2/21/2023 0 Comments Flat icon glueSo we all know that there will be parts of that 2x4 that are weak points, like at a dead knot, or where the grain runs off the edge of the board, right? But all that gets factored in and an average is calculated of many tests to come up with the expected strength of the average 2x4 of any given grade. Okay, tests have been performed under controlled conditions and the data studied by qualified people to get that rating, right? Let's say a 2x4 spanning 8 feet is rated to carry x number of psf. And I can't cite any engineering background or facts here, Dunc, but I'll try my best to explain my thinking. Let's see if I can say this.first off, the thing I said earlier about the way a horizontal framing member fails, by rolling.īut there's more. and WAY more than simply multiplying the individual span strength > times the number of boards. I'd be interested to hear how you intend to do that. At least if you are working in any type of siesmic sensitive area. Now as for that ledger on a brick wall, I think you might have some problems there. In fact, I think I remember a friend telling me he was renovating some turn of the century flat roofed commercial buildings in Tacoma, and that's exactly how the roofs were were framed, 2x4s on edge, nailed together across the entire width of the building. So my thinking would be, that the glulam is alot stronger because there no way for those individual 2xs to roll, and I am having a real tough time imagining the entire beam rolling into what would be vertical. (came back to say that that's why midspan blocking and cross bridging strengthen a span, because they keep the middle of those framing members from rolling under load) You've probably seen this many times, where the middle section of an overloaded ceiling joist starts to lean, or twist. Note that local code may require mechanical fastening in addition to adhesive when hanging mirrors.I sure hope some engineer chimes in here, but I think there is great strength in a glulam layed over on it's side - way more than the same number of 2x4's nailed together would have, and WAY more than simply multiplying the individual span strength times the number of boards.Īs I understand it, horizontal structural member most often fail when the center rolls over towards horizontal, even if the two ends are secured upright. Once the adhesive has set, remove the tape and the brace, patch and paint any small holes, and the installation is complete. Then, press the mirror firmly into the wall using a clean paint roller, and apply strips of painter’s tape to the top corners until the adhesive sets up. This helps spread the adhesive onto the wall surface. As the adhesive makes contact, allow the raised corner to slide back down to the support. To install, set one corner of the mirror on the support while keeping the other slightly raised, and press it into the wall. This mirror weighs 35 lb., so we need about 88 in. of standard-size bead for every pound of material. Additionally, the manufacturer recommends at least 2-1/2 in. In this application, the manufacturer recommends at least three continuous, horizontal beads spaced at least 1-1/2-in. Apply the adhesive in a pattern recommended by the manufacturer. To bond the mirror to the wall, use an adhesive rated for mirrors. Once the primer is dry, remove the tape, and attach a temporary wooden brace along the bottom edge to aid in positioning the mirror. When done sanding, wipe away any dust, and prime the area. To ensure a good bond between the mirror and the wall, sand down to the original substrate-in this case, we’re sanding down to drywall. Many paints have additives that make surfaces easier to clean, but these additives also make it hard for adhesives to stick to paint. This marks the area where the mirror will be bonded to the wall. Then apply painter’s tape about an inch inside of these lines. Start by marking the mirror’s location on the wall, using a level to make sure the lines are level and plumb. Hanging a mirror with no-slip adhesives is an alternative to mechanical fastening that can provide a clean look.
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