16

I am finishing my garage and I have come to the point I need to start drywalling. I ran into a roadblock and would like to get opinions on how to proceed. The roof is a pyramid shaped hip roof and each rafter has a small "notch" where it meets the top plate. It hangs down far enough that it would either require notching out the drywall on the ceiling and wall where they meet. This sounds like a big pain. I was wondering if it would affect the structural integrity by cutting the notch off so that I can get it flush with the ceiling joists, or if there is an easier alternative to notching the drywall. I have circled the "notch" in several photos below that I am referring too.

enter image description here enter image description here enter image description here

Yamaha32088
  • 273
  • 2
  • 6
  • 2
    Whoever did that compromised the load carrying capability of the roof rafter, IMO. Instead of a 2x8 or 2x6, you effectively have a 2x6 or 2x4, depending on the depth of the notch. Where that rafter sits on the top plate of the wall is the highest load point. – SteveSh Jul 06 '22 at 16:39
  • 20
    @SteveSh - I am not a carpenter or framer, but I do know that this is standard practice. – Glen Yates Jul 06 '22 at 17:54
  • 21
    That's an utterly normal/standard birdsmouth. – Ecnerwal Jul 06 '22 at 19:08
  • So it's already 8 feet from your slab floor to the top of the "top plate"? If it weren't for the notches, a sheet of drywall would fit perfectly? –  Jul 07 '22 at 14:04
  • 7
    Two words: *crown molding.* Notch the drywall around it and hide it behind crown molding if you don't want to see them. They are structural, do not remove them. – Chuck Jul 07 '22 at 14:47
  • @SteveSh - what you're saying like like saying cutting a stair stringer compromises the capability of a 2x12. The architect/builder understands the notch will be removed and selects a wider board to account for that. – Chuck Jul 07 '22 at 14:49
  • I agree that notches are cut into lumber all the time, whether for stairs, bird beaks in rafters, etc. But my statement that you are weakening (in this case) the rafter at the place where the shear force is greatest still stands. Like @Chuck said, you can make up for this weakening by using wider piece of lumber. – SteveSh Jul 07 '22 at 15:10
  • 1
    And when trussed roof framing is used, don't the flat bottom of the trusses just sit on top of the double top plates of the wall, with no bird beak? Those trusses are then attached to the top plates with hurricane ties. At least that's the cases with trusses I've seen up close. – SteveSh Jul 08 '22 at 13:08
  • I would say that cutting off the tabs is fine, **IF** you fasten the rafters to the adjacent joists with some substantial screws. – Hot Licks Jul 09 '22 at 02:50
  • @SteveSh Truss design is different, and includes lower tension members to prevent spreading. – Technophile Jul 09 '22 at 05:17
  • I think the point of those bits is to prevent spreading--I certainly wouldn't remove them! – Loren Pechtel Jul 09 '22 at 22:53

4 Answers4

84

Do not remove those. That small bit of wood prevents horizontal sliding of the roof beams, and therefore roof collapse. Those two screws that attach the horizontal beam can't compensate for that if you remove them. Roofs have to deal with dynamic loads (rain, snow, wind) and under those situations they'll need to be able to carry off extra weight.

This is your current situation:

enter image description here

Removing those will have this effect:

enter image description here

Imagine standing over a wide crevice with one foot on each side, flat on the ground. Your feet want to go further sideways, and eventually you'll fall. Now imagine resting your feet against the edges of the crevice. That's far more stable.

MiG
  • 2,370
  • 1
  • 7
  • 20
  • That horizontal beam with the 2 screws in it appears to be acting as a rafter tie – roasthead Jul 06 '22 at 21:10
  • 1
    it's not particularly well secured to the diagonal beam (if it were supposed to transfer load between these two, it would have been secured with a plate and lots of nails/screws). So it will probably only function to keep the vertical posts together (and the roof up combined with those birdsmouths). Removing them, especially in a region that sees heavy snow loads, is a bad idea. – MiG Jul 06 '22 at 21:16
  • 9
    The direction of forces are going to change. It might just crack the beam along the grain and you'll have to rebuild your roof, or witness it cave in. Something tells me just evaluating whether it is safe is already a major engineering construction job and not a DIY anymore. – Nelson Jul 07 '22 at 03:54
  • 5
    I've added some illustrations, maybe this will make it easier to understand. **Please do not remove these things** unless you plan on reinforcing the structure in another way. And if so, please involve an expert! – MiG Jul 07 '22 at 10:12
  • 1
    Your illustration makes it look like the walls are resisting the outward force from the rafters. That's never going to work - the walls will bow outwards without something tying them together. The horizontal joist would do that job - but from the OP's pics it looks to me as though the joist is attached to the rafter, and the rafter is then attached to the top-plate (with some diagonal nails). I don't see any direct attachment from the joist to the top-plate anywhere. So to me in this design it appears that the outwards force is only being counteracted by the joists screwed to the rafters. – brhans Jul 07 '22 at 13:17
  • That being said I would still not remove the notches and would instead use some 2x furring strips on the joists to lower the ceiling. – brhans Jul 07 '22 at 13:18
  • 4
    The walls are held together by that horizontal beam. One alternative would be to strengthen that connection, then you have a triangle leaning on the walls. This does not appear to be the case right now, there's the outward force from the rafters and separately there's the beam holding the walls together. That would mean the roof's gonna sag and under heavy (possibly even a moderate) load, collapse. – MiG Jul 07 '22 at 13:19
  • 1
    I would consider those notches (which will be at regular intervals) to be a nice architectural feature tbh, you could even paint them a different colour (like black). Otherwise you'd have a slightly lower ceiling and a featureless white rectangular box as a space. – MiG Jul 07 '22 at 13:22
  • Sure - the walls are *ultimately* held together by the horizontal joist - but I don't see any nails or screws attaching the joist directly to the walls. The joist is attached to the rafters, and the rafters are then attached to the walls. It's the horizontal joist which prevents the rafters from falling down (and pushing the walls apart), not the notches in the rafters. The only way there's going to be any outwards pressure from the notches onto the wall is if the horizontal joist has already failed - the roof beams together make a stable triangle independently of the walls. – brhans Jul 07 '22 at 18:14
  • I'd rather not bet on two screws considering the asker lives in Chicago. – MiG Jul 07 '22 at 19:21
  • You said "Do not remove those. That small bit of wood prevents horizontal sliding of the roof beams, and therefore roof collapse". There are other ways to accomplish that same thing without weakening the rafter. Nowadays hurricane ties are the preferred method. – SteveSh Jul 08 '22 at 13:09
  • i think the last diagram would be most illustrative if you showed the top two pieces flat and not connected. – Trevor Boyd Smith Jul 08 '22 at 13:30
13

It isn't a big pain. You plasterboard up the walls to the bottom of the bits you want to cut off (Don't). You plasterboard the ceiling till you reach the same bits. You put strips along that slanting line rather like coving would go. Not much more, if any, cutting to do at the end of it all. And, it'll look quite classy!

Those bits are an integral part of roof strength, better than the nails that hold it all together, so shouldn't be removed. Don't forget all the insulation bats.

Tim
  • 4,905
  • 11
  • 28
8

You would lose a bit of strength. I would recommend checking to ensure all rafters are secured to the top plate and to the horizontal members spanning the proposed ceiling. Given the snow load you would experience in Chicago (if you profile is correct), you need more nails and, I would recommend, ties if you try to go that route, but I do not recommend it.

I recommend furring the ceiling with 2x2s (or 2x3 laid flat for extra room to screw into) on the horizontal members and attaching the ceiling to that. You lose 1.5" of head height.

If that is a problem. Stain/paint the birdsmouth and drywall around it; that would make a nice visual in my opinion.

UnhandledExcepSean
  • 6,625
  • 5
  • 31
  • 38
  • How do you lose 1.5" of head height when you put 2" + plasterboard underneath? Best part of 3" I think. – Tim Jul 09 '22 at 08:39
  • @Tim, you would lose the drywall height either way so that I did not count that. a 2x2 or 2x3 is 1.5" thick. Google "us dimensional lumber sizes" – UnhandledExcepSean Jul 12 '22 at 13:04
  • Bit like in UK - 2" is 2" rough cut, but still called 2" when sold planed, when it's closer to 1 5/8". But why waste by using planed wood that's going to be covered anyway? Can't think of any reason! – Tim Jul 12 '22 at 13:09
  • @Tim rough cut lumber is not widely available; if you walk into any home improvement stores here, almost all lumber will be dimensional and not rough cut. – UnhandledExcepSean Jul 12 '22 at 13:15
  • But still inaccurately named?? Call a spade a spade over here! Still not true. – Tim Jul 12 '22 at 13:17
  • @Tim The board's tags normally show the true size. Like most things that don't make sense, it arises from simplicity and tradition. And everyone working in the trades understands when someone says a 2x4 that they are getting a 1.5"x3.5" board. – UnhandledExcepSean Jul 12 '22 at 13:25
  • Yes, that's true. I come from the days when a rough cut (readily available then) waas what it said on the tin. Compounded now by metric measure, which seems to affect all timber, and a lot of other commodities too. Gallon >5litres, although that's probably a different gallon from yours! But we digress somewhat. – Tim Jul 12 '22 at 13:34
0

with regard to the birdsmouth drywalling ceiling problem; I think that a ceiling framework with 2x4s or 2x6 at the recommended inches apart be installed below the obstructing pieces and then apply the drywall ceiling to that frame.

Frank O'Donnell
  • 55
  • 2