Hot answers tagged

68

Absolutely not safe. Those trusses were engineered with a heavy (critical) dependency on the bottom chords, which are in tension. Removal has left them extremely vulnerable to collapse due to spreading, especially under snow loads, but also under just the load of the roof itself. The roof system is basically a hinge now. To get a good mental image, ...


31

With no bracing above, you might want to check the out side walls - they are probably already spreading. Once they start moving the stabilization and repair can cost many thousands if the roof stays in place, tens of thousands if it comes down. There are ways to mitigate the damage done, but it needs to be done now before the walls spread, the rafters ...


29

I had an electrician notch the top 5" of a 2x10 (9" old growth Douglas fir) in the middle of an 18' span. I brought in a structural engineer and he said the 18' 2x10 was already over current span code limits without the 5" notch. He specified 3/4" continuous ply gussets nailed to each side of the joist extending 18" past each side ...


25

No, it’s not acceptable to cut the joist hangers. In order to determine if they are acceptable anyway, there are several issues to review: 1) hangers are notched, 2) incomplete nailing, 3) wrong nails, 4) wrong install of fasteners (angled install in lieu of perpendicular to joist installation). 1) Notching the hangers voids the allowable stresses ...


23

I would sister 2 pieces 3/4" marine grade Plywood Braces (since it's under a toilet) on one side of the damaged joist as shown below. Use Epoxy or Urthane glue and SS deck screws to tie them to the Damaged Joist. After both Sister Braces are set and in place, add a plug (not shown) in the gap of the Brace A's (purple) opening since it'll be under ...


20

Don't do it. The reason that you can drill through the face of a beam in the center is because the bending stress is essentially zero there. If you drill from the top to the bottom, you're removing the portions that carry the brunt of the loading (the top and bottom of the beam). If a joist that big is sistered, there's a good bet that it's a major load ...


18

The triangle is an extremely stable form of architecture precisely because it has three sides. You remove one side, and you have one of the least stable forms of architecture on account that two members connected at a point can be affected by torque, which is by definition a force multiplier. If you want to play around with it to get a sense, try gluing two ...


17

According to this document (PDF), accidental notches in the top flange may not need to be repaired if they meet specific criteria. To determine if a repair is required, we'd need a bit more information, including: The distance from the center of the notch to the end of the beam. The depth of the notch. The specific beam used, including beam height. If a ...


15

Point your home builder to page 9 of Weyerhauser's I-joist document here. See the bottom right of the page where it says "DO NOT cut or notch flange" It is typical of all I-joist manufacturers' installation documents. As Iggy pointed out, the I-Joist in question needs to be reinforced similar to a cantilever reinforcement. To fix this, the electrical ...


15

You are looking at tree sap. It's harmless. It's dried out so if it's gonna cause you to lose sleep at night, just scrape it off with a chisel.


14

Only if you're a "professional" plumber. Cut twice as much & then measure, hey lookie there just like they did in your place. Seriously no, you're completely right the I's of I-joists are NEVER to be touched nor any holes within 3" of the top or bottom edges. "Responsible" plumbers & builders re-spec a toilet with a deeper ...


13

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 ...


13

Good on you for leveling up your knowledge and learning where not to drill or saw on joists. On that same note, here's an excellent summary from BuildingAdvisor titled Guide to Notching and Boring Joists: Don’t make any holes with a diameter greater than 1/3 the depth of a joist. No holes closer than 2 inches to the top or bottom edge. No holes closer than ...


12

As pictured - very bad idea. It may work IF the roof is re-engineered to carry a lot more of the stress across the top and bottom of the cutout. That means a much beefier horizontal beam on all four sides of his hole AND a rework of the roof by re-trussing the entire structure. Some examples: This one is a Scissor Truss, and also wears the more ...


12

Cutting a hanger is never a good idea and should never be accepted. It's shoddy workmanship by the contractor and there were numerous solutions that could have avoided this (starting with properly measuring the bolt locations for the web blocking). However, the main issue is that these hangers are not designed for this application. They are meant to hang ...


9

You don't have joists or rafters. You have engineered roof trusses. The bottom chords are 2x4 because that's all that's required for your scenario. They don't span the ceiling themselves. They're part of a rigid structure that's supported by both the top chords and the diagonal truss members. This is typical and has been standard practice since the 1970s ...


9

You never cut hangers unless they are made for cutting. Call in a inspector who will advise you or the engineer who done the design but don't under any circumstances let this go without it being checked. As further down the line could cost you a lot of money.


9

I would say that the main issue with putting down boards like that is cupping or bowing of the wood especially since this is a high moisture area; that's dirt beneath the joists, right? Look at any wooden deck and you will quickly see what I mean by bowing or cupping. Additionally if you haphazardly layout the boards like that then there will obviously be ...


8

I just checked some Ontario tables. For an Attic, not accessible by stairs (i.e. not used as living space, a 2x12 every 12" can span 32 ft. But you can't put anything above it. I've found nothing in the tables that allows a 30 ft span supporting a floor. While this doesn't mean it can't be done, it means you need to consult with an engineer, and pay ...


8

Nah - most of the strength is in shear, and joist hanger nails are nice and fat so they have good shear strength. also, yanking them is likely to be harder than you think. The actual nailing schedule seems to be here: http://www.strongtie.com/products/connectors/H.asp That suggests that 10d are one size larger than you should use in a model H1Z hanger (...


8

Yes, your trusses will support insulation and gypsum board. The Building Code requires the bottom chord of trusses and ceiling joists to support a minimum of 10 lbs. per square foot. (See IRC Table R301.5) Gypsum board weighs about 3 lbs. per square foot and insulation (depending on the thickness and type) weighs between .3 and .5 lbs. per square foot per ...


8

I have dealt with this in older houses that have had water damage in a location in a bathroom. Basically you will need two things with maybe a third: You need metal sleeves around each of these. You need an engineer to sign off on how big they need to be and you might need to search around because the size of your hole is quite substantial - or possibly ...


7

OK normally load bearing walls will have 2 plates on top. But having 2 plates means nothing. People frame however they learned to or want. Checking door header also means nothing. Some people flip all door headers - doesn't make the wall load bearing. You can never get into the head of the guy who framed your house. I worked for a construction ...


7

First off let me quote the American Wood Council PRESCRIPTIVE RESIDENTIAL WOOD DECK CONSTRUCTION GUIDE (which I recommend looking through). MANUFACTURED WOOD I-JOIST: Many new homes constructed with wood I-joists include 1" or thicker engineered wood products (EWP) – such as oriented strand board (OSB) or structural composite lumber (SCL) including ...


7

If there is nothing in the code of practice which specifies a limit to the number of holes, then there is no limit to the number of holes. From an engineering standpoint, this is because a beam with holes in it can act like a truss (see e.g. the bailey truss). The minimum hole sizes and minimum spacing is to allow enough timber to act as the vertical/...


7

Yes, this is common. The load in any joist is carried in the top and bottom surfaces (the flanges) of the joist. That's why I beams/I joists work. The thinner web between the flanges basically serves to keep the flanges at the same distance from each other. There is no load in the center of the web. Thus, the center of the beam does not need to be the same ...


7

Looks like data entry error to me. The values were reversed for several rows at some point. Considering that they spelled 'fir' as 'fire' in one case, one can assume that accuracy was not a high priority here. That's not a flush beam, either, nor is '2x8' a 'length'.


7

Yes, you can. It will not affect it structurally, given you are only drilling relatively small (3/4” or so) holes. You won’t want to drill a large plumbing line through it.


7

Just add (nail, screw, and/or glue) additional framing material to the side face of the joist to provide more bearing area for the subfloor.


7

I did it both ways in a laundry/powder room I completed last year. Along the one wall, I installed the nailing plates your described. Along another wall, I didn't, in part because the sole plate for the wall had to be down before the subfloor, in order to run the plumbing. Also this area holds the washer/dryer & a utility sink, so no foot traffic. In ...


Only top voted, non community-wiki answers of a minimum length are eligible