Architecture/patio roof

Advertisement

Expert: - 4/7/2004


Question
I'm building a roof over my existing patio. The patio is approximately 18 foot wide and 12 foot deep. I've attached a 2x12x18foot ledger board to the second story of my house at a hight of about 11 feet off the ground. 2x8 rafters (16 in OC) are attached to the ledger on one end and attached to a glue lamb beam (3.5x15x18ft) on the other end. The glue lamb is attached to two 6x6x8ft posts. So the load is distributed between the two posts and the house.
My concern is the load on the house. I attached the ledger board to the sheathing and studs of the house wall with 2 lag screws per stud. The lag screws were half inch by 4 in. Is that too much load on the house wall, or am I just being peranoid?

Thanks for your help!

Answer
Jay:

Thanks for your question!

While I can't give you a true structural analysis in this forum, it does sound as though you're in the ballpark.

However, there are a couple of additional concerns you should examine.  The first is how you've attached the glulam to the posts.  You need to be sure that you have addressed side loads - in other words, can you push on the posts sideways without moving the structure?  The post/glulam connection needs bracing, either with diagonal bracing or a "moment" connector, something you can buy at the lumberyard.  Simpson Strong-Tie is a popular manufacturer of these and you can see them on their website at www.strongtie.com.  Look at "beam to post" connectors.

"Uplift" is also a concern.  Is the new roof secured in a way to keep a strong wind from lifting it off of the post and ledger?

And while the existing wall of the house will probably hold the vertical load of the new roof, it may not be stiff enough to handle the horizontal loads and may require additional bracing.  Best way to be sure is to contact a structural engineer to give it a quick look.  You can usually find a reasonably priced structural engineer through local builders or lumberyards.

Hope this helps!

Richard Taylor, AIA
Richard Taylor Architects, LLC
www.rtaylorarchitects.com

Architecture

All Answers

Answers by Expert:

Ask Experts

Volunteer

Richard Taylor, AIA

Expertise

Ask me about all aspects of house, remodeling. , and room addition design and construction. Ask me about historic homes, renovation, and restoration. Ask me about materials and techniques, and about how you can get the best value for your design and construction dollar. Ask me how you can make your home a very special place. I can't, however, answer specific structural engineering questions in this forum - that's something you'll need on-site observation for.

Experience

I own a full-service residential architectural firm, and have been designing custom homes, remodelings, and room additions across the country since 1983. Check us out at Richard Taylor Architects and RTA Plans. I have written and been published extensively on the subject of residential architecture.

Organizations
American Institute of Architects, City of Dublin Architectural Review Board, Vice Chair of City of Dublin Planning and Zoning Commission, American Planning Association, Board Member Historic Dublin Business Association, Past Editor of SPLASH (a software forum), Past Editor of Open Directory Project, Assistant Scoutmaster, Boy Scouts of America

Publications
Business First of Columbus, Suburban New Publications, About.com, Cleveland Plain Dealer, Columbus Dispatch Residential Architect Custom Home Architect Remodeling Architect

Education/Credentials
Bachelor of Environmental Design (Architecture) Miami University 1983
For more about home design, check out my blog at Sense Of Place and join the conversation on our Facebook Page.

Awards and Honors
2010 Dublin Chamber of Commerce Business Person of the Year

©2012 About.com, a part of The New York Times Company. All rights reserved.