# Tag Info

63

Screws are a "superior" fastener over a nail (they have far superior tensile strength) - especially if you're talking about screwing down decking. However there are many scenarios where a nail is the proper fastener for the application (attaching joists is one example - screws are brittle and will fail when subjected to the forces of a shear loaded ...

28

Nails are considered an "elastic connection". They handle wood movement much better than screws. Many times if you have severe wood movement with nails you will see things like nails that tilt or seem to back out. This is actually a good thing. Many times if a screw had been used in that case it would have caused the wood to split as it moved.

16

I'd go with @Aarthi's load bearing table resource for a general idea of what's reasonable. If you're looking for equations though, you can start with these: Beam Deflection Formulas Beam Deflection and Stress Calculator Area Moments of Inertia Using the Parallel Axis Theorem Wood Material Properties (Modulus of Elasticity (E) found in Table 4-3a) For ...

14

You asked for optimal: Follow a few thousand years of practical experience and put in a tension brace (lower outside corner to top hinge-side corner - opposite what you are going for, which is a compression brace) Go with the past few hundred years and make it a turnbuckle. The best form of compression brace "in plane" is none of the above, and has a point ...

10

Unless your holes match the bolt size very precisely (like, you have to hammer the bolts home), you will get racking, which will weaken the joint over time. Likewise, the bolts will loosen up (use lock washers and check it frequently). It's something you'll have to watch for; as the holes get stretched, you'll need to figure out what to do. Think about how ...

9

I'm not a hundred percent sure this answers your question, but I will say this much: 300lbs is actually much, MUCH too low of an estimate, if all of my trolling on this site is anything to go by. Also note that it's not weight but force (ie Newtons) that you need to be looking at. Second, this document should answer your load-bearing questions. It's kind of ...

9

Technically when using joist hangers, a specific kind of hardened galvanized nails are supposed to be used. This is because regular deck screws probably don't have the necessary shear strength. For a deck though, I've used screws before without any problem. Although if you were planning to put a lot of weight on the deck (say, a hot tub) I would be a bit ...

8

Nails are used in almost all framing and structural applications. Most code books are designed with nails in mind and will have specific minimum nailing requirements and patterns for different applications. Structural screws are coming more and more on the market every day, but because most code books don't include them you will need an engineer's approval ...

7

I found the following VERY detailed tutorial on determining joist span based on expected live and dead load: American Wood Council The weight your deck will need to support will depend whether you get snow and how much, whether there will be a roof over the deck, whether the deck will be sheltered by any other means, what do you expect to do with the deck (...

7

A welded connection can always be made the same strength as the original steel by using a full penetration but weld but this all depends on the quality of the materials used for the welding and the quality of the welding itself. Therei s a very good reason why there is a lot of non destructive testing used when welded joints are being used for structural ...

6

Static load affects structures much differently than dynamic (moving) load. A dynamic load will give periods of relaxation for members to return to their previous shape. A static load will promote bending. Considering the pressure and surface area, you basically need this to sit on your slab. The tank can't take pressure, and you don't want the tank pulling ...

5

Keep in mind that your load is not static, but dynamic, and the stresses will multiply during the movement of the swing. Also, the movement of the swing will apply stresses against the short dimension of the beam, which it was never intended to support. Looking at the swing sets available at building centers, I've never seen a main support beam smaller ...

5

There isn't enough information in that sketch to verify calculations (for instance, we have no idea what's on the floor above), but here are some reactions: Removing 60cm of support may be significant, depending on how much load that wall was carrying. If the arch is structural, removing it requires additional support. Your existing building may not be ...

5

What you described with the 45 degree bevel is called a french cleat. It's used for securing heavy items to walls and I've seen them used in upper kitchen cabinet installations. 1x6 hardwood cut in half on a 45 I think would suffice. I would consider putting one on the top and one on the bottom (mounted upside down) if you have enough room to slide the ...

4

Here would be my basic approach (Mechanical Engineer here, Statics TA for 4 semesters): For starters, you could figure out the weight of the mattress and box spring plus the weight of two people lying on it (W). Add in a safety factor (at a minimum 2, ideally a bit more) - remember, an uneven or dynamic loading will apply significantly higher stresses to ...

4

This is a fairly complex problem to answer starting from scratch as it has multiple components so I will just summarise the calculations that will need to be done. In terms of the stresses in the plank, typically as a minimum you will need to calculate the following forces: Bending moments Shear forces Bearing stresses Deflections These will need to ...

4

More or less a question for mechanics and machinists and an easy one. If you've ever busted a head stud off on a Jaguar, you know of the evils needed to get the remainder out of the block. Lots of methods out there, but aside from electrostatic erosion, most methods involve using a drill. This drilling machine is magnetic because the base is a very strong ...

4

You could truss the tubes as shown in the picture below. The center block helps to support the tube when the truss member is placed in tension. The truss could be constructed from heavy wire or threaded steel rod. The concept here would be similar to the scheme used on the wider steps of a wooden step ladder. I would have suggested the possibility to ...

4

If you can't use the truss technique described by @michaelkaras, the only real solution would be to move to thicker-walled tubing or larger diameter tubing. Anything you fill the tube with is not likely to make much of a difference at all. All the bending strength of the tubular member comes from its topmost and bottommost elements. The center of the tube ...

4

OK first let me say that if you're going to be making major structural changes to a building (and this counts as a pretty serious structural change in my mind) it would be well worth your while to get an engineer or other qualified building professional to help you with your design. If you just "wing it" you may be endangering the house and its occupants. ...

4

Once you have corrected your axis of rotation it should be obvious that the idea to lengthen the "clip" will not change anything with regard to the force required to raise the flap. Actually it could make things worse if the longer clip added more weight to the whole assembly. The force needed to raise the flap is measured in some units like foot-pounds (ft-...

4

If I'm reading this right(and looking at the final picture), the beam itself is sagging. It may have reached an equilibrium point, and simply jacking up an reattaching it will fix it. But you'll still have a bowed beam. My inclination is, a properly built beam should be able to span that distance and hold the weight without sagging. I have smaller, longer ...

4

Seeing as you're in the UK (lots of well-enforced building regulations) and you're wanting to remove at least one load-bearing wall (the old external wall), you absolutely need to bring in the pros and start dealing with all the hassles of permitted renovation. I'm not sure if you'll be allowed to do any of the work yourself, but if you are, it will ...

3

I can't speak as to how to calculate it, but from experience, 2x4s are overkill. For the beds I've seen, 1x3s slats (laid down, not vertical), with a vertical 1x4 perimeter, were sufficient unless both people weigh 300+lbs. You will want a center rail and possibly a center leg (some mattress warranties actually require one!). Reducing the span length is a ...

3

Lots of interesting answers for how to figure out the "correct" answer, but hopefully this will help a bit. We purchased a commercial play set similar to this. To cover a 12' span, they use three 2x6" beams laminated together - glue, nails and finally carriage bolts. This is to support 2 swings and a set of rings.

3

putting the legs on the inside will induce a shearing load on the connection. A better connection would be having the wood frame rest on the leg (with a notch). You also need to account for the needed strength in the corners so everything stays square. or you can do a google search on bed plans and get a tried and tested design the first link even only ...

3

"...the short answer is, don't use the 2 x 4 for your swing..." Otis' question was posted long ago, but I thought this may help other people researching similar structural questions. I'm not an engineer, but I've worked with wood for 30+ years. An interesting question, and one a lot of DIYers ignore, and limit their consideration to one thing: is that 2 x ...

3

One thing that no one has mentioned: screws WILL NOT pull down a deck board nearly as tightly as a nail. If you have a twisted board or a board with a crown, a screw is pretty much useless. Screwing deck boards also creates large holes for water to soak into and rot much faster. Using a 3 inch galvanized nail and nailing it flush will pull the boards ...

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