Sister (joists) are doing it for themselves

August 25, 2011 11:27 AM

How hard is it to "sister" floor joists or is it something a reasonably skilled home handy man/woman could do without breaking the bank?

We are looking to buy a 90 year old house and a home inspection has revealed that several of the floor joists in the basement have had foot long lengths removed or have been heavily notched to allow ducting to go through and one of them is starting to split.

The engineer we had come out said that the joists were not super bad but simply needed to have sister joists put on to stop things getting worse. There is only ever so slight uneveness in the floor above in one room, and well within "its an old house" tolerances and the engineer did not think it was a problem so we would not need to jack up or re level anything just put in the sister joists and reroute about a metre of ducting.

The person we are buying from is dithering about getting the repair done as she has over invested in the place and having seen other repairs they have done we worry about the quality of the work. We would like to simply say take x amount from the price and do it ourselves to simplify everything.

We are both reasonably confident at DIY type things, and I have FIL that has built extensions and decks and the engineer is going to include descriptions of just what needs to be done in his report

So basically I am just wanting to know is it as simple it sounds to do (ie glue and screw/bolt joists on either side of the ones that need supporting) and that we haven't missed anything and also we'd like suggestions on what would be a fair discount on the house price allowing for our time and materials.

posted by wwax to home & garden (6 answers total)

Yep, you can do this. Especially if you don't need to jack up the floor since apparently it's not sagging. I have recommended them before, but the Time Life Home Repair and Improvement series' volume on Floors and Stairways covers this exact topic and shows you what to do. You can get it cheap (get the "updated series" with the spiral binding) through eBay or Amazon.

Will you be moving the ductwork or leaving it in place and notching the new joists as well?

(Also, you can put into your contract that you will be involved on all the repairs if you're requesting that they fix XYZ "subject to buyer's final approval" etc.)
posted by resurrexit at 11:35 AM on August 25, 2011

It sounds like you've got a good handle on it -- get the duct out of the way, cut lumber, fasten in place as the engineer specifies. The materials aren't particularly inexpensive. The tools required are nothing unusual.

Are there any pipes or electrical wires bored through the joists near the duct? If so, they will have to be dealt with too, which will make it a bigger job.

My guess is that you're unlikely to get a "fair" discount for this. If the PO were willing to pay a fair price to fix this, she would've already hired someone to do it.
posted by jon1270 at 11:46 AM on August 25, 2011

Resuuexit - We thought we'd just move the ductwork as it really just needs a foot or so added to a down piece to make it fit and we thought that would be easier than notching.
posted by wwax at 11:52 AM on August 25, 2011

That makes it even more DIY-able then. On the duct, make sure not to make the bend too tight if you can help it. Curves, not right angles, etc.

On second read, I see that you do mention a slight unevenness in the room above the joist--you could fix this at the same time as adding the brace if you can rent one (or more) of those steel jack columns.
posted by resurrexit at 12:16 PM on August 25, 2011

Even if your floor is fairly flat it is a good idea to put some tension of the sister with the steel teleposts that resurrexit linked to before you fasten it. Use the post to flatten or slightly crown the floor. Apply construction adhesive where the two joist meet. Bolt the two together (or nail but it is often easier to drill and bolt in a joist space than it is to drive a nail). Wait as instructed for the adhesive to dry and remove the post. Make sure you distribute the pressure on the floor under the post with some cribbing. EG: A 4X4 sitting on a 2X6 sitting on a 2X8.
posted by Mitheral at 1:22 PM on August 25, 2011

Nthing that yeah, you can do this. It's AWESOME to have someone around who's done it before, though, highly recommended.
posted by desuetude at 10:58 PM on August 25, 2011