Tag Archive: house structure

Shipping Container House in Washington DC

Setting First Container

Our latest project is  in Washington, DC at 3305 7th Street NE, near Catholic University.  It’s a four story building made from 18 containers, it will have 8 apartments.  The architect is Travis Price Architects and we are the structural engineers.  The project moved extremely fast, we started design in April 2014 and by the first week of August 2014 the structural part was just about complete.  The media attention has been extensive, here is a link to one of the local newscasts.  We also got front page treatment from the Washington Post.

Structurally I am using the containers to do most of the work, there is very little extra structural steel added.  The biggest hassle was to provide the wind bracing in the basement, I have some massive foundations.  Here’s a couple of pictures:

To lift over neighboring homes and trees, a very large crane was required.

Placing Shipping Containers

 

Here we are setting the first level containers. Note the wrecking bar is being used to pry these into place.

Here is a photo where the container is being lifted into place. If you go through the web, there are more than a few sites that claim a container house is a great DIY project – I hope this shows why that is a bad idea. This takes professionals.

 

Cutting bolt holes with the plasma torch.

The balconies are being fabricated using structural steel and the containers themselves.

The interior is taking shape.

All three levels are up.

 

 

 

At What Point Do You Do Structural Repairs?

A lot of houses I look at have issues with settlement in the foundations and floor slabs.  A lot of times I only recommend cosmetic repairs.  Why is this?  If the house has settled, should you put in piers under your foundations to stabilize it?  Not always, and here’s my rationale:

In many cases I am looking at houses that have been in existence for 20 years or more.  The settlement is often rather minor, and can easily be hidden with simple cosmetic repairs like spackling cracks in the drywall, and filling cracks in exterior mortar.  Let’s say the repairs cost $200.  Usually settlement occurs at its maximum in the first five years or so of the life of the house, from there the settlement never really stops, but proceeds at a much slower rate.  So you would have to do cosmetic repairs on a fairly regular basis – maybe every two years or so.

Generally, it takes at least two foundation piers to repair settlement.  With a budget of about $1,100 a pier, the cost of the repair will be at least $2,200.  How many years will it take for your regular cosmetic repairs to be greater than this cost?  It will take 22 years!  Now with more severe cracking, recent settlement, or if windows and doors are affected, the piers are the best option.  However, in many cases it doesn’t really make economic sense to put out that kind of money.

The other issue is floor slabs.  Often garage slabs are built on soft soil, and they settle over time.  It costs about $6,000 to $8,000 in Atlanta to replace a two car garage floor slab.  If your garage slab has settled about 1/2″ towards the center, and only has minor cracking, do you really want to spend $6,000 to $8,000 for a room that you park your car in and store all your junk?  I wouldn’t.

So, oftentimes I give people the option in my reports – you can do a permanent repair for X amount of dollars and this will happen, or you can cosmetically repair the issue for Y amount of dollars and this other thing will happen.  It often times boils down to economics and personal preferences.

George

In this case, the cracking is probably due to minor settlement. It would require at least three piers to repair ($3,300), or you could reparge the block every couple of years for the cost of a bag of pre-mixed mortar..

Shipping Container House, New Haven, CT – The final product

The shipping container house that we designed in New Haven, Connecticut is now complete. Below is an excellent video that was produced by the builder which shows how the houses turned out. We’re beginning design shortly on the next house in that area, and were hoping the lessons we learned on this one can be applied to lower the costs and make it even better product. In previous posts of expressed a lot of skepticism about the costs of building shipping container houses. However, based on the lessons we’ve learned on this house and as we move forward I believe we can keep the cost down significantly below conventional construction.

The key is to proceed just how we have done. Build a prototype unit see what went wrong.and you are a there is the rare as see what went right and then build again.I’ve seen a lot of projects on the web and been contacted by a lot of people about a lot of projects that proposes very grandiose structures without first working on prototypes. The problem with doing this is there is not a large body of experience available on container housing construction, it’s  till somewhat experimental. So attempting a large project to start without first working out  he bugs and the smaller prototype is a huge  error in my opinion.

So, here is a video showing the house has its constructed and its interior.

Shipping Container House, Connecticut

The Final Product

Here’s some pictures taken by the client for the shipping container house in New Haven, CT. This house was built from six containers, and features a more traditional architecture for the front. This project was built by Marengo Structures, and the designer was Christian Salvati. We worked closely with him to produce the structural design, and the intent of the project was to build an attractive house at an affordable price.  The house was built on a vacant lot in an older neighborhood in New Haven, Connecticut.  The builder wanted to make the house fit well into the architecture of the neighborhood, which consisted of houses built in the 1920’s.  To make a container house do this, you have to cover the containers up to a certain extent, which was done in the front of the structure.  Please see the video to get the best feel for scope and intent of the Project:

 

The front is being furred out to allow a more traditional siding to be placed over it.

 

The house is finally starting to take shape!

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The Final Product

The final product is above.

The video below provides a very good explanation of the house and shows some interesting views of it while it was under construction:

3d for Residential Structural Design

Structural Rendering of Residence From the Side

This is one of my more recent projects, the architect was dencity Design in Atlanta.  It’s a very difficult house – look at the cantilevers:

3d Structure of Residence In Decatur, GA

 

 

 

 

 

 

 

 

 

 

 

 

 

 

This kind of strucutre is difficult to engineer because you have to visualize a very complex 3 shape from a 2 drawing.  To make things easier, the Architect, Staffan Svenson, sent me a rendering done in Google Sketchup so I could visualize what was happening.  I then built a 3 model in RAM Elements software to cover all the different forces we would encounter.  The problem you get is not only vertical forces in a complex structure as this, but the wind action.  How do you brace it?  I used fixed connections to the foundations, which required me to spend time engineering anchor plates, anchor bolts, and very large foundations.  I could do this by hand (and I have) would be very time consuming, and you run the chance of what I call “calculation fatigue” – you do so many calculations you get blind to the errors due to simple mental fatigue.

Here’s a view of the rendering from RAM Elements:

Rendering From Structural Design Program – RAM Elements

 

 

Working this way, I was able to model all of the effects of the structure – note how I put in concrete walls in the basement and OSB (Oriented Strand Board) walls on the first and second floors.  All of this could factor into the design.  Once the structural calculations are done, it’s time to do what the illustrious professors I had as an undergraduate didn’t think was important, but is actually critical – translate it into a drawing that can be understood and constructed.  This is a pet peeve of mine, I run into engineers that can’t seem to understand how to develop their ideas into drawings.  In such case you may as not have any ideas.

I personally had two choices for drawing this, well I guess three:

1.  I could send the drawing out to a CAD service with hand sketches of what I wanted.  We could go back and forth for a week or so until I got what I wanted.  Maybe two weeks.  Well, really four weeks.

2.  I could draw it myself in AutoCAD – there is another type of fatigue you encounter when drawing.  After working so hard to do the calculations, now you are drawing all these boring details, and repetitious joists, and then trying to make it all work.  I could do this drawing in about 40 man hours.

3.  Draw the drawing in Softplan, and use exported details from RAM Elements for the connections, foundations, and baseplates.  RAM Exports details in DXF (Drawing Exchange format), so it’s easy to import into Softplan.  Softplan generates drawings in 3d from your floor plans, and automates a lot of stuff like drawing columns, foundations, walls, and joists.  The beauty is you can have a 3d model that constantly updates as you create your drawing.  That way you can catch things you might overlook.  I was able to make sure I had load bearing walls stacking to the floor, and that I had foundations placed properly under all walls.  Also I was able to show the Architect, Staffan, what I was trying to do.  To do this, I shared the model over GoToMeeting with Staffan, and he did point out a few changes I needed to do.  I modifed the drawing, showed the model to Staffan again on GoToMeeting, and finished it.  It worked out really well.

As you can see, I chose Option 3 above.  My father was an engineer also, and he generally did his own drawings.  He could draw well and very fast, and he said the time it took to explain his ideas to a draftsman (women weren’t in the business in his day), he could the same drawing several times over.  I have the same issue.  I can’t hand draw like my father could, I never had to put the time into it to learn the skill like he had.  However, I’ve taken a lot of courses on AutoCAD, and I think I’m pretty good at drawing on the computer.  I’m also pretty fast, so like my father, it’s not worth it for me to use a CAD person.  I do use my son on many jobs because we’ve worked together enough he knows what I want, but some jobs like this I really feel like only I could do right.

Anyway, the design of this project worked out pretty well.  The next stage is construction.  I hope to intimately involved in the construction.  My contract requires the client to contact me for a minimum of two site visits.  I also explained to the builder that I want to go over everything with him to make sure there are no misunderstandings.  The builder told me he has  a great steel supplier, and he understands how critical this structure is.  I have great hopes for this job, the key to making any job work is close communications between all parties.

Here’s a final view of my model in Softplan:

Structural Rendering of Residence From the Side

 

Shipping Container House, New Haven, Connecticut

Connecticut Container House - Shipping Container Units

This house was designed in the winter of 2010-2011, and is currently under construction.  The containers have been fabricated and will be erected shortly.  Here is a video showing where we are at:

 

 

The house will be two stories, each story will have 3 – 45′ containers.  The containers were modified to have large openings between them and to have a stairway. The foundation is actually a deep crawl space, which we had to do because of site conditions.  The site is a vacant lot where a house was demolished, and there is poor soil to a depth of 5′, so the easiest way was to build an uninhabited basement under the house.

 

 

Second Shipping Container House, Atlanta

These are the first two shipping container houses in Atlanta, the one on the left was the first.  We performed the structural design of both.

These are the first two shipping container houses in Atlanta, the one on the left was the first. We performed the structural design of both.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The second house built of shipping containers in Atlanta was built next to the first one.  The builder was g a d Design, the architect was Francis Kirkpatrick, and we were the structural engineers.  This one was a little bit different from the first in that a balcony was put on the top floor, and there is a completely open floor plan on the top floor.

Click here to see a video:

House Design Project

House Design

This interesting project was for dencity design in Atlanta, GA.  It’s an interesting house with multiple cantilevers.  Here is a rendering of the house:

Rendering of proposed house.

 

 

 

 

 

 

 

 

 

 

The items in red are the steel beams.  Notice we have a cantilever deck on one side, and we are cantilevered over the garage.  This is not an easy thing to design, the beam sizing is hard, the connections are hard, and so are the baseplates and foundations.  To design this, we used Bentley RAM Elements.  Here is the rendering from the software:

This is a rendering for the steel cantilever structure in our structural software.

 

 

 

 

 

 

 

 

 

 

 

 

 

In the analysis process, RAM Elements solved 132 equations.  I could have designed this by hand, but figuring about 15 minutes per solved equation, it would take me 30 hours.  Considering I tried numerous alternatives, triple that number, it would be more like 90 hours.   Since you can’t just sit and solve equations day in and day out, humans did not evolve to do such things, we’re talking about month to do this design by hand.  That’s for an experienced engineer.  Of course the chance of error is extremely high in such a complex undertaking too – typically on projects this complex in the days before computers another engineer would have to be assigned just to go over the calcs done to make sure everything was done right.

What was the biggest hassle?  There is a bit of a gotcha in the way this house is built.  In the first run of calculations, I had all of the deflections (bending) of the beams in accordance with Code, but the end of the house dipped down a couple of inches, which is not a good thing.  What happened was the beam deflected ever so slightly, and so did the columns, and it all added up. So, I had to make the beams and columns really beefy to make sure there was next to no deflection.  The beneficial effect is the floors feel really solid, which is important in a house with this type of architecture.

Here are some of the pictures of the house under construction:

This picture shows the cantilevered deck in the front.

The house is nearing completion – the sheathing is up, and the contractor is putting on the vapor barrier.

Rear of House

This is the rear of the house – the temporary posts are still in place. This part was harder to engineer than the front part oddly enough.

Rounded Windows

View down the left side (from the street) showing the rounded windows.

This is a good view of the second floor cantilever – the floor feels as solid as concrete when you jump on it.

This walkway crosses a two story foyer to get from the front to the rear of the house. It looks different, but actually this was one of the easier things to design.

 

Would Shipping Container Houses be Safer In Tornadoes?

IMG_1697

I’ve been asked this question on my Facebook page, and it is a good question.  I originally wrote about this last spring, and I’m rewriting the post today (October 22, 2011).  The original post said no, but I’m going to change the answer to “yes and no” or let’s say – it depends.

Notice that heavy recliner that was deposited in the middle of the open area

 

 

The first thing I noticed is that tornadoes destroy in their own peculiar way.  I’ve seen buildings that have been destroyed by fire, falling trees, windstorms, and exploding bombs.  Each method of destruction leaves its own footprint.

With a fire, you have the charring of the wood, and the worst damage where the fire started.  Falling trees bash in a building where they hit, but the damage is generally localized.  Windstorms push a building over from one side.  Tornadoes are completely different.  Let me make a list:

1.  They tend to destroy worst about 10′ (2M) above the ground – see the photo above.

2.  They destroy from the outside in, like peeling an apple.

3.  They throw things – look at the debris in the picture above.

4.  The force they generate is phenominal.

Here’s another picture:

The building in the above picture was destroyed by pretty much a direct hit.  I think two people died in the tornado that did this, and while I don’t know exactly where it happened, I suspect it was in this block of buildings – the destruction was too extreme.

The problem with a container house is if you get a direct hit, there isn’t much it can do to protect you.  The debris can penetrate right through the windows and doors.  The force is so extreme it’s likely to destroy the building anyway, because you loose a lot of strength when you cut sections of it out.  You are better off with a safe room or basement (because the damage tends to be above ground, I think basements are the best).

However, what if you are on the outskirts of where the tornado hits?  The steel skin can do a much better job of stopping flying missiles than what is typically used in modern home construction – vinyl siding with thin foam sheathing behind it.  It also is likely to resist the higher winds that will hit it than conventional construction.  The first house we designed in Atlanta was unfortunate enough to be in the same neighborhood hit by the Cabbagetown Tornado.  While other houses around it had roof and siding damage, it had no damage whatsoever – although it was not in the direct path of the tornado.  In a direct hit it would have been destroyed.  However, it has a concrete subwall basement, so the owner would have had a refuge in such case and probably would have survived.

So, to modify my original point – container houses are not an adequate shelter for tornadoes in a direct hit, they can provide significant resistance to damage caused by a tornado that passes close by.

George

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