Sheath All That

Umbra on house siding 9

Dear Umbra,

I have been a homeowner for five years and gradually I am upgrading the 25-year-old house to be more green. I have finished replacing the single-pane windows with Energy Star-rated double-pane windows. Now I am turning my attention to the siding, since the roof is still in good shape. I have wood siding and there is a bit of rot (not to mention my puppy thought the house was a chew toy). I am trying to decide what is best both from an environmental standpoint as well as my budget. I know there are several siding options out there, but I don't know how environmentally friendly they are. Also I wonder if it would be better just to replace the damaged boards and repaint.

Donna
Bogart, Ga.

Dearest Donna,

A dog undaunted by the enormity of the undertaken task. Maybe you should just go with your dog's recommendation for tastiest siding: fiber-cement has a sort of musty taste, while painted wood has a classic earthy crunch. Vinyl cuts the roof of the mouth and aluminum is to be avoided due to laceration potential.

A little patching and a chew toy ought to
solve the problem.

Photo: Editor B

I do think you're right; it may be best just to replace the damaged boards and repaint ("a bit of rot" doesn't sound like very much). However, you need a knowledgeable person to come look at your house, and I'm booked on siding viewing through November '09.

You could start getting bids on replacement from siding companies and end up with several evaluations that way. The knowledgeable person will evaluate the type of wood, the age of the wood, the condition of the sheathing under the siding, and the extent of the damage. You should ask him/her how long the unchewed siding should be expected to survive under normal maintenance conditions.

If we look at the whole environmental picture, and there is nothing wrong with the sheathing under the siding -- you have no mold, leaks, or condensation -- this will lead us toward minor mending as the best environmental choice. Replacing any of the siding leads to energy consumption in the form of disposal of old siding and manufacture/shipping/installation of the new, so limiting the replacement as much as possible is a good way to go. Wood siding in decent shape should be easily spot repairable, a choice leading to least waste and least new wood.

As you may know, the best types of wood to purchase are reclaimed woods or FSC-certified wood. Reclaimed wood -- which you should be able to find online if you can't find a local source by phone book or word of mouth -- obviously requires no new trees, and the Forest Stewardship Council is recognized as the most thorough certifier of sustainably grown timber. The certification is widespread and may be available where you live. You need to make sure that you are buying decent, sturdy, siding-appropriate wood, and I'm not sure which type of wood is best for that purpose in Georgia homes. In Seattle, old-growth cedar is the wood siding of choice: local, water-resistant, and long-lasting.

Other than wood, the siding choices that may confront you with a full-on replacement are fiber cement, aluminum or steel, and vinyl. Vinyl siding is cheap, ugly, and environmentally toxic. In my circle of green folks, fiber-cement boards have been making inroads (the first I heard of were HardiPlank, but they come under many names). Fiber cement is Portland cement (that is, basic cement) mixed with natural fibers such as wood. Fiber cement is cheaper than wood, can be made to look wood-ish, holds paint well, won't rot or be eaten by termites, and is supposed to last 50 years. The long life of fiber cement is held out as compensation for the energy-intensive manufacture of Portland cement. Aluminum and steel siding are often made of recycled metal, so the high manufacturing input of virgin metal is not usually a worry. But steel can rust, and aluminum can get dented (usually experts say "by hail," but in your case it's "by dog"). Whether aluminum is appropriate to your home, only you and your local expert can tell. I aesthetically prefer wood or fiber cement.

If you do replace all the siding, one aspect to consider in weighing the benefits of these various materials is their actual weight and how far they will need to be shipped to get to you (or the siding store). I think aluminum and steel are likely the heaviest, so keep that under consideration. And buy local if you can.

Claddingly,
Umbra

 

Yours is to wonder why, hers is to answer (or try). Send your green-living questions to Umbra.

Umbra Fisk is Grist Research Associate II, Hardcover and Periodicals Unit, floors 2B-4B.

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  1. Rich Fein Posted 6:52 am
    20 Feb 2008

    Need to consider maintenance as wellAs a painting contractor, you have to remember the environmental impact of coating and recoating wood.
    Wood siding should be painted every 5-8 years. There are different grades of fiber cement.  Assume about the same time frame or slightly longer than wood.
    Aluminum needs painting purely for aesthetic reasons (the paint wears off), but only needs painting every 15-25 years.
    Vinyl is the same as aluminum in that after a long, long time, you'll want to paint it because it fades.  But it can eventually dry and crack, so it doesn't last as long as aluminum.
    Whatever you do, don't replace your aluminum siding.  It paints great, the coating lasts a long time and the siding itself will last longer than a lifetime.

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  2. ian Posted 10:38 am
    20 Feb 2008

    To side or not to side?Donna:
    If you have "a bit of rot" it might be just the tip and could spread over time; if your house is part of a development ask around to see if anyone else is getting similar symptoms.  One advantage of re-siding is you can take the opportunity to upgrade your insulation and/or house-wrap, which can have a dramatic effect on your heating/cooling bills.  As for new siding, I have a predilection for fiber-cement, as I expect it to last a lot longer than 50 years, and it's repaint cycle should also be much much longer than wood.  I (like Rich above) am a painting contractor, and if you do go with wood siding, you should A start with bare wood (not pre-primed, it is garbage primer) and B have your painter back-prime every square inch, and make sure the installers seal their saw-cuts.  Do those and you should never see the likes of me again!

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  3. kcrobison Posted 10:18 pm
    20 Feb 2008

    To Replace or NotI am reminded that although there is greater maintenance, the wood siding on my 100+ year old house has never been other than patched and painted. Of course on a house this old removing the wood also probably means having the hazard waste since there is lead in the old paint. Unfortunately, someone prior to me covered covered it with vinyl and so I feel compelled to leave that until it cracks and must be disposed. I have checked under the vinyl siding while doing a couple of repairs and the wood siding needs painted but is still in otherwise good repair. Should it need to be repaired in the future, as any siding may need to be, finding a match is far easier than any other product since wood is cut to size and the pattern is not phased out of production with time.

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  4. timhammond Posted 10:37 pm
    20 Feb 2008

    paint?Do you really HAVE to paint wood?  Isn't it just as well off if you don't paint it?  Can someone speak to this without bias?  

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  5. Des Emery Posted 3:10 pm
    22 Feb 2008

    wood sidingFor timhammond - yes, indeed, you really have to paint (or cover) wood.  Otherwise you risk rot on the wet hand, or warp on the dry hand.  Some wood, like cedar, changes from reddish to grayish over time, but is quite expensive.  Log houses aren't usually painted and provide their own insulation value, very expensive.  
    Have you ever looked at a barn closely?  Even they are protected with a coat of paint, but older and neglected ones turn gray with time, the planks dry out and split, pulling away from nails and fasteners, and then fall down.
    Lapped wood siding looks nice, with planks that can be replaced if necessary, and so does 'board and batten.'

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  6. themrfreeze Posted 6:11 am
    26 Feb 2008

    Painting woodIt all depends on the wood.  Some woods are extremely rot resistant and can last quite a long time without being painted.  Cedar, white oak, cypress, mahogany and ipe/ironwood are all examples.
    Other woods will rot very quickly if not protected from the elements.  White pine (commonly used as siding here in the Northeast) is one such wood.
    I personally wouldn't side my house with wood and not put some sort of treatment on it.  Warpage is a major issue with wood ...if one side of an unfinished board gets drier than the other, the wood WILL warp.  Heck, even putting a finish on one side and not the other can cause the board to warp.
    I think the thing that really should have been addressed here is replacing the old windows with new ones.  An old wood window, properly maintained and with a good fitting wood storm window, is almost as energy efficient as a new replacement window, and will CERTAINLY last longer.  Any window you buy today will last 20 years tops before it have to be completely replaced, and you'll never recoup the cost of it in energy savings.  Old wood windows need repainting every 5-6 years and reglazing every 20-25 years to keep them functioning indefinitely.

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  7. spaceshaper's avatar

    spaceshaper Posted 6:28 am
    26 Feb 2008

    My 8 cents

    If you want an impartial professional assessment, have a licensed general contractor, home inspector or well-recommended handyman/woman check your siding, not a siding contractor. Siding contractors are pretty much in business to sell re-siding jobs whether you need one or not.
    Be sure to deal with the condition that caused the rot in the first place. Even a rot-resistant siding replacement like Hardiplank can be insufficient to protect the framing below if the detailing is wrong. Rot in the frame is much more of a problem than in the siding, though they often go together.
    Wood grows with a protective skin called bark which is necessary to protect it from infection, infestation, UV degradation and excessive moisture. Siding is "flayed" wood, and not in its natural condition in any sense. Paint it to protect it.
    I agree, the life of a decent-quality fiber-cement siding properly installed and detailed should be much much longer than 50 years. It's mostly concrete, the material of the Pantheon in Rome - two millenia and still going strong. And in my experience the paint job will last at least twice as long as on wood.

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  8. willa Posted 1:29 am
    28 Feb 2008

    PaintActually, siding such as Eastern White Pine shingles can last for over 100 years with no paint, ever.  Which is not to say it's a bad idea to protect them, but linseed oil might do just as well, and doesn't look as ratty when it needs to be redone (of course, your house looking ratty may be just the reminder you need to re-do whatever coating you use).
    Wood siding lets your house breathe.  I would be very careful about encasing a house in products that don't breathe (including new insulation).  Yes, it seems like a good idea to insulate and then cover it with something durable and low-maintenance, but if in so doing you have created additional vapor barriers, all you've done is move the potential rot to a location where you won't see it until it's far, far too late.  Most heat loss occurs through improperly maintained windows (including crappy new "replacement" windows, as well as older windows that need to be reglazed or have new storm windows installed) and through uninsulated roofs/attics.  
    So blow some insulation into your attic, reside the house with sustainably harvested wood, and call it good.
    Oh, and as for fiber-cement products lasting as long as Roman cement structures?  Yeah, not so much.  Check out mid-20th-century concrete (bridges and such) and see how "indestructible" concrete is.  Unfortunately, the one type of siding that does seem to be completely impervious to the passing decades is the fiber cement with asbestos that was used in the early 20th century, but the stuff they're making today is unlikely to be that durable, if you ask me.

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  9. spaceshaper's avatar

    spaceshaper Posted 11:10 am
    28 Feb 2008

    To Willa:There's plenty of 19th and 20th century concrete in first class condition and of course there's plenty of rubbish too. Every age has its share of crap; older stuff (including Roman) that didn't make the grade vanished long ago. We only see the survivors. So far I've seen Hardiplank go fifteen years on one coat of paint and still look great and perform well, and that's as long as it's been in use in my area. I'm professionally involved in a lot of renovation work and I've yet to see any failures. I don't expect it to last less well than the asbestos shingles you despise. Time of course will tell.
    Fiber cement siding is not a vapor barrier. No lap siding is. Agreed that you need to pay careful attention to vapor barrier placement, especially in regions that experience prolonged cold weather.
    Agreed that split shake siding can be very durable if that's what you mean. Sawn shingles and sawn lap siding are generally much more vulnerable to decay as the face grain fibers are ripped open by the saw and absorb moisture like a sponge if not protected. Good roof overhangs and proper flashings are essential in any case.
    Agreed that poorly installed or poorly maintained windows are major energy sieves. Fix 'em. There are crappy modern windows and also excellent ones that will last several lifetimes if properly fitted to your house. You generally get what you pay for.

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