Advanced Framing for Tiny Houses
Advanced framing, though decades old, is still not nearly as well known as it should be. The goals of advanced framing match closely to the desired outcomes of most tiny house builders, so I'd advocate for its wider use throughout the tiny house building community (DIY included, of course!). For those of you you have not heard of it before, or want to learn more, this post if for you.
Green Building Advisor defines advanced framing this way:
Advanced framing, also called optimum value engineering (OVE), is a framing system that aims to pare the amount of lumber used to frame buildings to the bare minimum.
Above: Traditional Framing
Below: Advanced Framing (much less lumber!)
The Advantages
The idea is by making a few adjustments to the way walls are traditionally framed, we can use a lot less material, improve insulation, and reduce waste. In addition to (and because of) the reduced lumber use, advanced framing has many potential benefits:
- Less lumber needed, so lower materials costs and lighter weight (great for THOWs!)
- Potentially lower labor cost/time and shorter build time due to simpler framing with fewer pieces
- Reduced environmental impact because less lumber is needed (fewer trees need to be cut down)
- Reduced construction waste (lumber can be used more efficiently because wall dimensions use exact 2' increments)
- A reduction in thermal bridging and more room for insulation (because the walls and roof have fewer studs and rafters)
- Lower energy costs (due to better insulation, as noted above)
The Difference
How is this possible and why does normal framing not do this already? Let's look at advanced framing in more detail.
The main differences between traditional framing and advanced framing are as follows:
- Studs are placed 24” OC instead of 16” OC
- 2x6 studs used instead of 2x4 (more on this later related to tiny house building)
- Header hangers (Simpson HH header hangers) are used instead of jack studs
- Headers are insulated, and only used on load bearing walls
- Single studs are used at rough opening
- No extra cripple stud at each end of window openings
- Corners are created with just two studs
- Single instead of double top plate
- Stacked framing transfers vertical load directly (between floors)
The diagram below illustrates these points and a few others. Notice the reduced lumber, especially around window openings.
Source: Green Building Advisor
One thing that's important is lining up studs, joists, and rafters, so all the weight can be transferred directly downward. This eliminates the need for a double top plate.
You'll notice that 2x6" lumber is recommended. The extra width of the lumber helps account for the reduced number of studs and insures plenty of structural strength. But what if you don't want to use 2x6 lumber for the walls of your tiny house? You want to save those extra 4 inches (two in each wall) to maximize interior space, right?
The Tiny Project house using advanced framing
I am not a structural engineer, but I believe the general consensus within the tiny house community is that 2x4" studs are more than adequate for tiny house construction with advanced framing, primarily because these are single story structures, and without a second or third story to support, there is much less load on each wall. Since the walls need to support the weight of the roof and nothing more, 2x4's offer more than enough strength (and then some!).
I used advanced framing (with 2x4's) on my house, and I'm very happy with that choice!
The reduced lumber allowed for more insulation with less thermal bridging, and reduced the overall weight and cost of the house. What's not to like!
Want to know more?
Check out the following PDF resources for more info on advanced framing:
BeyondEfficiency.org and Green Building Advisor PDF
Building takes skill and patience...
But it also helps to have the right tools!
It’s hard to know how important some of these tools are until you realize the hard way (by wasting a lot of time!) how much energy and frustration a good tool can save you. So, without further ado, here are my top 10 must have tiny house tools.
I do like the simplicity of the advanced design better than the old way, but I do wonder why more people aren't building their Tinies using SIPs? (Structural Insulated Panels).
Many people do use SIPs and that's a great way to go!
Hi Alek,
I love your Tiny home plans but I'm wondering if this would be easy to translate into Metric for Australia ? Your Tiny is gorgeous I love so much about it but feel like if I had to convert everything over to Metric it would leave way more opportunity for error. Also the $ 99.00 deal you are offering at the moment does it come with all the sketch up etc for your house plans ( As per your $ 250 on your website. Thanks Kim
SIPs here in Oregon cost about $3,000 more than having a stick built completely dried in.
Also, the manufacturing time is a turn off. If I order my trailer it takes 3 weeks to arrive and the trailer is even a fraction off the SIPs will be off if you pre ordered. The flexibility is greater with stick built. I was quoted 8-10 weeks on SIPs. Here in Portland that is about the extent of the dry season.
I'd never touch them because they're full of toxic foam and glues. Yuck.
I am not a structural engineer either. I would not construct a tiny house on a trailer without plywood sheathing, corner bracing or without tying the framing from roof to trailer with steel anchors. Snow (vertical) loads are not the only forces acting on a mobile house or a house parked where there are higher winds. Rich
I agree. Definitely need plywood sheathing for a THOW! And yes, subfloor and walls need to be properly anchored to the trailer. You are completely correct on all of that. Wind sheer (while towing) might be the strongest load your house will endure.
Plywood really stiffens and ties the house together, and has other benefits. I built one house with and one without. The wobble factor difference was enormous.
How are the Simpson Header Strong ties working out?
I am about 1 week out from starting and about to make a large order on Materials and would love to cut down on the wood in the structure.
They're great! I think header hangers are very smart.
Instead of the current single horizontal top plate how about a dovetailed(one inch) ledger board that can have 2inches of spray foam on the interior.. or maybe a 2×6 to replace all headers.. this will provide better shear and less labor..building full headers over tiny homes seem ridiculous
Does the house you built have a loft in it? I am interested in smart framing for my tiny home with 2x4s, but you mention that one of the reasons 2x4a work with tiny house smart framing is they bear the weight of the roof only and are single story. Just looking for clarification, trying to be extra sure! Thanks for all of the great info!
Yes, it has a loft. By single story, I just mean no full second story. A loft doesn't count. Advanced framing can definitely be used with 2x4s with a loft as well.
Not that it matters 5 years later but this says "no cripple studs used under window openings" the picture clearly shows cripples under each window. With such simple terminology clearly misunderstood, it makes you wonder what else has been misinterpreted
Thanks for catching that. The wording is just slightly off. Should be something like "no extra cripple stud at each end of window openings" -- I'll make that edit.