Sunroom/Three Season Room Shear Wall Design?

[Socko525]

Hello all!
I'm in the process of building what started out as a screened porch and is seemingly shifting more towards a 3 season room. I wasn't originally worried about shear walls when it would all be screened in, but the client is looking to possibly add 4 track vertical patio windows (the vinyl memory film kind).

For a little background, the job is in Orange County, New York (so no major wind or seismic issues). The overall space is 16'x36'. The walls will be 2x6, with a 3' high knee wall around the entire perimeter. I plan to install 7/16" Zip system on the outside as well. The roof is going to be lean-to style standing seam metal.

The plans I have call for a 4'x4' shear wall at the outside corners, but the client isn't happy at how of the view would be blocked.

I've seen a lot of screened in porches converted to 3 season rooms or even sunrooms and they don't seem to go through the effort of building shear walls (though I wonder if that's because most of those conversions are smaller than this space).

So I'm trying to find a way to avoid or adjust the shear wall. I was thinking of adding diagonal lateral blocking within the knee wall for the entire perimeter. I also entertained adding 7/16" Zip system to the inside of the kneel wall as well and then covering it with wainscoting.

If I could lessen the shear wall to 2' or maybe even 3' that might work. Or perhaps add a decorative small window within the shear wall I think that would work.

I'm not sure what other information you'd need, but any thoughts, feedback or alternatives would be appreciated!

 

[ChorasDen]

Have you considered Simpson Strong Walls? Either the wood or steel types? Come as narrow as 12in and can be stacked up as doubles if needed. I've used them in the past for portal framing around garage doors, may be what you need for this situation?

https://embed.widencdn.net/pdf/plus/ssttoolbox/bs4wkbxyal/C-L-SW21-p12-16.pdf

 

[alt0]

Agreed... Simpson Strongwalls are the way. Or steel cantilever columns at the corners if you can get em to calc out.

 

[Socko525]

Have you considered Simpson Strong Walls? Either the wood or steel types? Come as narrow as 12in and can be stacked up as doubles if needed. I've used them in the past for portal framing around garage doors, may be what you need for this situation?

https://embed.widencdn.net/pdf/plus/ssttoolbox/bs4...

So I recently learned about them, but everything I've seen has them mounted into a concrete foundation. Given that I'm on piers I didn't know if they'd work. Could they be used with something like a Simpsom holddown run through the beam/joists?

 

[phamENG]

Best bet would be to call one of their reps - they have teams of engineers specializing in the applications of their products. If I remember correctly, they have a plate system that can be used to tie it into the beam below.

 

[Socko525]

I'll reach out to Simpson and see what they say. I also was looking at my plans, and saw this was the wind/seismic load calculations, for what it's worth. If my understanding is correct, the windload I'm trying to match is a V of 115, and Shear Walls are set at something like a V of 715, so looks like Shear Walls may be the way to go.

6GB

 

[ChorasDen]

What is your relationship to this job, are you acting as the EOR, or are you builder representing the client?

Basic wind speeds at 3-second gusts are the basis for developing design wind pressures and thus, diaphragm loads within the structural LFRS. Offhand, a value of V at 715 wind speed for importance factor of 1.0 doesn't make much sense, but then again, I am in seismic country, @pham, maybe this means something to you?

 

[Socko525]

What is your relationship to this job, are you acting as the EOR, or are you builder representing the client?

Basic wind speeds at 3-second gusts are the basis for developing design wind pressures and thus, diaphragm loads within the structural LFRS. Offhand, a value of V at 715 wind speed for importance factor of 1.0 doesn't make much sense, but then again, I am in seismic country, @pham, maybe this means something to you?

The builder. The client hired the engineer off of Upwork, and it seems the engineer sent them the stamped plans and then after reviewing the client is questioning some of the decisions. Although the design engineer seems to not be responding to questions or revisions anymore.

From what I've built and seen in the past, it does appear a little overkill the more I dig into the plans. I.e. everything is 5/8" through bolts instead of lags or structural screws, at point it was like 36" sonotubes and 2x14s for roof joists.

 

[phamENG]

The client hired the engineer off of Upwork

Of course they did.

V at 715 wind speed for importance factor of 1.0 doesn't make much sense

Sure doesn't. The 115 is the 3-second gust wind speed, so it's 115mph. Not a load per se, but the speed of a gust of wind you have to use (in conjunction with lots of other site dependent information) to figure out the pressure in pounds per square foot that the wind actually applies to the structure. The worst tornado shelters are designed for V=250mph...so 715mph would be bonkers.

Simpson's shear walls are not rated for a particular wind speed. They are rated for a particular base shear. If the engineer the owner hired is not responding anymore, then you may want to turn to a reputable company and have them provide you with a solution. Which may be a good idea anyway...I don't see a competent load path for those lateral loads as it is...you can put the strongest shear walls in the world in there but if you get a good wind blowing over the existing house, it could suck that sunroom right off its foundations...

 

[ChorasDen]

The client hired the engineer off of Upwork

Wow, I didn't even know someone could do that, I assume it's basically like fiverr? I'm with Pham on this one, I would be concerned with the quality and ownership of the design from a source like Upwork. I don't see the end rafter detail on the snippets you provided, but curious what is intended to resist uplift at the roof level? 15psf dead load likely isn't sufficient at the sunroom corners.

 

[Socko525]

The worst tornado shelters are designed for V=250mph...so 715mph would be bonkers.

That ones on me for not understanding, I think I misread some of the simpson literature I found with regards to attaching to a wooden beam and was confusing the allowable shear number.

I don't see the end rafter detail on the snippets you provided, but curious what is intended to resist uplift at the roof level? 15psf dead load likely isn't sufficient at the sunroom corners

I believe this is what you're asking for

 

[Enable]

As a contractor I would be very concerned about payment if my client was the kind to hire freelance engineers off of Upwork. Residential customarily has the builder paid before work is completed (at least around these parts), which helps. Just make sure you enforce that on this one.

Back to the design aspect of things. If you have a design engineer who is not responding, and changes need to be made, you need a new engineer. You would also probably want a local engineer with a good reputation. The cost of a redesign now will probably save money in the long run for the client, and certainly will help you as a builder since competent plans are always better to construct from (so faster turnaround - good way to sell the client on it).

 

[Socko525]

So I'm curious about something, and I'd love to get your opinions as engineer's. In an attempt to try and save the client some money on having to order an entire set of plans, would it be reasonable to ask a reputable firm to analyze the plans that already exist and provide feedback on it?

Basically asking for a rate to review the plans and highlighting the areas I have questions about. Then based on that feedback, ask for a rate on re-designing those areas. I'm not sure the mentality on reviewing another engineers plans/designs.

 

[Enable]

In these circumstances having another engineer review another engineer's work is likely going to be more costly than just commissioning another engineer to furnish a new design. First, out of professional ethics and duty to public safety the reviewing engineer has to review the entire scope (not just what you ask them to look at); in so doing they must infer the logic from someone they can't speak to, which takes time and isn't always a fruitful exercise (i.e. structural logic isn't there or cant be readily identified). Second, even if the logic checks out there are legitimate differences in opinion about details and items of concern, and you are liable to find the reviewing engineer wanting to do it their way. Third, a reputable firm will probably tell you it will be cheaper to design / draw it from scratch before they get into it and if they don't, they are probably not reputable.

 

[phamENG]

I'm with Enable on this. If I look at it and start making changes, I own the whole design.

I've been on the other side of this. I designed an addition to a house, but the contractor went rogue and made changes to the foundation. Not little ones. Changes that fundamentally altered the structure of the building while also violating the building code. They had another engineer who decided what they did was okay based on their opinion despite the fact that I could point to specific clauses in the building code that set minimum requirements that I was able to clearly demonstrate the new conditions didn't satisfy. In the end I gave in...sort of. I told them to go ahead and do it their engineer's way...but only if their engineer was willing to take responsibility for the entire project as Engineer of Record. After all, a foundation failure is a failure of the whole building. On the scale we're talking about, removing the building to replace the foundation is cheaper than some sort of shoring and underpinning. They stopped calling me about approving the change after that.

It is, unfortunately, normal in residential construction for different engineers to do different parts of the structure. One engineer designs the foundation, another designs the trusses, somebody else might design braced or shear walls, and nobody in particular sizes the walls/headers...probably just pulls them from a table. It works for the most part in a lot of places. But it's inefficient and can result in an unsafe structure. All of those parts are interconnected, and without a competent person overseeing those interconnections and how they work together (or don't), you can run into problems. That's why I insist on being the EOR on residential projects. If I don't have the authority to set minimum specifications and make decisions for delegated items (like trusses), I don't want my name on that building at all.

 

[jhnblgr]

Is the engineer licensed in NY? You can look up on NY office of profession’s website. I have found in NY that towns don’t verify this. Lost a job to a NJ engineer and found out he was not licensed in NY.

This structure really should have a frost wall. People think piers are a good idea but long term it will likely have issues.

A steel column designed to take the lateral load and foundation designed to resist the moment.

2/12 pitch I think will void any warranty on the roofing

 

[TORCHMAN]

Quick question: Based on the aspect ratio of width to length, do you even need shear walls? A rule of thumb is that if width>1.5*length then you may be able to design the roof connection as taking on all the load and so long as the wall has a strong enough shear wall, you may be okay.

Just a thought

 

[phamENG]

TORCHMAN - that may be, but then you'd have to confirm that the existing house can take it. If the owner hired the engineer to draw this up from Upwork, I doubt they ever set foot in the house. Easier to just design it as fully self supporting. Not more efficient or better for the owner, but certainly easier.