How to Attach a Pergola to Your House: The Ultimate Guide

Building an attached pergola is a rewarding project that adds value, shade, and visual appeal to your home. This comprehensive guide walks you through constructing a stunning pergola attached to your house, creating a sheltered outdoor area perfect for relaxing with family and friends.

Safety Requirements

Structural Safety:

• Use pressure-treated laminated lumber rated for ground contact (minimum 0.60 CCA retention). Laminated posts are engineered to resist twisting and warping, making them superior to standard lumber.
• Set all posts in concrete with minimum 24-inch depth (deeper in frost-prone areas).
• Allow concrete to cure for 24 hours before loading.

Working Safety:

• Wear appropriate safety gear: Hard hat, gloves, safety glasses, and steel-toe boots
• Use a helper when working at heights or with heavy lumber.
• Set up proper scaffolding rather than balancing on ladders.
• Measure twice, cut once.

Installation Safety:

• Allow epoxy to cure overnight before removing clamps
• Test all connections before final assembly
• Follow manufacturer instructions for all fasteners and chemicals

Essential Tools and Materials

Material/Tool	Purpose
Pressure-Treated Laminated Posts	Main vertical support
Ledger Board Lumber (2×8 or 2×10)	Horizontal attachment to house wall
Beam Lumber (2×10 or larger)	Main horizontal support between posts
Rafter Lumber (2×6 or 2×8)	Creates shade structure
Purlin Lumber (2×4 or 2×6)	Cross members for added support
Concrete Mix	Secures posts in ground
Concrete Blocks	Solid bearing at hole bottom
Wooden Shims (¾” × 1¾”)	Creates drainage gap behind ledger
½” Lag Screws with Neoprene Washers	Ledger attachment
½” Threaded Rod	Permanent beam-to-post connection
Two-Part Epoxy Anchoring Compound	Secures threaded rod
½” Metal L-Brackets	Reinforces rafter connections
6-inch Structural Screws	Fastens rafters to beam
3-inch Galvanized Deck Screws	Attaches rafters to ledger
String Line and Level	Alignment and accuracy
Measuring Tape	All measurements
Circular Saw and Chisel	Cuts lumber and creates notches
Drill with Various Bits	Holes for screws and rods
Impact Driver	Easier installation
C-Clamps and Post Braces	Holds components during assembly
Stud Finder	Locates wall studs
Primer and Exterior Paint/Stain	Weather protection

Measurements Reference Guide

Post Spacing:

• Distance from house to post center: 86.5 inches
• String line offset from house: 4 inches
• Corner line offset: 2.5 inches
• Concrete depth: 24 inches minimum (36-42 in frost zones)

Ledger Board:

• Height from deck to bottom: 105 inches (8’9″)
• Total length: 226 inches (18’10”)
• Lag screw spacing: 16 inches on center maximum
• Lag screw size: ½” diameter × 4″ long minimum
• Pilot hole size: ½ inch

Beam:

• Length: 225 inches (18’9″) – 1 inch shorter than ledger for overhang clearance
• Slope: 1:12 pitch (≈5 degrees) for drainage
• Drop for 7-foot span: 7½ inches
• Thickness: 2½ inches actual

Rafters:

• Quantity: 7 rafters (6 spaces between)
• Center-to-center spacing: 38 inches
• Thickness: 1⅝ inches actual
• Notch depth: ⅜ inch

Threaded Rod:

• Diameter: ½ inch
• Drill bit size: ⅝ inch
• Hole depth into post: 5 inches
• Total rod length: Beam width + 5 inches

Purlins:

• Quantity: 4 total
• Spacing: Divide span by 3 for even distribution

Step-by-Step Construction

Step 1: Locate and Mark Post Positions

Accurate post placement keeps your pergola square, aligned, and parallel to your house.

Process:

1. Measure from your house wall outward 84 inches to mark the outside edge of your first post location

2. Run a string line parallel to your house wall, 4 inches away from the wall
3. From this string line, measure 2.5 inches outward to find post center
4. Mark this spot clearly with chalk or carpenter’s pencil
5. Repeat for all post locations along the pergola length
6. If posts sit on an existing deck, you’ll need to remove deck boards around each location to access the ground

Helpful Hint: Verify measurements are consistent at both ends to maintain parallel alignment with your house.

Step 2: Dig Post Holes and Set Posts

Process:

1. If working on a deck, carefully remove necessary deck boards to expose the ground below
2. Dig holes at each marked location to the depth required by local building codes (minimum 24 inches in most areas, 36-42 inches in frost zones)
3. Place a concrete block at the bottom of each hole for solid bearing
4. Run a string line along the side of your house, parallel to the wall, as a positioning guide
5. Position your first post in its hole, exactly 2.5 inches from the reference string line

6. Check the post is plumb (perfectly vertical) using a level on two adjacent sides
7. Install temporary diagonal braces to hold the post steady
8. Screw the post to nearby joists or deck framing for additional stability
9. Mix concrete according to manufacturer’s instructions and fill the hole completely

10. Allow concrete to cure for 24 hours before continuing construction
11. Repeat for all remaining posts, checking each for plumb and alignment

Material Tip: Laminated posts won’t twist during the curing process, unlike standard lumber.

Step 3: Mark Ledger Board Location

The ledger board attaches to your house wall and supports one end of all rafters.

Process:

1. Measure up from your deck surface to 105 inches – this is where the bottom of your ledger board will sit

2. Drive a nail at this height as a reference point for your tape measure
3. Using a level and pencil, mark a perfectly horizontal line across your siding showing the ledger bottom edge
4. Locate all wall studs using a stud finder (studs are typically 16 or 24 inches on center)
5. Mark the center of each stud location on your siding

6. Note these measurements – you’ll transfer them to the ledger board

Note: For brick or masonry walls, you’ll need masonry anchors rated for structural loads instead of lag screws into studs.

Step 4: Prepare the Ledger Board

Preparing the ledger board completely before installation saves time and hassle.

Process:

1. Transfer all stud location marks onto the face of your 226-inch ledger board
2. Calculate rafter spacing: 226 inches ÷ 6 spaces = approximately 38 inches center-to-center
3. Starting from one end, mark 38-inch intervals along the top edge
4. At each center line, mark the rafter thickness: 13/16 inch on either side of center (total 1⅝ inches)
5. Square these lines down the face of the lumber
6. Set circular saw blade to ⅜-inch depth

7. Make multiple saw cuts between your marked lines, about ⅜ inch apart
8. Use a sharp chisel to remove material between cuts, creating smooth notches
9. Pre-drill ½-inch pilot holes through the ledger at each stud location
10. Cut wooden shims: ¾” thick × 1¾” wide (several needed)

11. Attach shims to the back of the ledger at each screw location with construction adhesive

The shims create airflow space between the ledger and wall, preventing trapped moisture.

Finishing: Apply wood primer to all cut surfaces and notches before installation.

Step 5: Attach Ledger Board to House

This critical structural connection must be secure and watertight.

Process:

1. With a helper, position the ledger board along your marked line with shims against the wall
2. Align pre-drilled holes with stud center marks

3. Place neoprene washers behind each shim at every screw location for waterproofing
4. Drive the first ½-inch lag screw through the hole, ledger, shim, washer, and into the wall stud
5. Tighten firmly with an impact driver or ratchet wrench – snug but not crushing the wood
6. Continue along the ledger, installing screws at each stud location (maximum 16 inches apart)
7. Verify the board remains aligned with your reference line as you work
8. Visually inspect – the ledger should appear horizontal from any angle

For masonry walls: Use high-quality masonry anchors or epoxy anchors rather than expansion anchors.

Step 6: Prepare and Mark the Beam

The beam spans between posts and requires proper slope for water drainage.

Process:

1. From the top of the ledger board, run a string line across to the posts
2. From this horizontal line, measure down 7½ inches – this is the top of your beam (creates 1:12 pitch)
3. From this mark, measure down another 2½ inches (beam thickness) – this marks the beam bottom
4. Cut the beam to 225 inches length (1 inch shorter than the 226-inch ledger to allow proper clearance)
5. Transfer all rafter position marks from the ledger board onto the beam – these must align perfectly
6. Mark rafter thickness on each side of center lines and square across the beam
7. Set saw to ⅜-inch depth and cut notches at each rafter position using multiple cuts
8. Use a chisel to remove material between cuts
9. Sand all cut surfaces smooth
10. Apply primer or sealer to all cut surfaces and end grain

Helpful Hint: Create a scrap template cut to the slope angle for consistent post marking.

Step 7: Cut Posts to Height

Posts must be cut to the exact height to support the beam at the proper drainage angle.

Process:

1. Using your earlier measurements, mark where the beam bottom will sit (7½ inches down from level, plus 2½ inches for beam thickness)
2. Use a speed square to mark completely around the post, keeping the line horizontal
3. Cut through the post at your marked line
4. Sand the cut surface smooth with 80-grit sandpaper
5. Apply wood sealer to the cut surface immediately to protect end grain
6. Run a string line from the top of your first cut post to the far post
7. Cut remaining posts so their tops just touch this string line
8. Sand and seal all freshly cut post tops

Optional Detail: Cut a 45-degree bevel on the back corner of each post for improved water drainage and visual appeal.

Step 8: Connect Beam to Posts

Threaded rod and epoxy create an incredibly strong, permanent connection.

Process:

1. Position beam on posts and mark the post center onto the beam side
2. Remove beam and transfer the mark to the beam’s top face, squaring it perpendicular to the edge
3. Find post center by marking diagonal lines corner to corner – where they cross is exact center
4. Using a ⅝-inch drill bit with extension, drill through the beam and 5 inches into the post
5. Thoroughly blow out all sawdust with compressed air or vacuum
6. Cut threaded rod to length: beam width + 5 inches
7. Prepare two-part epoxy according to manufacturer instructions

8. Fill the hole completely with epoxy from bottom up
9. Insert threaded rod into the epoxy-filled hole, pushing to full 5-inch depth

10. Twist slightly while inserting to distribute epoxy evenly
11. Position beam onto posts and clamp firmly
12. Leave clamped overnight (minimum 12 hours) for full cure
13. Repeat for all post-to-beam connections

Safety Note: Wear gloves and safety glasses when working with epoxy to avoid skin and eye irritation.

Step 9: Cut and Install Rafters

Rafters create the main shade structure and distribute structural loads.

Process:

1. Take a piece of rafter lumber slightly longer than needed
2. Position it between beam and ledger at one marked location
3. With the rafter resting in both notches, mark where it needs to be cut on both ends
4. Cut at both marks and test fit – it should fit snugly without wobbling

5. Test this rafter at the opposite end and middle locations to verify consistency
6. Cut all remaining rafters to the same length
7. Install first rafter by slotting into its notches
8. Drive two 6-inch structural screws through the beam face into the rafter end
9. At the ledger end, drive 3-inch deck screws through the rafter down into the ledger (minimum two screws)
10. Continue installing rafters from one end to the other
11. For the last rafter, pre-drill the beam face before installation

Helpful Hint: If a rafter is tight, use a wood rasp to ease the fit slightly rather than forcing it.

Step 10: Add Metal Brackets

Metal brackets reinforce rafter-to-ledger connections for a stronger structure.

Process:

1. Position a ½-inch L-shaped bracket centered over one notch on the ledger back
2. Drive galvanized nails through pre-punched holes to secure bracket to ledger
3. With rafter in place, fold the bracket up and over the rafter back
4. Drive nails through bracket into rafter (minimum 6 nails per bracket)

5. Install brackets at every rafter location

These brackets are hidden from view but provide substantial wind resistance.

Step 11: Install Purlins

Purlins run perpendicular to rafters, completing the structure and creating a grid pattern.

Process:

1. Plan for 4 purlins: one at each end (ledger and beam), two in the middle
2. Divide your pergola depth by 3 to find middle purlin spacing
3. Snap a chalk line across all rafters at your calculated spacing marks
4. Position first purlin along the rafters at the ledger board end
5. Fasten into each rafter using two 3-inch deck screws per connection, angling screws slightly
6. Install purlin at beam end
7. Install two middle purlins following your chalk lines
8. Verify all purlins are straight and properly aligned

Helpful Hint: If a purlin is bowed, fasten one end first, then use body weight or a clamp to straighten before fastening the other end.

Final Result

Your attached pergola is complete! You’ve created a beautiful sheltered outdoor space that:

• Provides shade during summer months while allowing filtered light
• Defines an outdoor room extending your living space
• Adds significant visual appeal and property value

Enhancement Ideas:

• Add climbing plants (wisteria, clematis, climbing roses)
• Install outdoor furniture for comfortable seating
• String outdoor lighting for evening ambiance
• Hang weatherproof curtains or roll-down shades

Troubleshooting Guide

Problem	Solution
Structure appears unlevel	Verify ledger is truly horizontal and all posts are cut to proper heights relative to the 1:12 slope
Rafters don’t fit notches	Use wood rasp to slightly widen notches, or trim rafter thickness with a plane
Post twisted during curing	Shouldn’t occur with laminated posts; if it does, replace before proceeding
Lag screws won’t tighten	You’ve missed the stud – relocate precisely and drill new hole
Beam won’t stay clamped	Add more clamps and verify post tops are cut square and flat
Epoxy didn’t cure	Temperature too cold – epoxy requires warmth. Remove failed epoxy and retry on warmer day
Water pools on top	Verify 1:12 pitch – you may need to adjust beam height

Attaching a pergola to your house is a great way to enhance your outdoor living space, adding both style and functionality. By following these steps, you can create a beautiful shaded area to relax in while adding value to your property. The finished result will provide you with a perfect spot for outdoor activities, and if you prefer a simpler approach, Aosom offers ready-to-install pergolas to suit your needs.

FAQs