Wednesday, February 8, 2017

Empathy for my Future Self: New and Improved Lab Entrance

I got a case of Titebond Polyurethane Fast Set Construction Adhesive in the mail two weeks ago. I was one of the first 50 people to email them after they talked about the product on the Fine Homebuilding Podcast. The shelf life on this stuff is only a year, so I was a bit worried about how I was going to use it up in time. I mentioned it to my brother and he said to bring it to him so he could use it between concrete blocks for a retaining wall around his pool. It needs to be high strength so he can compact the soil behind the wall and install pavers. I hadn't thought of using it for concrete blocks. Good idea.

The other day I missed the last step on my shitty back steps and hurt my foot. I mean, it was messed up. I looked up orthopedic treatments on WebMD and everything. Amazingly the ice worked great and it was all better in just two day. But while I was hobbling around with a walking stick for a day I really regretted that I had no handrails to help me in and out of the lab. Also I blamed myself for considering steps a luxury I couldn't afford. Were a couple dozen $1.69 cinder blocks more precious than my continued mobility? That's illogical. I resolved to fix them. I started with a dozen concrete blocks at Home Depot and started playing around with how to stack them around the doorway. I came up with something like this. By messing with the orientation of the lightweight blocks I planned to block all the openings so critters can't fill them with acorns. Which they have happily been doing for the past two years.

One one side I have to put solid blocks to cover the end. I made another run to Home Depot and got more supplies. I needed another whole row on the hinge side of the door and a lot of caps.


When I got back with more blocks I played with my arrangement some more. I had to work in something to hold onto. You can see in the above photo that I already have a cast aluminum handle screwed to the side of the Spartan to stop the door lever from slamming into the side and making a hole. Secondarily if you lift the door lever and drop it behind the handle on the wall of the Spartan it holds the door open. I decided to order some more of those same style cast aluminum handles since they were working well. I ordered two of the longest ones they have at McMaster. They cost around $20 each, more than all the stair components combined. While I waited for the UPS man I kept working on the steps.

I decided not to use the four old cinder blocks. They don't match the new ones. If I'm going to this much trouble it better look nice. But I was ready to glue caps on one side of some of the blocks. I did that in the morning so the glue could cure while I went to town.
Unstacked blocks to be glued up. I cleaned off all the loose sand with a brush
Puncture the inner seal on the adhesive
Run a bead of adhesive around the block
Place the cap on and twist it back and forth a bit. I had a bit of squeeze-out to clean off
on the first one but I learned to keep the bead away from the outer edge
After I finished with the glue here's how I saved the tube. Bamboo skewer and aluminum foil

I poke the skewer through the foil

Stick the skewer in and wrap part of the foil around the spout

Break off the skewer and wrap over the whole thing

Make a collar over the tube

Put the tube back in the caulk gun so the foil doesn't get knocked off
I used this method on a tube of this stuff after I secured a plastic door threshold at a client's office two days before the step project. The adhesive had barely even skinned over under the foil. I had to squirt out about an inch worth and throw it away. I will update this post when I try to use the half tube put away after this job. Two days definitely fine.

This product does not have an offensive odor to me. It's has the same lack of smell of other polyurethane glues. It's nothing like Liquid Nails construction adhesive that stinks like a silk screen shop. It's still good to have a lot of ventilation though, and wear gloves. It will stain your skin as bad as Great Stuff.

Mark Schroeder, the Titebond VP of Marketing, mentioned on the FHB podcast that they worked on the consistency so it doesn't keep shooting out of the nozzle when you put it down. I had no problem with that at all. Very well behaved stuff. I confess I probably have muscle memory for releasing the pressure when I put down the gun though. I probably automatically hit that lever on the back whenever I finish running a bead so I didn't really give it a chance to make a giant mess.

Squeeze out on the inside is better than on the outside
I wanted to stick the blocks to the slab with something that would even out the surface so they wouldn't rock, but I may need to disassemble this whole thing one day. I'm not using the construction adhesive there. It's way too sticky and doesn't have enough body to fill in gaps. I started on the main section using up some rapid set cement I had leftover from a septic tank repair. I only had enough for the main rectangle.

For the rest I used some polymer modified thinset leftover from the tile floor. I keep it in a 3 gallon bucket so it doesn't go bad. I prefer working with it so much I'm not even showing photos of the other stuff.

Let the thinset slake while getting ready to use it

Chalk outline around the blocks where I want them

Move the blocks out of the way and put some thinset down. I used a large notched trowel

I added a little bit of polyurethane adhesive between the blocks
After the steps were all done I left them overnight. I came back the next day to work on the handles.

Here's how they come from McMaster inside a box inside another box

I tested the enclosed screws with a neodymium magnet to be sure they were good stainless steel
They gave me a lot extra. I still have 6 of these nice oval head screws
The cast aluminum handle has a wallowed out place to allow it to go
over this rivet. Rivet means strut on the inside which is good
The top of the handle is not over a strut but it goes into the wood I added
when I was installing the deadbolt. It gets longer stainless steel screws
than the bottom of the handle

I always put gutterseal under my aluminum to aluminum connections

If a little gutterseal oozes out that's ok

Clean up the excess gutterseal with acetone on a rag

Here's the finished entrance from the outside

I mounted the second handle on the inside of the door.
This one turns out to be the one I use the most

Action selfie
The weird shape of the top step lets me grab the handle from the ground and then step right foot on the first step, left foot on the second step. Then I'm standing out of the way to open the door.

"Tetris" is not a valid step shape for a house built to code. But this is not a house. I'm not going to get a ding on the inspection report when I try to sell it. If I sold the lab it would require knocking these steps loose to put the whole thing on a flatbed and send it away. 

I'm already used to alternating tread stairs because of the ship's ladder to my loft in my house. To me it feels natural. I asked my aunt with the bum knee to come over and try it out. She gave it the seal of approval. She appreciated both the handles.

If the climate situation keeps going this way I will never have a problem with freeze/thaw cycles. I don't think it's going to freeze again this season. There's a lot of thermal mass here too. When it does freeze here it's only for a few hours. I don't expect the underside of these blocks on the south side of the lab to ever get below freezing.

I've been using the steps for a few days now. I mostly come from the non-handle direction and go straight in without grabbing any handle. I like being able to open the door from the top step. Now that I'm ready for inevitable infirmity I will probably enter an extended period of peak health. I would say my enhanced grace and lack of clumsiness is assured, but that pyrex pie plate I smashed in the kitchen sink this morning says otherwise.



Wednesday, February 1, 2017

March for Science on Earth Day

They set a date for the March for Science today. It's going to be Saturday, April 23rd, which is Earth Day. It seems like a pretty benign good thing. Everybody should be for it. But here I am writing a blog post because some white men can't catch a clue in a butterfly net.

First of all let me document for posterity my most valuable suggestion. The hat of choice for the March on Science shall be the boonie hat. Available on Amazon in all sizes and colors. Why? Because that's what the archeologist and the astrophysicist wear on Stargate SG1. That's how you can tell the dweebs from the straight up soldiers.


And now back to the origin stories of the March for Science. After the original hurdles of a rough draft logo and a website with disagreeing apostrophes, the organizers did what I always recommend to my editing clients -- rewrite.

Now instead of Scientists' March on Washington they quickly modified it to March for Science and looks like they got a real logo designer. If any scientist besides me is bothered by the fact that this orbital ring notion of atoms is no longer valid, let's just keep it to ourselves. I like the colors.


Early on in their existence the diverse group of anonymous organizers of the march had a Google Hangout and decided to announce that diversity is important.


And that's when the white men started throwing their shit in the fan. I saw it on my twitter feed with the enlightened white men getting berated by the touchy white men who have not examined their privilege.


Then the march organizers used a word that REALLY set off the white guys.


I had to look up intersectional the other day when one of my Twitter friends said she finally understood intersectional feminism because she's Mexican and a woman. What intersectional means in this context is that a lot of people are not just screwed for one easily defined thing, a lot of us are DOUBLY screwed. For example, I didn't even know I was screwed because I was a woman when I was in my 20's because I was working all my white youth privilege. I had to also be OLD before I found out that I was hugely disadvantaged in the workplace for being a woman because ageism and sexism is intersectional. And by old I mean 32 years old, because that was the end of the road for me in high tech. Before then I think men hired me just for the novelty of having a young blonde in a short skirt in the lab. After, well, I admit it, they moved the factory to Mexico and closed the lab. But still. I couldn't get another job in a different industry because of various versions of "she'll just get pregnant and quit" and "she's actually not a very good secretary." Yeah, I know, I forgot to book your flight, I'm a terrible secretary. That's because I'm a scientist. It's a different skill set, you sexist idiot. Have some respect for secretaries.

That's why I'm grumpy enough to consider a march. I've been stewing over this rage for a really long time.

But the white men keep pissing on our parade and don't even have the courtesy to call it rain. Here's Robert S. Young in an article for the New York Times who thinks it's a bad idea. A Scientists’ March on Washington Is a Bad Idea.
In 2010, I was a co-author of a report for North Carolina’s Coastal Resources Commission that said sea levels along the state’s coastline could rise by as much as 39 inches by the end of the century. That conclusion was based on the best peer-reviewed science and was intended to help policy makers plan for the future.
But it alarmed real estate and other economic development interests, which quickly attacked the report. The coastal commission ignored it. The authors, myself included, were widely slandered. And the Legislature passed a law that barred state and local agencies from developing regulations or planning documents anticipating a rise in sea level. “I think this is a brilliant solution,” the comedian Stephen Colbert said at the time. “If your science gives you a result that you don’t like, pass a law saying the result is illegal. Problem solved.”
OK, I have SO been there, man. I did my master's thesis on beachfront property in Walton County building illegal sea walls. Back in 2007 I was on the beach when contractors were laying the first level of dry stacked blocks in front of a condo. Not only did they not have a permit for that work, there were three very good reasons those condos could NEVER get a permit. First that kind of wall is strictly prohibited. Dry stacked blocks on the beach? Are you fucking kidding me?! Second the buildings were built on deep piers and are ineligible for a sea wall, full stop. I called the enforcement agency on the spot and told them to send the sheriff immediately to stop this illegal activity. They didn't do it. They let them finish the fucking wall. I bet it was destroyed by the storm system last weekend and it's a giant mess right now. And I have to tell you that makes me want to scratch some expletives on a poster board and wave it over my head in the street! I have been furious about shit like this for a decade already! I want to raise some hell! It doesn't make me think, "Nah, I don't want to upset the poor rich people." But that's what the author of the NYT story thinks.
Rather than marching on Washington and in other locations around the country, I suggest that my fellow scientists march into local civic groups, churches, schools, county fairs and, privately, into the offices of elected officials. Make contact with that part of America that doesn’t know any scientists. Put a face on the debate. Help them understand what we do, and how we do it.
Dude, that idea is so seven years ago. I mean literally, that's what I suggested on this very blog seven years ago. We are WAY past Neil DeGrasse Tyson on Big Bang Theory now.

One fun raindrop in the fry oil of the early days of the March for Science was Steven Pinker with this painful Tweet thread. The good stuff in in the comments. You need to click the link if you want to see it unfold in all it's privileged horror.


For the full analysis I give the floor to Danielle Lee, with this glorious tweet thread.



I notice just now in a new tweet Steven Pinker acts like his disapproval made The March for Science people change their mind.


Nah, dude, they just moved the statement to the tab labeled Diversity on the blog header. I can see how it never occurred to you to click that since you have all your privilege fully deployed. Goddam it. Fuck. All. Y'all. Get out the way and let us angry people do this. And make your own goddam travel reservations. Why you so stupid? I am too short for this shit.

Diversity tab on MarchforScience.com
In the past days, scientists have voiced concern over many issues - gag orders for government science agencies, funding freezes, and reversing science based policies. We recognize that these changes will differently and disproportionately affect minority scientists, science advocates, and the global communities impacted by these changes in American policies. Addressing these issues is imperative in understanding how recent developments will affect all people - not simply the most privileged among us. We take seriously your concerns that for this march to be meaningful, we must centralize diversity of the march's organizers at all levels of planning. Diversity must also be reflected in the march itself - both through the mission statement and those who participate.
At the March for Science, we are committed to highlighting, standing in solidarity with, and acting as allies with black, Latinx, Asian and Pacific Islander, indigenous, Muslim, non-Christian, non-religious, women, people with disabilities, poor, gay, lesbian, bisexual, queer, trans, non-binary, agender, and intersex scientists and science advocates. We must work to make science available to everyone and encouraging individuals of all backgrounds to pursue science careers, especially in advanced degrees and positions. A diverse group of scientists produces increasingly diverse research, which broadens, strengthens, and enriches scientific inquiry, and therefore, our understanding of the world.

Footnote: In quoting Terry Pratchett above I was reminded of another quote. (Cuddy the dwarf in Men at Arms says "Why you so stupid? I am too short for this shit."Also, while I'm giving citations for quotes, that saying about pissing is a Sigourney Weaver line in Avatar.)

"Angry people are not always wise." I know this one from one of my aunt's books where she says I quoted it by heart from Pride and Prejudice, which I am sure I never did. But I went hunting the quote to find the context. Rem acu tetigisti. This is what we need right now. We need Mr. Darcy to stand up to people who would accuse us under represented people of intolerable self-sufficiency.
"How very ill Miss Eliza Bennet looks this morning, Mr. Darcy," she cried; "I never in my life saw anyone so much altered as she is since the winter. She is grown so brown and coarse! Louisa and I were agreeing that we should not have known her again."
However little Mr. Darcy might have liked such an address, he contented himself with coolly replying that he perceived no other alteration than her being rather tanned, no miraculous consequence of travelling in the summer.
"For my own part," she rejoined, "I must confess that I never could see any beauty in her. Her face is too thin; her complexion has no brilliancy; and her features are not at all handsome. Her nose wants character--there is nothing marked in its lines. Her teeth are tolerable, but not out of the common way; and as for her eyes, which have sometimes been called so fine, I could never see anything extraordinary in them. They have a sharp, shrewish look, which I do not like at all; and in her air altogether there is a self-sufficiency without fashion, which is intolerable."
Persuaded as Miss Bingley was that Darcy admired Elizabeth, this was not the best method of recommending herself; but angry people are not always wise; and in seeing him at last look somewhat nettled, she had all the success she expected. He was resolutely silent, however, and, from a determination of making him speak, she continued:
"I remember, when we first knew her in Hertfordshire, how amazed we all were to find that she was a reputed beauty; and I particularly recollect your saying one night, after they had been dining at Netherfield, 'SHE a beauty!--I should as soon call her mother a wit.' But afterwards she seemed to improve on you, and I believe you thought her rather pretty at one time."
"Yes," replied Darcy, who could contain himself no longer, "but THAT was only when I first saw her, for it is many months since I have considered her as one of the handsomest women of my acquaintance."
He then went away, and Miss Bingley was left to all the satisfaction of having forced him to say what gave no one any pain but herself.

Monday, January 23, 2017

How does a tree slice through a house?

I was feeling privileged this weekend because of my high homebuilding standards. The bad weather that killed 20 people in the southeast this weekend went right over my place. But my built-with-screws tiny house was just fine. Even the jokes about tornadoes being attracted to mobile homes should apply to me since I have a restored bona-fide mobile home a few hundred yards from my house. But it was built in 1951 by an aircraft manufacturer to the same standards as a plane. It laughs at wind. And it isn't going anywhere because of steel straps and 4 augers securing it to a slab.
Frame of my lab with straps installed
New subfloor going in
1/4-20 stainless steel bolts and nuts secure the riveted aluminum body to the frame and subfloor between members. In the foreground note the metal building type screw holding
 the subfloor to the frame
(Yes, I painted the bottom of the plywood before I installed it. Then I painted the top as soon as it was in. I don't like the smell of outgassing plywood and I was trying to seal it. For more on my Spartan project see earlier blog posts, like this one about the finished floor.)

So mobile homes as they were originally conceived back in the 1940s were not doomed to be ripped apart by wind. I'm not sure when it all went wrong for them. But boy, did it go wrong.

Today I got in the car and went looking for signs of damage nearby. A map on weather.com shows 4 tornadoes touched down to the northeast of me less than 20 miles away on Saturday.  I headed that direction. I found the river greatly flooded and a few large trees twisted off but I couldn't find any obliterated mobile homes.

River in flood

Good luck with that
This is the only really twisted tree I saw. Saw several regular broken off ones.
I did see a lot of undamaged mobile homes. They all had skirting around them, which is a county rule that I don't understand. What is it even for? I have researched it and am unable to find any reason for it except varmints. They think it's going to keep them out? I say it's more likely to make it an attractive place for a varmint to explore. Next thing you know you're listening to the incessant chittering of a stressed out raccoon under the house because it went in and then couldn't find a way back out.

What is the purpose of this white mess around the bottom of the mobile home?

It always looks trashy.
I came home and tried to find stories online detailing the damage to homes where people were hurt. I found weather.com had a slide show of images. The mobile homes seem to mostly fail by being physically moved because they are inadequately anchored. Most of the pictures I saw they seemed to be merely resting on dry stacked concrete blocks on a slab. That's basically what I've got for my lab, but I cut holes in my slab and installed 4 augers into the subsoil and then patched the concrete. I ran steel straps over the steel I-beams of the floor and tightened them down to the augur anchors. I got the anchors at Home Depot. I don't see why anybody with a mobile home wouldn't install them.

I also see from the underside of the mobile home below that it is not built like mine at all. The aluminum channel at the bottom of my riveted aluminum strut walls has 1/4-20 bolts through the plywood subfloor every 16". The subfloor is screwed to the steel frame. I don't have any wood floor joists. All welded steel. And I still wouldn't sleep in here. I go in the house if it just rains hard. It's too loud in the all-aluminum lab even with the spray foam insulation.

Photo from weather.com showing underside of a modern mobile home
I feel the science on keeping houses together in the wind was well addressed after Hurricane Andrew. I don't know how many houses that failed in these tornadoes were built according to standards developed after Andrew. I'm guessing none of them.

For a compilation of suggestions and more pictures of failed houses check out Fine Homebuilding's Wind-Resistant Framing Techniques: Cost effective details to help houses weather the storm wind by Bryan Readling. There's an illustration showing something I did wrong on my house. I heard this on the Fine Homebuilding podcast and slapped my head. Hurricane ties go on the outside. Crap.

At least three people this weekend were killed by trees falling on their houses, basically splitting them in two. I'm not sure any building codes have been altered to make houses safe from this particular hazard. But I'm curious about it. At least three of my close relatives have had trees fall on their houses due to hurricanes or tornadoes, and two of them have had it happen twice. The trees didn't slice their house in two though. And they were big trees. What is required for a tree to slice a house in two? Here's some pictures of what I mean from Tallahassee that I saw on Twitter. I don't think anybody was hurt in these incidents.


Are roof trusses made of 2x4s more likely to fail than a house with large dimension rafters? Does a structural ridge matter? Does the tree have to fall in a direction that allows it to go between the rafters or trusses so it only has to slice through sheathing? Did these houses have OSB sheathing or plywood? Which is better? How come the trees were able to plow through the top plate so easily? Makes me feel pretty good about building a rigid frame house. Here's some photos of my roof framing.


I'd forgotten I had to add those blocks on top of the rafters under the purlins to make the metal roofing come out right. They are maple flooring cut offs. Another detail I can see if I zoom in on this photo is the sill seal I stapled to the purlins before I screwed on the metal. It was meant to reduce vibrations conducted through the structure into the house from rain on the roof. It helps.

Here are some photos I took right after the spray foam was installed. Reflects so much light it's easier to see what is going on.

Photo from the front door.
I have 2x6s atop 4x4 corner posts instead of a pair of 2x4s held up by studs like those sliced up houses above. I used Simpson Strong Tie framing brackets to mount the beams on top of the 4x4s.  The rafters are 2x8s screwed in place with the largest Deckmate screws. The 2x6s holding up the rafters are PT and I didn't want to take chances with inferior nail coatings that might corrode. The double 2x6s over the windows are not pressure treated. The outside one is lag bolted to the 4x4 and then another 2x6 is wedged between the posts and nailed to the bolted one. All the beams are spiked together with Simpson Strong Tie hot dipped galvanized nails driven with a palm nailer at the interval specified in my architectural graphic standards book.

Note my hurricane ties are on the wrong side of the beam. I was ignorant and I feel much shame. But I even used hurricane ties on that interior wall. What can I say, I like the palm nailer. I'm not going to sweat it this one mistake. I've got greater than average tie down per roof area.
View of roof framing from bathroom side. Easier to make out that it's a pair of PT 2x6s under the rafters. 
My ridge is a 12' 2x10. It is held up by complicated headers built to accommodate windows I got from Tallahassee Surplus and Salvage. All those big plate glass windows are sliding glass doors I got from my grandparents after a tree fell on their sunroom.

My tiny house plan allowed me to use 8' 2x8s for rafters, a much easier piece of lumber for me to work with alone. I put some 16' 2x6s across the roof on the pressure treated beams to stand on, but no amount of struggling with angles and arranging my center of mass could get the rafters to come out on my penciled line when I shot the nails in with the framing nailer. If the top moved off the line then the birdsmouth on the other end was all out of whack. So I gave up after the first one and started using a 9v battery powered impact driver and Deckmate screws. I could only do about 2 rafters before I had to recharge the battery. But I got the whole roof framed in a weekend. Then I covered it with a tarp and Hurricane Dennis hit Florida as a Category 3 Hurricane July 10, 2004. First chance for a tree to hit my house. Came through it wet but tree-free.

Now back to the present. This house near Albany that was torn all to hell this weekend clearly reveals it was made with trusses and OSB. I don't know if the brick veneer helped or hurt. I don't understand why there is OSB, house wrap, and then bricks, but the bricks don't seem to have been attached to the wall at all. That can't be right. It looks like the whole thing started when a gable end blew out. This seems to be a common failure as described in that Bryan Readling article about. Leaving out the sheetrock on the inside makes the ends blow out if it's sheathed with foam and then the whole thing pressurizes and blows apart.



One of my aunts had a large pine tree fall on her house right across the middle of the longest section of roof of her house, in line with the rafters. It came to a rest on the ridge. One limb punched through the metal roofing. And then later in a tornado an enormous limb from a giant live oak tree fell on another part of the roof. She has a hip roof framed with 2x8 rafters, if memory serves. It has industrial corrugated steel screwed to 2x4 purlins just like my house. No sheathing at all. She and my uncle built that house themselves with boat building precision. Neither tree-on-the-house incidents caused any structural damage. They just got out the chainsaw and removed the trees, unscrewed the sheets of metal with the holes punched in, and screwed on new sheets of metal.

This fall, September 2016, my mother had a huge poplar tree fall on her house in Tallahassee during Hurricane Hermine. She has a plywood roof deck under thinner gauge metal roofing than what my aunt and I have. The tree did not go through the top plate. It did fall over a French door though, so there would have been a big header there.
The photo my mother texted me in the middle of the night when this tree fell

Here's a photo of the poplar tree on the house in the daylight

The tree service came the very next day and cut the tree off the house
Here's the damage to the roofing where the tree fell
A close up of the little overhang where the tree fell shows the plywood sheathing on the roof
This is the second time my mother's house has been damaged by trees in a hurricane. Right after she had it built Hurricane Kate dropped a tree on the main roof. It was right over her bedroom too. But it didn't slice through the house and kill her. It did cost more to repair it than it cost to build the roof in the first place. That was when she had regular composite shingles. She got that metal roof when she built the addition where the poplar tree fell.

I'm curious now about what it takes for a tree to slice a house in two. I found an article about a study Clemson was going to do in 1999 simulating dropping a tree on mockups of walls.
"But if the tree were to fall between the roof structural members and impact the plywood roof sheathing, the roof wouldn't make much of a difference anyway," warned Ed Sutt, a Ph.D student who is helping with the research. "And keep in mind, we're only seeing the effects of a six-inch pine at this point. Larger trees could have far more devastating consequences."
The Clemson research will concentrate on identifying inexpensive techniques that could be used by a construction-savvy homeowner. Research findings will be used to develop technical guidance for contractors and practical application material for homeowners.
Low-tech fixes under study include installation of wood-reinforced wall panels, addition of a layer of metal decking under the wall panel, different combinations of plywood or common insulation foams.
I don't actually agree his assumption. That poplar tree in that photo above is way bigger than 6" and it didn't go through the sheathing. My aunt's house doesn't even have sheathing but the ridge of her hip roof was strong enough to stop a pine tree bigger than 6". The oak tree limb that fell on one of the hip ends was absolutely huge, easily 18" diameter. It didn't break the structure.

A shortleaf pine at least 20" in diameter fell on the gable roof of my grandparent's sunroom and it just spread the walls apart. Didn't even break the plate glass windows. I don't remember it slicing through the roof sheathing at all.

Is the difference in the prediction of that PhD student and my own experience that all the roof/tree incidents I know about involved traditional framed roofs and not trusses?

I feel like the distance of the tree from the house is going to have a lot to do with the damage inflicted too. That poplar tree was so close to my mother's house it hadn't really gotten up much momentum when it rested on the roof. It the house intersected the path when it was most of the way down it would have been much worse, like this giant oak tree that hit that poor air conditioner when it was going full speed.
Another tree that fell during Hurricane Hermine at my mother's house
I may have found the paper with the results of the study teased in the above article in the Journal of Architectural Engineering, but it's $30 to get a PDF. If it doesn't actually answer my questions I'd be annoyed. From the abstract:
The study also considered, on a limited basis, the threat of falling objects such as trees or large branches. Results suggest that a wall designed to resist debris impact will also exhibit satisfactory performance against tree-fall.
Green Building Advisor's article Pros and Cons of Advanced Framing by Martin Holladay is a checklist of ways you can make your house that much easier to slice in two with a tree. But they thought about that and Michael Chandler added a comment with these tree-strike-relevant points.
1- push the headers up to the (double) top plates and cripple down to the window head so the trees hit the header at the ceiling level hopefully stopping at the top plate and keeping most of the water out of the house.
3- solid block w/ 2X stock on the exterior of the upper top plate between the rafters stacked on the sheathing to help distribute the impact of trees to the sheathing and encouraging the rafter tails to break at the plate to help keep water out of the house after a tree strike.
4- block the ridge solid between the trusses, If vented just hold the blocking down on either side as shown in the attached drawing for the ridge vent, if spray foam, block solid and tie both planes of roof sheathing together at the peak.
Click the link above and scroll down to the comments for a drawing.

I would love to make a mockup of my roof and drop trees on it until I get some interesting results. It seems to be an underserved area of study. My online research just now reveals a lot of dubious advice like "cut down all the trees that could fall on your house." I also found a lot of studies advocating the energy savings you get from shade trees. You can't have both. I prefer trees.

Meanwhile whenever there is a tornado warning I will continue to climb down from my loft and get in my cast iron bathtub with my pillows and blankets. I don't have an interior room away from windows, but I feel like the sides of a cast iron tub offer pretty good secondary protection if one of my pine trees decides to fall on my house. It better have precision aim though, because my house presents a pretty small target.

*update*

I asked my father if he wanted to use his backhoe to help me drop trees on a model of a house. He said I should go back to knitting. He thinks the variables involved in trees falling on houses is too vast to be relevant. He thinks the roots of the tree slow the tree down a lot if it is near enough to the house, as in the case of the poplar tree above and the shortleaf pine on my grandparent's house. He doesn't think dropping a cut-off tree on a model would prove anything. I thought it might just be fun to watch it smash. He said if it's so much fun I should get Hollywood to pay me to do it. Anybody want to remake Twister in the Southeast? I'm available for consultation.

My father also told me that the wood is stronger at the bottom of a tree where it has to counteract the bending stress from normal wind loading. Small sawmill owners find this to be the case from vast personal experience with a chainsaw. This explains why I see trees either snapped off about 20 feet up or pushed down from the roots or twisted at the base and not even broken when I survey the woods after a wind event. I rarely see them snap off down by the ground. Only if they are seriously compromised by fire damage. I also rarely see dead trees that have fallen in the woods due to a storm. The insurance company policy of not covering damage from dead trees sounds like a scam to me. I perceive no inherent greater risk to property from a dead tree than a live one. I would like to see their actuarial data that says dead trees do more damage. It's prejudice against snags, which is bad environmental policy. Birds like snags.

So unless I come into a motorized winch for free I guess I won't be making a video of dropping logs on model houses. Sorry.

*** Update Feb 14, 2017 ****

I came across this video describing the Fine Homebuilding 2012 Editors Choice house that is specifically designed to withstand a big tree falling on it. This is pretty much exactly what my father said. If you want to build a house that can't be crushed by a tree you hire a structural engineer and build that house. But most people don't want to pay for that. Well, here's what happens when somebody does pay for it. Big honkin' I beams. Wonder what they do about condensation?