FHB Logo Facebook LinkedIn Email Pinterest Twitter X Instagram Tiktok YouTube Plus Icon Close Icon Navigation Search Icon Navigation Search Icon Arrow Down Icon Video Guide Icon Article Guide Icon Modal Close Icon Guide Search Icon Skip to content
Subscribe
Log In
  • How-To
  • Design
  • Tools & Materials
  • Restoration
  • Videos
  • Blogs
  • Forum
  • Magazine
  • Members
  • FHB House
  • Podcast
Log In

Discussion Forum

Discussion Forum

Building A Pergola

Woodchucks | Posted in Construction Techniques on March 24, 2011 01:55am

I have a couple of questions on designing/building a pergola.  I am a woodworker, but I do not have any experience with building construction.  One person suggested that I hire an engineer for the design, and another said just to copy other similar structures in the neighborhood.  There are two key issues that I have been wrestling with, and would very much appreciate hearing from those more knowledgeable.

The pergola will be detached, and it will be 6 inches from the house (fascia).  It will be 17′ x 12′ (cover size) and 10′ tall, and it will have a beam span of 14′.  The posts will be 6″ x 6″, and they will be attached to the concrete footings using Simpson connectors.  The rafters will be 2″ x 6″ and 16″ oc.  And I am proposing using 2″ x 10″ double beams notched into the front and back of the posts, and fastened with carriage bolts.  Also, there will be 2 knee braces on each of the two outside posts (away from the house).  The posts and beams will be pressure treated, and the rafters will be untreated Douglasfir.

I have two questions:

1)         Will the 2 x 10 double beams notched into the front and back side of posts will be adequate for the 14 foot span to keep from bowing?  (Some have suggested that I should either use a 4 x 12 beam across the 14 foot span, or use a third post to reduce the span to 7 feet.  This later suggestion is not feasible because the beam would fall in the center of a sliding glass door.

2)         As we occasionally get wind gusts up to 80 mph, I added knee braces in both directions, but only on the two exterior posts.  (Adding them to the posts near the house would create an obstruction, so I would prefer not to do this unless absolutely necessary.)   Is it enough to add the knee braces only to the outside posts, or should all the posts have knee braces?  And, other than providing lateral support, do these knee braces also work to support the 14 foot beam span?

Thanks for any help you can provide on these questions.  Without over-engineering, I am looking for a solution that is structurally sound and will last for years without sagging.

Reply
  • X
  • facebook
  • linkedin
  • pinterest
  • email
  • add to favorites Log in or Sign up to save your favorite articles

Replies

  1. DanH | Mar 24, 2011 07:12am | #1

    You're going to put a 17x12 kite out in 80 mph wind with a couple of knee braces to support it??

  2. User avater
    Lawrence | Mar 24, 2011 08:13am | #2

    Big Patio Pergola

    Here are a few principles to follow Woodchucks.  Don't notch pressure treated where it will trap moisture...leave the posts solid and mount your beams on the outside, or above. I prefer above, that way I can space them 1 1/2 which makes mounting your knee braces much easier, and much  more secure.

    Your span is fine for a beam size of 2x 2x10 in pt.  Blocks every 2'...

    Doug fir, though great stuff is heavy... which means you will need more beam and more lateral bracing.

    When it comes to braces, rather than using a 2x4 on an angle, which I agree is obstructive, use a larger piece and curve it so that people don't run into it. It will look better too. Braces should go anywhere possible, and if they oppose themselves you should be fine to resist 80mph events. Putting braces on only 2 posts will work great for those posts--so long as you don't mind the rest of the structure near the house wagging like a dog's tail. You should be mounting braces with an exposed face of more than 28". Yes, braces do add support and cut the functional span to about 12" per 24" of bracing.

    There's lots of examples on our website... gardenstructure.com

    1. MikeSmith | May 07, 2011 03:53pm | #8

      Lawrence

      i missed you around the internet

      how's your business going ?   my customers keep asking for garden structures and exterior  pergola type things..

       i think i'm re-inventing the wheel with all of the work you've done

       i should sign up as your first Rhode Island  associate

  3. User avater
    hammer1 | Mar 24, 2011 09:09am | #3

    Pergolas tend to be top heavy. The grid style structure doesn't provide much resistance to racking. I think your span will be fine, you aren't carrying weight. Well done braces will help both issues. At only 6" from the house, I would tie to the house in a couple of places, something that doesn't really show but will add stability. Maybe a heavy H or U connector. I'd probably have a metal shop fabricate something. In my mind I'm seeing a short piece of I beam with the flanges bored for bolts.

  4. oops | Mar 24, 2011 06:49pm | #4

    This was before your time, but sometime back, McDesign I belive, had come up with a system for anchoring the columns such that no bracing was required. It did require  hollow columns however where you have stated that you plan to use solid lumber.

    It had rebar extending 2' to 3' out of the pier / footing. The column was set upon the pier / footing with the rebar extending up into the column. Then the column was filled with concrete as required to cover the rebar. Once the concrete set, the column was firmly anchored and ridged.

    This is an over simplified description, but I used this on a free standing 12' x 24' pergola with good results. At least for the past 2 years.  It is more complex than bracing, but it does away with unsightly  bracing.

    From the what it's worth department.

  5. Woodchucks | Mar 25, 2011 09:58pm | #5

    Building A Pergola - Thanks

    Thank you all very much for your help.  Other than the 17x12 kite comment, the responses were very helpful.  It sounds like the consensus is that the double 2 x 10s beams are sufficient for the 14 foot span.  However, with the wind gusts coming off of the nearby delta, it sounds like everyone agrees that bracing is required on each of the posts to prevent racking.  And I've noted the alternate methods of mounting the beams instead of notching pt lumber, suggestions on bracing, possibly tying the structure to the house, and the idea for anchoring the columns so that no bracing would be required.  I will give all this further thought and modify my design.  This is a great community.  Thank you for taking the time to share your thoughts and knowledge!

  6. User avater
    Mongo | Mar 26, 2011 11:34am | #6

    more support be beddah

    Can you extend the 2x10s a few feet past the posts and use cross-braces to the outside the posts instead of the inside? Would that prevent the obstruction near the house?

    Structurally the 2x10s will be more than adequate. I'm thinking the 2x6s might look undersized, but that's my eye.

    With the 2x6 rafters, consider an overlay. That'll keep the rafters from wandering.

    There are pergolas where the posts run a couple of feet taller than the cross beams and cross bracing was done above the beam. An untraditional look, but it works.

    1. Woodchucks | Apr 28, 2011 10:27pm | #7

      more support be beddah

      Thanks, Mongo!  Some interesting ideas...thinking outside the box!

Log in or create an account to post a comment.

Sign up Log in

Become a member and get full access to FineHomebuilding.com

Video Shorts

Categories

  • Business
  • Code Questions
  • Construction Techniques
  • Energy, Heating & Insulation
  • General Discussion
  • Help/Work Wanted
  • Photo Gallery
  • Reader Classified
  • Tools for Home Building

Discussion Forum

Recent Posts and Replies

  • |
  • |
  • |
  • |
  • |
  • |
View More Create Post

Up Next

Video Shorts

Featured Story

Installing Prefinished Cabinet Molding

Use these assembly techniques when installing crown risers and molding to minimize visible gaps and nail holes.

Featured Video

A Modern California Home Wrapped in Rockwool Insulation for Energy Efficiency and Fire Resistance

The designer and builder of the 2018 Fine Homebuilding House detail why they chose mineral-wool batts and high-density boards for all of their insulation needs.

Related Stories

  • Affordable Scans, Accurate Plans
  • FHB Summit 2025 — Design, Build, Business
  • A Summer Retreat Preserved in the Catskill Mountains
  • Fine Homebuilding Issue #332 Online Highlights

Highlights

Fine Homebuilding All Access
Fine Homebuilding Podcast
Tool Tech
Plus, get an extra 20% off with code GIFT20

"I have learned so much thanks to the searchable articles on the FHB website. I can confidently say that I expect to be a life-long subscriber." - M.K.

Get home building tips, offers, and expert advice in your inbox

Signing you up...

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
See all newsletters
See all newsletters

Fine Homebuilding Magazine

  • Issue 331 - June 2025
    • A More Resilient Roof
    • Tool Test: You Need a Drywall Sander
    • Ducted vs. Ductless Heat Pumps
  • Issue 330 - April/May 2025
    • Deck Details for Durability
    • FAQs on HPWHs
    • 10 Tips for a Long-Lasting Paint Job
  • Issue 329 - Feb/Mar 2025
    • Smart Foundation for a Small Addition
    • A Kominka Comes West
    • Making Small Kitchens Work
  • Issue 328 - Dec/Jan 2024
    • How a Pro Replaces Columns
    • Passive House 3.0
    • Tool Test: Compact Line Lasers
  • Issue 327 - November 2024
    • Repairing Damaged Walls and Ceilings
    • Plumbing Protection
    • Talking Shop

Fine Home Building

Newsletter Sign-up

  • Fine Homebuilding

    Home building tips, offers, and expert advice in your inbox.

  • Green Building Advisor

    Building science and energy efficiency advice, plus special offers, in your inbox.

  • Old House Journal

    Repair, renovation, and restoration tips, plus special offers, in your inbox.

Signing you up...

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
See all newsletters

Follow

  • Fine Homebuilding

    Dig into cutting-edge approaches and decades of proven solutions with total access to our experts and tradespeople.

    Start Free Trial Now
    • Facebook
    • Instagram
    • X
    • LinkedIn
  • GBA Prime

    Get instant access to the latest developments in green building, research, and reports from the field.

    Start Free Trial Now
    • Facebook
    • YouTube
  • Old House Journal

    Learn how to restore, repair, update, and decorate your home.

    Subscribe Now
    • Facebook
    • Instagram
    • X
  • Fine Homebuilding

    Dig into cutting-edge approaches and decades of proven solutions with total access to our experts and tradespeople.

    Start Free Trial Now
    • Facebook
    • Instagram
    • X
    • LinkedIn
  • GBA Prime

    Get instant access to the latest developments in green building, research, and reports from the field.

    Start Free Trial Now
    • Facebook
    • YouTube
  • Old House Journal

    Learn how to restore, repair, update, and decorate your home.

    Subscribe Now
    • Facebook
    • Instagram
    • X

Membership & Magazine

  • Online Archive
  • Start Free Trial
  • Magazine Subscription
  • Magazine Renewal
  • Gift a Subscription
  • Customer Support
  • Privacy Preferences
  • About
  • Contact
  • Advertise
  • Careers
  • Terms of Use
  • Site Map
  • Do not sell or share my information
  • Privacy Policy
  • Accessibility
  • California Privacy Rights

© 2025 Active Interest Media. All rights reserved.

Fine Homebuilding receives a commission for items purchased through links on this site, including Amazon Associates and other affiliate advertising programs.

  • Home Group
  • Antique Trader
  • Arts & Crafts Homes
  • Bank Note Reporter
  • Cabin Life
  • Cuisine at Home
  • Fine Gardening
  • Fine Woodworking
  • Green Building Advisor
  • Garden Gate
  • Horticulture
  • Keep Craft Alive
  • Log Home Living
  • Military Trader/Vehicles
  • Numismatic News
  • Numismaster
  • Old Cars Weekly
  • Old House Journal
  • Period Homes
  • Popular Woodworking
  • Script
  • ShopNotes
  • Sports Collectors Digest
  • Threads
  • Timber Home Living
  • Traditional Building
  • Woodsmith
  • World Coin News
  • Writer's Digest
Active Interest Media logo
X
X
This is a dialog window which overlays the main content of the page. The modal window is a 'site map' of the most critical areas of the site. Pressing the Escape (ESC) button will close the modal and bring you back to where you were on the page.

Main Menu

  • How-To
  • Design
  • Tools & Materials
  • Video
  • Blogs
  • Forum
  • Project Guides
  • Reader Projects
  • Magazine
  • Members
  • FHB House

Podcasts

  • FHB Podcast
  • ProTalk

Webinars

  • Upcoming and On-Demand

Podcasts

  • FHB Podcast
  • ProTalk

Webinars

  • Upcoming and On-Demand

Popular Topics

  • Kitchens
  • Business
  • Bedrooms
  • Roofs
  • Architecture and Design
  • Green Building
  • Decks
  • Framing
  • Safety
  • Remodeling
  • Bathrooms
  • Windows
  • Tilework
  • Ceilings
  • HVAC

Magazine

  • Current Issue
  • Past Issues
  • Magazine Index
  • Subscribe
  • Online Archive
  • Author Guidelines

All Access

  • Member Home
  • Start Free Trial
  • Gift Membership

Online Learning

  • Courses
  • Project Guides
  • Reader Projects
  • Podcast

More

  • FHB Ambassadors
  • FHB House
  • Customer Support

Account

  • Log In
  • Join

Newsletter

Get home building tips, offers, and expert advice in your inbox

Signing you up...

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
See all newsletters
See all newsletters

Follow

  • X
  • YouTube
  • instagram
  • facebook
  • pinterest
  • Tiktok

Join All Access

Become a member and get instant access to thousands of videos, how-tos, tool reviews, and design features.

Start Your Free Trial

Subscribe

FHB Magazine

Start your subscription today and save up to 70%

Subscribe

Enjoy unlimited access to Fine Homebuilding. Join Now

Already a member? Log in

We hope you’ve enjoyed your free articles. To keep reading, become a member today.

Get complete site access to expert advice, how-to videos, Code Check, and more, plus the print magazine.

Start your FREE trial

Already a member? Log in

Privacy Policy Update

We use cookies, pixels, script and other tracking technologies to analyze and improve our service, to improve and personalize content, and for advertising to you. We also share information about your use of our site with third-party social media, advertising and analytics partners. You can view our Privacy Policy here and our Terms of Use here.

Cookies

Analytics

These cookies help us track site metrics to improve our sites and provide a better user experience.

Advertising/Social Media

These cookies are used to serve advertisements aligned with your interests.

Essential

These cookies are required to provide basic functions like page navigation and access to secure areas of the website.

Delete My Data

Delete all cookies and associated data