05/25/2021
The truth about building a post frame home.
When thinking about building a house many people these days will look into building a post frame house. There are many advantages to this type of building and you see tons of photos of open floorplans, texas sized barndominiums and many are absolutely beautiful. When looking at these types of buildings it is easy to get misled into believing that it's a less expensive way to build. You'll hear how the buildings require less lumber to contruct. You'll hear about how easy it is to pour a foundation into a building after it has been constructed. You may even go to some websites and price out some kits for a DIY pole barn. You will think to yourself, wow I can get a lot of space for not a lot of money.
This is somewhat true, but mostly false when it comes to building an actual home and not a shop or recreation room or barn for equipment or animals.
Sure, you can buy a cheap kit, drop some posts in the ground and be on your way. You can probably build a modestly appointed place for $60-80K and think you did really good for yourself.
Now let me hit you with some reality. Wood in contact with soil is going to rot. I don't care how well treated the posts are, I don't care where you read or heard otherwise. It's a fact and if you are lucky you will get 20 years out of those posts before they need to be replaced. There are plenty of farmers, ranchers, and forums online to confirm that this happens all the time. To further complicate matters, a bank will not loan money on a house that does not have a permanent foundation. F***y Mae, Freddy Mac, HUD, VA, FHA etc will not touch them. So sure, you can pay all cash and hope the building is still solid in 20 years, don't plan on selling it very easily. Another bank problem you will run into is that the building needs to be at least 60% living space in order to qualify for financing. So your dreams of a 3000 sq foot shop with living quarters are out the window as far as a primary residence goes.
So what is the solution and the cost?
First of all you need to come up with a permanent foundation. There are products out there that will meet this requirement. You can build a stem wall and mount brackets to hold the columns, you can drill holes and fill them with concrete and wet set brackets into them to hold the columns, you can use helical piers to mount the columns on, or you can use what are called Perma-Columns. Perma-Columns are reinforced concrete piers that attach directly to the columns and can be set like traditional post frame construction. You can plan on spending an additional $150-300 per column for those perma-columns. This is the route that we are going with.
We also had to make some alterations to our plans to meet the 60% rule, originally our building was going to be 50/50 but had to change to meet the finance requirements. Now we are paying cash for everything so we do not need a loan now, and we may never leave once we move in. The house and property will need to be sold at some point though. Whether by choice or us passing it will sell at some point. Do you really want to have problems for yourself or loved ones later?
Let's talk about roofing now. A traditional post frame will have trusses 8 feet on center with the metal attached directly to the trusses. This is done with sheet metal screws that provide opportunity for water to pe*****te at some point. It's also a prime location for condensation and mold issues later. To properly do a roof you really should do trusses 2 foot on center, then sheeted with OSB or Plywood, then underlayment, then roofing material. We decided to do this and go with Standing Seam Metal which has zero exposed fasteners. This greatly
reduces the chance of water pe*******on.
What about insulation? You can do fiberglass batts in walls, blow in fiberglass in the ceiling and meet code but you must make sure you have a ventilated attic space or again you will have condensation and mold problems later. You will also have a house that leaks air at a tremendous rate, so all your heating and cooling will simple be going out the proverbial window. What you really need to do is use closed cell spray foam to seal the building tight and also provide additional structural support, you seal everything including the attic space. This keeps any ductwork within the conditioned envelope and really makes for a far more efficient situation. Think of it as living inside an igloo cooler. When you do seal things up tight though you do have to replace some indoor air with outdoor air periodically. This is done with a ERV (energy recovery ventilation) these are basically fans that exchange outdoor air with indoor air with a built in heat exchanger and humidity exchanger.
Now that you have added everything to really make this pole barn into a residential building, you will find that you have not saved any money vs traditional stick frame construction. That does not mean that you should scrap the idea though. Done correctly a post frame structure has many advantages. If you want big open spaces and high ceilings it really is the best way to go about it.
