# Nails Driven Too Deep in Siding



## ms2069 (Aug 23, 2009)

Our home is 7 years old.  It's time to re-paint but I'm noticing that the nails in the siding were driven in too deep by the builder.  I'm hesitant to just paint over them because I'm not sure the paint will keep moisture out.  Any suggestions?  Can I fill each nail hole that went too deep with some sort of silicone?  I'm willing to do that but not sure what to use.  If that is the fix, I want to make sure it's some that is easily covered with paint so my house doesn't look like it has freckles when I'm finished.  Thanks for the input.

Mike


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## Nestor_Kelebay (Aug 23, 2009)

No, don't use silicone; nothing sticks to silicone, and you'll have trouble getting it all off later.

I'd use DAP "230" (advanced latex sealant) available at Home Depot.  Just put a dab over the nail head and then use a putty knife to spread it flush with the wood.  Water based products generally shrink as they dry, so you might have to apply a second coat to fill in the shrinkage.

The advantages of using a latex caulk is that:

a) latex primers and paints will stick well to it.  Oil based primers and paints will also, but the caulk will dry softer than the oil based primer or paint, so if someone presses on a covered nail head with a fingernail, the oil based primer or paint will prolly crack.

b) latex and/or acrylic products will allow humidity (that is, individual H2O molecules) to pass through them, but will not allow  liquid water to pass through them.  That's cuz the molecules that make up acrylics can be though of as being like a long wire scrunched up into a ball.  The spaces between segments of wire in that ball are wider than the diameter of a single H2O molecule, but smaller than the distance between H2O molecules in liquid water.  So H2O molecules can normally pass through acrylic or latex paints and caulks, but not liquid water.  This has the effect of allowing any moisture that accumulates inside your exterior walls over the winter to evaporate out through those walls during the spring, summer and fall.  But, at the same time, the acrylic or latex paints and caulks won't allow rain water into your walls during the spring, summer and fall months.

That ability to "breathe" is one of the advantages of latex primers and paints, but in my own opinion, exterior alkyd (oil based) paints simply stand up better outdoors than latex paints.  They simply seem to last longer on wood than latex paints.

So, I'd scrape off any old paint off that wasn't putting up a respectable fight to stay on, sand down to "feather edge" the edges of the existing paint so they don't show through the new paint, sand down to roughen to roughen the existing paint, use a latex caulk over the nail holes, prime any bare wood with an exterior alkyd primer, and top coat with two coats of a FLAT exterior alkyd paint.  The reason why I'd use a FLAT alkyd paint is so that I'd avoid having to sand that paint in future cuz a flat paint is rough enough for any subsequent coat of paint to stick to without sanding.  So, if you stick with a flat alkyd paint, you can just paint right over it with another flat alkyd in future, and still get excellent coat-to-coat adhesion.


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## inspectorD (Aug 24, 2009)

My painters use "window glazing putty". It holds up very well to movement and you can carry a ball of it around in your hand and apply as needed.
It was what was always used before caulks, still works very well.


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## Nestor_Kelebay (Aug 24, 2009)

Actually, window glazing putty is nothing more than raw linseed oil mixed with clay.

If you're planning to use an oil based primer, then the primer should stick better to the glazing putty than it would to acrylic caulk.  The reason why is that drying oil coatings (like linseed oil based paints and varnishes) and modern "alkyd" paints and oil based "polyurethane"s all cure through exactly the same chemical process called "auto-oxidation".  Auto-oxidation is the process by which O2 molecules in the air react at pairs of unsaturated sites in the unsaturated plant oils that all of the aforementioned coatings are made from.  When that happens, the O2 molecule breaks apart and forms a pair of C-O-C bonds (or cross links) between the two unsaturated sites.  The formation of those C-O-C bonds between unsaturated sites on the same molecule and between molecules is what gradually transforms the liquid oil into a solid.

So, if you fill the nail holes with glazing putty, and then paint over that glazing putty with an alkyd primer, you'll get chemical crosslinking between the glazing putty and the exterior alkyd primer, thereby ensuring excellent adhesion between the two.  Really, it wouldn't be called "adhesion".  What you'd actually have is chemical bonds forming between the putty and primer.  You probably can't call that "adhesion" but it would make the primer bond to the putty, so that it would seem just like good adhesion.


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## ms2069 (Aug 25, 2009)

Is using a primer just over the glazing absolutely neccesarry?  I'm only painting the house due to the nails being driven too deep.  I don't want to take the chance of water getting into the siding.  Was just planning on painting directly over the whatever it is I decide to use.  Thanks.


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## Nestor_Kelebay (Aug 25, 2009)

ms2069 said:


> Is using a primer just over the glazing absolutely neccesarry?  I'm only painting the house due to the nails being driven too deep.  I don't want to take the chance of water getting into the siding.  Was just planning on painting directly over the whatever it is I decide to use.  Thanks.



So, you were thinking of just filling in the nail holes and painting over them.

You WILL have the same "adhesion" (if you want to call it that) between glazing putty any any "oil based" product, be it an exterior alkyd primer or an exterior alkyd paint.

But, you have to keep in mind that the ability of your paint to hide an underlying colour depends on several factors, including the colour of the paint (which is determined by pigments in your paint) and the gloss level of your paint (which is also determined entirely by the pigments in the paint).  So, if you're wanting to paint over glazing putty with a high gloss organic colour like Navy Blue, Hunter Green, Blood Red or Canary Yellow, you may need several coats of paint to hide the light grey spot of glazing putty underneath.

The reason why it's common to see people priming over a wall with a tinted primer is because primers are white, so good quality primers will have a lot of titanium dioxide (the highest hiding white pigment) in them, and that allows one coat of a high hiding primer to hide better than several coats of some paints.

Also, primers (both latex and oil based) are made using binders that are chosen for their superior adhesion to common substrates, whereas the binders in paints are chosen based on how hard a film they dry to.  You want good adhesion in your primer and you want your paint to form a hard film because the harder the paint film, the more scrubbing it'll stand up to without losing it's gloss, the less of a mark furniture rubbing against it will make, the less of a mark scratches will leave behind and so the longer the paint will stay looking good.  The softer the paint film, the more easily it will be damaged by wear and tear, and the sooner it'll start looking like it needs a new coat of paint.

So, if you use glazing putty to fill the nail holes.  BOTH an oil based primer and an oil based paint will stick to it like chewing gum to the underside of a church pew.  So, you don't really need to use a primer to get good adhesion to glazing putty just cuz of the crosslinking between the putty and either alkyd primer or alkyd paint.

I'd say your best bet is to try one nail hole.  Paint over it with the paint you intend to use and see if it hides the underlying spot of putty well.  If so, then do the rest of your nails the same way.  If you can see the putty spot through the dry paint, and that bugs the he11 out of you, post again.


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## Nestor_Kelebay (Aug 25, 2009)

Actually, if you're most concerned about the water getting into the wood at the nail locations, you might consider mixing up small quantities of 2 part epoxy, and filling the nail holes with that.  Epoxy is highly water resistant, paintable, sandable and it doesn't shrink as it cures.


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## ms2069 (Aug 25, 2009)

Thank you very much for the great suggestions!


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## inspectorD (Aug 25, 2009)

Yes, thank you Nestor for the information. I knew putty worked well for the nailholes, just never really paid attention as to the why.
Learn something every day.


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## GBR (Aug 28, 2009)

When siding, if the nail head breaks the surface of the siding (against code), it is proper to add another fastener at the correct depth next to it. There are many sidings, with many thicknesses, and each requires proper nailing. If there are a lot or if you don't want drywall nail pops, rent a nail gun and compressor.    
Be safe, G


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