I'm planning to build a metal roof over the entrance measuring 4x2m, and I intend to attach it to the decking that goes around the house. I wasn't planning on casting or setting down support posts since it's so low, but thought to let the posts for the roof attach to the support beam of the decking, which in turn rests on paving stones. Surely the deck should weigh enough to avoid having to set support posts?
I've done the same at the back, but it's only a pergola without a roof; I figure it should work just as well with a metal roof.
It looks stable, but what about the foundation?
The beams are on paving stones. So far, no problem. What are the paving stones placed on? Is it drained with macadam or gravel from the house out to where the deck ends? If so, it's probably fine.
If the paving stones are on soil, it depends on how well packed the soil is... if it's rock-hard clay, then I would say it's okay too.
Regardless, it will be a few hundred kilos (?) that will burden the posts/beams/paving stones...
Personally, I would have installed footings "just because." Footings with some concrete around (just water down dry mix around in the hole). You can get them below the deck level so that they're not visible. I should add that I still hate setting footings
It looks quite stable, but how about the foundation?
The bearers are resting on paving stones. So far, no problem. What are the paving stones resting on? Is it drained with crushed stone or gravel from the house to where the deck ends?
Thank you for your response. Yes, the house was built in 2019 with a new retaining wall and there is a thick base layer where the decking will stand, so there shouldn’t be any issues with settlement. I also hate fiddling with pillars
surely the deck should weigh enough that you don't need to use plinths?
It's not about how much the deck weighs but how stable the foundation is. It's a bit hard to know how stable "rests on paving stones" is at your place.
Don't forget that with the snow pocket (caused by wind) on that structure against a higher rear gable wall, you will also be putting several tons of snow load on the foundation depending on which snow zone you live in...
It's probably not about the weight of the deck but about how stable the foundation is. It's a bit difficult to know how stable "rests on paving stones" is for you.
If you consider about 50 cm of well-packed base layer of macadam lying on about 100 cm of fill material with a lot of stones. Of course, it doesn't hurt to place pillars where the posts are to be on the safe side.
Ingenjören said:
Don't forget that with the snow pocket (from wind) on that construction against a higher rear wall, the foundation will also be loaded with a few tons of snow depending on which snow zone you live in...
Snow zone 3.5. How should one calculate this "snow pocket"?
If you consider about 50 cm of well-compacted bearing layer of gravel resting on about 100 cm of fill with a lot of stone. It certainly doesn't hurt to place footings where the posts will be to be on the safe side.
Snow zone 3.5. How should one calculate this "snow pocket"?
Now I understand why you don't "just dig down" a couple of footings
but it's possible with a hand-driven footing drill if you want to torture yourself. I have dug down about 15 footings through bearing layers. It was good old gravel too. Takes a little time, but it works. You probably have that modern bearing layer of smaller stone...
Then I understand why you don't "just dig down" a couple of concrete blocks
but it is possible with a hand-driven auger if you want to torture yourself. I've dug down about 15 concrete blocks through a sub-base. It was even the good old-fashioned crushed stone. It takes some time, but it is doable. You probably have that modern sub-base with smaller stones...
Yes, I'll probably go ahead and set concrete blocks where the posts will stand to be on the safe side. My posts for the roof will be 2 glued 45x145 joists. I can only find 3" or 4" concrete blocks, and 3" is 76 mm and 4" is about 100 mm, so my 90 mm posts will be loose.
Or should I attach the beam for the patio to the concrete blocks and then attach the posts to the beam?
Just to show how I did it if anyone is interested. I dug down two piers where the outer posts stand. Where the middle pier was supposed to be, there was a gigantic stone that was impossible to remove without machine help, so the middle post rested on a paving stone, but it feels very stable.
1977bjorn said:
Alfredo said:
Ingenjören said:
HomeboY said:
