caulk under all lap siding boards?

Sep 27, 2005 4 Replies

I'll second that. Any moisture that gets behind the clapboards needs a way to get out. Caulking will hold in moisture and rot the clapboards from the inside out. A general rule-of-thumb (but not always true) is to caulk vertical cracks, but not horizontal ones. Many times a horizontal seam is where water is meant to leave a structure.

Ken

I have noticed that a lot of my lap siding boards have a small (1/16 to 1/8) crevice where the boards lap over one another -- that is where the thin top edge of the beveled siding (3/16?)goes under the the thick (3/4?) bottom edge of the next upper board.



I am painting the boards. Should I caulk all of these crevices?



(Boards have been up and sun&weather-exposed for 23 years.)



Thanks,



FACE



Yes - in addition, lap siding is meant to expand and contract across the width of the board - sometimes a pretty significant amount on wider lap siding.

To Ranieri and Ken, thanks for the prompt response and I understand what you are saying and why. With the settling over the years, the vertical cracks/openings are plenty. :-)

I did close up the lower horizontal crevices on the chimney chase just above the shingles because of bouncing rain but left the upper ones uncaulked. (Mainly because I ran out of caulk -- another message. :-)) I know that the chimney cap has about an 1 1/2 inch lip-over is not watertight.

I am not "mr. construction" by any means -- I am trying to save several hundred bucks by doing stuff myself and I do a lot of "looks like" and "appears".

FACE

Join the Discussion

Have something to add? Share your thoughts — no account required.

Didn't find your answer?

Ask the community — no account required