vinyl siding-stud bleed through?

[Lorne]

Baby blue siding. Yuk.

On both ends of the house there are faint beige marks that correspond to the studs underneath [no underlayment].

From all appearances the siding and all the trim including large wood panels under the windows are original from 1987.

The siding is not touching these studs, but just close.
how can this be.

I will be undercoating with BIN or Kilz to prevent further bleed through.
I just wonder how this happens.

[Jim from Canada]

It is the same thing when you "see" the studs through drywall. Every place there is a stud, there is a thermal bridge from inside to outside. It does not have to be much of one, just so long as there is a temp. difference. This will transfer right through and the cooler spots will make the moisture in the air condense on the cooler spots. This will make dust etc. stick to it and show a line. Also, the water that has condensed where the studs are will act like a million little lenses for the sun and fade the siding a bit quicker. This is a long process, in your case from 1987. It is also one of the reasons I dislike metal studs for exterior walls as the metal is a much better thermal bridge than wood. Physics 101, class dismissed, lol

Jim

[Lorne]

Thank you so very much. I think I am pretty smart some days, but at 66 I think I'm on a dumb curve.

This forum is the best thing since sliced white bread.
My mind says, yeah, lets reclad the whole house the right way, but my body says NOT.

[Jim from Canada]

Well I am 20 years behind you but still get huge bouts of "brain farts" happening. The old, "walk into a room and then wonder what I came for" dilemma. lol. Seems there are always 3 more irons in the fire than can be handled. Anyway, if you are going to reclad the house, a layer of board insulation first will stop the stripping, and lower your HVAC costs. I am using a 1/2" foil faced exo-therm. The foil is on both sides of the board. It is rated as a air infiltration barrier (like tyvek, typar, or other house wrap) and has an R value of 5.5. It is an on going project but the difference is most definitley worth the price. Remember to tuck tape the seams.

Jim