skip to main content

The Old House Home Repair Remodeling

help needed with sistering floor joists

3 years ago

We recently had a section of Sill Plate replaced. Now the ends of (4) joists are failing due to moisture rot. I plan to sister new joists. The rot is less than 1 foot on each joist, should I run the entire length (12 feet) with the new joist or is a partial sister adequate?

Comments (14)

millworkman
3 years ago
Pictures would certainly help and I would be a bit concerned that sistering will help being these are the ends of the joists.
Leslie King
Original Author
3 years ago
Two of them
Related Discussions
Partial joist sistering?
Q
Comments (6)
Thanks folks, for the feedback. It's good to hear that I'm on the right track. The contractor who installed the beam in the kitchen below (we had to replace our ceiling, which led us to identify the sag initially) was fairly confident that the sag was due to the couple of cuts made in the joist to run plumbing back in the day. The house was built in the 1920's and the rest of the second floor is level, so hopefully that was cause. It sounds like we should check the spans to be on the safe side. We got a good view of the bottom of the joists during that project, but unfortunately didn't realize we'd need to work on the upstairs floor too - too bad, now we can only work on the joists from one direction, above. What advice do you have about hardware? I don't have a compressor, so I'll be pounding in nails old school. Some of the research I've seen suggests using bolts. Are there pros/cons I should know about when deciding to use nails versus bolts (or a combination?) for this project? Thanks again!
...See More
sistering joists bathroom
Q
Comments (1)
There are metal joist repair plates available but it the joist is cut all the way through you will have to sister or replace them. Here is a link that might be useful: repair plates
...See More
Attic Stairs - Sistering joists?
Q
Comments (8)
I felt like I may be reading too deep into the instructions...my neighbor didn't double up or anything and has had heavier wooden attic stairs in his house (same structure as mine) for 15-20 years with no garage sagging, so I guess there's my proof in the pudding. But, no roof trusses, just joists, rafters, and collar beams. The interior partition should be plenty fine (heh, cardboard...), and I won't be storing very heavy stuff up there. Just the basics like empty suitcases, seasonal clothing, old books & toys, etc. And I'll try & put down the plywood on the other half of the attic or on only the uncut joists, would that help? The 4 cut joists only span 1/2 the attic anyway, there are joists that also run from the other half of the attic, and then both halves overlap (side-by-side) over the single load bearing wall, they are nailed together where they overlap, who knows if this is even correct, but it's the hand I was dealt... So unless I feel adventurous and want to drive home from home depot with 6' of wood sticking out my sunroof, I'll probably just span the 2 interior walls with a 4' 2x6 and call it a day....
...See More
Do you think I need to sister my joists?
Q
Comments (10)
" Is there a danger based on the joist span that I am exceeding my dead load due to the tile, and shower glass, vanity, etc?" I certainly hope not but as Tim45 suggested,call in an engineer if you are still worried. This is a diy place with guys that have btdt and a few pros retired from the trades. Engineers are a funny bunch,they will not tell you a 2x8 will support a butterfly if he land's on it unless they come out and study the situation. Hence you aren't likly to find one here. Most of us fly by the seat of our pants based on experience,rely on common sense and just overbuild it since it only cost's a few dollars in extra material but no labor. An addition I put on my house 12 years ago has an 11" beam glued up on site from 5 layers of 3/4tr" plywood . 19 feet free span supporting fourteen 16'ceiling joists, 9 17' gable roof rafter tails plus one end of a 16' rat run supporting center of ten 2 piece 16' ceiling joists. When I did the beam I looked back collectivly on several engineered beams I had used and seen in the past. If my life depended on it,I couldn't tell you what the engineering specs on that beam are but after 12 years it's still string straight.
...See More
millworkman
3 years ago
Back up a little bit and take the pics again. Trying to see the system not just the rotten areas.
Leslie King
Original Author
3 years ago
Not on site. Each joist spans 12’ over to a main beam.
PRO
Joseph Corlett, LLC
3 years ago
That little bit of rot and mold isn't doing any significant structural damage. Make sure it's abated and forget about it please.
Leslie King
Original Author
3 years ago
Have already sprayed it for mold. House is being sold and wanting to make sure it passes inspection.
Seabornman
3 years ago
You don't need to sister the entire joist. I'd add a 24" piece of joist on both sides of each joist and nail or screw the heck out of it.
PRO
Charles Ross Homes
3 years ago
It appears that the joist has settled somewhat due to the decay. It's not possible to know the extent or effect of the decay, so your safest bet is to sister the joist the full length from plate to girder. Something else might work fine--including doing nothing, but I can tell you from recent experience, if you're planning to sell the home at some point, a home inspector won't likely accept anything other than a full length sistering or a structural engineer's report that an alternative is equivalent.
millworkman
3 years ago
As CRH Homes says and it is easier and cheaper to do it once correctly. You need (8) 12' 2 x 8's and $100 worth of galv bolts. Take the day and do it properly.
Leslie King
Original Author
3 years ago
Are you saying sandwich the original joist????
Seabornman
3 years ago
Yes, if you sandwich the joist you'll double the bearing and you won't encourage the repaired joist to twist. I'd use screws long enough to go almost all the way through all 3 pieces, if you can get a drill driver in between the joists. Structural screws like the GRK fasteners sold at HD would work. It wouldn't hurt to buy a couple of tubes of urethane construction adhesive.
Bruce in Northern Virginia
3 years ago
You might try using these ledger loks, since all inspectors seem to recognize them. and they are code compliant (for ledger board attachment). The instructions say to screw them in with a W-shaped pattern to ensure full attachment. https://www.homedepot.com/p/FastenMaster-3-5-8-in-LedgerLok-Coarse-Steel-Hex-Head-Ledger-Board-Fasteners-50-Pack-FMLL358-50/202268257

Bruce
strategery
3 years ago
I'm curious why the sill plate replacement project did not go further. That must have been expensive.

It's a good idea to sister the entire joist, or if possible, replace it.
PRO
GN Builders L.L.C
3 years ago
last modified: 3 years ago
Did so many repairs like this, existing joist will have to be jacked up to level the floor above and to fit the new joist over the plate since existing sagged a bit, other than that just sister the joist, apply glue along the top and nail into existing and you done. There is no need to sandwich anything like Charles said doing these "2' sandwich repairs" will only raise additional concerns.

Sign Up to Comment

Related Stories

TILE Why Bathroom Floors Need to Move

By By Any Design Ltd.

Want to prevent popped-up tiles and unsightly cracks? Get a grip on the principles of expansion and contraction

HOUSEKEEPING When You Need Real Housekeeping Help

By Becky Harris

Which is scarier, Lifetime's 'Devious Maids' show or that area behind the toilet? If the toilet wins, you'll need these tips

LIFE Decluttering — How to Get the Help You Need

By Alison Hodgson

Don't worry if you can't shed stuff and organize alone; help is at your disposal

KITCHEN DESIGN Design Dilemma: My Kitchen Needs Help!

By KitchenLab Interiors

See how you can update a kitchen with new countertops, light fixtures, paint and hardware

ORGANIZING Get the Organizing Help You Need (Finally!)

By Laura Gaskill

Imagine having your closet whipped into shape by someone else. That’s the power of working with a pro

MY HOUZZ TV My Houzz: Watch Jenna Fischer Renovate Her Sister’s Home

By Mitchell Parker

In this Houzz original video, the actor uses the site to plan a surprise makeover of her sibling’s main living spaces

REMODELING GUIDES Transition Time: How to Connect Tile and Hardwood Floors

By By Any Design Ltd.

Plan ahead to prevent unsightly or unsafe transitions between floor surfaces. Here's what you need to know

MATERIALS What to Ask Before Choosing a Hardwood Floor

By Mitchell Parker

We give you the details on cost, installation, wood varieties and more to help you pick the right hardwood flooring

MY HOUZZ TV My Houzz: Mario Lopez Gives His Sister a Family Fitness Studio

By Mitchell Parker

The TV host and actor uses Houzz to find pros to help build and furnish this garage addition in Texas

8 Ways Dogs Help You Design

By Molly Brandenburg

Need to shake up a room, find a couch or go paperless? Here are some ideas to chew on

Sponsored

More Discussions

Need some assistance with minor repairs on our Gaia SPC flooring

3

Hinge identification help

5

Finding discontinued vinyl plank

9

HELP - Awkward & Small bathroom

10

Bluestar range will not let gas flow to cooktop

1