Bag End: A Passive House. Huh?

Thanks for stopping by. Just a few short comments this week.

If you read the bar title “From Hobbit  Shed to Hobbit House” you would have come across a sentence or two mentioning that a Hobbit House would be considered an earth sheltered passive house.  An earth sheltered home is obviously a home with some form of soil as its cover. There are a wide range of what some would call an earth sheltered home. There are also quite a few products that architects use to call the roofs on their structures “Green”. So I think we can all agree that  Bag End would be an earth sheltered home.

Calling a home a passive house is another thing altogther. The passive house standard is, in my opinion, the state of the art in building technology. It is a construction standard that was developed by a German physicist named Wolfgang Feist in the 1990’s and is just catching on in the US today. In order to claim that your house is a passive house the home must meet certain requirements. If it meets these requirements then it can be passive house certified by the Passive House Institute. I will be trying to meet these requirements as I build Hobbit Hollow.

I’m not going to get into the nuts and bolts of the requirements but basically a passive house has these attributes: 1.Low air infiltration. 2. Super insulation 3. Triple glazed high performance windows and exterior doors. 4. Energy recovery ventilation. 5.Elimination of thermal bridges.

These items when combined together properly will result in a home that uses 90 percent less energy than a new typical home built today. That is probably hard to believe but it is true.  This is what we are going for with this project. I am very excited about getting started.

As we go along on this project I will delve into each of these attributes from time to time.

This past week I had the opportunity to attend a conference sponsored by the Journal of Light Construction. It was called JLC Live and was held in Providence, Rhode Island. The session I went to was about building to the Passive House Standard and was given by a guy named Chris Corson. He built a passive house in Maine and is currently working on a few others. The Maine house was featured in The Journal of Light  Construction last year in the May and June issues. It was very helpful for me to hear a guy like Chris speak about the nuts and bolts of passive house construction. Without getting too technical I have always felt that this Hobbit  House we will be building will be an excellent fit for a passive house. We will see!

Just a quick update. My building permit was approved this past week and the electric utilitycompany connected my meter. I hope to lay out the footings next weekend! Of course I picked up the DVD of “The Hobbit”  Friday at Best Buy.  Whoever designed Bag End is a genius. I mean, who wouldn’t want to live in a house like that?

To the free folk of Middle Earth enjoy your week!

Jim

 

Do Hobbit Houses have underground electric?

Hello again Hobbit Hollow fans. Todays topic: Getting power to a Hobbit house.

Remember the house that was standing on the property before we demo-ed it. That actually had electrical lines running to it from across the street.  Part of the demo process was to call the electric company and have them disconnect the overhead wires. These wires went from the road over the stream and were attached to the second story of the house. This is pretty typical of most homes.

House before demolition. Electric wires are on the upper left.
House before demolition. Electric wires are on the upper left.

Once the power was cut and the lines removed the problem was how to get power back to the property and into the new  house. I knew that the electric was going to have to go underground. The Hobbit house I am going to build is only going to be about eleven feet high. Running an overhead line to the house itself was not going to work.  The Hobbit house does not have an exposed side to attach wires to. Even if it did I would have to run a pole right beside the house and I didn’t think that would look good. Across the street stood the pole that the original house wires were attached too. I just figured I would have to add a pole in the general vicinity of where the original line came onto the property.

I met with an electrician on the site. I figured it might be a good idea to get some input into how much this is going to cost and if there is anything else  (i.e. permits, fees, etc.)  that I need to do before calling the electric company again. The guy I met with was great. His original idea was to run conduit under the stream from the pole on the street side right to the new house. As soon as he said that I was like: forget about that idea. This is a trout spawning stream in the state of New York. You want me to get locked up for killing all the baby trout in the state???? What is this guy, some kind of a wise guy? (For those of you who are unfamiliar with what a wise guy is watch the movie Good Fellas.) His next question was- OK but why do you want to put the new pole on the property in this location? Why not put it in the back and put a temporary service on it. This way the pole won’t be in the middle of your back  yard and you can trench the final service from the pole into the house later. You can also get temporary power and not have to use a generator for power during the construction phase. The Lord works in mysterious ways! What great ideas! I got a price from him.

This is the stream the power lines have to go over. If you look closely you can see the telephone pole on the right.
This is the stream the power lines have to go over. If you look closely you can see the street side telephone pole on the right.

After this meeting I got a few more prices and got quite a range in price. I forget the details but for some reason I was not able to have anyone do this work right away.I think the bridge wasn’t done and everyone said the truck to install the pole was to heavy for the wood bridge. Anyway, by the time I had the bridge done everyone was busy or didn’t return my calls. What’s up with these guys?

I go to the bank one day and I see a guy who’s got an electrician sign on the side of his truck. I ask him if he installs telephone poles and does service entrances. He says no but gives me a number for a guy who specializes in pole installation. I was like this is great. I call the guy up and he winds up giving me the best price for pole installation and I schedule him to come out and do the work. I finally have a pole!

I again try getting an electrician to come out and install a meter on the pole but have no luck. It is then that I remember my father. My father passed away a few years ago and he was the one who taught me how to wire houses. He wasn’t an electrician but he built and wired his own home way back when in the late sixties and was a real student of whatever he was working on. I built a few houses and renovated a few others over the years and he always was really into doing the electrical work. He really liked to do the service entrance the most and this would have been right up his alley. How could I not do it myself?

The big issue here is that you have to get an inspection for the service and have it approved by the fire underwriter before the electric company will hook you  up to the grid. So I have a pole, now the challenge was how do I mount the meter on the pole and run the conduit up 25 feet  to the top of the pole? There is no way you can use a ladder to do this. So I needed to set up a scaffold. I had some old scaffold at my house and had my sons help me put it up and secure it. I used 2X4s and what they call nailing cups to tie the scaffold to the pole. Once you have scaffold over 12 feet high it becomes unstable and can fall over if it is not securely braced. This scaffold was about 25 feet high. I used screws on the bottom to level the system up before I started. Here is a picture of the scaffold with the meter and conduit ready for inspection. The box below the meter is a 100 amp temporary service with 2 outlet boxes beneath it.

Electrical pole installed with working  scaffold in place.
Electrical pole installed with working scaffold in place.

 The wires that are used have to be resistant to sunlight because  when they are connected to the overhead wires they will be outside of the 2 inch conduit running up the pole. Another item that is critical is the grounding rods that have to be installed. The grounding system consists of two half inch diameter copper rods 8 feet long that have to be driven  straight down into the soil about 6 feet apart. I thought for sure we were going to have trouble doing this, there’s rock everywhere on this property. We took turns. I held the rod and my son used a 10 pound sledge hammer to drive the rods into the dirt. Then we would switch. It took us about 20 minutes or so. There was only one time I think we hit a rock but we were able to bust through it.  Here’s a close up of the grounding system.

Grounding system for the electrical service.
Grounding system for the electrical service. You can see the grounding rod attached to the green wires on the left.

Another very important part of the installation is to label the wires coming into the meter. There are two “hot legs” and one neutral. The neutral wire has to be marked with white electrical tape inside the meter and at the top of the mast where it comes out of the weather head. If you don’t do this the inspecter will fail the installation. Here’s a picture of the wires coming into the meter.  

Meter wired and ready for inspection.
Meter wired and ready for inspection.

 This was all about two and a half days work for me. I learned a lot and passed inspection. I should get hooked up to the grid within the next two weeks

My father would have been proud. I thought of him a lot while I did this work. I miss him.

I talked to the building inspector this past week, also. He said he should be done going through the house plans by the end of the week. Hopefully we will be issued a building permit by Friday.

And what is the matter with those New York Knicks? Maybe we need to write to the new Pope for some help on the court.

Best wishes, Jim

Building a Hobbit House: More than meets the eye or the eye of Sauron.

To the free folk of Middle Earth: Thank God the winter is almost over!

Hobbit shed in winter.
Hobbit shed in winter.

March is finally here and I can see the light at the end of the tunnel. I keep thinking of the time in Moria when Gandalf didn’t know which way to go. He restarted his journey with the Fellowship following his nose. The air seemed different in a certain direction. Sometimes during the winter months I get a little lost, if you will, but once March comes around I can see the light or smell the change of the new season coming. This particular winter wasn’t such a bad one for me though. But I digress.

I turned to a new page on my Hobbit calendar. It  is the classic one inside of Bag End looking out of the front door, I believe by John Howe. This picture was one they tried to replicate in the movie and is remarkable for its architectural beauty.

Hobbit houses are beautiful but the fascinating thing about them is what you don’t see. There is much more to a Hobbit house than meets the eye . The engineering that goes into it is significant and was much more of a challenge than I had anticipated. The passive house aspects of the design created a different set of challenges to the structure that I usually mulled over on my commute to my job in the city every day. I came up with some great ideas while heading to work. Lets just stick with the structure today.

The structure. The Hobbit house I will be making is essentially an arched highway overpass. I wanted to make the span 32 feet across and about 46 feet deep. Now instead of cars going over this bridge we have dirt and snow. These loads are substantial. Soil weighs in at about 109 pounds per square foot (psf),concrete is 150 psf and the snow load I used was 70psf. I wanted to use a 9 inch concrete slab. When you add the numbers up you are talking about a structure that has to support almost 300 psf. That equates to a vertical load of almost 440,000 pounds!  I don’t want to get too technical here but on a regular house the roof system is basically a triangle on top of two outside vertical walls.The vertical weight of the  roof and the snow load come down on the roof  and try to “flatten” it out,pushing the two outer walls away from each other. This force is resisted by the bottom chord of the triangle which are usually in the form of ceiling joists or collar ties. I did not want any collar ties in my Hobbit house. What I did was create a series of concrete buttress along the walls to resist the lateral force pushing the walls out. (You see buttresses on the outside walls of churches and cathedrals a lot) I  also made  the footings four feet wide to spread the vertical load on the soil. I wanted to keep the soil load under 3000 psf.

Here in New York you need a stamped set of drawings either by  a professional engineer or architect in order to get a building permit. So I took my set of design drawings that I had completed and brought them to an engineer. There aren’t a lot of engineers out there and there aren’t a lot of Hobbit houses out there either. Their proposal was twofold. One , analyze the structure and see if it is safe. If that all checks out: redraw my design drawings and make any necessary changes to meet code.

Sort of as a side note. In my head I was always thinking that this type of house would be something that would last forever. Did you notice the house I demoed in the last post. Six years after the owner’s passing the house was ready to fall apart. I wanted to over design my hobbit  house structurally so it would last 1000 years.  That is one of the reasons why I chose heavier than needed snow and soil loads.

So I met with the design team and went over what I was doing and what my thought process was and how I came up with the design. One of the things that I didn’t really figure on was that this was going to be “their” design. In other words if the structure fails they will be liable. Which kind of gets back to what I said before about over designing the structure.

A few weeks after this meeting I got a call from the engineer working on it saying I should come in and that he didn’t think the structure was workable in this form. My heart sank. According to his calculations the horizontal force pushing the walls outward could not be overcome by the buttressess I had penciled in. They also said that because of the site conditions (the house being next to a stream) they were worried about the soil condtions where the footings would go. They wanted to have soil borings done to make sure that the soil could withstand the snow and soil loads that would be placed on the footings.

If I remember correctly I think he said that horizontal force was on the order of 10,000 pounds per linear foot of wall. He wanted to put collar ties in or supports in the center of the building to mitigate the loading. But I didn’t like this at all.  We also tried larger buttresses but they were massive and complicated the building of the walls even further.

So the wheels started turning.I had to find another solution. I talked to my brother and he had a couple of good ideas. We are both civil engineers  but wound up getting into NYC  high rise concrete construction. Then an engineer who we know gave me the number of another engineer who he said is a concrete genius. I talked to the guys I had hired and they said  they would have no problem working with someone else to come up with a solution.

This guy was unbelieveable. He came up with a solution within a week and that is what we did. Thanks Nat T! What he came up with is a tapered slab. The slab would start at 9 inches and thicken to 16 inches over the walls.The walls would also thicken to 16 inches. Originally I had 10 inch concrete walls. The intersection of the walls and arched roof would be considered a rigid frame. The only other thing I had to add was horizontal rebar through a 6 inch concrete floor slab which would be tied to the walls. This is essentially the collar ties but you won’t see them. This design eliminated the buttresses  and will make building the footings and walls ten times easier. So the structure was really a collaborative effort and very satisfying.

By the time all this was said and done another almost 3 months had passed and it was nearly November!  So I took a pass on getting my building permit and decided to wait until spring to start. That’s where I am now.

I did have soil borings done. Here’s a picture of the rig they used to do them.

 

Soil boring rig getting test samples of the soil
Soil boring rig getting test samples of the soil

The borings actually came back OK. The only problem was on one side of the house I had rock and the other was soil. The engineers were worried about  a difference in settlement between the two. In other words, where the footings sat on rock there would be almost zero settling over time and on the side where the footings sat on soil there might be an inch or two of settlement. This could ultimately cause cracking in the roof which we obviously don’t want. The solution, a six foot wide footing on the soil side. It’s a little extra concrete but that will let us sleep better at night.

I’ve had a number of people ask about building a Hobbit house. It’s not to be taken lightly. There are some serious forces at work here that are considerable and could be dangerous if not considered by someone who is not trained in this kind of work. Those forces can change significantly depending upon the span and support system you or your engineer choose. The one thing that I like about my design is that it is a completely open floor plan. When the structure is finished you will basically be left with one gigantic room with no intermediate supports.This enables you to arrange the rooms however you want.

There were a number of other items that were problematic during the course of design but most of them would be hard to describe without sitting down with paper and pencil. So for now lets just call it a day. L ike I said there’s more to Hobbit houses than meets the eye.

Enjoy your weekend and week!

Jim