Properly installed siding should not need caulk except possibly around door and window openings, at corners, etc. The exposure to weather and the constant expansion/contraction of siding guarantees rapid caulk failure. Even around windows and doors, flashing beneath the siding is the best defense against water infiltration. Butt joints on horizontal siding ideally should be tapered so that one edge overlaps the other. A house built so recently should also have a rain screen beneath the siding to insure water can escape allowing the siding to dry rapidly.

I am in a similar situation as yourself. I am helping a friend who has a home identical to yours. I try focusing on the most needed area's that are easy to access first. It's fairly easy to dig out caulking with the tools they now have for that job. Caulking is pretty expensive though. If you do some of the re caulking yourself I suggest not to overbuy on the caulking. Caulking in my opinion has a short shelf life. I would say worse than dry cell batteries.

My friend also had his home siding plasticized with a UV resistant plastic coating.

The coating was my friends idea and he had to buy it and supply it to the contractor.

The idea of the coating is to keep from having to re stain the house every 5 to 7 years. The contractor put the coating on after the stain had been dried for about two weeks. The stuff was as thick as glue and I think the contractor was sorry he took that job.. The down side is if the coating fails he said the siding would have to be painted and not stained. That would not look so nice. So far the coating is holding up well.

Many thanks to you both for your comments! Appreciate you taking the time.

akamainegrower, the existing caulk is mostly around windows and doors and at the corners, apart from also the butt joints between pieces of siding. I bought this house last year and I have no idea how it was constructed - I just have to hope they did a good job on flashing/rain screens etc. Construction quality in this area is generally not great, but I understand mine is one of the better-constructed houses. (That said, there is a woodpecker hole in one piece through which you can see some kind of rigid backing.)

Given all of that, what do you think I should do? Just leave as is, if caulk should not generally be needed? Recall the corners and doors only, and not the butt joints?

If recaulk, should we only do the areas that are clearly failing? And would it be harmful to add another layer to areas that currently seem okay, just to reinforce them?

Thanks so much!

It's awfully hard to give "what to do" advice without actually seeing the siding. I think I would certainly skip the caulking at the butt joints. It won't last and even if the butt ends are not tapered/overlapping, siding installers usually/should slip an extra piece of felt or other water resistant material behind the joint. As for caulk around the doors and windows, if you assume that there was some reason for doing it in the first place, the old caulk should be scraped out and replaced. On the other hand, someone may have seen the gaps deliberately left for expansion and contraction and mistakenly decided they needed to be sealed with caulk. If you could get an experienced painter or carpenter to take a look, his/her advice would be far more valuable than my speculation.

You can't put new caulk over old. It won't stick or reinforce anything. If you do decide to caulk, use a quality product such as Lexcel (sp.?) The so-called painters caulks are pretty useless. The 30 year guarantees will get you nothing except a new tube of caulk.

Okay, aka, much appreciated. I'll look for a local expert for some quick advice