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56

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 ...


24

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.


13

I think you need to get a structural engineer out there ASAP to investigate; I would be worried too! Your city's by-law office might be able to refer you to someone who can help. It might also be worth getting in contact with your insurance company - they might have their own engineer come out. If you think it's really about to fall over you might opt to ...


10

Check if the wall is load-bearing See that link for how to do this. Try to see if there are are any high-voltage lines in the wall Look for light switches, receptacles, lights, hard-wired smoke detector In some cases, a wire may run though the wall, but not be visible. This is very hard to determine, and takes sleuth work (look for wires entering the ...


10

Good question Paul, The situation with your framing is not really normal, but not uncommon for a house that age. Any time there is separation of framing members, it is a reason for concern and should be addressed. However, I would not say it is a major or alarming problem. There could be a couple of different reasons for this separation. The joists may have ...


9

The pergola is much like a stick framed house--the framing itself resists vertical forces (gravity) but in and of itself, has no resistance to shear forces (side to side). For a house to stand up on its own, the sides need to be braced against shear forces...typically that's done with plywood sheathing. Barring that, diagonal bracing can be used. On the ...


8

I think they're there for stabilizing the brown beams/joists. Typically, a loft is unused space with no floor. Between the joists, there is insulation supported by drywall or other material depending on the age of the house (as in pic 2 and 3). Typically one would put in blocking between joists to stop horizontal flexing and torsion. Since an attic ...


8

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

Just found this useful document (direct link to PDF) on the web. It explains in a much clear manner than I can, plus it contains some good, easy to read diagrams. Notching & Boring Guide for Floor Joists & Stud Walls in Conventional Light-Frame Construction by Western Wood Products Association


7

A properly sized floor joist should never deflect. Is your bed a water bed?. Joists are supposed to be sized to handle a minimum of 60 to 80 pounds per square foot, which is actually a lot, since loads are distributed across the entire span. If you are seeing ridges, cracks, or movement under load, you have a problem. I have seen joists wain, crack or even ...


6

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 ...


5

I agree with everything Shirlock said regarding adding joist hangers, but first I would advise you to stabilize your joists from whatever is causing separation. Edit The gaps you are seeing are not caused by shrinkage. The gaps were either there when constructed or have developed over time. On a positive note, the joists you've shown don't appear to be ...


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 ...


4

Assuming the sag is new/progressing. There are countless hundred+ year old homes with proper structure that have floors that don't sag, bounce or shake. Sagging is never good. Sagging is a sign of either poor engineering to begin with or structural damage done later. bcworkz does raise a good point about older foundation methods and short term sags ...


4

Some physics. Assuming the same material, length and loading, the bending strength is limited by the Second Moment of Inertia (I) of the cross sectional area. The math is complex, and even given a calculator, it's a bit confusing. Assuming a vertical loading, You can estimate the relative change in the I value by cubing the scale change. (This estimate ...


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. ...


3

The simplest solution would be to run tensioned cables diagonally across the top of the trellis. Since it is tied to the (hopefully? ;-) ) solid brick wall, it will resist torsion along the diagonals. Then the posts will be relegated to their proper job of keeping things up.


3

Normal Vibrations in Buildings Have Identifiable Sources I've encountered a vast range of vibrations in multi-dwelling buildings I have lived. Hear are the ones I can remember: washing machine spin cycle (this happens often and, if it matches the resonance of the building can travel throughout multiple floors) dishwasher valves and drain pump (not very ...


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 ...


3

Screws would tend to be slightly thicker than nails (because of the threads) so you would probably want to watch out for splitting of the wood and might want to require drilling pilot holes if you switch to screws. For the most part though, screws would work better than nails in the long term (would not pop up over time) but would be harder to use (pilot ...


3

A 1" to 16" slope is huge. that would mean a 10 " drop in apx 13 feet. Did you mean 1" in 16 feet? Regardless, the fact that you are asking the question indicates that you need a professional to take a look. There are many possible reasons from maybe the cut center beam, collapsing or crushing support posts(top or bottom), settled footings, etc. This is ...


3

The total weight of materials in a room is not really the question. The concern, if any is how many pounds per square foot. This will vary depending on what size joists are supporting the floor. Common residential construction is build to handle a dead load (materials/fixtures) of 40 to 60 psf averaged over the entire floor not counting load bearing wall ...


2

I'm not sure how the cross beams are attached to the support beam near the house, but it seems to me that would be the point you need to focus on. Any small amount of flex in the outer most posts can be translated into movement, because the cross beams are able to torque at the ends. You may be able to eliminate this torquing, by adding in an additional ...


2

Assuming the lintel I see in the second picture travels over the block wall, it should be safe to cut the opening. I'm a contractor and if I could get a subcontractor to do it for $800 and guarantee it in writing, he'd be hired. It better be a good straight cut I can frame to. Be sure to calculate the proper rough opening you really need and add an inch. ...


2

You've essentially got a column buckling problem here. Factors affecting the maximum load include the geometry of the beam cross section, its material properties, and the manner which its ends are constrained. You can read up on it here. What makes it more complicated is a possible eccentric loading condition, as The Evil Greebo points out. Now you have to ...


2

From your description is does sound like the cut in the beam has had an effect, but you say it was only cut recently yet the sagging " has apparently been this way for a while". A more serious problem is if the house is still moving/sagging which would indicate an ongoing problem rather than something that happened in the past and has now stabilised. The ...


2

A general rule of thumb is use screws when you need pull strength and nails when you need shear strength. For example use a screw to hold down a decking board, but a nail to hold the joist up. Screws hold thing tighter then nails, but screws are brittle when hit from the side giving nails the advantage. This is not a hard fast rule, but covers 90% of of ...


2

Without looking at blueprints, all you can do is make an educated guess. Possible methods include: If it's an exterior wall, it's almost always load bearing. If the joists are not continuous over the wall (they are cut short and meet on top of the wall) it is load bearing. If there is a load bearing wall or beam directly above or below this wall, it is ...


2

"Normal" building movement would only be due to wind or earthquake. Movement due to normal wind would only be slightly apparent to very sensitive individuals in very tall buildings, as in dozens of floors. Most people would notice slight wind movement in very high winds or minor earthquakes, but nothing alarming. The only alarming movement anyone would ...



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