How to Splice a Joist or Rafter

Without seeing it, it's hard to say but probably splicing it with plywood on both sides would be fine and probably stonger. No need to use screws or bolts. Pepper 8D sinkers on both sides is usually ok. If you want to glue it then that's even better. Most screws are not rated for structural applications as they will tend to snap in half so just use 8D sinkers. Use a palm nailer if the space is tight so the nails go straight in. Good luck to you!

Thank you for your question. As long as there is enough overlap and the two boards act as one you're probably ok. With the glue and the structural fasteners it sounds like you have a good handle on the situation. Good luck.

Thanks for the question, however I can't advise you on that for several reasons. First I really don't have enough info but second it's an engineered product and trusses are not supposed to be cut. If they are cut or broken then an engineer from the truss company has to write up a repair method. You should follow the repair instructions and staple it to the side of the truss in case the repair is questioned in the future. If you don't know who made the trusses then a stuctural engineer could probably do it for you.   However if you had no choice and absolutly had to repair a truss without the advise of an truss engineer, then avoid screws. Most type of screws are not suitable for structural application because the tensile strenth of them is such that they tend to snap in half easily. Use regular framing nails like 8D sinkers. Follow the design that the trusses were originally manufactured in as close as possible. Regular plywood is an excellant gusset material. Hope this helps....

You make some good suggestions.....It's never easy, start with the skilsaw, then then sawsaw, then the oscillating saw is as good a suggestion as I've seen. Maybe some day someone will invent a type of oscillating band saw that cuts a joist clean through from underneath the floor. The idea about cutting the nails with the oscillating saw is a good idea too. That way you can fit the joist tight. If you glue the top edge of the replacement joist with construction adhesive before it is put in place it will help adhere the subfloor to the joist and help prevent a squeak in the floor later on.

Thanks for your question which is actually a good question. When done correctly the splced part is as strong or stronger than the original so where it is spliced shouldn't be a concern unless a concentrated load is expected to be on it (like a hot tub). I have never used the plywood splicing technique in an outdoor environment. In theory at least if treated plywood is used and if it is properly rated,  it could work. However even treated wood is not as good as it used to be 20 years ago. So while it could work I have no proof or experience that it would in an outdoor environment so for that reason I would opt for complete replacement of the joists or a full length sister. The choice is yours however. As a side note don't assume screws are better than nails. Most screws are not rated for structural applications (they're brittle and snap under load). Also avoid rang shank for structural apllications.

There is no advantage to putting a fancy angle on it....just a square cut is fine.....and if you're working in a crawlspace that's probably the only cut that's practical......thanks for reading my article and good luck with your project...

LOL....marriage counseling is beyond the scope of a standard home inspection....however....I think what you need is a board stretcher......look on EBAY....they have everything....

Yep.....You're on the right track.....fill it in and put plywood on both sides...

Thank you for your question. It sounds like your roof is trusses judging from the 2x4 ceiling joist spanning 14'. Trusses are designed for a little bit of light storage and many people just throw a piece of plywood up there so they would have a place for their Christmas tree etc. and be done with it.  If the area is insulated it is not uncommon to build up the floor (ceiling joist of truss) so as not to compress the insulation. Yes adding and properly nailing wood together does strengthen it and splicing that 2x6 would probably be ok. Of course since I can't see your project its had to say for sure what would be acceptable but if you're not storing engine blocks, water heaters or lumber up there you're probably be fine. Hope this helps.....

Thank you for your question....as you know most trusses allow for a little bit of light storage anyway....if you're planning on more then you're have to beef it up so to speak which is what it sounds like you have in mind. My thought is that single ply 2x8's won't span 20'. So if you're splicing two pieces together with plywood it will make a longer piece but the span rating will not be longer than a 2x8 would be rated for normally. A 2x8 spanning 20 foot will sag under it's own weight over time. Alterations to a trusses is generally not allowed but you can nail lumber to the side of trusses already in place. It probably won't improve it's designed rating because that would require an engineer, however it won't make it weaker. Hope this helps....

Thank you for your question. It sounds like you're asking if you can build a beam or joist in place with shorter pieces spliced with plywood.  In most cases yes but remember the built up single member piece will probably not be stonger than a single member full length piece. Probably the best glue to use would be waterproof type elmers wood glue that they sell in one gallon jugs at the hardware store. If you don't have that then construction adhesive will work too. Hope this helps....

I have sucessfully spliced rafters using plywood on both sides glued and nailed many times. If done correctly it does not matter where the splice is...in most cases....If you're going to sister a rafter to make it longer it's probably better to sister it at the top. Of course this is not a blanket statement as there are too many variables involved like the projected load or other bracing for instance. Hope this helps.....Ray

Yes....examples given are typically regular 2x dimential lumber. I'm not sure if steel plates would work, every case is different and there would be too many variables to comment on (thickness of the metal for instance).  They do make a variety of metal connective hardware and you would have to look at the listing on the hardware to see if it is approved for a particular use. Hope this helps...

Thank you for your kind words...In answer to your question....it is heard to give advice on any particular situation without seeing it because what I imagine you're talking about and what you have planned may be two totally different things. In general however regualr framing nails are ok to use like 16D sinkers or 8D sinkers. If using a hanger try using hanger nails. Deck screws are not recommended because they will snap in half under a load. Same is true of rang shank nails. Structural screws are ok (check the listing). Screws can be used to "pull" the wood together and then you can finish it off with nails.....if space is limited you can use a palm nailer. Drive the nails straight (no slanted fasteners). If you're building up a beam from fresh wood three nails on seams and stagger 8 inches on center should be adequate for most situations. If you're sistering damaged wood don't be stingy on the nailing pattern....hope this helps....Ray

Thank you for your question. Properly repairing a TJI joist would require a written detail from the truss company about how it should be done. This is because you are repairing their product. So their engineer should specify exactly how the repair should be made and how many and the type of fasteners to be used. So to recap...their product is an engineered product so it will take an engineered solution to fix it. Could it be fixed through prescriptive means....maybe....Typically we do like to see bearing on both sides of at least an inch and a half. Maybe a ledger could be installed.  But really there are too many variables involved to make a determination sight unseen. You do have some valid concerns however.....Good luck to you...

Thanks for your question. If I understand correctly and I'm not sure from the wording of the question, but it sounds like you want to make a long joist out of shorter pieces or either you're trying to make a laminated beam to support a load. In the old days carpenters would make their own laminated beams with plywood and glue nailed together. This practice fell to the wayside over legal concerns because in reality this aspect would fall under engineering analysis. Even when there is an engineered drawing showing how it is to be built carpenters often do not follow the instruction to the T. The same would be true if you wanted longer joists to cover a certain span. Many lumber companies and Truss manufactures do offer engineered girders etc. and will calculated the beam design to support certain design loads for you. Then they're sell you the correct lam beam or truss for your needs. Anyway I hope this helps.....

Thank you for your kind words and for your inquiry. It sounds like you have a good grasp on what's going on. I couln't be sure about your last question however. I actually like the pvc flashing as long as it's going to be covered up or painted. PVC is resistant to salts which are often found in treated wood. These salts can eat up galvanized and metal flashing. PVC flashing can be bent on a metal break if needed.

So essentially you just need longer members and you want to know if you can splice the wood together with plywood to form a longer unit.....Yes....you can successfully splice 2x8  rafters with 3/4 plywood strips 32" long nailed and glued on both sides in most cases. To me plywood is preferable than sistering with a similar member because plywood is extremely strong in the vertical position and won't crack like real wood. As long as you're not exceeding the original span rating for the lumber you're using you should be fine. Hope this helps....Ray

Thank you for your question....I don't believe there would be any advantage to using carrage bolts. Don't use normal deck or sheetrock screws as they are not rated for structural applications. They now make some structural screws (make sure they are listed and labeled for that use). Typically normal 8D sinkers are good enough. Use a palm nailer if space is limited. Depending on the load above....you might be better off with 32" pieces of plywood. The glue is a good idea.  Hope this helps....Ray

Thank you for reading and that is a good question. I prefer to use plywood rather than OSB because in my tests plywood has proven superior for this use...though my tests are not in any way scientific. As far as plywood grades is concerned any plywood graded for use on roofs  (typically 1/2") or floor (typically 3/4") will work fine. These types of plywood is generally already on the jobsite (at least they used to be before OSB came along). and are easy to work with and relatively cheap. They also have some exterior glue in them which will make them more suitable and durable than interior grades. I would avoid interior grades of plywood.

Thank you for your question....it sounds like you're asking if you can take two pieces of lumber and splice them to act as one without losing strength. The answer is yes in most cases if you use real plywood to splice the two pieces on both sides and nail appropriately. Avoid making the joint in the center 1/3 of the span.  Make sure your joist is straight because once you splice it this way it cannot be repositioned. The splicing material would not have to have bearing if the replacement is the same size as the original lumber. Hope this helps....

Thank you for your question.....I see two problems insufficient nailing and not nearly enough overlap. It should have enough overlap to make the unit act as one.  If the break is in the center of the span it's going to need a lot of overlap to keep it from sagging later. Hope this helps....Ray