threefold:
1) when we have used the log fire, it didn't kill us, or pull the door open.
2) there is still a slight draft,
3) we have a missing floorboard in the understairs cupboard
Whilst all of the air bricks in the rooms were covered, the suspended floor still has four bricks exposed. The triple glazing is sealed UPVC, however in the loft conversion we were forced to have trickle vents (I think thats overkill)
It doesn't ever feel stuffy, which is good. I do need to get a real CO2 monitor though.
One last bit of evidence is how quickly particulates from cooking disappear
I think houses often have air to air heat exchangers. They suck in air from the outside, and through the power of physics somehow warm it up or cool it down to match the room temperature.
I live in a '30s UK semi detached. It had an air brick , a blocked up fire place and blown double glazing in each room. (barring two that were replaced)
We had to re-render the place, as it was starting to fall off at the front, and the back was scarred from unfinished renovations.
We replaced the double glazing with triple (it was cheaper than double glazing at the time, so a no brainer. has a u-value of about 1.0)
We also put 90mm of external wall insulation round the outside as part of the re-render. This cost an extra £4k compared to just a normal re-render.
before the insulation, in summer the front room would reach 37 degrees C with the blinds down, and in winter with a 5kw wood burner and central heating on full we'd reach about 18 degrees c when outside was either windy or -3c
Now in summer the hottest we've had it is about 29, with the blinds open. In winter we reach 20 within 30 minutes of the heating coming on. ( no need for the wood burner)