Kit Home Structural Engineering and Design

Kit Home Structural Engineering and Design

Show Notes:

More in depth design details and their benefits. What is structural engineering and design?  Why do I need it.  WUI, Wildland Urban Interface and how it affects my home and permitting.  Different structural design concepts and Mechanical Design.  Plumbing, Electrical and HVAC design.


Interviewer: Hello and welcome to the Panelized Prefab Kit Home Building Show. With me is the President and Founder of Landmark Home and Land Company, a company which has been helping people build their new homes where they want, exactly as they want across the nation and worldwide since 1993, Mr. Steve Tuma. Steve, how are things going over there at Landmark?

Steve Landmark: Yeah, it’s a busy day. We’re having some fun and a lot of people are building interesting homes, nice families building unique homes, fun homes in different parts of the country.

Interviewer: Yeah. Your job of just helping people design their – that has got to be a lot of fun just helping people get into a brand new house.

Steve Landmark: Well, it is. It’s interesting and even after – since 1993, every single project is interesting because it’s not just a house that someone is going to live in. It’s their home and it affects the way they live. It affects the relaxation, their good days or bad days, the hobbies they have and their attitude about like their savings, their retirement. It’s a big move but you know, we try to simplify it so people can get a house that they enjoy at a price that makes sense for them and works on the land and our plans make it easy for them to get permits. So it’s a lot of fun because you’re transforming people’s lives by getting it done properly.

Interviewer: That’s pretty cool. I thought today we would talk just about general design and some of the things – I’ve read through some of the questions that potential customers have sent to you guys and I thought some of them might be interesting to cover. Not so much specific questions but just general overall inquiries that people make. Let’s talk about structural design and design details. Can we get into that a little bit? Yes. A lot of people think you just get some wood together or have someone give you some rough idea about oh, this beam works here and this post works there and this stud works there.

But there’s actually a little bit more of a science behind it to make sure that the home is structurally sound. There are more and more areas that are requesting engineer-stamped plans just for snow load situations, high winds, hurricanes, flood situations, earthquakes and whatever it may be. What has happened previously, if people have put houses together, maybe they failed or haven’t been as good as possible, so they request structural engineering and a lot of people kind of think, “Well, that’s just a guy stamping something.” I could just go buy a set of plans and have someone stamp it.

Well, that’s not really structural engineering. Structural engineering is actually doing calculations and justifying why the components of the home are strong enough, making sure that the truss is designed as properly, making sure the foundation is designed as properly.

So some areas of the country, they don’t require it in simpler homes. But if you get into something more complex where the site conditions or the natural conditions like wind speeds or snow loads or earthquakes are bigger, the building departments will want it, generally all along the West Coast, most of Colorado. You know, anywhere along the East Coast now with the hurricanes will require and then we’ve read in spots in other parts of the country where the building departments require it. Sometimes because they just want to know that it’s done right and kind of pass the buck to the structural engineer involved.

So that’s what we like to do is make sure that the structure is right. So what I want to do is get rid of the myth that structural engineering is someone that just stamps plans. No, they’re actually doing calculations. They’re generally conservative. So beams will be a little bit bigger. The connections from the floor or the foundation to the floor, to the wall, to the roof will be reinforced and everything will be justified.

Now there are also other situations where people are getting into different designs. Homes with 10, 15, 20-foot tall ceilings, chalets with big glass walls. They need a lot of reinforcement. So it’s good to know that it’s built properly to make sure that it’s structurally sound. A lot of people think you’ve got to support the snow or the roof going down to the ground. Well, there are other things like winds. You can have a wall that’s 20 feet tall. Well, that wind, if it pushes against there, can bull the wall. People say, “Well, what’s the big deal?” Well, then you end up with cracked windows or cracked drywall. It’s better to avoid that.

Interviewer: Right.

Steve Landmark: So the proper design of that is what we help people with and I think they will find it to be very important in the longevity, in maintaining the value of the home and not just that but making it easier to build and making sure that the building departments give you permits.

Interviewer: There’s something I wanted to – I had just heard about it recently, something I wanted to ask you about. It’s something called the “wild land-urban interface”. I want to know what it is. Why is it important and how does it affect the overall home design?”

Steve Landmark: Well, every year the fires in Colorado or the West Coast are getting bigger and bigger and bigger and bigger for whatever reasons that they’re started. What that basically is, is a situation where you’re creating a home that has fire-resistant materials, fire-resistant roof shingles. The eaves are covered. Cement board sidings, stones, different situations like that. Different design elements that are resistant to it. A lot of people don’t realize it but an ember from a fire can fly two miles.

Interviewer: Wow.

Steve Landmark: When I first heard that, I was like, “This is crazy. What are you talking about? Doesn’t it blow out?” I mean a birthday candle blows out.

Interviewer: Right.

Steve Landmark: It’s like how does this happen. So what they’re doing is they’re developing regulations to make homes that are resistant to the fires and we had one up in Paradise. It survived. Everything around it burned.

Interviewer: The house that you guys built up in Paradise?

Steve Landmark: Yeah. We helped a customer. They built it and I thought with the mass disaster up there, the campfire, that it was gone and they said, “Steve, it survived,” and I saw the layout from the campfire and it was the only house within blocks. I’m not quite sure. I mean we did a good job designing it but there probably could be a little bit of luck there. But we do work to make sure that’s taken care of.

So in this family’s case, it saved their house. Just a little bit of design, making sure you have the right roof shingles, the right window situation, the right types of siding. You know, the right types of defensible space and things like that.

So it’s a very important thing. When I first heard of wild land and urban interface, I thought, “OK, we’re keeping bears out.” But it was – it’s a situation to make it safe and the interaction of communities as it goes into wild lands. You know, wooded areas, open areas, whatever it may be. So we’re able to help people with that, to make sure that the home complies with the regulations and then make sure that the house is built properly.

Interviewer: For those of our listeners who aren’t aware of Paradise, California, in northern California this past summer was completely wiped out. I mean virtually wiped out by a major fire.

Steve Landmark: I think it’s the biggest one ever.

Interviewer: Yeah. Every storefront, every Laundromat, every garage, everything just …

Steve Landmark: Except for our house.

Interviewer: Well, it’s not something to laugh at but of course we’re happy that the house that Landmark built or that the Landmark customer put together is still standing and they’re one of the very few. So that says a lot about Landmark I would think.

Steve Landmark: Pretty cool.

Interviewer: Let’s talk about something that will be near and dear to the carpenters’ heart out there in the audience. Let’s talk about the differences between two by six and two by four walls. What are the benefits and the pros and cons of each?

Steve Landmark: Well, generally most people today will build with a two by six. There are some parts of the country where there aren’t a lot of structural engineering concerns or the insulation doesn’t have to be as high. So generally two by four, you’re going to save some money just because the materials are actually less, so that they cost less. So a lot of people go through that and then the areas where there’s a climate that doesn’t have the extremes – you can justify it or if energy costs are low.

Pretty much every house that we build is two by six. It’s stronger. It allows more space for insulation. It helps the resale value because people ask for it and it’s just a stronger situation for supporting the home. So generally two by six construction is the way to go. Sometimes people come through and say, “Hey, I heard about value engineering. I could go two by six instead of sixteen inches on center. We could space the studs at 24 inches on set.”

Interviewer: Oh, yeah. Wow

Steve Landmark: Yeah. They’re working with the idea that hey, that’s using less wood. It does use less wood. But depending upon the code application for your area, you may or may not be able to do that. Then there are other situations that happen in the insulation, the finishing of the home or it could be a little different. But basically two by six walls are the way people do it. Sometimes they will go two by four in the garage to save all the money because that’s generally not a heated area.

Interviewer: Right.

Steve Landmark: In all situations. But we like to go through and make sure that we’ve got a well-built home, a solid home. We kind of consider the framing system that we supply. The skeleton, you know, and Steve like you know, if you have a bad back, life is a little harder. We like to know that your house is a solid home so that it retains its value. It looks good. It’s comfortable to live in.

Interviewer: So it’s not moving about like an old man.

Steve Landmark: Exactly. Hopefully it’s not moving at all. That’s the idea.

Interviewer: Let’s go from the walls now to the floors. Floors are pretty darn important in the house. Let’s talk about floor joists. What are they and what are my options as a home builder?

Steve Landmark: Generally the options are dimensional wood like two-by-tens and two-by-twelves, which are very common. Sometimes people will go with an engineering I-joist or an open web floor truss. So the dimensional wood, the two by ten, two by twelve, they can be spaced in certain increments and they have limitations on the span. The I-joist can – they’re engineered. They can span a little farther as the open web floor trusses. Sometimes it’s not a structural issue but a convenience issue in the construction of the home.

An open web floor truss, you can actually run duct work through it and plumbing and electric. So it’s easier for plumbers, electricians, heat people to install their items into the home. Some of those, more and more people are getting in the clear span areas. They want basements 26 feet wide without posts in them for entertainment rooms, workshops, hobby rooms, whatever it would be.

So in those cases, you go beyond the capability of dimensional wood, the two-by-tens and two-by-twelves. So you go to I-joists or open web floor trusses.

Sometimes people prefer the open web floor trusses because it will allow you to have a taller finished basement ceiling. So if you have an eight-foot basement cement wall and you have to put duct work underneath the floor system above it, you might lose a foot of your ceiling in certain areas with a soffit.

So it makes it a little bit less usable. Now it’s still usable but there are soffits running around or dropped areas. It’s not a big deal but some people say, “Hey, I want a big walkout basement. I want to have usable space. I want to make it feel like a regular part of the house.” So in those cases, the open web floor truss is a work. Where people just want a larger span at a lesser cost, the I-joist will work.

So that’s one of those conversations that we have like I mentioned previously. How is the family using their home? What’s their intent? What’s their budget? What are they going to do with it in the future? A lot of people will have a basement with the idea of a future bedroom or a future workshop or home office. So we have to design the home to have proper egress windows but also the proper structure so that they can do what they want.

We’ve got a lot of customers that have hobbies whether it’s restoring old cars, sewing, gaming, wood shops, whatever it may be. So these different floor systems allow us to design the usability of the home. A lot of people are – they will do like garages with living space above it. You know, for toys, jet skis, boats.

Interviewer: Oh, right, yeah. I see.

Steve Landmark: Motor homes, bigger trucks, whatever it may be and with these different floor systems, we’re able to get rid of some of the posts and beams. Sometimes all of them so that it works. Steve, I’m sure you’ve done it.

If you’re pulling a boat into the garage, that post is always in the wrong spot no matter where you put it.

Interviewer: Right.

Steve Landmark: So this allows us to have bigger clear span areas for people to enjoy the space.

Interviewer: I’m going to throw an overall at you because you’ve been getting – your company for one reason or another, you guys are asked the question of layouts in your design. There’s like plumbing layouts, electrical, heating layouts, ventilation and air conditioning layouts.

What are these exactly and how does Landmark tackle that?

Steve Landmark: Well, basically what it is, is like electrical layout. We will show where the electric sockets are, where the lights are, ceiling fans, different circuits, different circuits for kitchens where you need dedicated circuits or layouts for front door lighting, yard lighting, whatever it is.

So an electrician could look at it and know what work he needs to do but also so a building department understands what’s being done. So that will happen for electrical layouts. Some building departments will ask for plumbing layouts or your contractor might just to know, “Hey, where’s the water coming in? Where is it servicing in the house and then the house and leaving and the sewage system and where is it going to?”

So they want to know for layout where to place a toilet in the floor system and the slab, cement slab or whatever it may be. Then the same thing with heating, ventilation and air conditioning. HVAC, HVACs some people may call it and in some places, they will just want to know, “Hey, where is the furnace? Where is the air conditioning unit outside?” and it’s simple.

But what’s happening is more and more people are realizing that hey, stuff isn’t always being done right. So sometimes people will go through and say, “Hey, what’s the price to heat and air my house? And someone will say a certain price and someone else will be higher and someone else will be lower.

Well, the idea is to make sure that it’s done right. So since there have been issues before, some building departments are asking for pipe sizing and plumbing, load calculations for electrical to make sure that there’s enough power going into the house. But also calculations for the heating, ventilation and air conditioning systems to know that furnaces are sized right so that someone isn’t getting a low ball quote just to find out that it can’t heat your home properly.

So that’s where we’re able to help is if someone just needs a simple layout, we can supply it. If they request or the building department requests or their contractor requests the different calculations, pipe sizing for plumbing – and plumbing also includes gas piping. It’s not just water.

We can do those. We can do the electrical load calculations. But we could also do the HVAC system as well and it’s pretty rare. But more and more building departments are asking for it, what they call the manual J, S and D. There are three different calculations that have to be put together. The manual J is to calculate the heating and cooling loads. Like what needs to be done to this house? How much air or how much heat will it need? The manual S is sizing the equipment to know that hey, you need a furnace of 1000 BTUs or whatever or a two-ton, 14-SEER air conditioning unit.

Then a manual D shows the duct layouts to make sure that the air is heated or cooled properly and then removed from the house and circulated properly. So the key element to that is you don’t want to pay for a furnace and find out it’s not big enough or it’s too big. Too big of a furnace will eat up energy as well.

Interviewer: Right.

Steve Landmark: Or to make sure that the duct work isn’t done right, to make sure that air can’t be properly distributed and circulated around your home. So again it’s a little bit of plan work upfront to make sure that things work properly. As you know, people are using more and more power. You know, bigger TVs, more TVs, more computers, kitchen appliances. Now some of them are becoming more and more efficient. But the thing is, it just seems that houses have more and more utility needs. So that’s what that is. You want to make sure that those things are designed properly and we can help whether it’s a simple design or an engineered calculation to justify the plumbing, electric or the HVAC systems. It’s very important to know it’s done right.

Interviewer: So let me see if I got this straight. So I can’t just build my house and then start thinking about where the electrical wires and the heating and air conditioning will go.

Steve Landmark: We don’t suggest that. We don’t suggest that. There’s a funny little analogy. That’s kind of like going to the grocery store and saying, “Hey, let’s get food,” and so a guy goes and gets hamburgers and chips and beer to watch TV and then the wife is thinking of cooking a salad and chicken. I mean you should have an idea of what you’re doing.

Interviewer: Yeah.

Steve Landmark: So it’s a situation where you want to go through and understand what you’re doing. That’s what the planning phases are for to know what it is. The time you spend upfront planning it properly will help with permits. It will help with your schedule. It will help keep you on budget. It will help with your sanity as well. You’re not doing changes. You’re just following a well-planned home and people will learn that that’s the best way to do it. It makes it easier for them.

Interviewer: One of the things that I’m hoping we achieve on these podcasts is to let people know just how knowledgeable you are and everyone over at Landmark Home and Land Company. You have so much knowledge and you know what you’re talking about and that has got to be a comfort to somebody who’s sort of going into a situation, like a deer in the headlights building a new home.

Steve Landmark: Well, that’s exactly right. Like the heating and air conditioning situation that I have, someone might say, “Hey, I can save you $1000.” Well, are you really saving $1000 if that furnace is going to eat more fuel or if your family is not warm? No, you’re not saving money. You’re – it’s going to cost you more money in the long run. So doing it right the first time is the way we like to do it.

Interviewer: Great. So we’re going to bounce out of here and just want to thank everybody for joining us again on the Panelized Prefab Kit Home Building Show. Before we go, of course Steve, as always please let us know how to contact you guys at Landmark Home and Land Company.

Steve Landmark: Well, we have our website at It’s just four letters for Landmark Home Land Company. It’s actually Landmark Home and Land Company, but it’s You can call us at 800-830-9788. You can email Mike. He can work with people initially at and I could be contacted at We’re very responsive and customer service-oriented. We enjoy what we do. We want to help people build their house properly.

We’re also on like Facebook, Instagram, Pinterest, Twitter and YouTube.

Interviewer: Nice. Well, all right. There you go. So for Steve Tuma and myself, thanks again for joining us on the Panelized Prefab Kit Home Building Show and we will see you next time.

Steve Landmark: Have a great day.

About Landmark Design Team