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Questions tagged [joists]

Horizontal support structures beneath the floor running between load bearing walls.

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34
votes
1answer
154k views

What are the guidelines for holes in joists?

I've been unable to find a good reference for the size/amount/location of holes I can drill through joists. This is mostly in order to pass cabling or pipes through the joist crosswise. Also, what ...
29
votes
5answers
5k views

Is it safe to remove the bottom chords of a series of garage roof trusses?

See attached picture. Looks like an 8x10 cut-out. He wants to lift cars up so he can walk under them. Is this safe? Doesn't removing the joists affect structural integrity?
17
votes
3answers
12k views

Is notching a flange on an I-Joist ever acceptable?

My home builder said that the following notch in a flange on an I-Joist was acceptable, but I've read that you're never supposed to do so. Is that true?
16
votes
5answers
14k views

Contractor cut joist hangers to make them fit

(edited with additional info re. header) We are removing a couple of load bearing walls as part of renos in our home. The engineer specified a W8x21steel beam to replace the load bearing wall. The ...
14
votes
4answers
42k views

How do I meet the 7 feet high ceiling requirement after finishing the basement?

My basement ceiling joists are exactly 7 feet above the concrete slab. The requirement for finished living space is 7 ft from the finished floor to the finished ceiling. Since I'll loose a couple of ...
11
votes
2answers
6k views

Is joist sag at connection with header a problem?

I am having the ceiling in the finished part of my basement redone, and have it fully open now. I can see the connection of the joists to the headers have given somewhat, as the house is 85 years old ...
10
votes
1answer
3k views

Are there any dangers to sistering a joist with oversize lumber?

I've done some research lately on joist sistering as a solution to bouncy floors. The logic seems to revolve around the following principles. The stress of carrying a load is at the center of the ...
9
votes
1answer
2k views

How do I get to the wall cavity above a double floor joist from below?

I am running some new romex for a couple of electrical outlets. One of the outlets is on one side of a wall in one bedroom and the other outlet is on the other side of the wall in another bedroom. ...
8
votes
4answers
4k views

Floor joists connection to eaves

Apologies if this is a duplicate. I'm attempting to floor my loft space. It currently has 47mm x 75mm ceiling joists, not enough for a floor. I am going to add something like 47mm x 200mm along ...
8
votes
2answers
4k views

Is there a limit to the number of holes bored in a joist?

I already know that a hole bored in a sawn lumber joist cannot be within 2" of any edge or any other notch or hole. And that the hole can only be a maximum of 1/3 the depth of the member (...
8
votes
2answers
1k views

Structurally required? I-beam support under stair opening header

The stair opening into my basement is framed like this: A partition wall (non-load bearing) sits on top of the header. A square duct runs parallel to the header, and on the other side of this duct ...
7
votes
6answers
5k views

How do I remove floorboard nails from joists?

How do I remove floorboard nails from joists? The nails are ~3-4mm diameter with no heads. I've tried claw-hammer and wrecking bar with no success because without nail-heads, I cannot get purchase. ...
7
votes
3answers
6k views

Is it OK to drill vertically through a joist?

I just bought a new house and I'm looking to run some cables. One of the areas I would like to run it to would require drilling through a 2x10 sistered joist. Realizing that going through the joist ...
7
votes
6answers
3k views

Increase size of ceiling joist compromise roof strength?

I am in the middle of renovating my home and discovered a major problem in my livingroom. The room is 20 feet by 20 feet (400 sq ft) and the ceiling is built out of 2x4s spaced 24 inch on center. Each ...
7
votes
1answer
5k views

How should I attach a chin-up bar to floor joists?

I want to mount a chin up bar to engineered I-beam floor joists. Am I safe to mount it directly up into it with lag bolts? If the spacing isn't correct and I span some joists with 2x4s, should I run ...
7
votes
3answers
36k views

What size ceiling joists and rafters should I use for a 14' span?

I'm going to build a single story addition to my home with a width of 14ft. I plan on using ceiling joists every 16" but I'm not sure which size to get. The roof will be asphalt shingles and the attic ...
7
votes
2answers
3k views

How do I measure joist deflection?

I have a 3 story townhouse that was built in 2004. We recently redid the flooring in the top floor, and while we had the subfloor exposed we tried to eliminate the squeaking that we've been hearing by ...
6
votes
2answers
1k views

How to improve wooden joists without removing them

First floor bathroom in a Victorian terrace house. Floor joists run left to right with floorboards laid front to back. Joists are approx 10 foot long. At some point in the past, the previous owner ...
6
votes
1answer
5k views

Is a toilet drain permitted to run through I Joists?

It was suggested by a plumber, but is it common practice? The I joists are 11 7/8" but a 3.5 or 4" toilet drain line seems like a large hole to be cutting even if it's in the middle of the joist's ...
6
votes
1answer
75k views

How do I determine if a wall is load bearing?

I'm considering removing a wall in my master bathroom but I can't tell if it is a load bearing wall or not. I've done a fair amount of research. I don't have the house blueprints, and it's difficult ...
6
votes
1answer
28k views

How can I attach a ledger board to my house?

Spring is here so I finally started to take measurements for materials I will need to build a new deck on my recently constructed home. I just realized that this isn't going to be quite so simple as I ...
6
votes
1answer
2k views

Should I worry about sagging joists?

I have a two story house and some of the joists between the floors are sagging about an inch or two. When I walk around upstairs I can feel the level difference and downstairs you can slightly see the ...
6
votes
1answer
5k views

Do the guidelines for holes in joists apply to band joists?

This question have a great answer with all the guidelines for drilling holes in joists. The question: Are the guidelines the same for band joists? A bit of context: I'd like to add an exterior ...
6
votes
2answers
7k views

What should I do about a hardwood floor that's sagging between the joists?

I recent bought an older (1890) house. On the original floors, the wood flooring is sagging between the joists--you can feel the height difference as you walk, up and down, up and down. It's firm, it'...
6
votes
1answer
6k views

Is there a correct orientation for hurricane clips?

When installing hurricane clips to joists where it crosses a beam, is there a preference to mounting the clips on the inside or the outside of the beam? And should the ears on the clips point inward ...
6
votes
1answer
1k views

How do I fit a joist in this small space?

This is a follow on question from here: Floor joists connection to eaves Since this question, I have been told I need 8" joists for my span and I have exposed my eaves area to see what space I've ...
6
votes
1answer
5k views

What does blocking refer to in relation to floor joists?

This question was triggered by the following line in a home inspection: Blocking is not installed for I joists above beams in basement. I have found pictures of blocking at http://www.diychatroom....
6
votes
1answer
1k views

How to properly seal the transition between basement wall framing and spray-foamed box joists?

We're looking at insulating the box joists of our concrete foundation. We have 2x3" walls framed which are holding batt insulation, which are 3-4" away from the wall (to accommodate a layer of batt ...
5
votes
4answers
557 views

How to install 2x10 joists of slightly different sizes?

We are trying to install the joist hangers and the joists, but the 2x10s are slightly different sizes. The problem is that some of the boards are 9.25" and some are 9.5" and some in between. So if all ...
5
votes
4answers
9k views

How do I repair a floor joist which has a hole drilled less than 2 inches from the bottom?

I have three floor joists that have approximately 1/2 inch hole in them less than 2 inches from the bottom. Is there a recommended fix or approved method to correct this to meet code? These joists ...
5
votes
1answer
795 views

Can I place ventilation ducting on top of joists if there is space?

I'm installing a ceiling-mounted extractor fan above a kitchen island. The problem is with the placement of ventilation ducting in the ceiling: the joists are running in the opposite direction to the ...
5
votes
2answers
4k views

Should I add plywood or OSB between sistered beams?

I'm going to stiffen up my main floor joists by sistering then bridging them. In the past a friend put something in the middle, is that standard? Should I put 1/2" plywood or OSB in between?
5
votes
4answers
6k views

How do I deal with a joist in the way of where I need to run a pipe?

I'm in the process of installing central vac lines (2" OD) in a finished house, and I am trying to run a line into the upstairs hallway. I have removed drywall in the garage below and drilled a hole ...
5
votes
5answers
5k views

Can I cut a hole in a 2“ x 8” joist that is less than 1/3 the height of the joist, leaves at least 2“ above and below the hole, but is 10” wide?

I would like to redirect a 5" air pipe to the other side of a 2" x 8", second story, floor joist so that I can have the vent exit a bathroom vanity kick plate. I realize I cannot just drill a 5" hole ...
5
votes
2answers
6k views

What should I do about this load bearing wall that is only supported by a joist floor?

My floors pitch in the same spots as they do on the 1st and 2nd floors. My home was built in the 1890's. I have some soft spots in the basement joists and added 4x4" posts to each side of the main ...
5
votes
2answers
1k views

Free-standing deck joist layout

I'm trying to plan out a free-standing deck in an irregular-shaped garden. It currently has railway sleepers marking a garden bed around the west, north and east edges and the missus would like to ...
5
votes
5answers
9k views

How to support the subfloor around a toilet between I joists

I'm replacing some rotted subfloor around a toilet, and I want to add blocking around the flange for extra support, and to give me a place to support the new pieces of subfloor (I'm not planning on ...
4
votes
1answer
1k views

Joist re-enforcement instead of sister

So I've got a scenario where I'd like to re-enforce my joists, and I don't currently have the ability or time to sister the entire length of the 12' joists. Now I could remove blocking, insulation, ...
4
votes
2answers
818 views

How do I reinforce the ends of 2x8s that are sistered to 2“x5” (actual size) joists?

I want to strengthen the floor of my office. Currently the joists are 2"x5" (actual size). I want to put a 2"x8" (1.5"x7.5" actual size) which will double the existing joists. I will have to reduce ...
4
votes
1answer
959 views

Do I need blocking between 2x8 joists with an 8-foot span in a kid's fort?

About to embark on a DIY project to build my kids a fort. It will be a deck using 4x4's for legs, holding up a box of 2x8's. Three interior joists for a total of 7 2x8's will make up the frame for the ...
4
votes
2answers
194 views

What to be done about cut I-joists? Cut is in lower flange above load bearing point

I am a first time homebuyer in the due diligence phase with this house. We identified in the crawlspace that a few of the I-joists had been cut, looks like with a reciprocating saw, for unknown ...
4
votes
1answer
10k views

How can I permanently fix a sagging floor?

I have a home I purchased roughly 18 months ago. The house is a traditional 2 story cape code (3BR 1BA) and is structurally very sound and extremely stable. However, on the primary floor of the house,...
3
votes
1answer
1k views

Hurricane ties installed using joist hanger nails top AND bottom. Should I yank them out?

I'm using double sided hurricane ties to secure my joists to my beams for a deck I am building. The tie looks like below: I had been using 1.5" joist hanger nails for the 6 holes at the top that ...
3
votes
2answers
195 views

Joist hangers to use for rough cut 2x8 (2 3/4“ x 8 3/4”)?

I'm looking for the right size joist hangers for my project. I have an old house with rough cut oversized joists and can't seem to find a joist hangers that will work. I'm nailing into a 2x10 ledger. ...
3
votes
1answer
9k views

How can I remove just one tongue-and-groove subfloor board?

I am not talking about laminate planks, but actual subfloor sections. My entire room consists of tongue-and-groove boards. I was under the impression that the point of this was so you didn't have to ...
3
votes
2answers
4k views

How can I hang a heavy bag from this beam in my garage?

I'm renting a house that was built about 10 years ago. The attached, finished garage is under the master bedroom. It has two large beams running across it, see picture. The larger one is 6.5" ...
3
votes
2answers
181 views

Run conduit perpendicular to ceiling joists in garage

I have a sub panel on a finished wall in my garage. I want to add two 20 amp circuits and run them go outlets on two unfinished walls on the sides of the garage. Is it okay to run metal conduit ...
3
votes
1answer
1k views

Why does the maximum deck overhang sometimes decrease with joist spacing?

The deck construction guide for my area contains this table: Look at the "Allowable Overhang" columns. It's odd that a wider joint spacing (24") permits a longer overhang. For example, look at the ...
3
votes
1answer
3k views

Where in the span of a floor joist can I drill holes to run wiring?

How far from the end of a 2x12 or 2x10 floor joist can I drill a hole? NEC 502.8 does not give this answer, only that you have to be 2" above or below the edges, not in what part of the span it has ...
3
votes
3answers
6k views

How to hang a chair from the ceiling joists (with attic access)

I'm planning on hanging a chair from the ceiling. From what I can tell the best method is to add a crosspiece above multiple joists, and mount the chair to that using an eye bolt. The problem with ...