Why EPDM roofs, European vinyl windows, but vinyl siding is evil?
I have seen so many “green” buildings focusing heavily on occupancy health, while having EPDM or TPO roofs, vinyl windows, and yet I never see vinyl siding.
So I guess this is a two part question based on heavily processed materials and their effects on indoor air quality.
I’m designing a single story slab on grade home. Without a basement or crawl space, I am constantly debating a conditioned pjtched trussed roof with stand seam metal, or a conditioned assembly of open web floor trusses with a minimally pitched over roof and a 60 or 90 mil EPDM cover.
The flat roof assembly is just simpler to run ductwork through the open web trusses than deal with dropped ceilings, or enclosing and conditioning a pitched trussed roof without spray foam.
I hate rodents and bugs with a passion so any roof assembly is going to be unvented in as much an attempt to keep them out as possible.
So my questions are these:
1: Are there health concerns with EPDM rubber that would make it far less preferential than a standing seam roof?
2: Why are triple glazed vinyl windows so highly sought after but vinyl siding is shunned? Is there any brand of vinyl siding made from the same kind of vinyl as the windows that would make them more acceptable?
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Replies
CC,
When looking at materials that may possibly have negative health effects, it's important to distinguish between whether they are used inside a building's air-barrier, or outside. Neither vinyl siding nor EPDM roofs should have any effect on indoor air quality. Perhaps a case could be made that extremely chemically sensitive people should avoid vinyl windows, as their interior frame is exposed to the indoor air.
I think the case against some plastic uses comes not from their health effect so much as when a large amount is needed to make a product that has reasonable alternatives. I think that's the problem with vinyl siding for most critics.
A lot of vinyl siding looks like sh--t.
Besides most of these green builds that you see around here are either big $$$ custom homes or rehabs on a shoestring budget where existing siding will remain in place.
I think the main reason vinyl siding is frowned upon is that many green builds are very high end homes, and they tend to use premium materials. Vinyl siding is usually considered to be be a cheaper alternative to fancier siding materials like fiber cement. This is similar to the difference between using laminate or granite for your kitchen countertops.
As Malcolm mentioned, materials used on the exterior shouldn't really contribute to indoor air quality concerns. Any smell coming off of a new EPDM roof, for example, will be quickly dissipated outdoors and is unlikely to be a problem for the occupants of the structure. Vinyl windows are the only one of the three items you mentioned that are inside the home's envelope, but I'm not aware of anyone complaining of health problems due to vinyl window frames.
In my opinion, many of the supposed health concerns regarding modern materials used inside homes is due to people misunderstaning things, or just being scared, often because of bad information floating around on the Internet. Modern plastics tend to be VERY stable materials, which means they don't react with many other things, so they don't release any of themselves into the air. The major exceptions to this tend to be more related to improper installation (such as a bad spray foam install) rather than any inherent problems with the materials themselves. I have often seen people get scared of materials when they hear the scientific name (for example, table salt sounds much more chemical-y when you call it "sodium chloride", but it's the same thing). For a funny take on this, check out the dhmo.org website. "Dihydrogen monoxide" is a different way to say H2O -- water. That site is commonly used by science teachers to point out the just because something might have a chemical-sounding name doesn't necassarily mean it's bad for you.
Bill
The main reason I would choose standing seam over EPDM is longevity; steel roofing can last 50 years or more with a little maintenance, while EPDM will last 20-25 years at best. At the end of its life, steel roofing can be recycled while EPDM will be landfilled or possibly burned for energy. Eating either one is not good for your health. For what it's worth, I've never heard of bugs or rodents getting into a vented roof if there are screens over the openings.
Martin Holladay, former editor of this site, recently discussed the vinyl siding issue here: https://www.greenbuildingadvisor.com/article/environmentally-responsible-siding. Every product choice involves a set of decisions. With triple-glazed windows, I think most of us would prefer to use a wood-framed unit, but they cost more than PVC--sometimes a lot more--and either have higher maintenance needs or they use aluminum on the exterior, which like vinyl has a negative environmental impact. For roofing, EPDM or TPO are used on low-slope roofs because few other products will work, and those that do--such as flat-seam copper--are astronomically expensive and have a significant environmental impact. With siding, there are many options to choose from. If lowest cost is a priority, and aesthetics are not a high priority, Martin argues (and I agree) that vinyl is a good choice. But I've never had a client who found the aesthetics of vinyl siding to be acceptable.
There is little difference between the PVC used for siding and windows. Some window reps make a bid deal about windows using unplasticized vinyl, but as far as I know there aren't plasticizers in vinyl siding either.
Thanks, Michael. Here's a link to another relevant article on this topic: "Vinyl Windows and Vinyl Siding"
Martin,
That article brought into focus something I have noticed around me. My neighbours are a pioneering family in the area. They lost one son to logging accident, and his younger brother uses a wheelchair from another. And yet, while they seem to view these events fatalistically, I bet they would recoil from losing a family member to cancer that was related to a workplace exposure. We are a funny species, and don't always make designs based on purely rational considerations.
Michael,
The pest infestations I've found ion roofs and attics have often been due to the ventilation strips protected by bug screen. That's one of the reasons I'm not keen on relying on them for the bottom of rain-screen cavities.
Malcolm, I briefly thought about the best choice of word and went with "screen" for expediency. Have you seen infestations when the screening is metal, as required by the IRC, or when punched aluminum strip vents are used?
Michael,
No it's all been regular screen door mesh from probably the '70s or '80s. I just evicted two recently deceased rats from the eaves of our Community Hall which has the added bonus that the screening was stapled from the now inaccessible top side. I'd like to replace it all, but with current material prices I'd probably have to sell a kidney first.
I put up a lot of fiberglass screening before seeing the code requirement for metal screening, and I imagine this is why it's there. But yeah, everything is $$$ these days for sure!
>"There is little difference between the PVC used for siding and windows. Some window reps make a bid deal about windows using unplasticized vinyl, but as far as I know there aren't plasticizers in vinyl siding either."
You are probably correct there. Plasticizers are used to modify the physical properties of the material, which in this case usually means to make it more flexible. The example I like to use is between PVC pipe and PVC extension cord insulation. PVC used in pipes is in it's natural rigid state, so no plasticizers are needed or used. PVC used for extension cord insulation needs to be relatively soft and flexible, so plasticizers are used to make the normally stiff PVC resin more flexible. Modern plasticizers are much more stable than they once were, so there are less problems with them getting out of the material over time. If the material looses the plasticizers over time, it will gradually get hard and crack.
I agree the PVC resins used in windows and siding are probably very similar. Both will likely have UV stabilizers, and both probably have some kind of fire retardant (maybe), but in terms of plasticizers, both applications use a rigid PVC so plasticizers aren't needed.
Bill
I like you flat roof idea the question becomes can you insulate it to a reasonable level a reasonable cost?
If you go with EPDM consider putting the insulation on top of the roof using reclaimed foam if you can source it.
Architecturally your flat roof may look out of places in most neighborhoods.
In my opinion triple pane windows do not make sense until you are very far north.
I think of my home as green complete with vinyl siding and windows.
Walta
I used Vinyl siding on my vacation home in Canada 25 years ago, mostly so I didn't have to maintain it. It aged well and only required power washing a few times. Would I use it for my main residence here in the NE? No, but I see it all the time. It's relatively inexpensive and maintenance free.
Blue Vinyl the Movie from 2002
https://www.imdb.com/title/tt0303307/
https://en.wikipedia.org/wiki/Blue_Vinyl
What happens at the end of the vinyl siding life. Couldn't recycle it then, not much has changed.
The biggest problem with vinyl siding visually is the corner. I think money could be made with high end corner treatments.
EPDM roofing will last much longer than 25 years. Mine is 12 years old and still has the white printing on it. Metal,. other than soldered is not really a flat roof material. I don' t think EPDM ever fails in the way a shingle roof fails.