T1-11 Siding Vertical Joint Sealing

Hi. I have old T1-11 siding on the back of my 36 y.o. townhome that I purchase about 4 months ago. I noticed that one section of siding definitely needs repainted. While inspecting it I noted that I can push in slightly on the bottom half of this overlapped joint. It hits the stud about 1/8-1/4 inch behind it. The panel on the left side is solid against the stud or backing top to bottom. It is only the bottom half of the underlap of the panel on the right. I think you can see from the photo. The siding is otherwise solid and in good shape. Going to re-prime this side with triple thick peel stop then coat with the color exterior paint.

My question is for this joint. I don’t want to replace this siding but want to seal that overlap somehow before painting. A good flexible, paintable caulk? Liquid nails? No signs of water intrusion inside or out that I can see but in Southern Arizona, we definitely get driving monsoon rains.

 

The seam of the siding (where one panel laps over the edge of another one) is supposed to be directly over a stud. The one in front is supposed to be nailed, holding that joint tight. If there is no wood behind that joint, I would say you need to go inside and add a 2x4 or something so that it can be nailed. Those joints don't normally need to get caulked. If you have no access to the wall framing from inside then you could maybe glue it or caulk it.

 

The only times I've caulked the seam on T-111 is when it was fit poorly - but still nailed tight. Caulk will fail if the wood isn't secured decent.

 

The one in front (left side) is nailed to a stud and is very tight and solid. No give whatsoever. The lower 4 feet or so of the panel lipped behind (right side) has that very small give to it. The photo shows it pushed in. Goes back tight against the lip in front when I let go. It also hits solid wood at that point when pushed in. I cannot get behind it without tearing out the drywall in the bedroom closet. I’m pretty sure it would be secure enough to glue or caulk. I can give that a try and give it a try and keep tabs on it every few weeks. You know it has probably been like that for a long time and never noticed. Not many idiots like me go around pressing in on the siding joints. No give on any siding anywhere else. The house is half brick. definitely won’t break the bank to cut a small section of drywall and put in another nailer if I absolutely had to. Saving that for last though. Or upgrade that small section of siding to a cement base t1-11 that’ll match that,style. HOAs you know.

 

Only other idea might be to predrill a few tiny holes and put a few small brass screws in to such those pieces together. Brass so that they don't rust.

Exterior screws would probably be a little too big.

 

Good thought.