Wood Building with Parapet - Sloped (2) 2x6 Top Plate / Chord at Side Walls 1

[ThorenO2]

Hello, I am working on a restaurant with a flat roof (1/4" per ft.) that slopes front to back. At the front/rear, the parapet is currently detailed in a platform manner with a continuous sill plate, vert studs, and kickers @ 32" o.c. My question is for the side walls parallel to the sloped trusses. Is it too difficult to have the contractor slope the top plate to align with the trusses and extend the roof sheathing over top, where you can install the parapet in the same manner as the front? It seems that a ledger setup would be good here with balloon framing, but it'll require some detailing (LVLs, SDS screws, clips, blocking, etc.) This may be end up being more complex to install than the sloped (2) 2x6s - save for at the side walls they'd have to stagger the cuts again for the parapet studs. So pros and cons. Were the parapet to cantilever a reasonable height, balloon framing and the ledger would work best, except that in this case the parapet studs still need kickers, which adds merit to the platform construction matching the front. I appreciate any input on detailing this. Thanks,

 

[phamENG]

I would avoid the sloped platform because every single stud will be cut to a different length. If they're all the same, it's a lot easier and a lot faster. Depending on your location and the size of the project, the carpenter may be able to order all of his studs precut, which saves quite a bit on build time. That's a lot harder to manage if each stud is 0.3325" shorter than the one before it. I don't think it's all that complex. What is your truss spacing? A ledger fastened to the studs to catch the edge of the roof deck won't be that bad. And it'll probably be easier to get the slop on that just right than it would be to get the wall slope just so.

Now if the studs end up being too long to make it happen, then platform might not be a terrible idea.

 

[dik]

DELETED... I misunderstood the question...

Dik

 

[KootK]

You might have the truss supplier make the trusses with 1/4" pitch on the top chord and a level bottom chord. Sit a matching gable end truss over the end walls. This will allow the use of level wall top plates and platform construction.

 

[jayrod12]

You might have the truss supplier make the trusses with 1/4" pitch on the top chord and a level bottom chord. Sit a matching gable end truss over the end walls. This will allow the use of level wall top plates and platform construction.

This.

Make sure you pay attention to lateral stability at the junction of the top of wall stud and underside of gable truss. Might need additional bracing etc.

 

[phamENG]

KootK's suggesting is a good one. Is your parapet uniform height along the side, or does it slope with the roof? If it slopes, then go with KootK's suggestion. If it's a uniform elevation, I'd still be hesitant to do it for the same reasons stated above.

 

[KootK]

If it's a uniform elevation, I'd still be hesitant to do it for the same reasons stated above.

With the right direction from the team, a truss supplier could make short work of that too. A commonly fabricated element in a truss shop is the "ladders" used to frame overhangs over top of dropped gable end trusses. And, sometimes, those ladders are variable width for use in prow roofs which makes them pretty much identical to what you'd need here for a variable height parapet wall. Maybe fab them in 8' lengths and nail the mated verticals together on site.

 

[phamENG]

Are you suggesting having the truss fabricator fabricate the parapet? That's a pretty neat idea. Haven't heard of anyone doing it, but it makes sense.

I did notice a lot people throwing around the term "gable" earlier, and both of KootK's pictures are of gable end walls - we are talking about a low, mono-slope roof with parapets, right? Wouldn't be the first time I completely missed the mark...

 

[KootK]

Are you suggesting having the truss fabricator fabricate the parapet?

Yesir.

...we are talking about a low, mono-slope roof with parapets, right?

Yup, were all in synch. "Gable" was just a way for me to convey "last truss over end wall" in a way that I'd hoped other folks familiar with the technology would understand without a sketch.

 

[phamENG]

Ok, thanks for clarifying.

Added bonus for the truss fabricator - cut the "ladder rungs" to be the right height from top plate of wall to top of parapet, then cut them at the varied lengths. The off cuts from the end ladder truss would work as the studs for the parapet.

 

[ThorenO2]

Thank you for the replies, everyone. I think with the height of the building and since the parapet jogs up & down, balloon framing with the ledger system would wind up with 22-24' 2x6s in places, which are problematic. I believe the platform construction with the 0.333" staggered cuts is a feasible way of going about this and only a bit of a pain. The owner won't be surprised and it'll match his prototype set. I'll be happy the top chord stays uninterrupted and there won't be any out of plane issues. Going to see how this works out without having the architect (which would be a real pain) and myself both change multiple sections for a ledger setup or endwall truss, which is also a good idea. I also like the idea of the truss supplier creating the parapet, but in this case since it is very irregular with projections and the like, I believe it'll be easier to stick build. Thanks again for the conversation. Will use these ideas going forward.

 

[radiocontrolhead]

What about rip strips to build your slope? Does this not work?