Here’s a thread in which a home inspector recommends scraping out old window caulking before re-caulking
I generally just recommend to my clients that they re-caulk the gaps in the old caulking. Scraping out the old caulking can be a big job and I don’t see the need.
What do you think?

I agree with the Halton Home Inspector where he says:

“You should definitely cut away the old caulking. You should also fill the gaps behind the caulking with a foam insulation or even better, a foam backer type insulation. This foam backer material comes in different diameters and will provide a backing for the caulking to sit on. One of the reasons your caulking has opened is because it’s just sitting over a large gap that should have been filled in the first place.”

I agree Larry, get rid of as much of the old as you can. And backer definitely helps as well.

Rationale please.

The old caulking is cracked and loose.

Exactly. You are basically trying to bond new caulk to old caulk that is already loose, so you won’t be getting a good attachment so to speak to get a good seal that keep the weather out.

Agreed, but if the old caulking is sound and tight (just cracked) then I don’t see why it needs to be removed.


Most old caulk does not move ( Stretch ).
Look at picture in above post and see why Backer rod is recomended ,
The thiner caulk stretches easy .
Most new Caulks ( Urethane example ) can move and stretch for years and stick like Baby poo they work great .

I agree with removing the old. But I don’t spoon feed my clients about how to do it. I just defer it to a competent individual.

Couldn’t agree more Joe. Not my job to monitor how they are doing repairs after the inspection. Unless, I am paid for my opinion.

My windows are due for a re-caulk; anyone knows of an easy way to remove the old hard like a rock caulking?

Hair dryer and a scraper, and some elbow grease.

I wonder if the WD40 trick would help.

Home inspection rule # 104. “Caulking is not flashing”.

Make sure that there is backer rod or some other flashing in the “crack” before you caulk. Caulking, for the most part, is more cosmetic than waterproof.

Hope this helps;

I agree also.