How far a span can I build a Pergola over?

[JonT]

We'd like to put a pergola over part of the pool area for some shade but the span it would need to cross is 30ft (ish). How can I do this without putting posts in between? It may be unavoidable but I'm starting my research on it. Thanks

[gordner]

There is no real loading on a pergola, so that makes it easier. But 30 feet is not an insignificant distance. Are you willing to have structure to support it on both sides? It's possible to lend support from above with tension cables if you extend the supporting posts on the sides above the pergola height.

[MBAtarga]

Are you planning to use solid lumber, laminated beams or I-beams?
Good luck finding solid lumber in 30' lengths. Laminated beam or I-beam - no problem. Do you want 18 inch high support beams though?

[wilnj]

Not sure where you’re located or what time of day you’re typically using the pool but depending on the above you could construct it at an angle so that it casts a shadow without spanning the pool.

It wouldn’t fully block the sun but provide a dappled effect.

[RWebb]

what is max. wind loading in Omaha?

you may want to look at glue-lam

there are some new wood products in Orygun that they are using to build 4-5 story buildings from; maybe in demo stage

[vash]

i just did some rough numbers.

30 foot span. simply supported at the ends. a 250 lb man can do a chin up in the middle and deflect a 4x12 beam 0.48 inch. i think the code allows 1/360 deflection. (?)
i dont know how deep this thing will be so i couldnt add the weight of the pergola slats.

[john70t]

Might want to go with welded and sealed end boxed (or I-beam) metal instead of wood.
Welded and sealed with seriously heavy duty paint.
Braces on corners.

No guarantee on rust in ten years.

[wswartzwel]

Cables and canvas.

[Eric Coffey]

Probably knee braces, at the very least (assuming posts/support on either side).

[Eric Coffey]

Originally Posted by john70t

Might want to go with welded and sealed end boxed (or I-beam) metal instead of wood.
Welded and sealed with seriously heavy duty paint.
Braces on corners.

No guarantee on rust in ten years.

Good call. Forgot about those. There are several pre-fab metal-beam/frame pergola kits out there (still using wood slats/ribs). Usually with heavy-duty/weatherproof coatings/paint.

[dad911]

Sun Sail?

Keep in mind the sun warms the pool. Cover it and you'll drop 5-10 degrees plus.

Just changing our plaster from white to grey raised our pool a few degrees.

[look 171]

Originally Posted by vash

i just did some rough numbers.

30 foot span. simply supported at the ends. a 250 lb man can do a chin up in the middle and deflect a 4x12 beam 0.48 inch. i think the code allows 1/360 deflection. (?)
i dont know how deep this thing will be so i couldnt add the weight of the pergola slats.

Damn, nice to have Vash around.

[john70t]

Anything that catches wind...

[look 171]

Just to give you a bit of reference. I am building a 24' (with 3' over hang on both side) second story deck. My engineer called out for 7.0' x 11.85" Parallam. I am debating on getting Alaskan glue lam for wet areas ( It never rains in socal but when it does, I not a happy camper). I can't get Parallam Plus plus here on the west coast or socal so am beating my head against the wall because that big ALaskan beam is 1400 bucks.

[porsche930dude]

maybe a couple of these instead

[pavulon]

Cantilevered stuff looks great. Wind could be a deal breaker.

[Crowbob]

Originally Posted by Eric Coffey

Good call. Forgot about those. There are several pre-fab metal-beam/frame pergola kits out there (still using wood slats/ribs). Usually with heavy-duty/weatherproof coatings/paint.

This gets my vote. The welded triangular steel truss/beams or whatever won't look nearly as heavy as wood beams and more light gets through.

^^$$$ probably.

[LakeCleElum]

Is snow load a consideration in Omaha????

Around here, our county Building Dept would be your best source of info.......

[vash]

Originally Posted by LakeCleElum

Is snow load a consideration in Omaha????

Around here, our county Building Dept would be your best source of info.......

Snow can’t build up on pergola, can it? I don’t think you even have to account for any live loads (people).

[Crowbob]

Snow builds up on my pergola, which is covered by an American Wisteria. The damn thing grows so fast if you're not careful, it'll grab you as you walk by. It's always trying to get into my house, too.