[Greenbuilding] moisture and painting issues in Seattle

John Salmen terrain at shaw.ca
Sun Jul 6 15:16:22 CDT 2014


We are getting more intense rains followed by sunshine – as well as the typical continuous mist. Wood no longer seems to have the opportunity to dry sufficiently during the winter. No longer a great substrate for paint finishes. Bottoms of walls are especially prone to splashback from surrounding ground as well as moisture simply draining down the wall – or rising up the wall from ground air movement. We also have a limited painting season (which if not followed strictly affects longevity substantially)

 

The real issue is not how to fix it for appearance and what to put on it but how to deal with it as a lead abatement problem. That involves either leaving it all the paint on and encapsulating it with a lead containment product (that limits how much remediation you do and basically dictates the paint and cost of) – or removing the paint entirely in which case you have a fresh start on the building but probably not much of a budget left.

 

As for venting with wedges. Clapboard was a great product in that the laps provided continuous support and some nail coverage but also allowed for movement and gaps for air. Over numerous paint jobs the laps would get sealed – so wedges could be useful and you can buy them for that purpose but I suspect your cladding is old fir and the wedges will probably split the boards or put too much tension on them. I would recommend clearing the gaps from paint (as part of the lead remediation) and gently prying them open to renew a natural gap.

 

As for paint. Paint industry is extremely complex seemingly based more in tradition, fashion and economics than it is in science or common sense. No paint can do everything so there is no such thing as a good brand or good paint. It depends what you are covering and what you want from it. If you have stripped the old lead paint from the house you will be left with nice old boards with splits and exposed knots and god knows what. It is unlikely that you will find a paint that will form a smooth reliable film over that. Paint is basically filler – chalk mostly with a little pigment – held together with a binder. Durability is really about the quality of ingredients (how finely ground and how much) and how the binder fills in the spaces. Coarsely ground material has sharp edges and breaks the film that holds it. Also holds dirt which holds moisture breaking down the film allowing moisture behind etc... hence the price.

 

If you are encapsulating (the lead) I would look at a top coat paint that would form a lasting film – waterborne alkyds or acrylics with ceramic spheres as filler (nanospheres) would be the best performing (behr actually makes one, dulux, etc.). If you are stripping I would look at penetrating solid stains rather than a ‘paint’. Penofin coverall might be a good type of product but I have not used it. Benefit of a solid stain is that it wears off by oxidation as opposed to peeling off as a film.

 

I think Behr gets recommended because of price and it is true that a potentially better quality paint can be purchased for equivalent or less cost by painters.

 

John

 

 

 

 

 

 

From: Greenbuilding [mailto:greenbuilding-bounces at lists.bioenergylists.org] On Behalf Of Sacie Lambertson
Sent: July-06-14 9:35 AM
To: Greenbuilding
Subject: [Greenbuilding] moisture and painting issues in Seattle

 

​All,  I would appreciate advice vis a vis the following:

An old 1904 house gutted and insulated not real well with fiberglass batts, rewired, plumbed and painted by the previous owner.  The paint job, done probably within the past 6-7 years over both old and new clapboard is failing.

A number of painters have looked at it, each having their own theory and practice.  Photos taken of the outside in the cold indicate likely, moisture from the inside, usually where the studs and floor rims are.  (Paint failure no more here than elsewhere).

Paint company reps suggest climate does not allow thorough clapboard drying. Sun on damp clapboard causes previous paint to blister pulling up all layers of previous paint to expose raw clapboard.  Notable, up high where overhang protects, the paint is in good shape.  Best practice would be to first scrap/sand as necessary, allow air behind clapboard via 'widgets' placed every 12-18 inches followed by an application of oil OR water-based primer and two coats of good paint.

Would appreciate comments/advice on all aspects, including the use of oil OR latex primer and why and the idea of allowing air behind clapboard.

Curious too why paint reps, (two different known brands), sniff at Behr paint the single most often recommended paint by Consumer Reports.  Assume no discount from Home Depot to painters??  

Thanks, Sacie

 

 

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