Hello,
I’m planning to build the entry I made on the 3D Warehouse here:
This is my first time using SketchUp or building a large structure so I thought I would ask the community if they thought this would be stable or any tips or changes you all would recommend.
Thanks!
I took a quick look. Only problem I see is that, with the use of 12’ 6" 6x6s and 12’ 6" 2x4s, you essentially have TWO 12’ 6" sheds connected only by the roofing!
I’d want to see some detail on how you plan to do a better job tying together the two halves of the structure.
As far as model organization goes, I suggest you use some layers! Just so you can isolate various portions. At the very least:
But if you do this, remember to leave the raw geometry on Layer0 - only assign your groups/components to one of the other layers. The grouping will then be controlled by layer visibility, while the geometry each grouping contains will remain on Layer0 - as it should be!
The horizontal beams across the posts seem to have a joint between two posts. That’s not good. Better to have the joint fall on a post. Same goes for the pieces across the top of the rafters. Also, how closely spaced are the rafters that support the roofing? I’ll bet you could eliminate every other one without affecting the stability of the roof.
Hope this helps.
Best,
dh
Thank you both for your advice and help!
I was planning to join the 12’ pieces with another piece of the same type with bolts. Really this was just because I didn’t want to make cuts to have everything line up on the posts.
But I guess I’d be making cuts for this joins anyway. If you rotate around behind the shed you will see on the posts how I was thinking to join those. I would have to do the same on the balusters. Would this be good/OK? If not I’ll redo the 12’ pieces. Thanks!!
I’m no architect, so don’t take my word for it. But adding triangles might reduce the sheer stress.
Also, a fascia board might help prevent the rafters from rotating.
And adding grooves to where the rafters connect to the beam might help prevent slipping.
Strengthening corners with triangles is very effective, so great job on the posts. Also, it reduces stress to make the roof as light as possible. So maybe consider switching from corrugated metal roofing to asphalt shingles. Also, it might be cheaper because metal is expensive.
Asphalt shingles weight a lot - 200 to 300 pounds per “square” (i.e., 100 square feet), or 2 to 3 pounds per square foot. A quick web search for corrugated sheet metal weight suggests around 0.6 to 1 pound per square foot.
I think comments so far are too pessimistic. I design structures and believe this is essentially fine although much depends on the jointing. As it is open sided, wind resistance is not a major issue.
I’d agree with this. Much better to have joints on posts. You can do it your way but you will need a really well designed and constructed joint if you do.
True but I doubt there will be much sheer stress. The roof covering will act a bit like a sail so that is the biggest worry. If you glue and screw your slats, I think it would have enough sheer resistance. A bigger worry if the structure is not tied down is that it might blow over. Especially if you live near Chicago.
The “grooves” referred to are called birdsmouths where I come from. And yes, birdsmouthing over the supporting beam or plate is that standard method and much improves stability.
I think that is what you have indicated for the covering. No problem with weight unless you envisage really big snow loads.
Ideally, the posts would be mortice and tenoned into the beams and pegged. I think I might make the diagonal braces a bit longer, though they don’t need to be as thick as the posts. In the best work they too would be let into post and beam and pegged.
I presume this is to be freestanding. You show some kind of disc as feet. Not sure what that would be made of. If it’s bigger than the post base as shown, you need to be careful not to create a flat impervious surface that encourages water to be drawn up into the end grain of the post. There is some danger that each cross panel could move apart without any means of tying them together at the base.
If the posts are embedded into the concrete footings (like post frame structures) then they will provide the lateral stability. Otherwise you will need to provide some mechanism (eg. shear walls, triangular bracing) to prevent the structure from racking.
I’ll update the sketch to use the joints on posts. Seems like this will be a better idea generally speaking.
Will do this as well. I was just going to use hurricane clamps and call it a day but it seems that birdsmouths will help with the integrity.
Yes, that is correct, this is metal corrugated (exposed fastener) roofing. I live in the mountains and we have had snow of 2-3 feet at times.
Those discs are concrete forms. I plan to bury them 3 feet (6" below our frost line) and attach the posts with metal brackets which would be set into the concrete.
I wasn’t planning to embed the posts into the concrete so I will look into additional triangular bracing to further reinforce the structure. I could embed the posts but I’m not super confident that I would be able to do that and get everything square/lined up. I think I might hire out that part of the job (making the post holes and setting the posts.
Thanks everybody for the help!
That’s what I call a serious snow load. I’m told an inch of snow equates to about 1lb per sq.ft. A depth of 3 foot would mean 36lb per sq.ft. of live load. That might impact the depth of your rafters and the top heaviness of the structure as a whole.
If the discs are underground, does that mean quite a bit of your posts are too? We wouldn’t do that her in the UK or they would rot away in no time. Similarly, encasing in concrete would be nearly as bad. Normal procedure here would be to have a plinth of some kind (concrete/brick) sticking up out of the ground at least 6". We would set a non-ferrous dowel in the centre and drill the base of the posts to locate onto the dowels. And we would probably slope the top of the plinth away from the post to avoid water sitting between post base and plinth, plus insert a damp proof course at that point. The structural problem with this method is that you end up with what engineers call a pin joint. It has no lateral resistance so you have to provide that by other means, such as triangulation (mentioned in various posts here).
Yep, this is how I was planning to do it. The post would not touch the concrete.
The more I think of my lack of expertise here the more I think I’m going to get some quotes for the work. That way the contractor can handle the plans, inspections, etc.
