Spans of beams are based on the size of lumber and the load. You haven't given us enough info to even give an intelligent reply. Is the pergola 11x11? 16x11? 24x11? 1 beam? 2 beams? 3 beams? 4 beams?
Generally you want engineering info from a reputable source, and we are not your structural engineers.
That being said, IF your pergola is roughly 11x11, and IF the load does not exceed 10 lbs per sq ft, 11 ft would be about the maximum a #2 pine 4x6 should span. (Red cedar is slightly weaker, so an 11' long red cedar 4x6 beam would be slightly overspanned at 11' @ 10 lbs per sq ft) But your load will likely be less than 10 lbs per sq ft, so technically it's probably okay.
10 lbs per sq ft would = 1210 lbs of lumber on an 11x11 area, with 2 beams, one on each end that is (1210/2=605 lbs per beam) or 1 beam and 1 ledger. But we don't know the dead load of your lumber or your design.
You should not skimp on beam size, however. And not just for span and load considerations. A small beam will look undersized and anemic from a distance. You'd be wise to use larger beams for that reason alone.
Also, if you go to pick out a 4x6, and you look at them, you may have to pick through a few of them to find one that is straight... so if they aren't straight... what do you think they will be like in a few years if you go maximum span, and add even a little weight on top?
Due to that fact, if you are dead set on using 4x6s, you "could" select 4x6s that have a little crown, and place them crown up. That would give you the best chance of them not sagging short term.
Spans of beams are based on the size of lumber and the load. You haven't given us enough info to even give an intelligent reply. Is the pergola 11x11? 16x11? 24x11? 1 beam? 2 beams? 3 beams? 4 beams?
Generally you want engineering info from a reputable source, and we are not your structural engineers.
That being said, IF your pergola is roughly 11x11, and IF the load does not exceed 10 lbs per sq ft, 11 ft would be about the maximum a #2 pine 4x6 should span. (Red cedar is slightly weaker, so an 11' long red cedar 4x6 beam would be slightly overspanned at 11' @ 10 lbs per sq ft) But your load will likely be less than 10 lbs per sq ft, so technically it's probably okay.
10 lbs per sq ft would = 1210 lbs of lumber on an 11x11 area, with 2 beams, one on each end that is (1210/2=605 lbs per beam) or 1 beam and 1 ledger. But we don't know the dead load of your lumber or your design.
You should not skimp on beam size, however. And not just for span and load considerations. A small beam will look undersized and anemic from a distance. You'd be wise to use larger beams for that reason alone.
Also, if you go to pick out a 4x6, and you look at them, you may have to pick through a few of them to find one that is straight... so if they aren't straight... what do you think they will be like in a few years if you go maximum span, and add even a little weight on top?
Due to that fact, if you are dead set on using 4x6s, you "could" select 4x6s that have a little crown, and place them crown up. That would give you the best chance of them not sagging short term.
You should probably use dimensional lumber vs a post, posts are generally used vertically, so a 2x10 or 2x12 doubled up would be significantly stronger. Think deck construction.
Granted, my initial post was short.There seems to be no definitive beam spans for pergolas and thus why I asked the initial question. My original design was for a 10' x 22' pergola with six 6x6 posts and three 6x6 beams spanning 10' (with a brace on one side reducing that amount by about 8'-6"). The initial rafters (4x6), spaced 16" o/c spanning approximately 11' from beam to beam, with a 18" overhang. I then, was hoping to put another row of 4x6 rafters spaced 16" o/c at 90 degrees creating a boxed appearance of 4x6 (granted this would add weight). my drawing is not yet complete or I would have shared.
Last edited by bdgregston; 04-05-22 at 07:31 AM.
Reason: change inches into feet
You say there is no load. Unfortunately, you can't calculate or "look up" to see if the timber is sufficient for no load. Charts don't exist for no load situations. You can look at existing span tables and guestimate and apply your own safety margin. But, in general you are on your own in the common sense zone. Yes, a 4x6 or 6x6 can span that distance. You can see that simply by lifting up one end of a 12' timber and it doesn't snap in half under it's own weight. But, will it warp or sag over time?
Multiple members bolted together would be about as strong but could be more resistant to sagging and warping if using less than perfect lumber, similar to how plywood gains it's strength. Good quality wood can also be more resistant to sagging and warping but that can be hard to tell for certain when staring at a pile of lumber. You can also buy the timbers now and let them acclimate outside where air can get to all sides and see what happens. Then you only use the straight material (and curse because you lost the receipt and can't return the warped ones).
I’m rebuilding my deck, I’ve decided to use decking tiles for easier maintenance, cleaner look, design
My question is; can I use treated fence boards instead of thicker decking boards as a base to hold the interlocking deck tiles?
I’m trying to cut cost but is this saving worth it or even an option?
any advice? Thanks
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Hi community,
I have an issue with water diversion (pink arrow = flow of water) issue due to negative slope of my driveway towards the home corner of my foundation.
The dark blue arrow notes the point where soil keeps getting lowered. (erosion?) Btw, the pipe opening in that section is an underground pipe that is currently broken, so temporarily I just used extension for gutter drain.
I want to fix the broken concrete as denoted in sky blue, and I think I want to use thin edging stones (basically add these stones on the soil of skyblue section, basically replacing the broken concrete blocks)
My questions are:
1. Is this the right approach? (will it basically work?)
2. If I use edging stones, how do I seal it from water? Do I need to apply something between asphalt driveway and the edging stones? (and I guess between each edging stone as well)
3. Once I fix the issue, do I just use top soil and then mulch to cover the sunken parts?
Thank you.
[img]https://cimg2.ibsrv.net/gimg/www.doityourselft.com-vbulletin/624x1248/pic_0dc3b88f36fe9a01ec4e449bd79d8deb8062202f.jpeg[/img]
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04-01-22, 09:32 AM
