Not in steady rain, and a careful crew will not leave fresh joints exposed to it. Fresh mortar needs to set and dry at a controlled pace, and the published masonry guidance we rely on covers temperature and curing, not an exact rainfall limit. So the practical answer is a judgment call: stop when it is wet, protect finished joints, and resume when the wall can take mortar. Ask your contractor what their rain plan is.
Can tuckpointing be done in the rain? Not in steady rain, and not with fresh joints left open to it. A wet wall and fresh mortar don't get along, and the real skill is knowing when to stop and how to protect what is already pointed.
We want to be straight about one thing. The sources we trust for mortar work give clear guidance on temperature and curing, but they do not publish an exact "this much rain is too much" rule. So what follows is the logic from those sources plus plain contractor judgment, and we label it that way.
Why rain is a problem for new mortar
New mortar is a controlled mix of water, binder and sand, and it has to set and dry at a steady pace. Two things go wrong when that pace is interrupted.
- Too much water at the wrong time. Fresh joints that get hit by rain before they set can be washed or softened at the surface. That is a general masonry risk, not a figure from the code or a cited standard, so a good crew treats it as a reason to cover the wall.
- Too fast drying. The NPS warns that high-lime mortars dried too quickly can chalk and lose adhesion and durability, and advises misting after joints are thumbprint-hard and covering walls with burlap for the first three days (National Park Service). The point is controlled moisture. Rain is uncontrolled moisture.
The NPS also notes that wall temperatures between 40 and 95 degrees F avoid freezing or too-fast evaporation (National Park Service). A cold rain that turns to frost overnight is worse than rain alone, since saturated brick that freezes can spall (BIA).
What a careful crew does when rain is coming
- Watches the forecast and stops early. No new joints get filled if rain is on the way before they can be protected.
- Covers finished work. The NPS says to protect finished mortar from freezing and to cover walls with burlap, or plastic held off the wall, during early curing (National Park Service).
- Doesn't work into a soaked wall. What counts as too wet is a judgment call. We can't point you to a published rule, which is exactly why you are hiring someone with experience.
- Keeps the cold rules in mind. Below 40 degrees F the cold weather rules apply, and below 32 degrees F mortar has to be kept above freezing (BIA).
Chicago weather doesn't give long clean windows in spring and fall. Showers roll in after a dry morning, and a crew with no rain plan ends up with open scaffolding, uncovered joints and a wall that dries unevenly. The questions below tell you quickly which kind of crew you have.
Rain also affects the schedule. Our article on how long tuckpointing takes covers what moves it, and the best time to tuckpoint in Chicago covers the seasons. If scaffolding is up on the sidewalk or alley, remember it needs a separate CDOT permit (City of Chicago).
What to ask your contractor
- What do you do if rain is forecast during the job?
- How do you protect joints that are already pointed?
- Who decides when the wall is dry enough to continue?
- How does that change the schedule, and who tells me?
Want someone on your building who has a plan for Chicago weather? Our tuckpointing crew can look at it, and the full picture is in the Chicago tuckpointing guide. For cure times after the work, see how long new mortar takes to cure.
Common questions
Not in steady rain. Fresh mortar needs to set and dry at a controlled pace, and finished joints should be protected. The published guidance we rely on covers temperature and curing but not an exact rain limit, so ask your contractor what their plan is.
It depends on how set the mortar is and how hard it rains. Unprotected fresh joints can be washed or softened, and drying that is too fast or uneven can also hurt mortar. This is why crews cover finished work. If it happens, have the contractor look at the joints.
We can't speak to anyone else's warranty. Ask your contractor in writing what the warranty covers and how weather delays are handled. It's a fair question before you sign.
Sources
- National Park Service: Preservation Brief 2: Repointing Mortar Joints in Historic Masonry Buildings (PDF)
- Brick Industry Association: Technical Note 1: All-Weather Masonry Construction (PDF)
- City of Chicago: Guide to Building Permits: What Types of Work Do Not Require a Building Permit?
Facts last checked: October 7, 2026.
This article explains general rules and common situations in Chicago. It is not legal advice, and City rules change. For a specific property, check with the Chicago Department of Buildings or a licensed professional.