Design
What a Cover Does to the Water Coming Off a Patio
Posts pass through a paver field rather than resting on it, and a solid roof stops rain landing on the patio and starts it leaving along one edge. Both are base-stage decisions.
A pergola over a patio does not sit on the patio. It sits through it. The posts have to reach ground that can carry them, which means they pass down through the paver field instead of resting on top of it, and that turns post positions into a base-stage decision rather than a furniture decision. Then there is the part almost nobody asks about until the first heavy rain: put a solid roof up there and the water that used to fall evenly over the whole surface arrives in a line along one edge instead - on most Kenosha County lots, the edge closest to the house. Here is what actually changes underneath, and how to hold the option open cheaply if you have not made up your mind.
Why the posts cannot stand on the paving
Think about what a paver surface is for. Hundreds of separate units share the load between them, each one free to move a fraction, and the whole field rides a southeast Wisconsin winter by flexing rather than cracking. That is exactly the behaviour you want under a table, a grill and people walking around. It is exactly the behaviour you do not want under a post.
A post is the opposite sort of load. All of it arrives through one small footprint, it stays exactly where it was put, and downward is not the only direction it works in. Wind against a cover reaches the base of each post as a sideways shove and a twist, over and over, for as long as the structure stands. A surface built to spread and absorb distributed movement has nothing useful to offer that.
So the support for a post goes past the paving into ground of its own. How far down, how wide, and what form it takes is a designed answer for one structure on one lot, and it belongs to whoever draws and builds the cover and to the official who inspects it. You will not find a footing depth, a post size or a beam span on this page, and you should be wary of finding them on any page written by somebody who has not seen your plans. The same caution applies to what a roof has to carry through a winter here. That is a design figure produced for your structure, not a number to lift off the internet.
What a retrofit actually opens up
Adding a cover to a finished patio is possible. It is just a different job than most people picture. It means opening the surface at four or six separate points, getting down far enough at each to build proper support, then rebuilding the paving outward from every one of those openings.
Each of those is a repair in a field that was laid as a single piece. Units get cut. Compaction has to be re-established in a small space surrounded by finished paving. Joints get refilled and the edge restraint has to be made honest again wherever it was disturbed. The paving immediately around a post rarely knits back into the pattern quite as invisibly as the rest, and a border cut around a square post is a detail that reads well when it was planned and reads like a patch when it was not.
Set that against the same decision made before the paving goes down. The supports go in while the ground is already open, the machine is already on site, and the first course is laid around them. Nothing gets cut in later because nothing has to be undone. The work is the same work. The difference is whether you do it once or do parts of it twice.
A cover moves the rain, it does not remove it
This is the argument that gets skipped, and it is the one with the longest tail. An open slatted pergola barely changes the water at all - most of the rain drops straight through the gaps and reaches the ground on its usual path. What it changes is light and drying time, which matters in its own way: the strip that sits in shade most of the day stays damp longer, and damp shade is where organic growth turns up first. Our piece on reading the marks that appear on a paver surface covers what that looks like and what to do about it.
A solid roof is a different animal. Now the rain never touches the patio. It lands on the cover and leaves along the lowest edge, all of it, in one line. A surface that was designed to shed evenly across its whole area is suddenly being fed by a concentrated source at one boundary, and because covers usually go where people sit, that boundary is normally the one nearest the back of the house.
Two things follow. The first is that the fall of the patio and the route the water takes off the site both have to be worked out with the cover in the picture, not added afterwards. The second is seasonal. In this county that line does not only run in July. It runs in the freeze-thaw months as well, dripping and refreezing in the same place day after day, and water that cannot get away from a surface is the whole mechanism described in why patios heave and crack here. We are describing what happens, not sizing anything - gutters, volumes and the arithmetic that goes with them are the designer's work.
| What you build | What happens to the rain | What has to be settled underneath |
|---|---|---|
| Open slatted pergola | Most of it still falls through | Post support; a shaded strip that dries slowly |
| Pergola with a solid roof panel | Leaves along one edge in a concentrated line | Post support; fall direction and a route off the site |
| Retractable canopy over the frame | Changes with the season and the setting | Post support; a drainage route that works either way |
| Anything fixed to the house | Depends on the design | Answered by the trades that build and inspect houses |
Where this sits with the local rules
A plain patio at grade usually sits in one category. A structure standing on footings, or anything with a roof over it, can sit in another one entirely, and that shift is the reason a cover deserves a phone call that a patio on its own might not. Which side of the line your project lands on is not ours to state. That determination belongs to whoever issues permits where you live, which in this county means your village or Kenosha County. Our guide to patio permits and zoning checks lays out how to frame that call so you get a useful answer the first time.
Attaching the cover to the house is a separate conversation and it is not a landscaping one. Whether anything can be fixed to your wall, and how, is answered by the trades that build and inspect houses. Get that answer before the design is drawn, because it changes whether you are planning a free-standing frame on four posts or something else.
Holding the option open when you have not decided
Plenty of people want a cover eventually and cannot commit to it now. That is a completely reasonable position, and it costs almost nothing to protect - as long as you say it out loud at the walk-through instead of six months later.
Three things are worth fixing on the plan even when nothing else about the cover is decided. Mark where the posts would land, so the layout, the furniture and the border courses are drawn around them rather than through them. Agree the water route as though the cover already existed, because a drainage path that suits a solid roof also suits an uncovered patio, while the reverse is not true. And keep that ground in a state that can be opened later without disturbing more of the field than necessary.
That is the whole trick. You are not building anything you have not paid for. You are refusing to build the one thing that would make the decision expensive later. The same logic applies to a hot tub you might add one day, and to any outdoor kitchen or fire pit that would need a fixed position of its own.
Thinking about a cover, now or later?
Tell us where you would want the posts and we will draw the patio around them - get a free quote.