Is it OK to build an awning/covered pergola on my wooden deck?

Submitted by devengnerd t3_127101d in DIY

I've looked online and can't find examples or info on what I want to build. I want to build a simple lean-to awning on my wood deck, right outside my back door. About 12' wide, 8' deep and 8' tall against the house. The purpose is to provide an area on the deck with rain/weather protection. The house is brick veneer and I don't want to anchor the awning to the brick. My plan is to put up four 4x4 posts, anchor those to the deck boards at a floor joist, frame around the top with 2x6's and run 2x4 roof joists. Then put on a roof with plywood, tar paper & shingles. Will this be safe and stable, and am I not thinking of anything?

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lvlint67 t1_jec6dxf wrote

> anchor those to the deck boards at a floor joist

I assume you'll get a lot of questions answered when you try to pull the permit.

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PurplePotamus t1_jecckx9 wrote

You need a permit for that?

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lvlint67 t1_jecdqy7 wrote

You need a permit for a lot of stuff that is permanently affixed to the structure. Will vary by locality but "do I need a permit" is going to very quickly answer the question of safety...

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bbpr120 t1_jeciwps wrote

maybe, really depends on the town and their building codes.

Mine for example, will let you build a garden trellis structure over your deck for plants or open lattice (for some shade) without needed a permit, regardless of the deck coverage or material used. But the moment you want to put an solid roof of any sort (including those cheap plastic panels) over it, you need a permit that includes structural drawings.

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dominus_aranearum t1_jeclfoa wrote

Has a lot to do with safety in regards to snow load, uplift, wind shear, etc. and impervious area size compared to the size of your lot when added to your house, driveway, etc.

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DAecir t1_jedfbo8 wrote

Yes. Depends where you live. Generally, plans must include where exactly the structure will sit on your property. Is your property considered city or county? The size, including height, when completed. What type of foundation. Is it permanent structure. They have rules about how far it can stand from current structures and boundary fencing sometimes, too.

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dominus_aranearum t1_jecn01t wrote

This all depends upon where you live, what the weather conditions are and your knowledge of minimum safety standards (code).

As a GC, I could build something that would be safe because I have the experience. As a novice, are you taking into account snow load, wind shear, uplift and other various weather situations? Roof slope? Drainage? You've now created an impervious area that depending upon your lot size vs. your current impervious coverage percentage, may exceed local regulations.

Additionally, attaching posts to deck joists, then adding a roof creates a completely different load on those joists. Typically, posting up for a deck roof, especially a detached structure, would have those posts carry all the way down to concrete piers where the piers are the proper size and depth for your local conditions.

One awning I built many years ago at the back of a house was listed as being in a 120mph wind belt. That required stronger and more connections. I wouldn't have known had I not made drawings and submitted them for the permit.

So, no, your plan is not okay. You need to get with your local building department first.

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BullOak t1_jecxkc3 wrote

This, plus there's often regulations around setbacks and zoning that can come into play. Many areas allow an uncovered deck to extend into required side yards or rear yards. but once you put a roof on it, you have to stick to the setbacks.

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Iamdanno t1_jegctw6 wrote

In some places it's freestanding vs attached that's important.

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caucasian88 t1_jecuahg wrote

I'm going to be honest with you. I'm an inspector and posts like this freak me out. Please don't build this. If you don't know how the basics of framing, code requirements, how to size members based on local design criteria, then this could end poorly. If your posts are 4x4s, I'd bet your deck is from the early 2000s or earlier. It's probably already undersized compared to current codes. Adding a roof on top without taking into account all factors is a bad idea.

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Walkop t1_jeefs78 wrote

Most deck posts are 6x6 now, right?

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cttrocklin t1_jebzq8f wrote

Do you need footings underneath the deck to support all of this?

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LuvCilantro t1_jecjaiv wrote

Check your local building code. We're doing similar, and we need to have posts that go below the frost line (northern climate)

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Walkop t1_jeefwge wrote

We don't allow posts below ground, period (northern climate). Code prohibits it for decking. Needs to be tied in above ground to concrete footers.

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LuvCilantro t1_jeexhbi wrote

All the more reason to check local building codes! Our concrete footers need to go below the frost line before you can attach a deck to it if you want any type of structure on it.

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Walkop t1_jef4pr6 wrote

Oh, right. The concrete footers need to be below frostline of course. The posts need to be above ground though. Posts can't be in the concrete.

All things considered it's much cheaper to do it posts above ground vs in-ground. Less wood.

But yes! Definitely check your local building codes 😁

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essaitchthrowaway3 t1_jee58ha wrote

I built my pergola using components from this company:

https://tojagrid.com/

They got a fantastic look and super easy to go together.

I did not secure it to the deck.

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boofee t1_jeeb1h2 wrote

Our next door neighbors bought a premade one at a big box store and bolted it to their deck. We live in a hurricane area and it has survived so far.

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flyize t1_jeelv4b wrote

Hope and pray isn't good engineering.

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ScarletCaptain t1_jeex7a2 wrote

Building codes vary by where you live, but structure-wise, I'd at least want to pull the deck boards where the posts will be, notch the base of the post so half of it sits on the joist and lag bolt it to the side, then add additional bracing around the post between the joist it's bolted to and the next one over, maybe even on both sides. Make VERY sure your structure is secure.

This guy has a lot of good info, he's Canadian so codes are different, but he explains the why and how very well.

https://youtu.be/p3Z2Bpez31c

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Jazz_Cyclone t1_jee9y72 wrote

You could put up a custom sized shade sail and not have to worry about any codes.

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Tutor_Turtle t1_jefoifm wrote

As an alternative you might consider a roll up awning such as those on RVs. Use for shade and light misty rain but roll up when heavier rain is forecast, snow or any winds.

EDIT: Also don't leave up over night or any time it isn't attended, weather can change on a moments notice.

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