Surprise in the attic - Please advise

[Raymond Fries]

Went into my attic today and found this:

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Several rafters are cracked. It appears that the floor has sagged and pulled the rafters downward. The rafters are 2 x 6. The vertical 2 x 4 boards are nailed into the boards that make the floor. Three of them have pulled loose. I bought a post jack to push the floor back into place; the area is above the attached garage. I bought some 2 x 4's to replace the vertical boards. Any reason why I cannot apply some glue to the cracks and use some 5" screws in to run into the edge of the 2 x 6's to draw them back together. Think this approach will be strong enough?

Thanks

[Chris Padilla]

I suppose the glue could work but I'd sister some new 2x6s onto the cracked ones with as much length as you can get.

I wonder if some metal tie-plates might help, too?

[daryl moses]

I don't think I would trust glue and screws only for a fix. If you can draw the crack closed I would attach a 2x6 on both sides using lag screws.

[Malcolm McLeod]

Went into my attic today and found this:

Several rafters are cracked. It appears that the floor has sagged and pulled the rafters downward. The rafters are 2 x 6. The vertical 2 x 4 boards are nailed into the boards that make the floor. Three of them have pulled loose. I bought a post jack to push the floor back into place; the area is above the attached garage. I bought some 2 x 4's to replace the vertical boards. Any reason why I cannot apply some glue to the cracks and use some 5" screws in to run into the edge of the 2 x 6's to draw them back together. Think this approach will be strong enough?

Thanks

Level the 'floor' below. Remove the 2x4s (1 at a time). While the 2x4 is detached, sister a 2x6, or better 2x8, on each side of the damaged rafters. New sistered rafters should be supported at both ends by same structure supporting the existing rafters (assume this is the ridge pole and the top plate). Glue & screw thru both sistered rafters and the existing rafter. Re-attach the 2x4. Repeat for the next one, etc.

But big picture, I can't imagine the 2x4 were ever intended to be in tension! Which makes me think the that either the ceiling joists below are undersized - and allowed them to sag. Or, the attic floor is carrying a load it was never intended to carry. ...Are you storing gold bullion up there?

Edit: The existing rafters are compromised and can't reasonably be repaired to their full original strength. The sistered rafters basically need to replace them.

[David Helm]

Just want to reiterate what Malcolm said. When you sister the rafter the sister must go from bearing point to bearing point. If that is not done you will only exacerbate the problem by adding more weight to the split rafter.

[Raymond Fries]

Thanks for all of the good info. I kinda like the idea of the metal plates a little better than the sisterboard just because I think it would look better. Any thoughts on if they would be strong enough if I also ran the screws into the edge of the rafters to keep them from spreading. It appears that there is no sag to the roof and the damage is from the crack down. Not sure if I can get a sister board the full length of the existing rafter in place. Actually, I do not think I can get a board long enough to go from bearing point to bearing point through the pull down attic stairs.
Hmmm. To David's comment, the metal plates would not add any weight.Thoughts?

[Larry Frank]

IMHO....I would not worry about how it looks and worry only about structural integrity. I think you have the beginning of a potential major problem and should be fixed properly before winter and any additional snow load on it.

[Malcolm McLeod]

Raymond,
You have a serious structural issue. A couple of screws and a metal plate (aka band-aid) aren't going to solve the problem.

There may be many ways to address this, but the only way I've personally seen it done is to sister new rafters in place. The old ones are toast, a single new rafter gets you back where you were - and this is the condition that's failed once already. Double them and sleep soundly at night. And tear out the (drywall?) ceiling in the garage if that's what it takes to get the new lumber where it needs to be. It will be money well spent.

Take care,
Malcolm

[Bruce Page]

There are some serious issues going on. You should be talking with an eyes-on structural engineer.

[Ken Fitzgerald]

Raymond,
You have a serious structural issue. A couple of screws and a metal plate (aka band-aid) aren't going to solve the problem.

There may be many ways to address this, but the only way I've personally seen it done is to sister new rafters in place. The old ones are toast, a single new rafter gets you back where you were - and this is the condition that's failed once already. Double them and sleep soundly at night. And tear out the (drywall?) ceiling in the garage if that's what it takes to get the new lumber where it needs to be. It will be money well spent.

Take care,
Malcolm


There are some serious issues going on. You should be talking with an eyes-on structural engineer.

Some pretty sage advice here! Trying to save a penny now, could be terribly expensive in the future!

[Raymond Fries]

Agreed here. Looks like sister boards are the solution. I always just research alternatives.

To get around my problem getting a 14' max 2 x 6 through the space I have available, I had this idea and would like your opinions on this. Could I make a rafter that was joined in the middle with a 1' long half lap joint and assemble it in the attic? Surely that would be strong enough? Do you think?

[Chris Padilla]

I think you'd need someone who is a structural engineer to be able to answer that question definitively. If I found such things in my attic, I'd likely be paying a pro (engineer and perhaps construction) to look at things IF I couldn't 'simply' replace the whole thing and wanted alternatives. Sometimes, as has been said, this could be the tip of the iceberg and that there are other problems going on in your house OR it could be an isolated thing and just a bad piece of lumber...or something. :)

The point is, we can't fully diagnose things here on the good old Forum since we aren't there to see the full picture.

[Wayne Lomman]

Malcolm is exactly right. His advice is good. As far as your idea of half lapping the centre of the rafter, that will only work if you have support at this point. Can you add in an under purlin to support the rafters? It's the sort of job I do in my sleep when I can look at it first hand but yours is a bit far away. A good carpenter will know what to do. Find one who knows the timber framing code. He will be cheaper than an engineer. Cheers

[Lee Schierer]

I agree that you need to get some qualified help to at least show you how to correct the cause of your problem. I think the rafters are just a symptom of what is happening elsewhere in the structure. The fact that the vertical supports have pulled loose would indicate that the ceiling (attic floor) is sagging and possibly the floor below . If this is a multi-level house, it is likely that someone has removed a load bearing wall,or one was omitted when the house was built, on one or more of the lower levels and placed excessive load on the rest of the structure. In this case a poor patch may only make the problem worse.

[Malcolm McLeod]

As far as your idea of half lapping the centre of the rafter, that will only work if you have support at this point. Can you add in an under purlin to support the rafters? ...

^+1

This support for a lap joint in the rafter typically needs a 'strongback' (aka purlin - I believe names for this vary by region). A strongback is usually 2 pieces of 2x nailed to form an "L" and is then run perpendicular to the rafters and supports the mid-point of all the rafter laps - one strongback on each side of a symmetric roof (which yours seems to be in pics). Two or more vertical braces under each strongback then carry any resulting load down into a load bearing wall. The last part of this 'system' is the critical one - transferring any resulting load to the ground as nearly vertically as possible. Sorry, Google images didn't yield a good view.

If your garage roof (and resulting open floor plan below) is framed like 95% of the homes in North America, any lap joints will be too far from a wall to give them enough vertical support.

The sistered rafter's tails don't need to extend into the eaves as originals did. Just cut the lower end with the proper bird's mouth angle to rest on the top plate and match the angle at the ridge. This simplifies getting them in place.

Good luck,
Malcolm
(if it helps - - BSME, GC'd my own house, and have been framing my dad's workshops for yrs.)

http://www.jwkhomeinspections.com/system/files/userfiles/Roof_framing_members_1.jpg
Purlin brace must sit on top of a wall, a post, or a beam designed to carry the load!!

[Patrick McCarthy]

Absent a clear understanding of the cause, you are only addressing the symptoms. . . . and even then, perhaps for the first of several timeS??? Where I live, along the coast, we have Adobe clay soil, which is highly expansive, so things move with the change in soil moisture. I have no idea re soil issues in your area, but the comment about getting a structural engineer to look at it is, IMHO, excellent advice. I would caution against being "penny wise and pound foolish".

Something caused significant stress to cause the damage. Fixing the damage does not address the cause. The cause is your real problem. I will get off my soapbox now. I wish you well with this, and will be curious to learn what you find.

[Karl Andersson]

Raymond,
Those 2x4s are not part of a "normal" structural assembly - it appears that the installer hung the floor below off the rafters by using the 2x4s -like hanging a catwalk from cables. I've done numerous heavy residential carpentry builds/ repairs and I have never seen anything like that offered as a solution to achieve a joist span support - there is probably a bearing beam or similar structural component missing. It may meet some code loophole, but what you're seeing is a result of the someone trying to span too great a distance with too small joists. The deflection must have been several inches and there may be some damage to the floor joists as well, or they may have taken the bow permanently. As some have said, you must have had some heavy load on the floor; if not, then the floor is extremely under-built to deflect that much with just sheetrock on them - I would make sure it's strong enough to support your weight (or add more jacks before going up). T

he 2x4s look like they are lighter than the rafters, so they may have been added after the fact by a homeowner who removed a wall or support beam with columns so they could have more open space in the garage. If you look at the garage floor, you may even see anchor holes or other remnants of a missing wall. I seriously doubt a qualified carpenter installed those 2x4s originally. You could do the repairs yourself if you're confident in your ability to understand span tables and basic carpentry; the difficult repair is the floor sagging - the rafters can be addressed more easily AFTER you fix the floor. There are ways to fix failed rafters/ joists with plywood faces glued and bolted to them (the plywood can be in 8' sections, with joints staggered 2' on each side) - there are online sources for ideas like that if you google "sistered joist", so don't tear up the sheetrock until you have looked at all the possibilities.

Of course, this is a lot of assumption, based on two pictures:)
good luck,
Karl

[Mike Cutler]

There are some serious issues going on. You should be talking with an eyes-on structural engineer.

I couldn't agree more.

Raymond
You really need to find the reason that the rafters are splitting. It could be as a simple as the truss design is incorrect, maybe more.
A "mending plate" can be used ,as with all things, there are rules and codes that apply to their installation. They will be much longer than the area that is split,and being as close to the end as it is, I don't know if it would work. The same goes for a sistered rafter, beam, or joist. They can be used, but there are code requirements. Basically they have to go full length, equal width and thickness, and be supported, if they are carrying the load.
You need a civil guy, as Bruce suggested.

[Brian Tymchak]

Agreed here. Looks like sister boards are the solution. I always just research alternatives.

To get around my problem getting a 14' max 2 x 6 through the space I have available, I had this idea and would like your opinions on this. Could I make a rafter that was joined in the middle with a 1' long half lap joint and assemble it in the attic? Surely that would be strong enough? Do you think?

Without more pictures it's impossible to tell, but can you tear out the soffit (if it exists) and slide boards up into place from below?