Lead paint, old clapboards, honoring history
I purchased an 1860 house in Beacon, NY, with 1820 masonry. The aim is to honor the history of the structure while updating the materials where needed with products free of fossil fuels.
A major challenge at this stage is the clapboard. It’s slathered with lead paint, of course. The issue is how to move ahead: figure out a way to remove the lead paint and apply a coat of 50-50 pine tar-raw linseed OR cut losses, remove the old clapboard, replace with cedar clapboard, and apply 50-50 pine tar-raw linseed OR suck it up, paint over the lead paint with decent lead-free paint, and embrace compromise.
A few more points:
– we removed the asbestos siding already
– vapor permeability must be maintained throughout system
– no space between the balloon frame and the clapboard
– plan for envelope is clapboard, Airkrete, and a mag board TBD
A major concern with painting over the lead paint is vapor permeability. It seems to be the option involving the lowest financial outlay; however, it may not meet permeability requirements.
Thank you for your consideration.
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Replies
User-6871803,
First, can you tell us your name?
As I'm sure you know, preparing the old clapboard for repainting can only be done by a contractor who follows lead-safe procedures. Here are links to two GBA articles on the topic:
Managing Lead Paint Hazards
Lead-Based Paint and Green Remodeling
If you have a contractor scrape and repaint, you'll still need to follow lead safe procedures in 7 or 8 years (the next time you need to repaint), because you won't be doing a full abatement.
Finally, if you leave the existing clapboard in place, you'll have a wall without a rainscreen and without a decent exterior air barrier. (Airkrete has a tendency to shrink away from the framing, so the Airkrete won't be airtight).
I advise you to install new sheathing (installed in an airtight manner), new furring strips to create a rainscreen gap, and the siding of your choice. You'll have a much better wall if you follow this advice.
By the way, your worries over vapor permeance are groundless. Even if your old siding has a layer of lead-based paint, the paint won't cause any problems related to vapor diffusion. (The risk has to do with poisoning children, not vapor diffusion.)
Leaded paint is a true vapor barrier. If it's clapboards nailed directly onto the balloon framing (no plank sheathing) insulating the cavities will almost certainly cause the paint to fail in short years due to the high moisture content of the clapboards, followed by the nails &/or the clapboard it self. It has survived until now due to the clapboards' ability to dry quickly into the empty framing cavities. That rapid drying will no longer happen if the insulation is allowed in contact with the clapboards.
Whether keeping the original clapboard or installing new ones, providing at least a 1/4" deep (1/2" would probably be easier and better) vent cavity between the clapboards and the insulation would provide significant mitigation against those issues.
I've never been able to figure out how to access settings and do so, Martin! My name's Gregg Zuman.
Note I'm a first-time homeowner, and I'm not an industry contractor.
Thanks for the feedback. You seem to indicate that "full abatement' is impossible save removal, abatement, and reinstallation of clapboard I assume (so replacement would seem to be in order as the trouble and expense must be tremendous). When you mention new sheathing, I don't quite understand what that means: new clapboard or an additional layer such as MgO board between the existing clapboard and the Airkrete. Furring strips between the clapboard and Mgo board would make sense, e.g. I figured as much - thanks for pointing me in the right direction here.
Regarding Dana's point, he reiterates the point that furring strips plus MgO board (on either side of the Airkrete) is the way forward. I'll need to cut the MgO board to size between each stud unfortunately - but that's one of the prices of rehabilitation as opposed to new build I reckon (unless I end up choosing to replace the clapboard, which I'm trying hard not to do).
Greg,
You wrote, "I'll need to cut the MgO board to size between each stud unfortunately." I have no idea why -- but it seems clear to me that the MgO board won't be installed as sheathing.
These days, there is almost always a solid layer on the exterior side of studs, between the studs and the siding. This layer is called sheathing. Typical examples include boards (for example, 1x6s or 1x8s), plywood, or oriented strand board (OSB).
Old houses often lacked sheathing. In many cases, clapboard siding was nailed directly to the studs.
For more information, see Wall Sheathing Options.
Another critically important thing to do when insulating &/or re-siding a balloon framed antique is to add the proper flashing details on window & door openings. In the same way that the empty stud bays allowed the siding to dry quickly, bulk water incursions at window penetrations also dried quickly.
This is often difficult to do without at least partially removing the original clapboards so that the windows can be pulled out, flashed and replaced or re-installed. The flashing needs to direct any bulk rain water getting by the windows back out to the exterior side of your exterior MGO board, whether it is installed as sheathing, or between the studs with the vented air gap to the siding to drain. Raw MGO wicks moisture fairly readily, but any type used on the exterior needs to be treated with something (wax?) that will reject bulk moisture. I've never designed with it, and I'm not sure what grades of MGO out there would be appropriate for the exterior sheathing of a wood framed structure without some other weather-resistant barrier material for a non-wicking/less-wicking drain plane.
Greg,
While Dana is correct that a perfect coat of lead-based paint, adequately thick, is a vapor barrier, you aren't legally allowed to have that. You'll end up with old clapboards that have been scraped and prepped (using lead-safe practices) and coated with a modern lead-free paint.
So if you keep the old clapboard and repaint it, you won't have an exterior vapor barrier. You'll have old clapboard with some flecks of older paint still clinging to it, but you won't have 100% coverage of lead-based paint.
Martin, I’m seeking preferably a solution to keep using the original clapboard, which is in fine shape. Yes, sheathing cannot be installed as you know in such a situation; therefore, I’d need to slot mag board between the studs. Many thousands of 19th C homes labor under such conditions today (yet subsist), and the subtext of your Post is that all owners ought to pull the wonderful wood clapboard off of them and replace them with anything that can accommodate sheathing no matter the situation. Fair enough.
Dana, the exterior MGO board spaced with furring between the clapboard may get overwhelmed with moisture? The whole system I propose is designed to manage moisture, but maybe it gets overwhelmed in this case. Of course the studs as well as the entire timber frame are right up against the clapboard already going on 170 years and look great...
On the topic of MGO boards, I’m having a tough time to date sourcing a fossil fuel free product. They all so far seem to feature fiberglass mesh, and I continue to seek alternatives to this material.
Airkrete is wonderfully imperfect. Since mold cannot form in this system, I reckon the major issue will be the insulative value. I plan to make up for it with over a foot of Pavatex insulating the roof. It seems to fit the bill as far as I can tell.
Gregg,
You may want to read this article: Insulating Walls in an Old House With No Sheathing.
Gregg,
Few homeowners aim for building materials that don't require fossil fuels. It's an interesting (if unusual) goal.
Since your house is in New York, I'm wondering why you have chosen to insulate the roof with a material manufactured in Switzerland and France (Pavatex) instead of something like cellulose (manufactured in the U.S.). It will probably require a fair amount of fossil fuel to transport your Pavatex from central Europe to New York.
Martin, basically all housebuilders until the end of WWI crafted homes using nontoxic materials. Since my house is in NY, I've chosen to insulate the roof with a material that's nontoxic and produced from a regenerative resource (cellulose has its own issues, though it was my first choice until I executed additional research). Sadly, the housebuilding industry in the states IMHO is stuck with subpar options on so many levels. The embodied energy involved in producing the inputs and in producing the logistics related to production of the inputs of a final product typically so far outweighs final delivery mileage that I don't even consider such miles as relevant. That noted, shipping items between places is about 10x more efficient on a fossil fuel basis than motor trucking items.
On a related note, the local buildings department rep is demanding a vapor barrier be installed - which would destroy the entire flow of moisture in and out of the house that's the purpose of this envelope system in the first place. Ah, America...
Thanks for the link, too!
Gregg,
You wrote, "All housebuilders until the end of WWI crafted homes using nontoxic materials."
Would that you were correct! But you're wrong. The use of lead-based paint (so-called white lead) dates back to colonial times -- that is, before the American revolution. Moreover, the Johns Company began mining fibrous anthophyllite for use as asbestos insulation at the Ward's Hill quarry in Staten Island, New York, in 1858.
These days, there are far fewer toxins in U.S. homes than there were 100 years ago. Modern homebuilders no longer use lead-based paint or asbestos insulation -- two of the most toxic building materials known.
Ludwig Hatschek developed an asbestos fiber cement process in what is now the Czech Republic at the end of the 19th century. He later introduced asbestos shingles and siding to the US in 1907. Lead solder and pipes and lead-containing paint (the focus of this post) had been in use for centuries until restricted by the EPA in 1978. Coal and wood fires and open-flame lighting made the indoor air quality in many now "historic" homes quite dangerous for occupants.
If the old clapboards are scraped and repainted with a semi-permeable latex it will still suffer paint & clapboard failure if the insulation is in contact with the back side. It still needs a vent space to dry into, and for the bulk water to drain.
If they are being left in place, paint the back side of the clapboards with a heavy latex primer. That will slow the drying rate of the clapboards, but it also evens-up the moisture in the wood from the exterior to interior, making them less likely to warp or split.
MGO is isn't "overwhelmed" by moisture- it's moisture tolerant. But it can wick moisture to less-tolerant materials. The cementicious insulation also wicks and stores moisture. Unless there is something non-wicking at the drain plane any bulk water getting by the clapboards or windows gets sucked into the building materials. Water harbored in cementicious materials that are in direct contact with wood framing puts the wood at risk.
Yes, lead paint has been around at scale for a while now - centuries, indeed. Touché. Asbestos, Portland Cement, and coal came around in the 19th C before WWI. I took down the asbestos siding, I plan to lay Sorel and Natural Cement in part to cover the cracked Portland in the shed, and I'm installing wood stoves for heat with radiant heat fed by a geothermal system via Dandelion as backup if all goes well.
So that seems to bring us back to the lead paint issue. Notwithstanding budgetary issues, the direction I'm sensing from the experts is to tear down all the old clapboard and install cedar clapboard with a superior sheathing system as part of the new fossil fuel free moisture-managing envelope system. Quite painful on the wallet not to mention the historical value; however, many "historic" homes are in fact quite dangerous for occupants unlike recently constructed "air tight" houses with offgassed materials that never fail to produce desired results.
Dana, the coating of both sides of the clapboard with appropriate materials is intriguing. I hadn't even considered it. With furring strips providing a "drain plane", the MGO-Airkrete-MGO would seem to work well enough notwithstanding the unique spacing between each stud...
Tough choice here, as the more I remove from the structure the more of a fool I feel - what did I purchase again? I'll be left with the balloon frame, the masonry, and the stone foundation including a stone lower floor wall that's an insulation challenge all in itself. New cedar siding would remove more character and history while meeting my fossil fuel free threshold with the proper coat of material. $$$ May be leave the studs exposed while insulating from the outside of the studs... But then the house may look funny jutting out of its original foundation...
Gregg,
You are learning a painful lesson: if you buy an old house, you are often acquiring dangerous toxins that need to be abated or mitigated -- in your case, lead paint -- as well as a leaky thermal envelope that will never be as energy-efficient as a modern house without very expensive renovations.
It's been brutal, Martin.
At the moment, I'm feeling lead paint removal by a proper service is the best route forward; however, I'm now searching on line for one, and I'm having a heck of a time finding any in the region. Any support from the advisors would be wonderful...
Plan B? Hmm. Still noodling. This exchange has been very helpful, to be sure. Thank you for the tough love.
Greg,
You could approach your "deep energy retrofit" project in stages. It's even possible (if NY law allows) you could strip and reinstall your existing siding. Almost anything is possible, but sometimes you have to consider what is practical and affordable.
@Steve
"Almost anything is possible, but sometimes you have to consider what is practical and affordable."
Answer: Lightning
Gregg,
By the way, great resolution on the photo. I enlarged it (see section below). I'm not as convinced as you that the siding is in "fine shape" (as you claimed in Comment #7).
[Click on the photo attached to this comment if you want to get a real close-up view.]
.
iPhone 5SE. That's the worst spot, Martin. That corner actually isn't properly supported, and there's a bit of structural work raising that corner that remains to be executed. Also, some yahoo plumber or such 100 years ago hacked into a support beam between the top two floors - discovered as part of the gut process; as a result, the plan is to support the wood beam with metal filch plates on either side of it. Good catch on the issue there.
"Lightning", @John?
BTW, I'm set to work with a local contractor who's game to scrub the siding and see how it goes. The thinking is to achieve a "pretty good" historic clapboard situation in which the clapboard is cleaned up as best as possible; then, coat it with pine tar & raw linseed or may be another breathing type of coat. Fingers crossed.
Gregg: In my area cedar siding can be purchased pre-primed on both sides, with the primer-paint applied at the mill.
The exterior MGO in your stackup would be serving as the drain-plane, and the only MGO I've seen (a limited sample, to be sure) wicks up rather than rejects bulk moisture. My sense is that there are different grades of the stuff- maybe there is a type that works just fine as a drain plane- I'm just flagging it as an issue to be absolutely sure of before going forward with it. The types I've seen would need to be painted to limit water absorption, and I'm not sure what paints would even hang onto MGO for the next 100 years, and it would need to last at least that long if used as the drain plane behind siding.
Traditional 20th century wood sheathing (whether plank, plywood, or OSB) has been asphalted felt between the sheathing & siding as a drain-plane material. But spun polyolefin housewrap has gained a majority market share over the traditional #15 felt by builders over the past decade or three (for better or ill), and more recently factory applied spray-on weather resistant barrier on the sheathing itself (eg Huber Zip) seems to be coming on strong. If the MGO won't cut it on it's own, asphalted felt would.
@ Gregg Zuman
Yes, as in burn it down (I'm joking,,kinda of). I don't put much weight in the historical value of old wooden homes. They're usually drafty, odd dimensions, short ceilings, have structural issues, and much of their "value" is locked up on lot itself.
Conversely you could always do a gut rehab and just get it fixed. Maybe look into a HomeStyle Renovation mortgage where the cost to renovate is no more than 50% of the "as completed" value of the home.
https://www.thisoldhouse.com/ideas/how-to-strip-years-paint-house