The short answer
A pergola attached to the house hangs one side on a ledger fastened to the house band joist, with posts only on the outer side. It works only if there is solid framing at rafter height, usually 9 to 11 ft up, and the wall is not brick veneer, hollow masonry or a bay window. If the wall fails the test, build a freestanding pergola, which needs braces or deep posts in place of the house.
A pergola attached to house framing is cheaper in posts and stiffer against the wind than the same pergola standing alone, but only when the wall can take it. The question that decides it is not about looks. It is whether the house has solid framing at the height where the rafters meet the wall, and whether the wall is a type the rules allow a ledger on. This guide gives you the ledger test, how an attached pergola is fastened, what a freestanding pergola needs, and the snow and distance questions people forget.
We are not your building department or your engineer. Where a number is our own design choice, we say so.
Pergola Attached to House or Freestanding: Side by Side
The two layouts differ in what carries the sideways load. Everything else follows from that.
| Attached to the house | Freestanding | |
|---|---|---|
| Posts | Outer side only; the house end rests on the ledger | Both sides |
| Sideways load across the beam | Passes into the wall through the ledger | Braces, or deep posts |
| Sideways load along the beam | Braces at the posts | Braces at the posts |
| Wall requirement | Solid framing at rafter height, no prohibited wall | None |
| Local approval | Ask; touching the house can change the answer | Ask; not automatically exempt |
What the house does for an attached pergola
In our designer, the house receives the cross load through the ledger, and braces handle the direction along the beam. That split is our design choice. The DCA61 deck guide has no lateral table for it, and it assumes that the house resists the sideways load of a deck.
What replaces the house when it stands alone
A freestanding pergola has to resist wind on its own, with braces in both directions or with posts buried deep enough to do the job. No code table sizes either, so they are calculated. See the freestanding section below.
Which one fits your wall
Start with the wall, not with the design. If the wall passes the test in the next section, either layout is open to you. If it fails, the choice is made.
- 1American Wood Council Prescriptive Residential Wood Deck Construction Guide (DCA 6, 2015 IRC version) (2015)
Can Your Wall Take a Ledger?
The ledger rules we use come from the free AWC1 DCA6 deck guide, which is the only primary source we have for ledger fastening. A pergola ledger follows the same rules as a deck ledger, with one big difference: where it sits on the wall.
Is there solid framing at rafter height?
A deck ledger sits near floor level, where the house has a rim or band joist. A pergola ledger sits at the height of the tops of the rafters, usually about 9 to 11 ft up. On a one-story house there is often no solid band at that height, only studs and a top plate. Our designer always asks you to confirm that the wall has a band at that height and always flags it amber. If you cannot confirm it, build freestanding.
Walls that rule out a ledger
DCA61 prohibits a ledger on brick or stone veneer, on hollow masonry, on a floor overhang or bay window, on a truss ribbon board, and on an I-joist band less than 1 in thick. A veneer wall cannot carry the load, and the others were not built for it. On any of these, the answer is a freestanding pergola.
Ledger size and spacing
The ledger is pressure-treated lumber, at least a 2x8, No. 2 grade, fastened only into the band or rim joist, with staggered fasteners and flashing. Our deck ledger board guide has the table of lag and bolt spacings.
A pergola has no joists, so our designer converts the rafter load into an equivalent deck span. It finds the DCA61 column whose reaction per foot of ledger matches the rafter reaction. That equivalence is our own method. At a 10 ft equivalent span, 1/2 in lag screws in a 1-1/2 in band go 18 in apart, and a rafter load that works out above an 18 ft span is out of range.
- 1American Wood Council Prescriptive Residential Wood Deck Construction Guide (DCA 6, 2015 IRC version) (2015)
How to Attach a Pergola to a House
The method is the one for a deck ledger. Do it in this order.
Siding and the wall
Take the siding off where the ledger will sit, so the board bears on the band and not on cladding. Flashing must be continuous with a drip edge, in metal at least 0.019 in thick. Do not use aluminum on copper-treated lumber. Pilot holes are 1/2 in in the ledger and 5/16 in in the band, and the lag tip must pass fully through the band. Never use lead anchors.
Brick and masonry
Veneer is out, as above. A solid concrete wall is a different case: the guide points you to the maker’s instructions for 1/2 in expansion or adhesive anchors. We have not verified a rating for any anchor, so follow the maker’s table.
Gutters and the roof edge
We found no rule that tells you how to deal with a gutter or the edge of the roof, so we will not make one up. Keep the ledger on solid framing and flashed, keep it out of the water path from the roof, and ask your building department or an engineer if the gutter is in the way.
Checking the layout
Before you lift anything, mark the ledger line on the wall with a level or a laser, and mark the post centers from it, not from the corner of the house. The house may not be square. Measure from the ledger line out to each post, so the beam ends up parallel to the wall and the rafters have the same run at every point.
Fasten and brace
Stagger the fasteners along the ledger on the spacing for your equivalent span. Then add the braces along the beam at each post, because the ledger does not resist movement in that direction.
Flashing the ledger high on the wall
A pergola ledger is flashed the same way as a deck ledger, with the siding off, the wall’s water barrier lapped over the top of the flashing, and the drip edge below. The difference is the height. At 9 to 11 ft you work from a ladder or a scaffold, so plan the flashing before the ledger goes up, not after. A ledger that holds a heavy beam load in place cannot be taken down easily to flash behind it. The usual practice of lapping the barrier over the flashing is our advice, not a DCA61 figure.
Try it
See the ledger in your own pergola
In the pergola designer, switch the mount to attached and the ledger, equivalent span and amber wall check appear on the plan. Free to use, no account. Prepared to NDS 2018 and DCA61 methods, not engineer-stamped. Check with your building department.
- 1American Wood Council Prescriptive Residential Wood Deck Construction Guide (DCA 6, 2015 IRC version) (2015)
Which Should You Build? A Short Decision Path
You can settle most cases with four questions, in this order.
Is the wall allowed?
If the wall is brick or stone veneer, hollow masonry, a bay window, a floor overhang, a truss ribbon board or a thin I-joist band, stop here and build freestanding.
Is there a band at rafter height?
If the house has solid framing at the height of the tops of the rafters, and you can confirm it, go on. If you cannot confirm it, build freestanding or ask a contractor to open the wall and look.
Can the roof snow reach it?
If a roof above can shed or drift snow onto the pergola, plan for that load whichever layout you choose, and ask your building department what it wants.
Does your office accept it?
Attached or freestanding, ask your building department before you buy lumber. The answer may differ, and our pergola permit guide lists the questions to ask.
Freestanding Pergola: What Replaces the House
A freestanding pergola solves the wall problem by not using the wall. It then has to solve the wind problem itself.
Knee braces in both directions
Our designer uses 2x6 braces at 45 degrees, bolted along each beam at every post and also across it, with the post top tied to a rafter. The brace leg runs 24 to 48 in, and a brace whose foot lands below 6 ft 8 in is flagged for head clearance. The bolts at each end are counted from the NDS 2018 yield equations, with the end and edge distances checked. The method is our own, since the code gives no lateral table for a freestanding frame.
Posts buried in the ground
A post can resist wind alone if it is set deep enough. The IBC formula for embedded posts gives a deep hole, and an 8 ft 6x6 held only by the ground needs about 62 in in our design. We have an open question with an engineer about the safety factor for isolated posts. See our pergola footings guide.
Footings and uplift
Whether attached or not, the footing has to hold the posts down in the wind. We size each footing for the soil and for uplift, so the freestanding case gets no shortcut.
Snow Sliding Off the House Roof
A pergola next to a roof can get more snow than the ground does.
What our loads include
For snow we start from the ground snow load you enter, with 30 psf as a starting value if you give none, and apply the ASCE 7 flat-roof method. We could not read the ASCE 7 text, which is paid, so the snow results are a check and not a final answer.
What they leave out
The loads do not include snow that slides or drifts off the house roof onto the pergola. That is a “check before you build” item in our designer. The size of that load depends on the roof pitch, the height and the pergola’s position, none of which we model.
What to do
If your pergola sits below a roof in a snow region, look at how the roof sheds. Ask your building department what snow load it wants, and ask an engineer if the roof drops onto the pergola.
How Close Should a Pergola Be to a House?
The honest answer is that no distance appears in the code sources we hold.
Setbacks, HOA and zoning
Local approval is not checked here. Pergola permit rules, setbacks, HOA and zoning vary, and an attached pergola touches the house in a way that a freestanding one does not. Confirm with your local building department. Our pergola permit guide covers what changes the answer.
Where to measure
Ask whether your office measures from the post, the beam or the edge of the roof, because the overhang of the rafters can reach past the posts.
Next to a covered patio
If what you want is a solid roof over the patio, that is a different structure with different rules. Our patio cover attached to house guide covers the ledger, the snow and wind a solid roof adds, and the footings.
Try it
Test your wall, then draw the pergola
Open the pergola designer and choose attached mode to see the ledger, the equivalent span and the amber wall check. The $29 pergola plan then adds the member schedule, cut list and shopping list. Read how to build a pergola for the order of work. Prepared to NDS 2018 and DCA61 methods, not engineer-stamped. Check with your building department.
- 1American Wood Council Prescriptive Residential Wood Deck Construction Guide (DCA 6, 2015 IRC version) (2015)
Sources
Every number in this guide that does not come from our own deck designer was checked against these 2 documents, numbered in the order the text first cites them and read between Oct 25, 2026 and Nov 4, 2026. 2 are code guides and official pages.
