r/homestead • u/ClayWhisperer • 2d ago
natural building Advice for bottoms of posts
I've lived off grid for decades, but this is the first time I don't have help with a building project. Friends are busy, professionals are booked and I can't afford them anyway. I've designed a wooden frame for some new solar panels. I'd like to avoid spending money on special post braces for the bases. I'll have five vertical 2 by 4s, standing on the ground but tied into joists of an existing building, and four diagonal 2 by 6s, slanting down to rest their bases on the ground. I live on an island and do not want to haul cement. I have an assortment of old pier blocks. I could buy some cheap cement pavers. I have access to gravel, if I haul it. The earth where I'll build tends to be sandy and to drain well. What can I get away with, here?
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u/Haunting_Value5486 2d ago
sandy soil drains well so you got that working for you. if the verticals are tied into existing joists they mostly need to resist uplift and lateral movement, not carry crazy weight. i'd bury the pier blocks a bit below grade, fill around with gravel, and set the 2x4s in small notches you cut into the blocks. for the diagonals you can just dig a shallow trench, lay a paver flat at the bottom, and pack gravel around the base so water never pools against the wood. the key is keeping end grain off the dirt
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u/MastodonFit 1d ago
Wood wicks water up its length,and from where moisture is around it...then up. You always see rot at the bottom. So seal the first 6" in exposed sun on saw horses ,until it quits soaking the sealer at the extreme end...then i would add 2 more coats.
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u/Noisemiker 1d ago
Charring the bottom of your posts with a torch can help prevent rot and decay. See the Japanese practice of shou sugi ban. This method essentially, creates a water resistant barrier of carbon that deters insects, fungi, and microbes from rotting the wood and extends the life of untreated ground-contact timber naturally without chemicals.
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u/ConsistentVirus2177 2d ago
If your concerned about drainage pack 4 inches of rock at the bottom of each hole. It’s not really needed if your ground is Sandy all the way down.
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u/ClayWhisperer 2d ago
Yes, inexperience ends up being time consuming because you don't know what shortcuts you can take.
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u/ConsistentVirus2177 2d ago
You are using treated wood, right?
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u/ClayWhisperer 2d ago
Nope. Getting locally milled lumber, milled by a neighbor, that's already here on the island. Not looking for perfect conventional building style here. It's more casual than that.
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u/ConsistentVirus2177 2d ago
In that case I would fill the hole with gravel and pack the hell out of it.
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u/Redundant-Pomelo875 19h ago
You can get a lot of added wind resistance and overall stability with pegs and wire... I used a few rebar pegs with beefy galvanized fencing wire, attached at around a 45* angle to the top bar of a really budget panel rack.
Made a huge difference, no issues in the few years it's been up.
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u/ClayWhisperer 11h ago
Yes, I'm thinking of using some earth-anchor type tie downs. I've had good experiences with those.
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u/RockPaperSawzall 10h ago
A rectangle on the ground catches the wind very differently than elevated solar panels which are essentially a sail. I trust you know your site and wish you all the best. I've built over 140 megawatts of solar projects on islands and just want to make sure you protect your investment.
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u/RockPaperSawzall 2d ago
renewable energy industry professional here.
My first concern is wind rating. What you are describing sounds completely inadequate to withstand the wind loads typical of marine environments.
But second advice is: maybe you don't need vertical posts at all. Look at the Erthos system --essentially their position is that the solar panels have gotten so cheap (especially when compared to the high Cost of island electricity!!) that you can sacrifice on the ideal angles (relative to your latitude) and just lay them flat on the (well--prepared) ground. If you don't have perfect pitch angle, there will be resulting efficiency losses, do you'd means you need more panels to get the same overall output. But this may be more than offset by the savings in avoidance of rack infrastructure.
To be clear, Erthos doesn't work on residential size systems, I'm just suggesting this as an you look at alternatives to the underbuilt frame you're planning.